Anatomy Median Nerve Lecture 9

Vocabulary-style flashcards covering the course, branches, and clinical correlations of the median and ulnar nerves based on the lecture transcript.

Median Nerve Roots

Nerve roots $C5, 6, 7, 8, T1$ arising from the medial and lateral cords of the brachial plexus.

Median nerve course (forearm)

Descends in the front of the forearm between the $2$ heads of the pronator teres, then between the flexor digitorum superficialis and profundus.

Carpal tunnel

The space deep to the flexor retinaculum where the median nerve enters the palm of the hand.

Median nerve muscular supply (forearm)

Supplies all superficial flexors except the $FCU$ and all deep flexors via the anterior interosseous nerve, except the medial $\frac{1}{2}$ of the $FDP$.

Palmar cutaneous nerve (Median)

A branch arising above the wrist that passes superficial to the flexor retinaculum to supply the lateral $\frac{2}{3}$ of the palm.

Median nerve terminal branches

Medial and lateral branches that supply the thenar eminence muscles ($3$ muscles), the $1^{st}$ and $2^{nd}$ lumbricals, and the palmar aspect of the lateral $3 \frac{1}{2}$ fingers.

Median nerve injury at elbow (Motor effects)

Loss of pronation, weak wrist flexion with ulnar deviation, inability to flex index and middle fingers, loss of thumb flexion, and paralysis of thenar eminence muscles.

Ape hand deformity

A condition resulting from median nerve injury characterized by a flat thenar eminence and lost thumb opposition (counting test).

Supracondylar humeral fracture

A common cause of median nerve injury when the damage occurs at the level of the elbow.

Median nerve injury at wrist (Sensory effects)

Loss of sensation in the palmar surface of the lateral $3 \frac{1}{2}$ fingers, while sensation in the hollow of the palm remains normal.

Ulnar Nerve Roots

Nerve roots $C7, 8, T1$ arising from the medial cord of the brachial plexus.

Ulnar nerve course (elbow)

Enters the forearm by passing behind the medial epicondyle.

Ulnar nerve muscular supply (forearm)

Supplies the flexor carpi ulnaris ($FCU$) and the medial part of the flexor digitorum profundus ($FDP$).

Ulnar nerve supply (hand)

Supplies all muscles of the hand except the three thenar eminence muscles and the $1^{st}$ and $2^{nd}$ lumbricals.

Dorsal cutaneous branch (Ulnar)

Arises in the forearm and supplies the skin of the medial $\frac{1}{3}$ of the dorsum of the hand and the dorsum of the medial $1 \frac{1}{2}$ fingers.

Ulnar nerve injury at elbow (Motor effects)

Weak wrist flexion with radial deviation, paralysis of all interossei (loss of abduction/adduction), paralysis of adductor pollicis, and partial claw hand.

Partial claw hand

A deformity caused by paralysis of the medial $2$ lumbricals (while the lateral $2$ lumbricals remain intact) and all interossei.

Paper test

A clinical test used to assess the loss of finger abduction and adduction, typically indicative of ulnar nerve injury.

Ulnar nerve injury at wrist (Causes)

Commonly caused by a stab wound, leading to motor loss in hand muscles and anesthesia in the palmar surface of the medial $1 \frac{1}{2}$ fingers.

Adductor pollicis

A muscle supplied by the ulnar nerve; its paralysis leads to the loss of thumb adduction.