nerves of the hand Flashcards
(18 cards)
Which dermatome corresponds to the thumb?
C6.
Which dermatome corresponds to the middle finger?
C7.
Which dermatome corresponds to the little finger?
C8.
Which nerve supplies the digital nerves to the skin of the lateral 3.5 digits on the palmar surface and the nail beds of the lateral 3.5 digits on the dorsal surface?
Median nerve.
Does the palmar branch of the median nerve pass through the carpal tunnel?
No.
What area does the palmar branch of the median nerve supply?
The skin of the palm.
Why is the palm sensation not affected in carpal tunnel syndrome?
because the superficial palmar cutaneous branch passes superficially to the carpal tunnel
What is the movement that is completely lost when the median nerve is damaged?
Opposition (Ape hand)
Which branch of the ulnar nerve divides into palmar digital nerves to the medial 1.5 digits?
Superficial branch of the ulnar nerve.
Which branch of the ulnar nerve passes through the hypothenar muscles around the hook of hamate?
Deep branch of the ulnar nerve.
Which muscles are supplied by the deep branch of the ulnar nerve?
Three hypothenar muscles; one adductor pollicis muscle; three palmar interossei; four dorsal interossei muscles; and two medial lumbricals.
What are the effects of ulnar nerve injury at the medial epicondyle (fracture)?
Flexion weakness; radial deviation of the wrist; and claw hand (paralysis of the 3rd and 4th lumbrical muscles of the hand).
What are the effects of ulnar nerve injury at the hamate bone (Guyon’s canal syndrome)?
Weakness of the intrinsic muscles of the hand (claw hand) and loss of skin sensation on the medial palmar aspect of 1.5 digits.
How do you test for damage of the ulnar nerve?
A patient with ulnar nerve injury cannot hold a sheet of paper between the index and middle finger due to interosseous muscle paralysis.
What are the two terminal branches of the radial nerve in the forearm and hand?
Superficial branch and deep branch.
What does the superficial branch of the radial nerve supply?
Skin of the posterior surface of the lateral 3.5 fingers up to the proximal phalanges; it is located in the anatomical snuff box.
What does the deep branch (posterior interosseous nerve) of the radial nerve supply?
All the extensors of the forearm (except brachioradialis and extensor carpi radialis longus; which are innervated directly by the radial nerve); as well as the distal radioulnar; wrist; and carpal joints.
How do you test for radial nerve function?
Ask the patient to extend the MCP joints while the examiner provides resistance.
