What is a test for ulnar nerve function?
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Ask the patient to abduct the fingers against resistance or hold a thin object between two fingers by adduction.
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What is a test for ulnar nerve function?
Ask the patient to abduct the fingers against resistance or hold a thin object between two fingers by adduction.
What area does the palmar cutaneous branch of the median nerve innervate?
Skin over the thenar eminence and lateral 2/3 of the palm.
Which muscles are primarily supplied by the ulnar nerve?
Almost all intrinsic muscles of the hand responsible for abduction and adduction, specifically the palmar and dorsal interossei.
What is the effect of an infraclavicular block?
Loss of sensation of all deep structures of the upper limb and loss of cutaneous sensation distal to the middle of the arm.
What causes atrophy of the thenar muscles?
Lack of stimulation from the recurrent branch of the median nerve.
Why is the palmar cutaneous branch spared in carpal tunnel syndrome?
Because it is given off before the median nerve enters the carpal tunnel.
What should a patient with ulnar nerve injury be unable to do?
Perform actions involving finger abduction and adduction.
Where should intramuscular injections at the deltoid muscle be administered?
Approximately 2 inches below the acromion, at the middle of the deltoid muscle.
What muscles are supplied by the axillary nerve?
Deltoid and teres minor.
What is Saturday night palsy?
A condition caused by prolonged adduction of the arm with a hard object, often during deep sleep after alcohol intoxication.
What symptoms are associated with median nerve injury?
Numbness/tingling at the lateral 2/3 of the palm and palmar surface of the lateral 3.5 digits.
What is the sensory function status over the lateral palmar surface in carpal tunnel syndrome?
Intact.
What is Guyon's canal syndrome commonly known as?
Handlebar or Cyclist's palsy.
What is the primary function of the musculocutaneous nerve?
It supplies all flexor muscles of the anterior compartment of the arm.
What can poor intramuscular injection technique lead to?
Damage to the axillary nerve or radial nerve.
What leads to atrophy of the deltoid and teres minor muscles?
Prolonged denervation or chronic lack of stimulation.
What is a common cause of level II radial nerve injury?
Midshaft fracture of the humerus.
Where does the radial nerve cross in the arm?
The inferior boundary of teres major.
What are the causes of median nerve injury?
Wrist laceration and carpal tunnel syndrome.
What nerve supplies the medial half of the flexor digitorum profundus (FDP)?
Ulnar nerve.
What are the clinical presentations associated with the palmar cutaneous branch of the median nerve?
They are the same as level II median nerve injury.
What causes Guyon's canal syndrome?
Constant pressure on the medial wrist, repetitive wrist movements, fractures/injuries causing swelling at Guyon's canal, and ulnar artery thrombosis.
What sensory loss is associated with musculocutaneous nerve injury?
Loss of sensation over the lateral forearm.
What are some causes of long thoracic nerve injury?
Trauma to the lateral thoracic cage, surgical procedures, and inflammation affecting the nerve.
What is a common cause of axillary nerve injury related to the shoulder?
Anterior inferior dislocation of the GH joint.
What is a common cause of Quadrangular Space Syndrome?
Frequent carrying of heavy backpacks.
Where does the radial nerve descend in relation to the humerus?
In the radial groove of the humerus, alongside the profunda brachii artery.
What is cubital tunnel syndrome?
Ulnar nerve entrapment.
Where does the ulnar nerve travel in relation to the ulnar artery?
Medial to the ulnar artery through Guyon's canal.
What nerve roots does the long thoracic nerve originate from?
C5 – C7 nerve roots of the brachial plexus.
What is a key clinical presentation of median nerve injury?
No hand of benediction; the patient is able to make a fist.
What happens if the palmar branch of the ulnar nerve is severed in wrist laceration?
It leads to total loss of sensation (anesthesia) over the skin of the hypothenar eminence.
How is the biceps tendon reflex tested?
By tapping the biceps tendon at the cubital fossa.
What anatomical structure does the radial nerve travel with in the arm?
The profunda brachii artery.
What is the author's opinion on Prof. Shum's description of the radial nerve block at the wrist?
The author doubts its accuracy.
What syndrome can cause axillary nerve injury?
Quadrangular space syndrome.
What is the effect of a midshaft humeral fracture on elbow and shoulder extension?
There is no problem with elbow and shoulder extension due to prior motor branches to the triceps.
Which activities can lead to Quadrangular Space Syndrome in athletes?
Frequent arm abduction and medial rotation.
What happens to the claw hand in a lower (level II) ulnar nerve injury?
It becomes more severe due to unopposed flexion from both FDP and FDS.
What are common causes of ulnar nerve entrapment?
Frequent flexion of the elbow, arthritis, bone spurs, previous fractures/dislocations of the elbow.
What are the two branches the ulnar nerve divides into within the tunnel?
Superficial sensory and deep motor branches.
What muscles does the median nerve innervate in the forearm?
All muscles in the flexor compartment except flexor carpi ulnaris and the medial half of flexor digitorum profundus.
What is Klumpke's palsy?
A lower plexus (C8-T1) injury caused by sudden upward pull of the upper limb or excessive pull during delivery.
Where does the long thoracic nerve run in relation to the clavicle and the first rib?
It passes between the clavicle and the first rib.
Where does the ulnar nerve run at the elbow?
Superficially at the posterior aspect of the elbow, posterior to the medial epicondyle and medial to the olecranon.
What are the medial and lateral boundaries of Guyon's canal?
Medial boundary: Pisiform bone and pisohamate ligament; Lateral boundary: Hook of hamate.
Which branches of the median nerve are affected in this condition?
Both the palmar cutaneous branch and palmar digital branches.
Where does the radial nerve descend in relation to the axillary artery?
It descends posterior to the axillary artery.
Why is the radial nerve prone to compression?
It is located near the upper arm close to the axilla.
What indicates a normal response during the biceps tendon reflex test?
Involuntary contraction of the biceps (flexion of elbow).
Which head of the triceps brachii is likely paralyzed in a level II radial nerve injury?
The lateral head of the biceps.
Which fracture can damage the axillary nerve?
Fracture of the surgical neck of the humerus.
Which fingers cannot be adducted in ulnar nerve injury?
All fingers; 2nd to 5th fingers cannot be abducted.
Where does the author believe the superficial branch of the radial nerve is situated?
Directly lateral to or even posterior to the styloid process of the radius.
What are the boundaries of the quadrangular space?
Superior: Inferior margin of teres minor; Lateral: Surgical neck of humerus; Inferior: Superior margin of teres major; Medial: Lateral margin of long head of triceps brachii.
Where does the ulnar nerve travel in relation to the humerus?
Posterior to the medial epicondyle of the humerus.
What happens to the median nerve after traversing the cubital fossa?
It passes between the ulnar and humeral heads of the pronator teres.
What are the clinical presentations of level II ulnar nerve injury?
They are the same as level I ulnar nerve injury.
What happens in a level I median nerve injury?
Almost all flexor muscles in the forearm are paralyzed, except flexor carpi ulnaris and the medial half of flexor digitorum profundus.
What are common causes of Klumpke's palsy?
Sudden upward pull of the upper limb or excessive pull of a baby's upper limb during delivery.
What area does the dorsum of the hand supply?
The skin of the posterolateral surface.
What muscle does the long thoracic nerve provide sole motor innervation to?
Serratus anterior.
What forms the roof and floor of Guyon's canal?
Roof: Palmar (volar) carpal ligament; Floor: Transverse carpal ligament (flexor retinaculum).
Where can an ulnar nerve block be performed at the elbow?
Just proximal to the cubital tunnel.
What anatomical structure does the radial nerve cross to enter the extensor compartment of the arm?
The inferior boundary of teres major.
Why can the remaining heads of the triceps maintain extension despite the injury?
Because they have already received motor branches from the radial nerve before the site of injury.
What causes radial nerve entrapment (Supinator syndrome)?
Repetitive supination and pronation, common in swimmers and violinists.
What can cause median nerve entrapment?
Prolonged and repetitive gripping or pronation movements.
What area does the superficial branch of the radial nerve supply?
The skin on the dorsum of the lateral 2.5 digits (except tips).
What are the causes of level I median nerve injury?
Lower plexus injury, supracondylar fracture of humerus, and median nerve entrapment.
At what point does the superficial branch of the radial nerve start winding around the radius?
Around 2/3 of the way down the forearm.
What structures pass through the quadrangular space?
The axillary nerve and posterior circumflex humeral vessels.
From which part of the brachial plexus does the axillary nerve arise?
The posterior cord.
What is the sensory loss area for the palmar aspect of the medial 1.5 digits?
Superficial branch of the ulnar nerve.
What can cause compression of the median nerve?
Hypertrophy of the pronator teres due to excessive use.
What is the action of the biceps brachii?
Forearm flexion.
What anatomical structure forms the cubital tunnel?
The tendinous arch joining the two heads of the flexor carpi ulnaris (FCU).
What is the 'hand of benediction' sign?
Inability to flex the lateral three fingers while flexing the medial two fingers due to median nerve injury.
What is one cause of ulnar nerve injury?
Lower plexus injury.
Where may the superficial branch of the radial nerve be compressed?
At the wrist.
Which nerve roots are most affected in Klumpke's palsy?
C8 and T1 nerve roots.
What is a common presentation of long thoracic nerve injury?
Winged scapula.
What structures are associated with Guyon's canal syndrome?
Flexor retinaculum, hamate, pisiform, pisohamate ligament, ulnar artery, and ulnar nerve.
What is the effect of an ulnar nerve block at the elbow?
It is similar to level I ulnar nerve injury.
What is the condition known as Saturday night palsy associated with?
Compression of the radial nerve by hard objects between the arm and the trunk.
What should be considered when evaluating elbow extension in a midshaft humeral fracture?
Only the action of the long head of triceps should be considered.
What are the common causes of level I ulnar nerve injury?
Wrist laceration, pisiform/hamate fracture, and Guyon’s canal syndrome.
What does the 'Hand of Benediction' indicate?
Median nerve injury.
What are the clinical presentations of radial nerve injury?
They are the same as those for level I radial nerve injury.
Which nerve supplies the dorsal aspect of the tips of the lateral 3.5 digits?
The median nerve.
What activities might lead to median nerve entrapment?
Prolonged hammering, cleaning dishes, playing tennis.
From which cords of the brachial plexus does the median nerve arise?
From both medial and lateral cords.
What does the author suggest to follow for exam purposes?
Prof. Shum's teachings.
What is the primary function of the spinal accessory nerve (CN XI)?
Motor innervation of the trapezius and sternocleidomastoid (SCM).
What can cause impingement of the axillary nerve?
Hypertrophy of the quadrangular space muscles.
What does the deep branch of the radial nerve continue as?
The posterior interosseous nerve.
Where does the axillary nerve run in relation to the GH joint?
It runs laterally, passing inferior to the GH joint.
Which area is spared from sensory loss in ulnar nerve injury?
Medial half of the dorsum of the hand.
What are the clinical presentations associated with median nerve compression?
They are the same as level I median nerve injury.
How does elbow flexion affect the cubital tunnel?
It reduces the space of the cubital tunnel, potentially exacerbating the condition.
Which nerve innervates the biceps brachii?
Musculocutaneous nerve (C5, C6).
What is the 'ape hand deformity'?
Inability to oppose the thumb due to paralysis of thenar muscles from median nerve injury.
What can excessive stretching of the arm above the head cause?
It may directly tear the C8-T1 nerve roots from the spinal cord.
What injury is associated with olecranon fracture?
Ulnar nerve injury.
What causes the pointer and middle fingers to appear clawed?
Paralysis of the first two lumbricals and unopposed actions of flexor digitorium and extensor digitorium.
What happens to the scapula when there is an injury to the long thoracic nerve?
Lack of protraction and severe retraction of the scapula.
Where can the ulnar nerve be blocked at the wrist?
Lateral to the flexor carpi ulnaris tendon and medial to the ulnar artery.
What two cutaneous branches does the radial nerve give out in the radial groove of the humerus?
The inferior lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm.
What does the radial nerve bifurcate into after crossing anterior to the lateral epicondyle of the humerus?
Deep and superficial branches.
Where does the ulnar nerve traverse in the wrist?
Through Guyon’s canal, situated between the pisiform and hook of hamate.
What test is used to assess median nerve function by asking the patient to make a fist?
Hand of Benediction test.
Where does the radial nerve run in the cubital fossa?
Lateral to the biceps tendon and medial (or deep) to the brachioradialis.
From which part of the brachial plexus does the ulnar nerve arise?
As a continuation of the medial cord.
What spinal nerve fibers are contained in the median nerve?
C5 to T1.
What anatomical structures are mentioned in relation to the radial nerve?
Superficial branch, deep branch, biceps tendon, and brachioradialis.
What does the posterior interosseous nerve supply?
All extensor muscles of the forearm.
How can you test the function of the spinal accessory nerve?
Ask the patient to shrug their shoulders and rotate their head against resistance.
What are common clinical presentations of axillary nerve injury?
Shoulder pain and difficulty in abduction of the arm.
What is affected in wrist laceration regarding sensory loss?
Palmar branch of the ulnar nerve.
What vessels does the axillary nerve accompany?
The posterior circumflex humeral vessels.
What are the clinical presentations of cubital tunnel syndrome?
They are the same as level I ulnar nerve injury.
What are some causes of carpal tunnel syndrome?
Trauma, repetitive use of vibrating machinery, rheumatoid arthritis, and pregnancy.
Which nerve innervates the adductor pollicis?
Ulnar nerve (C8, T1).
What can cause ulnar nerve injury related to the elbow?
Medial epicondyle avulsion and elbow dislocation.
What happens with an injury to the musculocutaneous nerve and C5, C6 segments of the radial nerve?
Lack of flexion.
Which nerve experiences the greatest degree of injury in Klumpke's palsy?
Ulnar nerve (C8-T1).
What is the role of lumbricals in finger movement?
They flex the MCP while extending the PIP and DIP joints.
What is the effect of an ulnar nerve block at the wrist?
It is similar to level II ulnar nerve injury.
Which muscles are involved in the action of scapular retraction?
Trapezius and rhomboids.
What muscles does the radial nerve supply branches to?
The lateral head of triceps and the brachioradialis.
Where does the deep branch of the radial nerve descend?
Between the superficial and deep heads of the supinator muscle.
What is a more severe form of ulnar nerve injury presentation?
Ulnar claw hand.
What does the inability to oppose the thumb indicate?
Median nerve injury.
What happens when the radial nerve is blocked at the cubital fossa?
Causes finger drop and sensory loss over the dorsum of the lateral 2.5 digits.
Which nerve roots contribute to the ulnar nerve?
C8 and T1.
How does a lower plexus injury affect the median nerve?
It damages the medial cord (C8, T1), leading to significant functional deficit.
What discrepancy does the author point out?
The difference between the illustrations by Netter and Prof. Shum.
What can cause entrapment of the deep branch of the radial nerve?
Between the two heads of the supinator muscle.
What branch does the median nerve give off just before entering the carpal tunnel?
Palmar cutaneous branch.
What muscle does the ulnar nerve supply after branching off to the FCU?
The medial half of the flexor digitorum profundus (FDP) muscle.
What happens to the skin supplied by the dorsal and palmar branches if the injury is only to the main branch of the ulnar nerve?
It will not experience sensory loss.
Which nerves experience the greatest degree of injury?
Axillary nerve (C5 – C6), Musculocutaneous nerve (C5 – C7), Radial nerve (C5 – T1), Suprascapular nerve (C5 – C6).
Which muscle is primarily affected by axillary nerve injury?
Deltoid muscle.
What forms the carpal tunnel at the wrist?
A deep arch of carpal bones and the flexor retinaculum.
What happens if the spinal accessory nerve is damaged?
The patient will be unable to perform shoulder shrugging and head rotation.
What syndrome is associated with ulnar nerve injury?
Cubital tunnel syndrome.
What cutaneous branch does the axillary nerve give off?
The superior lateral cutaneous nerve of the arm.
What happens to finger positions when lumbricals are paralyzed?
The patient presents with extended MCP and flexed DIP and PIP joints.
What is the role of the opponens pollicis?
It medially rotates the thumb for opposition.
What is the result of long thoracic nerve injury on the action of trapezius and rhomboids?
Their action is not antagonized, leading to retraction.
What type of fracture can damage the radial nerve?
A midshaft fracture of the humerus.
Which muscles are innervated by the deep branch of the ulnar nerve?
3rd and 4th lumbricals, interosseous muscles, and flexor digiti minimi brevis.
What are the clinical presentations of Klumpke's palsy?
Consistent with level I ulnar nerve injury and level I median nerve injury.
What happens to arm extension at the shoulder when the triceps brachii is paralyzed?
Extension is compromised but not totally lost due to the unaffected deltoid.
What is the action of the triceps brachii (long head)?
Forearm extension.
What does the deep branch of the radial nerve continue as in the extensor compartment of the forearm?
The posterior interosseous nerve.
Where does the ulnar nerve first travel in the arm?
On the medial aspect of the brachial artery in the flexor compartment.
What is the 'Ape Hand' sign?
Inability to oppose the thumb, indicating median nerve injury.
Where can the superficial branch of the radial nerve be blocked at the wrist?
Lateral to the flexor carpi radialis tendon and medial to the styloid process of the radius.
Where does the median nerve descend in relation to the brachialis?
On the surface of the brachialis to the cubital fossa, medial to the brachial artery.
What is a presentation of a level I radial nerve injury?
Elbow in a flexed position / unable to extend forearm.
How does the median nerve enter the hand?
Through the carpal tunnel, deep and lateral to the palmaris longus tendon.
What does the palmar cutaneous branch of the ulnar nerve supply?
The skin over the hypothenar eminence and medial palm.
What deformity is associated with the inability to oppose the thumb due to median nerve injury?
Ape hand deformity.
What is the Waiter’s tip sign?
Arm adducted and medially rotated; forearm pronated and extended.
What movements are associated with the trapezius muscle?
Scapula elevation.
Which bones form the base of the carpal arch medially and laterally?
Medially by the pisiform and hook of hamate; laterally by the tubercles of scaphoid and trapezium.
What happens to thumb abduction in median nerve injury?
Abduction is still possible to a lesser degree if the abductor pollicis longus is intact.
What sensory deficits occur with wrist laceration injuries?
Sensory loss over the lateral 2/3 of the palm and palmar surface of the lateral 3.5 digits.
What does the radial nerve do after piercing the lateral intermuscular septum?
It enters the flexor compartment of the arm.
What is the action of the 3rd and 4th lumbricals?
Flexes MCP joint while extending DIP and PIP joints of the 4th and 5th fingers.
Where is the anesthetic injected for a brachial plexus block?
Directly into or immediately adjacent to the axillary sheath surrounding the brachial plexus.
What is wrist drop and finger drop a result of?
Paralysis of all extensor muscles of the forearm due to radial nerve injury.
What anatomical structure does the ulnar nerve penetrate at the level of the coracobrachialis?
The medial intermuscular septum.
What is the effect of blocking the superficial branch of the radial nerve at the wrist?
Similar to level IV radial nerve injury.
What is the action of the biceps brachii when the forearm is pronated?
Forearm supination.
What condition can lead to compression of the median nerve near the cubital fossa?
Compartment syndrome due to a torn brachial artery from a supracondylar fracture.
What condition can lead to compression of the deep branch of the radial nerve?
Hypertrophy of the supinator muscle.
What does the abnormal pinch sign test for?
Anterior interosseous nerve injury.
What happens to the triceps brachii muscle in a level I radial nerve injury?
It is completely paralyzed.
What is the condition of elbow and shoulder extension in a radial nerve injury?
There is no problem with elbow and shoulder extension because the triceps brachii has received full motor supply proximal to the site of injury.
What accompanies the ulnar nerve at the distal forearm?
The ulnar artery on its lateral side.
What condition can cause compression of the median nerve within the carpal tunnel?
Carpal tunnel syndrome.
What is the main action of the 1st and 2nd lumbricals innervated by the median nerve?
Flexes MCP joint while extending DIP and PIP joints of the 2nd and 3rd fingers.
What movements are associated with the sternocleidomastoid (SCM) muscle?
Neck rotation to the contralateral side.
Which muscles are involved in arm adduction?
Supraspinatus, Deltoid, Pectoralis major, Latissimus dorsi.
How does the median nerve enter the hand?
By travelling within the carpal tunnel, lateral and deep to the palmaris longus tendon.
How does carpal tunnel syndrome affect sensation in the palm?
The sensation over the lateral 2/3 of the palm is unaffected.
What is the effect of median nerve injury on thenar muscles?
All three thenar muscles are paralyzed, severely affecting thumb opposition.
What happens when the lumbricals and interossei are paralyzed due to ulnar nerve injury?
Cannot flex MCP while extending DIP and PIP joints.
Where does the superficial branch of the radial nerve pass down?
The anterolateral aspect of the forearm, deep to the brachioradialis muscle.
What are the common sites for brachial plexus nerve block?
Interscalene block and supraclavicular block.
Which nerve innervates the supinator muscle?
Posterior interosseous nerve (branch of radial nerve) (C6, C7).
At the elbow, where does the ulnar nerve pass in relation to the medial epicondyle?
Posterior to the medial epicondyle of the humerus.
What are some causes of radial nerve injury?
Nerve injection injury, posterior glenohumeral dislocation, Saturday night palsy.
Why do the wrist and fingers drop?
Due to the unopposed action of flexor muscles and the effect of gravity.
What does a 'pinch' posture during the 'OK' sign indicate?
Absence of flexion of the interphalangeal joint of the thumb and DIP joint of the index finger, indicative of isolated anterior interosseous nerve injury.
Where is the median nerve prone to entrapment?
Between the heads of the pronator teres (PT).
Which nerve innervates the biceps brachii?
Musculocutaneous nerve.
Why is there no wrist drop in this radial nerve injury?
The extensor carpi radialis longus has already received innervation from the radial nerve near the cubital fossa before the nerve bifurcates.
