Gross Anatomy Palpation Lab 5

median nerve (cutaneous)

Area of skin lateral to the imaginary line is the cutaneous supply of the median nerve, except for the skin covering the area where you palpate to find the opponens pollicis muscle. Except for the area of skin covering the dorsum of the distal phalanges of digits, one, two, three and the lateral half of digit four. These areas of skin are supplied by the median nerve.

Metacarpal phalangeal crease

Example: metacarpal phalangeal crease of digit 4.

radial nerve (cutaneous)

Except for the skin covering the area where you palpate to find the opponens pollicis muscle. That area of skin is supplied by the radial nerve. Area of skin lateral to the imaginary line is the cutaneous supply of the radial nerve, except for the area of skin covering the dorsum of the distal phalanges of digits, one, two, three and the lateral half of digit four.

Opponens pollicis

If one goes to the lateral aspect of the first metacarpal and palpates along the bone (underneath the abductor pollicis brevis) you will be palpating the opponens pollicis muscle. You will feel mostly bone, so to prove that you are palpating the opponens pollicis, have the patient press the tip of their thumb to the tip of their fifth digit. You will feel and see a muscle bulging out along the lateral aspect of the first metacarpal, which will be the opponens pollicis.

Extensor pollicis brevis

Immediately medial to the tendon of the abductor pollicis longus will be found the tendon of the extensor pollicis brevis. If the thumb is extended at the MP joint against resistance the tendon becomes prominent. On some individuals these tendons are quite prominent and easily distinguished from one another, while on others they are not.

Flexor pollicis brevis

Just medial and parallel to the abductor pollicis brevis will be found the flexor pollicis brevis muscle. There appears to be a slight crevice, just medial to the abductor pollicis brevis and that is where you palpate to feel the muscle. By having the patient flex their thumb at the MP joint, you should feel the muscle contract.

Ulnar nerve (cutaneous)

Looking at the palmar side of the hand, draw an imaginary line down the middle of the fourth digit, continuing down the palm. Area of skin medial to the imaginary line is the cutaneous supply of the ulnar nerve. Looking at the dorsal side of the hand, once again draw an imaginary line down the middle of the fourth digit, continuing down the dorsum of the hand. Area of skin medial to the imaginary line is the cutaneous supply of the ulnar nerve.

Abductor digiti minimi

The abductor digiti minimi is the most superficial muscle of the hypothenar group. Palpate the muscle mass on the palmar surface of the fifth metacarpal and have the patient carry out abduction of the fifth digit against resistance.

Adductor pollicis

The adductor pollicis muscle is found in the web space between the thumb and the index finger on the palmar surface of the hand. By having the patient adduct their thumb against resistance, you should be able to feel the muscle contract.

Distal palmer crease

The distal palmar crease starts at the most medial aspect of the palm and runs about ¾ of the way across.

Thenar eminence

The prominent muscular eminence associated with the first metacarpal is known as the thenar eminence. These muscles are associated with movements of the first digit and are easily palpated and tested. The thenar eminence of the dominant hand may look and feel somewhat more developed than its counterpart on the opposite hand.

Proximal palmer crease

The proximal palmar crease starts at the lateral aspect of the palm and runs about ¾ of the way across. Sometimes only one crease will be found, this is known as a simian crease.

Abductor pollicis longus

The tendon of the abductor pollicis longus is the most lateral and shorter of the two tendons which make up the lateral border of the anatomical snuffbox. To make the tendon prominent, have the patient abduct their thumb at the MP joint against resistance.

Extensor pollicis longus

The tendon of the extensor pollicis longus is found along the medial aspect of the snuffbox and continues up the dorsum of the first digit. It becomes more prominent when the patient carries out extension of the thumb at the IP joint.

Thenar crease(s)

You will find one or two creases which border the most medial aspect of the thenar eminence. There are the thenar crease(s).

Proximal and distal interphalangeal creases

digits 2 through 5.