Reddy-Clinical Exposure_BLAD_Final (2)

The scalp has a rich blood supply from branches of the external carotid artery and is innervated by the trigeminal nerve and cervical nerves. This vascularization and innervation are crucial for surgical procedures to minimize bleeding and ensure proper sensation post-surgery.

The atlas (C1) is the first cervical vertebra that supports the skull and allows for nodding motion, while the axis (C2) has a peg-like odontoid process that allows for rotation of the head. Atypical cervical vertebrae may have variations in structure or function compared to typical vertebrae.

Frey's syndrome, also known as gustatory sweating, occurs when the auriculotemporal nerve, a branch of the facial nerve, regenerates abnormally after injury, causing sweating in the parotid gland area during eating. This condition highlights the importance of the facial nerve in facial sensation and autonomic functions.

Facial nerve palsy can lead to asymmetry of the face, loss of facial expression, and difficulties in eating and speaking. It may indicate underlying conditions such as Bell's palsy or tumors, necessitating prompt diagnosis and management to prevent complications.

Waldeyer's lymphatic ring consists of the palatine tonsils, pharyngeal tonsil (adenoids), and lingual tonsil. It plays a crucial role in immune response, particularly in children, and its enlargement or infection can lead to obstructive sleep apnea or recurrent throat infections.

The maxillary sinus is located within the maxilla and is the largest paranasal sinus. Its anatomy is significant for dental procedures, as infections can spread from the sinus to the teeth, and vice versa. Understanding its drainage pathways is essential for treating sinusitis and performing sinus lifts in dental implants.

The intrinsic muscles of the larynx control sound production and include the cricothyroid, thyroarytenoid, and vocalis muscles. The extrinsic muscles support the larynx and include the sternothyroid and thyrohyoid muscles. Their function is vital for phonation and protecting the airway during swallowing.

The recurrent laryngeal nerve innervates most intrinsic laryngeal muscles, playing a key role in voice production and airway protection. Injury to this nerve can lead to hoarseness, loss of voice, or breathing difficulties, highlighting its importance during thyroid and neck surgeries.

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Myringotomy

Swellings in the second layer of the scalp (dense connective tissue) are small but painful because this layer is highly vascularized and innervated, leading to increased sensitivity and pain response.

The components of the lacrimal apparatus include:

• Lacrimal glands
• Lacrimal ducts
• Lacrimal sac
• Nasolacrimal duct

The secretomotor pathway of the lacrimal gland involves:

1. The facial nerve (CN VII)
2. The greater petrosal nerve
3. The pterygopalatine ganglion
4. Postganglionic fibers to the lacrimal gland

Dacryocystitis is an inflammation of the lacrimal sac, often due to obstruction of the nasolacrimal duct, leading to pain, swelling, and discharge.

Epiphora is the condition characterized by excessive tearing or overflow of tears onto the face, often due to obstruction of the tear drainage system.

The superior parathyroid gland develops from the fourth pharyngeal pouch, while the inferior parathyroid gland develops from the third pharyngeal pouch.

Classification of the temporomandibular joint:

1. Simple, complex, synovial type, condylar variety, biaxial, 2 degrees movement.

Peculiarities of the joint:

• Formed by the articulation of two different condyles of the mandible with the cranium, acting as bilateral components of a single craniomandibular articulation.
• Movements occur simultaneously at both joints (concomitant action).
• Joint cavity divided into upper (menisco-temporal) and lower (menisco-mandibular) compartments, allowing gliding and rotatory movements.
• An atypical synovial joint with articular surfaces covered by fibrocartilage instead of hyaline cartilage.

Factors that maintain the stability of the joint:

1. Occlusion position of the mouth.
2. Lateral (temporomandibular) ligament of the joint.
3. Muscles: Tension of the temporalis prevents excessive forward (protrusion) movement, while tension of lateral pterygoid prevents excessive backward (retraction) movement.
4. Bone: Articular tubercles restrict forward displacement, and post-glenoid tubercle prevents posterior displacement.

Anatomical basis of the dislocation:

• The joint is stable when the mouth is closed (occlusion position). When the mouth is open, the condyles move forward, leaving the mandibular fossa and lying underneath the articular eminence, creating an unstable position.
• Excessive opening of the mouth (e.g., yawning) can lead to anterior dislocation due to spasm of the lateral pterygoid muscle, preventing mouth closure.
• Minimal trauma or a sideways blow to the chin can predispose to dislocation, while posterior dislocation is uncommon due to anatomical structures that provide stability.

Reduction of the dislocated temporomandibular joint can be achieved by:

1. Placing both thumbs on the last molar teeth.
2. Applying downward pressure to depress the joint.
3. Simultaneously elevating the chin to push the condyle backward into the articular fossa.

Contents of the infratemporal fossa:

The primary muscles of mastication are the lateral pterygoid, medial pterygoid, masseter, and temporalis.

The suprahyoid muscles (digastric, geniohyoid, mylohyoid) help to depress the mandible when the mouth is open widely against resistance.

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Components of an intervertebral disc:

• Annulus fibrosus: Outer fibrous ring made of fibrocartilage, providing strength.
• Nucleus pulposus: Inner gel-like center, a remnant of notochord containing loose fibers in a mucoprotein gel.

Functions:

• Imparts resiliency (flexibility) to the vertebral column.
• Offers resistance to compression and acts as a shock absorber.

Intervertebral disc prolapse is the herniation of the nucleus pulposus through the annulus fibrosus, commonly occurring postero-laterally in regions where a mobile area meets a relatively immobile area, such as the cervicothoracic and lumbosacral junctions.

The symptoms are due to decreased disc space and the formation of bony spurs (osteophytes) that can compress nearby nerve roots, leading to pain and altered sensations in the arm. Additionally, cervical spondylosis can affect blood flow or nerve function, contributing to vertigo.

The costal elements of the cervical vertebrae include:

1. Transverse processes: Lateral projections that serve as attachment points for muscles and ligaments.
2. Costal facets: Articular surfaces for rib attachment, present on the transverse processes of some cervical vertebrae.

The carotid tubercle is a bony prominence on the transverse process of the sixth cervical vertebra (C6). Its clinical importance lies in its use as a landmark for locating the common carotid artery during medical procedures and for assessing cervical spine injuries.

The structures passing through the foramen transversarium of cervical vertebrae include:

• Vertebral artery: Supplies blood to the brain.
• Vertebral vein: Drains blood from the cervical spine region.
• Sympathetic nerve fibers: Contribute to autonomic functions in the head and neck.

Structures typically seen on a radiograph of the cervical spine include:

• Cervical vertebrae: C1 to C7.
• Intervertebral discs: Spaces between vertebrae.
• Spinous processes: Posterior projections of vertebrae.
• Transverse processes: Lateral projections of vertebrae.
• Facet joints: Articulations between adjacent vertebrae.

Cervical spondylosis is a degenerative condition of the cervical spine characterized by the wear and tear of the intervertebral discs and vertebrae, leading to symptoms such as neck pain, stiffness, and neurological deficits due to nerve compression.

Cervical spondylosis is primarily a degenerative condition due to aging and wear, while spondylitis refers to an inflammatory condition affecting the vertebrae, often associated with autoimmune diseases. Spondylitis typically involves inflammation and can lead to fusion of vertebrae, whereas spondylosis involves degeneration without inflammation.

Cervical vertebrae are more prone to dislocation without fracture due to their anatomical structure and mobility. The cervical region has a greater range of motion compared to other vertebral regions, making it more susceptible to dislocation from trauma or sudden movements.

Compression of the thoracic vertebrae is uncommon due to:

1. Rib cage protection: The ribs provide structural support and protection to the thoracic spine.
2. Limited mobility: The thoracic spine has less range of motion compared to the cervical and lumbar regions, reducing the risk of injury.
3. Stability: The thoracic vertebrae are more stable due to their articulation with the ribs and sternum.

Compression of the C7 spinal segment leads to pain and numbness in the posterior aspect of the arm, forearm, and middle and index fingers.

Tension of the dura mater produces headache, pain in the back, and neck stiffness.

Diminished biceps and triceps jerk is caused by compression of the C6 and C7 spinal segments, which innervate the corresponding muscles.

The carotid tubercle is important for compressing the carotid artery to relieve symptoms of supraventricular tachycardia and serves as a landmark for anaesthesia of the brachial and cervical plexus.

The second part of the vertebral artery and the vertebral vein pass through the foramen transversarium of the cervical vertebrae.

Radiopaque shadows include cervical vertebrae (one to seven), hyoid bone, mandible, and parts of the occipital and temporal bone.

Cervical spondylosis is a degenerative condition affecting cervical vertebrae, leading to nerve root compression, particularly affecting the C6 vertebra, which is crucial for neck movement.

In judicial hanging, the ligature around the neck causes a powerful jerk, leading to rupture of the transverse ligament of the atlas and/or fracture of the odontoid process of the axis vertebra. This results in posterior displacement of the fractured odontoid process, crushing the medulla oblongata, which contains vital centers for respiration, cardiac function, and vasomotor control, causing immediate painless death.

A hangman's fracture is a fracture of both pedicles of the second cervical vertebra (axis) caused by hyperextension of the neck, commonly occurring in falls from a height.

Fontanelles are unossified membranous gaps at the corners of the parietal bone, allowing for flexibility during birth. There are six fontanelles: anterior, posterior, two anterolateral (sphenoidal), and two posterolateral (mastoid). The anterior fontanelle is the largest, measuring about 4 cm by 2.5 cm.

Fontanelles facilitate the birth process by allowing the skull to compress and change shape during delivery, which helps in the passage through the birth canal.

Fontanelles are clinically important as they provide information about the growth and development of the skull, and can indicate conditions such as increased intracranial pressure if they are tense or bulging.

The metopic suture is the suture that runs down the middle of the forehead, separating the two halves of the frontal bone. It typically fuses during early childhood, but if it remains open, it can lead to a condition known as metopic craniosynostosis.

The skull of a newborn differs from an adult skull in several ways:

1. Size: The newborn skull is proportionally larger compared to the body.
2. Fontanelles: Newborns have fontanelles that allow for growth and flexibility during birth.
3. Sutures: The sutures in a newborn's skull are not fully fused, allowing for expansion as the brain grows.
4. Shape: The shape of a newborn's skull is more rounded and may appear elongated due to the birth process.

Wormian bones are small, irregular bones that can occur within the sutures of the skull. They are considered normal anatomical variations but can also be associated with certain syndromes or conditions, such as osteogenesis imperfecta or craniosynostosis.

A tense anterior fontanelle indicates raised intracranial pressure. It can be caused by conditions such as hydrocephalus, encephalitis, and meningitis.

The anterior fontanelle helps to determine the position of the fetal head in vertex presentation during a per vaginal examination.

The closure of the fontanelle is useful to determine the age of the child. Failure of closure after the age of 2-3 years may suggest a calcium metabolism disorder or deficiencies such as vitamin D.

The parietal tuber is significant for several reasons:

1. It marks the beginning of ossification of the parietal bones.
2. The biparietal diameter (BPD) is measured between the parietal tubers, which is important for assessing fetal growth and determining cephalopelvic disproportion (CPD).
3. Wernicke's sensory speech area lies deep to the parietal tuber in the left cerebral hemisphere.
4. It serves as a reference point for surface anatomy in the region.

The middle cranial fossa is commonly fractured due to its structural weakness, which is attributed to:

• The presence of numerous foramina and canals.
• Hollow cavities such as the middle ear and sphenoidal air sinus, which make it more susceptible to injury during trauma.

The passage of blood and clear watery fluid is explained by:

1. The endosteal layer of the cranial dura mater, which is torn in skull base fractures.
2. Fractures through the cribriform plate can cause epistaxis or CSF rhinorrhea.
3. Involvement of the tegmen tympani and tympanic membrane allows blood or CSF to appear in the ear.

The cranial nerves likely to be injured in a middle cranial fossa fracture are the VII (facial) and VIII (vestibulocochlear) cranial nerves.

Damage to the spine of the sphenoid can lead to:

1. Decreased saliva production due to injury to the auriculotemporal nerve (affecting the parotid gland) and chorda tympani nerve (affecting submandibular and sublingual glands).
2. Loss of taste sensation from the anterior two-thirds of the tongue due to the involvement of the chorda tympani nerve.

The specific structures seen on a lateral view of the skull X-ray are not detailed in the provided text, but they generally include:

• Frontal bone
• Parietal bone
• Occipital bone
• Temporal bone
• Sphenoid bone
• Zygomatic bone
• Nasal bone
• Mandible

The structures passing through the major foramina of the cranial fossae include:

• Foramen magnum: spinal cord, vertebral arteries
• Jugular foramen: internal jugular vein, cranial nerves IX, X, XI
• Foramen ovale: mandibular nerve (V3)
• Foramen rotundum: maxillary nerve (V2)
• Optic canal: optic nerve, ophthalmic artery

1. Frontal air sinus
2. Orbital plate of frontal bone
3. Pituitary fossa
4. Sphenoidal air sinus
5. Maxillary air sinus
6. External auditory meatus
7. Ramus of mandible
8. Head of mandible
9. Mastoid air cells
10. Coronal suture
11. Lambdoid suture
12. Nasopharynx
13. Oropharynx

• I (olfactory) CN

• II (optic) CN
• Ophthalmic artery
• Sympathetic plexus around the ophthalmic artery

• Mandibular nerve
• Accessory meningeal artery
• Lesser petrosal nerve
• Emissary vein connecting the pterygoid plexus to the cavernous sinus
• Anterior division of middle meningeal vein

1. Crista galli
2. Frontal air sinus
3. Ethmoidal air cells
4. Inferior nasal conchae
5. Maxillary air sinus
6. Cribriform plate of ethmoid bone
7. Petrous ridge of temporal bone
8. Nasal septum
9. Base of skull
10. Mastoid air cells

The pterion is the H-shaped junction of four bones: frontal, greater wing of the sphenoid, parietal, and temporal. It is clinically significant because it overlies the middle meningeal artery, making it a critical area where skull fractures can lead to extradural hematomas due to arterial injury.

The main types of intracranial hemorrhage include:

1. Epidural hematoma - accumulation of blood between the skull and the dura mater.
2. Subdural hematoma - blood collection between the dura mater and the arachnoid layer.
3. Intracerebral hemorrhage - bleeding within the brain tissue itself.
4. Subarachnoid hemorrhage - bleeding in the space between the brain and the tissues covering it.

An extradural hematoma is a type of intracranial hemorrhage that occurs between the dura mater and the skull, typically due to a tear in the middle meningeal artery following a skull fracture. Its anatomical basis lies in the pterion region, where the skull is thin and vulnerable to fractures that can disrupt the artery, leading to rapid accumulation of blood and increased intracranial pressure.

An extradural hematoma is considered a surgical emergency because it can lead to rapid cerebral compression and increased intracranial pressure, which can result in brain herniation and death if not treated promptly. Immediate surgical intervention, such as decompressive craniotomy, is often required to evacuate the hematoma and relieve pressure on the brain.

Signs of cerebral compression are less common in children due to the elasticity of their skulls and the presence of fontanelles (soft spots) that allow for some expansion. Additionally, children's brains are more adaptable, and they may tolerate increased intracranial pressure better than adults, leading to fewer immediate symptoms following skull fractures.

The incidence of skull fractures in children is less common compared to adults due to several factors:

1. Thinner skull bones - Children's skulls are more flexible and can absorb impact better.
2. Less severe trauma - Children often experience less severe trauma compared to adults.
3. Protective reflexes - Children may have better protective reflexes that help prevent head injuries.

The role of CT scan in imaging for head injuries includes:

1. Rapid assessment - Provides quick visualization of brain structures and potential hemorrhages.
2. Detection of fractures - Identifies skull fractures and their relationship to underlying brain injuries.
3. Guiding treatment - Helps in planning surgical interventions by revealing the extent and location of hematomas or other injuries.

The pterion is a weak point in the skull, being the thinnest area on the lateral wall. It is the most common site for fractures in the temporal region, which can lead to injury of the anterior division of the middle meningeal artery, resulting in extradural haematoma. It serves as an important neurosurgical landmark for assessing structures in the cranial fossae, such as pituitary tumors and the circle of Willis.

Extradural hematoma (EDH) is a collection of blood in the extradural space, located between the inner skull surface and the outer dura mater. It is typically associated with head trauma and fractures of the temporal or parietal bone. The condition arises from the rupture of the middle meningeal vessels, particularly the anterior division of the middle meningeal artery, which lies deep to the pterion.

The palpable midline structures on the front of the neck include:

1. Symphysis menti
2. Fibrous raphe
3. Body of the hyoid bone (at C3)
4. Thyrohyoid membrane
5. Thyroid notch (at C4)
6. Angle of the thyroid cartilage (Adam's apple)
7. Median cricothyroid ligament
8. Cricoid cartilage (at C6)
9. First tracheal ring
10. Isthmus of the thyroid gland (second to fourth tracheal ring)
11. Inferior thyroid veins
12. Suprasternal notch (between T2 and T3)

The C6 vertebra is significant because:

1. The carotid tubercle at this level allows for compression of the common carotid artery.
2. It serves as a landmark for brachial and cervical plexus anesthesia.
3. The larynx ends and the trachea begins at this level.
4. The pharynx ends and the esophagus begins at this level.

The hyoid bone is clinically significant because:

1. It serves as an attachment point for muscles involved in swallowing and speech.
2. A fracture of the hyoid bone can indicate strangulation or trauma.
3. Its position aids in the assessment of neck injuries and potential airway obstructions.

The layers of the scalp from superficial to deep are:

1. Skin
2. Dense connective tissue
3. Occipitofrontalis muscle and its aponeurosis (galea aponeurotica)
4. Loose areolar tissue
5. Pericranium

The first three layers are inseparable and are called surgical layers of the scalp.

The various appendages of the skin include:

• Hair follicles
• Sweat glands
• Sebaceous glands
• Nails
• Arrector pili muscle

The sebaceous gland secretes sebum, which helps in lubrication and prevents the skin from drying.

A sebaceous cyst is a retention cyst produced by blockage of the opening or duct of the sebaceous gland, leading to distention of the gland by its secretions.

Sebaceous glands are classified as holocrine glands, characterized by the disintegration of the entire gland to release its secretion, which is the most damaging type of secretion.

Common sites for the formation of sebaceous cysts include:

• Scalp
• Scrotum
• Vulva
• Face

These areas are rich in sebaceous glands.

Sebaceous cysts are absent in the palm and sole region, as this area is devoid of sebaceous glands.

A black eye, or periorbital hematoma, occurs due to bleeding in the loose connective tissue around the eye, often resulting from trauma that causes blood vessels to rupture.

Wounds of the scalp bleed profusely due to the rich vascular supply of the scalp, particularly the presence of numerous arteries and veins that are closely associated with the scalp layers.

Deep wounds of the scalp tend to gape due to the tension in the scalp layers and the fact that the first three layers (skin, dense connective tissue, and muscle) are closely connected, causing retraction when cut.

Incisions during craniotomy are made in the center of the skull to minimize damage to the vascular supply and to allow for better access to the brain while ensuring that the flap can be reflected downwards without tension.

The loose areolar tissue layer is known as the dangerous area of the scalp because it allows for the potential spread of infections and blood accumulation due to its loose structure. This layer can facilitate the movement of fluids and infections across the scalp, leading to complications such as swelling and hematoma formation.

The fourth layer of the scalp is composed of loose areolar tissue, which allows for the accumulation of fluid without significant resistance. This anatomical feature, combined with the rich vascular supply, can lead to generalized swelling that is painless due to the lack of nerve endings in this layer.

Safety valve haematoma in children refers to the phenomenon where blood collects in the loose areolar tissue of the scalp, particularly in the fourth layer, due to the elasticity and compliance of the tissue. This allows for the accommodation of blood without significant pressure buildup, acting as a 'safety valve' to prevent more serious complications.

Caput succedaneum is a type of swelling that occurs on a newborn's head due to pressure during delivery, characterized by soft tissue swelling that crosses suture lines. Cephalohaematoma, on the other hand, is a collection of blood between the skull and the periosteum, which does not cross suture lines and is typically more localized.

Extensive scalp surgeries are performed under general anaesthesia to ensure complete patient comfort and immobility, as the scalp is a highly vascular area with rich sensory innervation. General anaesthesia allows for better control of pain and movement during the procedure, reducing the risk of complications.

Profuse bleeding from scalp injuries is primarily due to the rich vascular supply from both the internal and external carotid arteries, which anastomose in the scalp. Additionally, the adherence of blood vessels to the fibrous network in the scalp prevents retraction when vessels are torn, leading to significant blood loss.

The anatomy of the scalp contributes to the formation of a black eye due to the lack of bony attachment of the frontalis muscle, allowing blood from injuries to spread anteriorly into the eyelids. The firm attachment of the galea aponeurotica and occipitalis muscle restricts blood flow posteriorly, leading to accumulation in the eyelids and resulting in periorbital edema.

The gaping of a scalp wound occurs because the epicranial aponeurosis is divided. This tough fibrous layer, formed by the insertion of the occipitofrontalis muscle, creates tension that causes the wound to gape if divided transversely. For proper healing, the opening in the aponeurosis should be closed with sutures.

During craniotomy, the scalp is supplied by five arteries on each side that enter the second layer of the scalp from the periphery. Incisions are made in the center of the scalp, allowing the flap to be turned downwards while maintaining its peripheral attachment and arterial supply.

The sub-aponeurotic loose areolar connective tissue layer is termed a dangerous area because it can collect pus and blood. It contains emissary veins that connect scalp veins to intracranial dural venous sinuses, allowing infections to spread from the scalp to the meninges, potentially leading to meningitis.

The fourth layer of the scalp is made of loose areolar tissue, which allows for extensive fluid accumulation, resulting in generalized swelling. The absence of nerve endings in this layer makes the swelling painless.

The most probable diagnosis is left-sided facial palsy, specifically upper motor neuron (UMN) palsy, due to lesions above the facial nerve nucleus involving corticonuclear fibers.

The presenting features of facial palsy include:

• Facial asymmetry due to unopposed action of muscles on the opposite side (involvement of all branches of the facial nerve on the opposite side).
• Dribbling of saliva due to paralysis of the orbicularis oris (involvement of the lower buccal branch).
• Loss of nasolabial furrow due to paralysis of the levator labii superioris alaeque nasi (involvement of the upper buccal branch).

The presence of wrinkles on the forehead when the patient raises their eyebrows indicates upper motor neuron (UMN) facial palsy because this area has bilateral representation in the cerebral cortex. In UMN paralysis, the lower half of the face on the opposite side is affected, while the forehead muscles remain functional due to bilateral innervation.

In UMN lesions, there is paralysis of the lower face on the opposite side, while in LMN lesions (such as Bell's palsy), there is paralysis of the entire face on the same side as the lesion.

In LMN lesions, the ipsilateral orbicularis oculi muscle is affected, whereas in UMN lesions, the upper muscles of the face, including the orbicularis oculi, are spared.

Facial muscles primarily regulate the orifices of the mouth, eye, and nose as sphincters and dilators, and they play an important role in non-verbal communication.

The muscles involved in frowning are:

1. Corrugator supercilii - creates vertical wrinkles.
2. Procerus - creates transverse wrinkles.

The Frontalis muscle is responsible for expressing surprise or fright by elevating the eyebrows and creating transverse wrinkles on the forehead.

The muscles that contribute to the expression of sadness include:

1. Levator anguli oris - accentuates the nasolabial fold.
2. Levator labii superioris.
3. Zygomaticus minor.

The muscles involved in expressing anger are:

1. Dilator naris - dilates the anterior nasal aperture.
2. Depressor septi - depresses the mobile part of the septum.

The Zygomaticus major muscle is associated with the expression of doubt by drawing the angle of the mouth upward and laterally.

The Mentalis muscle contributes to the expression of worry by puckering the chin and protruding the lip.

The Orbicularis oculi muscle plays a role in expressing worry by creating skin folds that radiate laterally from the lateral angle of the eye.

The three divisions are:

1. Ophthalmic division (V1)
2. Maxillary division (V2)
3. Mandibular division (V3)

Trigeminal neuralgia is characterized by episodes of severe, sudden, shock-like facial pain along the trigeminal nerve divisions on one side of the face. Triggers include:

• Touch to the face
• Eating
• Talking
• Shaving
• Brushing teeth
• Wind and chewing can aggravate the condition.

The upper one-third of the face is supplied by the ophthalmic division of the trigeminal nerve (V1), which derives from the frontonasal process.

The sternocleidomastoid muscle is likely to be injured in congenital torticollis.

The boundaries of the posterior triangle are:

1. Anterior boundary: Sternocleidomastoid muscle
2. Posterior boundary: Trapezius muscle
3. Inferior boundary: Clavicle

The contents of the posterior triangle include:

• External jugular vein
• Accessory nerve (CN XI)
• Brachial plexus
• Cervical plexus
• Lymph nodes

The boundaries of the sub-occipital triangle are:

1. Superior boundary: Rectus capitis posterior major
2. Lateral boundary: Obliquus capitis superior
3. Inferior boundary: Obliquus capitis inferior

Contents include:

• Vertebral artery
• Suboccipital nerve (C1)

The vertebral artery is significant as it supplies blood to the posterior part of the brain. Injury or blockage can lead to serious conditions such as vertebrobasilar insufficiency, which can cause dizziness, vertigo, and even stroke-like symptoms.

The sternocleidomastoid and trapezius muscles are affected.

Both muscles are innervated by the spinal accessory nerve (XI CN); sensory and proprioceptive sensations from the sternocleidomastoid are carried by the ventral rami of C2-C3.

Congenital torticollis is caused by the shortening of the sternocleidomastoid muscle, leading to twisting and slanting of the neck, often due to intravascular clotting during labor.

The types of torticollis include:

1. Rheumatic - due to exposure to cold.
2. Reflex - due to irritation of the spinal accessory nerve from inflamed cervical lymph nodes.
3. Spasmodic - due to maladjustment of the pillow during sleep or exposure to cold, characterized by painful contractions of both muscles.

Unilateral contraction of the sternocleidomastoid muscle tilts the chin to the opposite side, useful during an upward sideways glance.

The trapezius muscle is involved in:

• Shrugging the shoulders (upper fibers with levator scapulae).
• Retracting the scapula (middle fibers with rhomboids).
• Overhead abduction of the shoulder joint (upper and middle fibers with serratus anterior).

To test the right sternocleidomastoid muscle, ask the patient to turn their chin to the left side against resistance. If the right spinal accessory nerve is intact, the muscle will contract and become prominent; failure indicates paralysis.

To test the trapezius muscle, ask the patient to shrug both shoulders against resistance. The muscles should become prominent if intact.

The sternocleidomastoid muscle divides the neck into anterior and posterior triangles.

The anterior triangle is bounded medially by the anterior median plane, laterally by the anterior border of the sternocleidomastoid muscle, and superiorly by the base of the mandible and an imaginary line from the mastoid process to the angle of the mandible.

The anterior triangle is subdivided into sub-mental, digastric, carotid, and muscular triangles by the superior belly of the omohyoid and digastric muscle.

The sub-mental triangle contains sub-mental lymph nodes, which lie in the superficial fascia.

The posterior triangle is bounded anteriorly by the posterior border of the sternocleidomastoid, posteriorly by the anterior border of the trapezius muscle, and at the base by the middle one-third of the clavicle.

Cervical lymphadenopathy in the posterior triangle is commonly due to enlarged deep cervical lymph nodes, often caused by metastatic cancer or infections such as tuberculosis.

Virchow's lymph node is the left supraclavicular lymph node, which is commonly involved in cancerous conditions arising from the stomach, gonads, and other abdominal organs.

The floor of the posterior triangle is formed by the semispinalis capitis, splenius capitis, levator scapulae, and scalenus medius muscles.

Injury to the spinal accessory nerve is common in the posterior triangle, especially if the deep cervical lymph nodes along the nerve are enlarged.

The posterior triangle is an ideal site for the supraclavicular brachial plexus block, which involves injecting local anaesthetic agents near the brachial plexus to facilitate surgical procedures in the upper limb.

The boundaries of the Sub-occipital triangle are:

• Superomedially: Rectus capitis posterior major, supplemented by Rectus capitis posterior minor.
• Superolaterally: Obliquus capitis superior.
• Inferiorly: Obliquus capitis inferior.

The Sub-occipital triangle is significant as a site for a cisternal puncture, a diagnostic procedure to collect cerebrospinal fluid (CSF) through the cisterna magna for analysis.

The course of the vertebral artery is divided into four parts:

1. First part: Cervical (origin to C6 vertebra).
2. Second part: Vertebral (foramen transversarium of C6 to C1).

External jugular vein.

Superficial veins lie between the platysma and the investing layer of deep cervical fascia; an incised wound bleeds profusely until the deep fascia is cut. Bleeding continues due to failure of the collapse of the vessel wall, which is prevented by retraction of the cut muscle and its firm adherence to the underlying fascia. Once the deep fascia is divided, the veins retract, and the bleeding stops.

Venous air embolism, which occurs when air enters the vein due to its adherence to surrounding fascia, preventing collapse and leading to air entry during inspiration.

1. External jugular vein
2. Internal jugular vein

1. Investing layer
2. Pretracheal layer
3. Prevertebral layer
4. Carotid sheath

The deep cervical fascia provides support and compartmentalization for structures in the neck, helping to limit the spread of infections and providing pathways for nerves and vessels.

The subclavian vein lies outside the axillary sheath to allow for greater mobility and to accommodate changes in position and movement of the upper limb.

The spaces of the neck are clinically important as they can serve as potential pathways for the spread of infections and can also be sites for abscess formation.

Careful suturing of the skin and edges of the platysma is important to ensure proper healing, minimize scarring, and maintain the integrity of the neck structures.

The main veins include the superficial temporal vein, maxillary vein, facial vein, common facial vein, external jugular vein, internal jugular vein, subclavian vein, and brachiocephalic vein.

The internal jugular vein is preferred because of its constant position and alignment with the superior vena cava and right atrium, making it more suitable for central venous access compared to the tortuous external jugular vein.

The six layers are: 1. Investing layer of deep cervical fascia 2. Pretracheal fascia 3. Prevertebral fascia 4. Carotid sheath 5. Buccopharyngeal fascia 6. Pharyngobasilar fascia

Superficial neck wounds can lead to profuse bleeding due to the involvement of superficial veins like the external jugular vein. The adherence of the cut muscle to the fascia prevents vessel wall collapse, risking venous air embolism. Pressure or division of the deep fascia can help control bleeding.

Thyroid swellings move up and down during swallowing due to the ligament of Berry, which supports the thyroid gland and connects it to the laryngeal cartilages.

The pretracheal layer blends with the arch of the aorta and fibrous pericardium, allowing infections in the neck to spread into the superior and posterior mediastinum due to the continuity of the pretracheal and prevertebral layers.

Infections of the retropharyngeal space may extend into the posterior mediastinum via the superior mediastinum, leading to mediastinitis. Additionally, a retropharyngeal abscess can cause unilateral swelling in the pharyngeal wall, which must be differentiated from a cold abscess of cervical vertebrae (Pott's abscess).

The retropharyngeal space is bounded:

• Anteriorly by the buccopharyngeal fascia.
• Posteriorly by the prevertebral fascia.
• Laterally by the carotid sheath and its contents.
• Superiorly by the base of the skull.
• Inferiorly it is open and continuous with the superior mediastinum.

The parapharyngeal space contains branches of the maxillary artery and fibrofatty tissue.

The carotid sheath is a tubular structure that encloses the common carotid artery, internal jugular vein, and vagus nerve, providing protection and structural support to these vital structures in the neck.

Carotid sinus hypersensitivity syndrome can lead to recurrent syncope due to episodes of cardio-inhibition and vaso-depression, which can result in sudden drops in heart rate and blood pressure, causing loss of consciousness.

The branches of the external carotid artery include:

1. Superior thyroid artery
2. Lingual artery
3. Facial artery
4. Occipital artery
5. Posterior auricular artery
6. Maxillary artery
7. Superficial temporal artery

The boundaries of the carotid triangle are:

1. Anterosuperiorly: posterior belly of digastric and stylohyoid
2. Anteroinferiorly: superior belly of the omohyoid
3. Posteriorly: anterior border of the sternocleidomastoid muscle

Roof: Skin, superficial fascia containing platysma, cervical branch of the facial nerve, and investing layer of deep cervical fascia.

Floor: Hyoglossus, thyrohyoid, middle constrictor, inferior constrictor.

Carotid sinus syndrome is characterized by:

• Bradycardia (decreased pulse rate)
• Hypotension (fall in blood pressure)
• Cerebral ischaemia, leading to dizziness or fainting (syncope).

This syndrome occurs due to pressure on the carotid sinuses, often triggered by head rotation or tight collars.

The contents of the carotid triangle include:

The external carotid artery has eight branches categorized as follows:

The carotid triangle is clinically significant for:

1. Palpation of the carotid artery: Ideal site to feel a carotid pulse, important during CPR.
2. Internal jugular vein: Used for assessing venous pressure and central venous catheterization.
3. Embalming: Common carotid artery is used for injecting embalming fluid.
4. Carotid sinus syndrome: Relevant for understanding clinical conditions related to carotid pressure.

The carotid sheath is a condensation of deep cervical fascia that extends from the base of the skull to the arch of the aorta.

The boundaries of the carotid triangle are:

1. Posterior belly of digastric
2. Sternocleidomastoid
3. Superior belly of omohyoid

The floor of the carotid triangle consists of:

1. Hyoglossus
2. Thyrohyoid
3. Middle constrictor of pharynx
4. Inferior constrictor of pharynx

The contents of the carotid sheath include:

• Common carotid artery
• Internal carotid artery
• Internal jugular vein
• Vagus nerve (located posteriorly between the vessels)

The ansa cervicalis supplies all infrahyoid muscles except the thyrohyoid, which is supplied by the nerve to thyrohyoid from the hypoglossal nerve.

Iatrogenic damage to the ansa cervicalis during neck surgeries can lead to difficulty in deglutition and is also useful for the reconstruction of the recurrent laryngeal nerve.

The suprahyoid muscles, including the digastric, function as:

• Depressor and retractor of the chin during mouth opening
• Assist in deglutition by lifting the hyoid bone

The key arteries include:

• Superficial temporal artery
• Maxillary artery
• Posterior auricular artery
• Occipital artery
• Facial artery
• Lingual artery
• Superior thyroid artery
• Ascending pharyngeal artery
• Internal carotid artery
• Common carotid artery

The Mylohyoid muscle helps in the first stage of deglutition by elevating the floor of the mouth and tongue.

The Stylohyoid muscle elongates the floor of the mouth by drawing the hyoid bone upward and backward.

The Infrahyoid muscles:

• Act as depressors of the larynx, hyoid bone, and the floor of the mouth.
• Stabilize the hyoid bone during the depression of the mandible.
• Help determine the position of the hyoid bone.

Artificial tears are used in Bell's palsy to lubricate the eye due to decreased tear production and inability to close the eyelid, preventing dryness and damage to the cornea.

The conjunctiva is important for:

• Protecting the eye from foreign bodies and pathogens
• Providing lubrication to the eye surface
• Contributing to the immune response of the eye

A person's nose runs when they cry due to the overflow of tears from the lacrimal glands, which drain into the nasal cavity through the nasolacrimal duct, leading to nasal discharge.

A stye is an acute infection of the eyelid's oil glands, causing a painful lump, while a chalazion is a chronic inflammation of the oil glands, resulting in a painless lump.

The lacrimal gland is non-functional for the first few months (3-6 weeks) after birth, leading to a condition called alacrimia, which is physiological.

Functional alacrimia occurs when the duct carrying tears from the orbital part of the lacrimal gland is obstructed due to the removal of the palpebral part, preventing secretions from reaching the conjunctival sac.

Preganglionic fibres arise from the lacrimatory nucleus in the pons, passing through the nervous intermedius, geniculate ganglion, greater petrosal nerve, and nerve of the pterygoid canal to the pterygopalatine ganglion. Postganglionic fibres then travel through the maxillary nerve, zygomatic nerve, zygomaticotemporal nerve, and lacrimal nerve to the lacrimal gland.

Dacryocystitis is an infection of the lacrimal sac, typically secondary to obstruction of the nasolacrimal duct at the junction of the lacrimal sac.

Epiphora is the overflow of tears from the conjunctival sac over the cheeks, caused by:

1. Hyper-lacrimation (emotional outbreaks or spicy food).
2. Obstruction in the lacrimal apparatus.
3. Ectropion (eversion of the lower eyelid).
4. Paralysis of orbicularis oculi due to facial nerve injury.

The boy presented with fever, facial pain, and difficulty chewing, with a clinical examination revealing swelling around the left ear, leading to a diagnosis of acute viral parotitis (mumps).

Acute viral parotitis is an inflammation of the parotid gland caused by the mumps virus, characterized by unilateral or bilateral enlargement of the gland, pain, and fever.

Parotid swellings are painful due to the outer layer of the parotid capsule, which is thick and adherent to the gland, and its rich innervation by greater auricular nerve fibers.

The nerve supply of the parotid gland includes:

• Parasympathetic: Preganglionic fibers from the inferior salivatory nucleus travel through the glossopharyngeal nerve, tympanic branch, tympanic plexus, and lesser petrosal nerve to the otic ganglion, with postganglionic fibers reaching the gland via the auriculotemporal nerve.
• Sympathetic: Fibers from the superior cervical ganglion travel along the external carotid artery to the gland.
• Sensory: Supplied by the auriculotemporal and great auricular nerves.

Pain increases during mealtime due to the compression of the swollen glenoid process between the TM joint and external acoustic meatus during mastication, along with increased saliva accumulation. Pain is relieved after meals when the activity subsides.

Hilton's method is used for draining a parotid abscess because it allows for effective drainage while minimizing damage to surrounding structures.

Precautions during parotidectomy include:

1. Identifying and preserving the facial nerve.
2. Minimizing blood loss.
3. Avoiding injury to surrounding structures.
4. Ensuring proper drainage post-surgery.

Frey's syndrome occurs due to aberrant regeneration of parasympathetic fibers, leading to sweating in the cheek area during eating, as the fibers mistakenly innervate sweat glands instead of salivary glands.

Complications of acute parotitis in adults can include:

1. Abscess formation
2. Dehydration due to reduced oral intake
3. Sepsis in severe cases
4. Chronic parotitis if not treated properly.

Salivary glands develop from epithelial buds that grow into the surrounding mesenchyme during embryonic development, differentiating into the major and minor salivary glands.

The parotid duct is a duct that carries saliva from the parotid gland to the oral cavity. Its tortuous course is functionally important as it allows for efficient drainage and prevents backflow during mastication.

Hilton's method involves a horizontal incision extending from the root of the auricle to avoid injury to the branches of the facial nerve, which are embedded superficially in the parotid gland and radiate horizontally.

Precautions during parotidectomy include:

1. Understanding that the parotid gland has a superficial and deep lobe connected by an isthmus.
2. Recognizing that branches of the facial nerve and retromandibular vein pass through the faciovenous plane, which helps in tumor removal without nerve damage.

Frey's syndrome occurs when there is an accidental injury to the greater auricular and auriculotemporal nerves. During wound healing, the parasympathetic secretomotor fibers of the auriculotemporal nerve join the fibers of the greater auricular nerve, leading to sweating and flushing instead of salivation when stimulated.

Complications of parotitis due to viraemia include:

1. Epididymo-orchitis (inflammation of the epididymis and testis).
2. Oophoritis (inflammation of the ovary).
3. Pancreatitis.

The parotid gland develops from ectoderm, while the sub-lingual and sub-mandibular glands are derived from endoderm.

The parotid duct drains saliva from the parotid gland into the oral cavity by:

1. Emerging from the anterior border of the gland.
2. Running forward over the masseter muscle.
3. Turning inwards at the anterior border of the muscle and piercing the buccal pad of fat, buccopharyngeal fascia, and buccinator muscle.

The tortuous course of the duct provides a valve-like mechanism that prevents inflation during excessive mouth blowing, such as in trumpet playing.

1. Presence of a tense swelling below the mandible, greatest before or during meals.
2. Physical examination reveals absence of saliva discharge from the duct orifice.
3. Diagnostic methods include ultrasound, sialography, and CT scan.

An incision should be made at least 1 inch below the mandibular angle to avoid injury to the marginal mandibular branch of the facial nerve, which lies 1 inch posteroinferior to the angle.

A swollen sub-mandibular salivary gland can be palpated bimanually in the mouth and below the mandible, as it lies partly inside and partly outside the mouth. In contrast, enlarged sub-mandibular lymph nodes cannot be palpated bimanually since they do not lie above the floor of the mouth.

The most common complications include damage to the facial artery and lingual nerve, as these structures are located close to the gland during surgical removal.

Thrombosis is the formation of a blood clot inside a blood vessel, obstructing blood flow, which can lead to ischaemia or necrosis (in arteries) or congestion (in veins). An embolus is a dislodged thrombus that travels through the bloodstream.

Thrombus formation in the superior sagittal sinus can occur due to extracranial infections from dangerous areas of the face or scalp, which spread into the sinus through emissary veins.

The functions of the dural venous sinuses include:

• Draining blood from the brain
• Providing a pathway for venous blood to return to the heart
• Acting as a reservoir for venous blood during changes in intracranial pressure.

The peculiarities of dural venous sinuses include:

• They are formed between the endosteal and meningeal layers of the dura mater.
• They do not have valves, allowing bidirectional blood flow.
• They are susceptible to thrombosis due to their location and drainage patterns.

The paired dural venous sinuses include:

• Transverse sinuses
• Superior petrosal sinuses

The unpaired dural venous sinuses include:

• Superior sagittal sinus
• Inferior sagittal sinus
• Straight sinus
• Occipital sinus
• Anterior and posterior intercavernous sinuses.

The dural venous sinuses commonly affected by thrombosis include:

• Superior sagittal sinus
• Transverse sinus

The anatomical basis for this includes their drainage patterns and susceptibility to infections from the face and scalp via emissary veins, leading to thrombosis.

Emissary veins are veins that connect extracranial veins to the dural venous sinuses. Their clinical significance lies in their role in the spread of infections from the scalp or face to the intracranial venous system, potentially leading to conditions like thrombosis.

A sinus is a cavity or channel that collects venous blood, often located between layers of tissue (like the dura mater), while a vein is a blood vessel that carries blood back to the heart. Sinuses do not have valves, unlike most veins.

Diploic veins are veins located within the diploë of the cranial bones. They drain blood from the skull and communicate with the dural venous sinuses, playing a role in venous drainage of the cranium.

Thrombosis of the superior sagittal sinus can lead to increased intracranial pressure and venous congestion, which stimulates pain receptors in the meninges, resulting in headache as a common symptom.

• Receive blood from the brain through cerebral veins.
• Receive cerebrospinal fluid from the sub-arachnoid space through arachnoid villi.

• Lie between the layers of dura mater (except inferior sagittal and straight sinus).
• Devoid of muscular coat and valves.
• Receive venous blood and CSF.
• Non-compressive in nature, keeping the lumen patent.
• Communicate with extracranial veins through emissary veins and vertebral venous plexus.

Thrombosis of the cavernous sinus can occur due to the spread of infection from the dangerous area of the face through emissary veins.

• Connect intracranial sinuses with extracranial veins.
• Allow bidirectional blood flow, helping maintain venous pressure equilibrium and preventing cerebral compression.
• Facilitate selective cooling of the brain.

• Dural venous sinuses lack smooth muscles in their walls.
• They are valveless, similar to emissary veins.
• They receive both venous blood and cerebrospinal fluid (CSF).

• Thin-walled, valveless veins that connect the outer and inner tables of the skull.
• Develop around 2 years of age and connect intracranial and extracranial veins.

Thrombosis is the formation of a blood clot within a blood vessel, which can obstruct blood flow.

The face is drained mainly by the facial and retromandibular veins. The angular vein, formed by the supratrochlear and supraorbital veins, continues as the facial vein. The retromandibular vein, formed by the superficial temporal and maxillary veins, divides into anterior and posterior divisions. The anterior division joins the facial vein to form the common facial vein, draining into the internal jugular vein, while the posterior division forms the external jugular vein.

Clinical significance: The dangerous area of the face (lower part of the external nose, upper lip, and adjoining cheeks) connects to the cavernous sinus through the deep facial vein and pterygoid venous plexus. Since these veins are valveless, infections in this area can lead to septic emboli traveling to the cavernous sinus, causing thrombosis and meningitis.

The cavernous sinus communicates with the facial vein through the deep facial vein, pterygoid venous plexus, and emissary veins.

Clinical significance: Infections from the dangerous area of the face can spread to the cavernous sinus via these communications, potentially leading to serious conditions like cavernous sinus thrombosis.

The cavernous sinus is related to several important structures, including the internal carotid artery, cranial nerves (III, IV, V1, V2, and VI), and the pituitary gland. These relations are crucial for understanding the potential complications arising from conditions affecting the sinus.

The cavernous venous sinus contains:

1. Internal carotid artery
2. Cranial nerves III (oculomotor), IV (trochlear), V1 (ophthalmic), V2 (maxillary), and VI (abducens)
3. Venous blood from the facial and pterygoid venous plexus

These contents are significant for the function and pathology of the sinus.

The tributaries of the cavernous sinus include:

1. Superior and inferior ophthalmic veins
2. Sphenoparietal sinus
3. Emissary veins from the face and pterygoid plexus

These tributaries play a role in venous drainage and potential pathways for infection.

The symptoms of cavernous sinus thrombosis, such as headache, neck rigidity, and ophthalmoplegia, arise from the increased intracranial pressure due to impaired venous drainage and the involvement of cranial nerves within the cavernous sinus. The proximity of the sinus to the brain and cranial nerves explains the neurological symptoms observed.

1. Facial vein → angular vein → ophthalmic veins (superior and inferior) → cavernous sinus.

2. Facial vein → deep facial vein → pterygoid plexus of veins → emissary veins → cavernous sinus.

These communications provide potential pathways for extracranial/facial infections to spread intracranially, which can lead to conditions such as cavernous sinus thrombosis and meningitis.

The lateral wall of the cavernous sinus contains the following structures (from above downwards):

1. Oculomotor nerve (III CN)
2. Trochlear nerve (IV CN)
3. Ophthalmic nerve (V CN - first division)
4. Maxillary nerve (V CN - second division)

The relations of the cavernous sinus are as follows:

• Superiorly: Optic tract, optic chiasma, internal carotid artery.
• Inferiorly: Foramen lacerum and the junction of the body and greater wing of the sphenoid bone.
• Medially: Pituitary gland (hypophysis cerebri) and sphenoidal air sinus.
• Laterally: Temporal lobe with uncus.
• Anteriorly: Superior orbital fissure and the apex of the orbit.
• Posteriorly: Apex of petrous temporal bone.

The internal carotid artery and abducent nerve pass through the cavernous sinus. It is unique as it is the only venous structure in the body through which an artery travels completely.

The cavernous sinus receives blood from three regions:

1. From the brain:

   • Superficial middle cerebral vein
   • Inferior cerebral veins

2. From the orbit:

   • Superior ophthalmic vein
   • Inferior ophthalmic vein
   • Central vein of retina

3. From the meninges:

   • Sphenoparietal veins
   • Anterior trunk of the middle meningeal vein

The presenting symptoms include:

1. Headache and pain - due to involvement of the ophthalmic nerve.
2. Periorbital oedema and exophthalmos - due to obstruction of superior ophthalmic veins.
3. Ophthalmoplegia - due to involvement of cranial nerves III, IV, and VI.
4. Neck rigidity - due to spasm of the extensors of the back from irritation of nerve roots in the infected sub-arachnoid space.

Pulsating exophthalmos is characterized by the protrusion of the eyeball that pulsates with each heartbeat. It indicates an arteriovenous communication (carotico-cavernous fistula) between the internal carotid artery and the cavernous sinus. Other signs include a loud bruit, ophthalmoplegia, and periorbital oedema.

The pituitary gland is often referred to as the master endocrine gland because its hormones influence the activities of many other endocrine glands. It is controlled by the hypothalamus and is divided into an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis).

The pituitary gland is located in the sella turcica of the sphenoid bone and has the following relations:

• Anteriorly: Sphenoidal air sinus
• Posteriorly: Dorsum sellae, basilar artery, and pons
• Superiorly: Diaphragma sellae and optic chiasma
• Inferiorly: Sphenoidal air sinus and body of the sphenoid
• Laterally: Cavernous sinus and its contents

Bitemporal hemianopia is caused by the compression of the optic chiasma, which affects the crossing fibers from the nasal retina of each eye. This results in impaired peripheral vision in the outer temporal fields of both eyes.

Manifestations of pituitary tumors include:

1. Visual disturbances - such as bitemporal hemianopia due to optic chiasm compression.
2. Hormonal imbalances - leading to conditions like acromegaly, Cushing's disease, or hyperprolactinemia, depending on the type of hormone secreted by the tumor.
3. Headaches - due to increased intracranial pressure.
4. Neurological symptoms - from local invasion of surrounding structures.

The pituitary gland develops from:

1. Rathke's pouch: A small diverticulum from the ectoderm lining the roof of the stomodeum, forming parts of the adenohypophysis.
2. Neuroectoderm: The neurohypophysis develops from an evagination of neuroectoderm of the hypothalamus.

Symptoms due to pressure from a pituitary adenoma include:

• Headache: Due to stretching of the diaphragma sella.
• Bitemporal hemianopia: Compression of the optic chiasma.
• Exophthalmos and ophthalmoplegia: Due to pressure on the ophthalmic veins and cranial nerves in the cavernous sinus.
• Enlargement of the pituitary fossa: Appears as ballooning on radiographs.
• Bilateral papilloedema: Due to increased intracranial pressure.

Goitre is the enlargement of the thyroid gland. Physiological conditions that can lead to thyroid enlargement include:

• Pregnancy: Increased demand for thyroid hormones.
• Puberty: Hormonal changes can stimulate growth.
• Thyroiditis: Inflammation of the thyroid gland.
• Iodine deficiency: Leads to compensatory enlargement of the gland.

Thyroid swellings move up and down during swallowing due to:

• The thyroid gland's attachment to the trachea and larynx, which allows it to move with these structures during the swallowing process.

Precautions during thyroidectomy include:

1. Identifying and preserving the recurrent laryngeal nerve to prevent vocal cord paralysis.
2. Careful dissection to avoid damaging surrounding structures such as the parathyroid glands.
3. Monitoring for bleeding to manage any potential hemorrhage during the procedure.

The normal dimensions of the thyroid gland are:

• Each lobe: 5 cm long, 3 cm wide, 2 cm thick.
• Isthmus: Approximately 1.25 cm in vertical and transverse diameters.

The thyroid gland is situated in front and at the sides of the trachea opposite the fifth, sixth, seventh cervical, and first thoracic vertebrae. The isthmus lies anterior to the second, third, and fourth tracheal rings.

Goitre is defined as the pathological enlargement of the thyroid gland, which results from a lack of iodine and is associated with hyper or hypofunction of the gland.

Physiological conditions that can lead to enlargement of the thyroid gland include menstruation, pregnancy, lactation, and puberty.

Pressure symptoms caused by a large goitre include:

1. Hoarseness of voice (dysphonia) due to compression of the recurrent laryngeal nerve.
2. Dysphagia (difficulty in swallowing) due to compression of the oesophagus.
3. Dyspnoea (difficulty in breathing) due to compression of the trachea.
4. Venous congestion in the neck region due to compression of veins in the superior mediastinum.

The thyroid gland is covered by:

1. A true capsule, an inner layer derived from the condensation of the fibrous stroma of the gland.
2. A false capsule, an outer layer derived from the pretracheal fascia of the deep cervical fascia.

The space between the two capsules contains parathyroid glands along the posterior borders of the lateral lobes, and a dense venous plexus lies deep to the true capsule.

The upward growth of thyroid swellings is limited by:

1. The pretracheal layer of fascia and sternothyroid, which are attached superiorly to the oblique line of the thyroid cartilage.

Backward growth is easier due to a thin and ill-defined layer of the capsule along the posterior border of the lateral lobe, while downward expansion is not limited, allowing for retrosternal goitre.

The thyroid gland moves up and down during swallowing due to its attachment to the laryngeal cartilage via the ligament of Berry, which anchors it to the cricoid cartilage. The larynx moves up and down by the extrinsic laryngeal muscles during swallowing, causing the thyroid gland to follow this movement.

The thyroid gland has a rich blood supply from three main sources:

1. Superior thyroid artery (a branch of the external carotid artery).
2. Inferior thyroid artery (a branch of the thyrocervical trunk from the subclavian artery).
3. Thyroidea ima artery (present in 10% of cases, a branch of the brachiocephalic artery or direct branch from the arch of the aorta).

1. Superior thyroid artery
2. Inferior thyroid artery
3. Thyroidea ima

• Superior thyroid vein drains into the internal jugular vein.
• Middle thyroid vein drains into the internal jugular vein.
• Inferior thyroid vein drains into the left brachiocephalic vein.
• Thyroid vein of Kocher drains into the internal jugular vein.

1. Remove the thyroid gland along with the true capsule to avoid hemorrhage.
2. Retain the parathyroid gland.
3. Be cautious of the external and right recurrent laryngeal nerves, which are commonly affected during surgery.

The parathyroid gland secretes parathormone (PTH), which is essential for calcium and phosphorus metabolism. It maintains blood calcium levels by removing calcium from bones. Excessive secretion leads to hyperparathyroidism, causing weak bones, hypercalcemia, and kidney stones.

Carpopedal spasm occurs due to decreased plasma calcium levels from post-thyroidectomy hypoparathyroidism, resulting in increased neuromuscular activity and severe involuntary muscle spasms.

During thyroidectomy, the posterior part of the thyroid gland should be retained to preserve the parathyroid glands, which are essential for secreting PTH and maintaining plasma calcium levels.

The inferior parathyroid gland develops in close association with the thymus. If it fails to separate before the thymus descends into the mediastinum, it may become ectopic, potentially located near the bifurcation of the common carotid artery.

The condition characterized by a tonic spasm of the masseters is known as trismus or lockjaw, which is a symptom of tetanus.

The lateral pterygoid muscle is primarily responsible for the depression of the temporomandibular joint, assisted by the suprahyoid and infrahyoid muscles.

The movements produced by the temporomandibular joint include depression, elevation, protraction (protrusion), retraction, and side-to-side movement.

All chief muscles of mastication are derived from the first pharyngeal arch and are supplied by the mandibular nerve.

The primary action of the masseter muscle is elevation of the mandible, making it a powerful elevator of the temporomandibular joint.

The lateral pterygoid muscle is the only principal muscle of mastication that acts as a depressor of the temporomandibular joint.

The digastric, geniohyoid, and mylohyoid muscles help to depress the mandible, while the infrahyoid muscles fix the hyoid bone.

The joint cavity is divided into an upper compartment (menisco-temporal) and a lower compartment (menisco-mandibular). Depression is initiated in the lower compartment with a forward and downward rotatory movement of the head of the mandible, followed by a gliding movement in the upper compartment.

The mandibular nerve branches include:

1. From trunk:

   • Motor: nerve to medial pterygoid
   • Sensory: nervus spinosus (meningeal branch)

2. From anterior division:

   • Motor: masseteric nerve, deep temporal nerves, nerve to lateral pterygoid
   • Sensory: buccal nerve

3. From posterior division:

   • Motor: nerve to mylohyoid (from inferior alveolar nerve)
   • Sensory: inferior alveolar nerve, lingual nerve, auriculotemporal nerve

Note: The anterior division is mainly motor, while the posterior division is mainly sensory.

The middle meningeal artery is clinically significant as it is involved in extradural haematoma, while the sphenopalatine artery is significant in cases of epistaxis (nosebleeds).

• Anterior tympanic artery
• Middle meningeal artery
• Accessory meningeal artery
• Inferior alveolar artery
• Deep auricular artery

• Branch to the pterygoid, masseter and buccinator muscle
• Deep auricular branches

• Posterior superior alveolar artery
• Pharyngeal artery
• Pterygoid canal artery
• Infraorbital artery
• Greater palatine artery
• Sphenopalatine artery

Eagle's syndrome is a clinical condition characterized by recurrent throat pain in the tonsillar fossa and neck, often radiating into the ear. It is caused by either an elongated styloid process or calcification of the stylohyoid ligament.

• Infection
• Nerve injury (e.g., inferior alveolar nerve)
• Hemorrhage
• Dry socket (alveolar osteitis)
• Damage to adjacent teeth

The area commonly fractured is the ramus of the mandible.

The inferior alveolar nerve is blocked, and the anaesthetic is administered near the lingula on the medial surface of the ramus of the mandible.

Referred pain can occur in the anterior two-thirds of the tongue, around the ear, and in the temporal region. This pain is innervated by sensory branches of the mandibular nerve: the lingual nerve, inferior alveolar nerve, and auriculotemporal nerve.

The commonest site of cancer of the tongue is the lateral margin of the anterior two-thirds, and it is typically squamous cell carcinoma.

The tongue is supplied by the hypoglossal nerve for motor function, except for the palatoglossus which is supplied by the cranial part of the accessory nerve. The muscles derive from occipital myotomes that migrate around the pharynx during embryonic development.

The tongue serves several functions:

1. Taste sensation
2. Mastication and deglutition
3. Speech production
4. Facial expression
5. Moistening lips and cleaning teeth
6. Medicolegal identification through tongue prints
7. Acts as a clinical mirror for various bodily disturbances.

The lymph nodes draining the tongue include:

• Submental nodes
• Submandibular nodes
• Deep cervical nodes Peculiarities include that the anterior two-thirds drains primarily to the submandibular nodes, while the posterior one-third drains to the deep cervical nodes, indicating a complex lymphatic drainage pattern.

The muscles of the tongue include:

1. Genioglossus - protrudes the tongue
2. Hyoglossus - depresses the tongue
3. Styloglossus - retracts and elevates the tongue
4. Palatoglossus - elevates the posterior part of the tongue All muscles are involved in manipulating food, speech, and swallowing.

The genioglossi muscles are called safety muscles because they help prevent the tongue from obstructing the airway, especially during unconsciousness or anesthesia, thus maintaining an open airway.

The tongue develops from the first four pharyngeal arches during embryonic development, with contributions from the mesoderm and ectoderm. The anterior two-thirds arise from the first arch, while the posterior one-third comes from the third and fourth arches.

The anterior two-thirds of the tongue are supplied by the lingual nerve (general sensation) and chorda tympani (special sensation). The posterior one-third is supplied by the glossopharyngeal nerve for both general and special sensations.

Referred pain occurs due to the lingual nerve carrying sensation from the anterior two-thirds of the tongue, the inferior alveolar nerve from the lower jaw, and the auriculotemporal nerve from the ear and temporal region. These branches of the mandibular nerve can refer pain to one another.

Lymphatic drainage from the tongue occurs through four sets of lymphatics:

1. Apical set: Drains the tip and frenulum into sub-mental, sub-mandibular, jugulodigastric, and jugulo-omohyoid lymph nodes.

2. Marginal set: Drains the marginal part of the anterior two-thirds unilaterally into sub-mandibular, jugulodigastric, and jugulo-omohyoid lymph nodes.

3. Central set: Drains the anterior two-thirds bilaterally into jugulodigastric, jugulo-omohyoid, and sub-mandibular lymph nodes.

4. Basal set: Drains the posterior one-third bilaterally into jugulodigastric lymph nodes.

The peculiarities of the lymphatics draining the tongue include:

• Free decussation across the midline, allowing lymphatics to pass bilaterally.
• Lymphatics do not accompany blood vessels.
• The tip of the tongue has the richest area of lymphatic drainage.

The principal lymph nodes of the tongue are the jugulo-omohyoid lymph nodes, which receive drainage from all sets of lymphatics from the tongue.

Cancer of the tongue spreads mainly through lymphatic channels.

• Lateral margin of anterior two-thirds: Better prognosis due to minimal cross-communication of lymphatics across the midline.
• Central part, tip, and posterior one-third: Poor prognosis due to rich anastomosis between lymphatics, allowing cancer to spread to both ipsilateral and contralateral sides.

Intrinsic muscles of the tongue have no bony attachments and alter its shape:

Extrinsic muscles of the tongue are attached to nearby bones and alter its position:

The genioglossus muscles form most of the bulk of the tongue and are crucial for airway safety:

• They protrude the tongue and prevent it from falling backward, which could obstruct the airway.
• Paralysis of both muscles can lead to airway obstruction and suffocation.
• In anesthetized patients, an airway tube is inserted to prevent the tongue from falling back.

The tongue has four types of papillae, each with distinct functions:

Adenoids, or nasopharyngeal tonsils, are part of Waldeyer's lymphatic ring. When they become enlarged or hypertrophied due to infection, they obstruct nasal respiration, making mouth breathing necessary, which can lead to adenoid facies.

The internal Waldeyer's ring consists of:

1. Pharyngeal tonsil (superiorly)
2. Tubal tonsils (superolaterally)
3. Palatine tonsil (laterally)
4. Lingual tonsils (inferiorly)

The external Waldeyer's ring is formed by peripheral lymph nodes arranged in outer and inner circles, providing a defense mechanism against infections in the head and neck region. It includes nodes such as sub-mental, sub-mandibular, pre-auricular, post-auricular, and occipital nodes.

Cervical lymph nodes are crucial for filtering lymphatic fluid and trapping pathogens. Their enlargement can indicate infections or malignancies in the head and neck region, making them important for diagnosis and treatment planning.

The glossopharyngeal nerve, responsible for taste and sensation in the posterior one-third of the tongue, is closely associated with the tonsillar artery. Damage to this nerve during tonsillectomy can lead to loss of sensation in that area.

Quinsy, or peritonsillar abscess, is an accumulation of pus around the tonsil, presenting with fever, throat pain, and difficulty opening the mouth. Treatment includes antibiotic therapy and incision and drainage of the pus. Tonsillectomy may be indicated for recurrent tonsillitis.

Preventing blood clot formation is crucial because post-tonsillectomy bleeding can occur due to damage to the paratonsillar vein. Clots can interfere with vessel wall retraction and muscle contraction, leading to potential complications if not removed.

It is a case of acute tonsillitis.

The palatine tonsil is part of Waldeyer's lymphatic ring, helping to defend the respiratory and alimentary tracts by destroying microorganisms from the external environment.

Relations of the palatine tonsil include:

• Loose areolar tissue containing paratonsillar vein
• Pharyngobasilar fascia
• Superior constrictor muscle
• Buccopharyngeal fascia
• Glossopharyngeal nerve
• Styloglossus muscle

Clinical significance: A paratonsillar vein is a source of hemorrhage during tonsil removal due to its close relation to the tonsil.

The palatine tonsil is supplied by tonsillar branches of:

1. Facial artery (mainly)
2. Ascending palatine artery (branch of the facial artery)
3. Dorsalis lingue (branch of the lingual artery)
4. Ascending pharyngeal (branch of the external carotid)
5. Greater palatine (branch of the maxillary artery)

The lymph node of the tonsil is called the jugulodigastric lymph node.

The earache is caused by referred pain, as both the tonsil and ear are supplied by the glossopharyngeal nerve.

The loss of taste sensation in the tongue after tonsillectomy can occur due to damage to the glossopharyngeal nerve, which supplies taste to the posterior part of the tongue.

Formation of a blood clot is prevented after tonsillectomy due to the close proximity of the paratonsillar vein, which can lead to continuous bleeding if damaged during the procedure.

Quinsy, also known as a peritonsillar abscess, is a complication of tonsillitis characterized by the accumulation of pus beside the tonsil, leading to severe throat pain and difficulty swallowing.

The palatine tonsil develops from the second pharyngeal pouch during embryonic development, which gives rise to the tonsillar crypts and the tonsillar bed.

Waldeyer's ring acts as a first line of defense by trapping microorganisms like bacteria and viruses from the oral and nasal cavities, preventing their entry or spread into the lower respiratory tract.

Deep cervical lymph nodes are located along the internal jugular vein, extending from the base of the skull to the root of the neck. They are significant as they are the terminal lymph nodes for lymph drainage from the head and neck, receiving lymph directly or indirectly from peripheral nodes.

The two groups of deep cervical lymph nodes are:

1. Jugulodigastric (superior) lymph nodes: Located deep to the anterior border of the sternocleidomastoid muscle, in a triangular area bounded by the posterior belly of the digastric muscle, facial vein, and internal jugular vein. They are the principal nodes for palatine tonsils.

2. Jugulo-omohyoid (inferior) lymph nodes: Situated just above the intermediate tendon of the omohyoid muscle.

The lymph nodes forming the inner circle (Waldeyer's internal ring) include:

1. Pharyngeal tonsil
2. Tubal tonsil
3. Palatine tonsil
4. Lingual tonsil

The lymph nodes forming the outer circle (Waldeyer's external ring) include:

1. Occipital
2. Postauricular
3. Preauricular
4. Submandibular
5. Submental

Palpation of cervical lymph nodes provides important information about lymphadenopathy, indicating local or systemic disease when nodes are enlarged. Normal lymph nodes are usually invisible and hardly palpable. Key aspects to assess include:

• Consistency
• Size
• Tenderness
• Fixity to surrounding structures

The cervical lymph nodes to be palpated include:

Cervical lymph nodes should be palpated using the following method:

1. Position the patient: The patient should be seated with the neck exposed.
2. Palpation technique: Examine the nodes from in front and behind, palpating bilaterally.
3. Use gentle circular motions: Apply gentle circular motions with the fingertips to assess the nodes.