Upper limb neuromuscular supply Flashcards
Which spinal roots contribute to the axillary nerve?
C5 + C6
What are the sensory functions of the axillary nerve?
gives rise to upper lateral cutaneous nerve of the arm = innervates skin over lower deltoid (regimental badge area).
What muscles are innervated by the axillary nerve?
Teres minor and deltoid
Which mechanisms of injury can commonly affect the axillary nerve?
Fracture of humeral surgical neck
Shoulder dislocation
If the axillary nerve is disrupted, which motor function if pathognomonic?
Unable to abduct arm to >15 degrees.
If the axillary nerve is damaged, which sensory impairment is pathognomonic?
Loss of sensation over regimental badge area.
What is era’s palsy?
Clinical condition resulting from damage to C5 and C6 roots of brachial plexus.
What causes era’s palsy?
Excessive increase in angle between neck and shoulder = stretches nerve roots.
In erb’s palsy, how will a patient normally hold their arm?
Internally rotated adduction.
**Unable to externally rotate or abduct their arm.
Which nerve roots form the musculocutaneous nerve?
C5, C6, C7
What are the motor functions of the musculocutaneous nerve?
Anterior compartment of arm (biceps, coarcobrachialis, brachialis)
What are the sensory functions of the musculocutaneous nerve?
Innervates anterolateral aspect of forearm (lateral cutaneous nerve)
Which movements is the musculocutaneous nerve responsible for?
Flexion of arm at elbow and shoulder.
Biceps also supinates forearm.
Which mechanisms of injury can commonly damage the musculocutaneous nerve?
Penetrating trauma to axilla
What clinical findings are present if there is damage to the musculocutaneous nerve?
Loss of sensation over anterolateral aspect of forearm
Elbow and shoulder flexion are weakened
Forearm supination is weakened
Which nerve roots form the median nerve?
C6, C7, C8, T1
What are the sensory function of the median nerve?
Lateral aspect of the palm (palmar cutaneous branch)
Lateral 3 and a half fingers anteriorly (digital cutaneous branch)
Lateral 3 fingertips
What is the motor function of the median nerve?
Flexor (anterior) compartment of forearm (not FCU or lateral half of FDP)
Thenar muscles
Lateral 2 lumbricals
What movements do muscles supplied by the median nerve do?
Forearm pronation
Wrist flexion
Digital flexion
Thumb flexion, opposition and adduction
Index and middle finger MCP flexion + IP extension
How is the median nerve normal damaged at the elbow?
Supracondylar fracture of the humerus
What characteristic sign is seen when the median nerve is damaged?
Hand of benediction.
How is the median nerve often damaged at the wrist?
Lacerations just proximal to flexor retinaculum.
Which nerve roots form the radial nerve?
C5 to T1.
What is the motor function of the radial nerve?
Triceps
Extensor (posterior) muscles of forearm.
What are the sensory innervations of the radial nerve?
Skin of posterior arm
Lateral aspect of dorsum of hand
Dorsal surface of lateral 3 and a half digits
How can the radial nerve be damaged at the axilla?
Shoulder dislocation
Proximal humerus fracture
Excessive pressure on the nerve within the axilla
What characteristic sign is seen with radial nerve damage?
Wrist drop
How can the radial nerve be damaged at the radial groove?
Fracture of the humeral shaft
How can the deep branch of the radial nerve be injured in the forearm?
Fracture of radial head or posterior dislocation of the radius
How can the superficial branch of the radial nerve be injured in the forearm?
Stabbing or laceration of the forearm
If the superficial branch of the radial nerve is damaged what happens to motor function?
No effect.
**Superficial branch is purely sensory.
If the deep branch of the radial nerve is injured, what happens to sensory function?
No effect.
Which nerve roots form the ulnar nerve?
C8 -T1.
What is the sensory innervation of the ulnar nerve?
Medial one and a half fingers and associated palm area.
What are the motor functions of the ulnar nerve?
FCU
Medial half FDP
Intrinsic muscles of hand (except thenar muscles and lateral 2 lumbricals).
What is a common test for ulnar nerve palsy?
Froment’s test
Why is the ulnar claw worse when the ulnar nerve is damaged at the wrist compared to when damaged at the elbow?
Because the FDP is intact.
What are the 5 main vessels providing blood supply to the upper limb?
Subclavian artery
Axillary artery
Brachial artery
Radial artery
Ulnar artery
When does the subclavian artery become the axillary artery?
At the lateral border of the 1st rib when it enters the axilla.
When does the axillary artery become the brachial artery?
As it passes the lower border of Teres major.
Which vessels supply the triceps?
The profunda brachii arteries
When does the brachial artery become the ulnar and radial arteries?
It bifurcates underneath the bicipital aponeurosis after moving through the curtail fossa.
Where do the radial and ulnar arteries terminate?
Anastamose in the hand by forming two arches (superficial palmar arch and deep palmar arch)
Which palmar arch gives rise to the digital arteries?
Superficial palmar arch
What are the major superficial veins of the upper limb?
Cephalic and basilic
Which vein connects the cephalic and basilica veins?
Median cubital vein
Which is the more medial superficial vein?
Basilic vein
Which is the more lateral superficial vein?
Cephalic vein
Which are the largest deep veins of the arm?
Brachial veins
Where are the brachial veins situation?
Either side of the brachial artery
