Small Muscles of the Hand

Question 1

Palmaris brevis

Answer 1

O - Flexor retinaculum, palmar aponeurosis
I - Skin of palm
N - Superficial branch of ulnar nerve
N - C8, T1
A - Corrugates skin to improve grip of palm

Question 2

Lumbricals (4)

Answer 2

O - Tendons of flexor digitorum profundus
I - Extensor expansion of medial four fingers
N - 1st and 2nd (i.e., lateral two) median nerve; 3rd and 4th deep branch of ulnar nerve
N - C8, T1
A - Flex metacarpophalangeal joints and extend interphalangeal joints of fingers except thumb

Question 3

Palmar interossei (4)

Answer 3

O - First arises from base of 1st metacarpal; remaining three from anterior surface of shafts of 2nd, 4th, and 5th metacarpals
I - Proximal phalanges of thumb and index, ring, and little fingers and dorsal extensor expansion of each finger
N - Deep branch of ulnar nerve
N - C8, T1
A - Palmar interossei adduct fingers toward center of third finger

Question 4

Dorsal interossei (4)

Answer 4

O - Contiguous sides of shafts of metacarpal bones
I - Proximal phalanges of index, middle, and ring fingers and dorsal expansion
N - Deep branch of ulnar nerve
N - C8, T1
A - Dorsal interossei abduct fingers from center of third finger; both palmar and dorsal flex metacarpophalangeal joints and extend interphalangeal joints

Question 5

Abductor pollicis brevis

Answer 5

O - Scaphoid, trapezium, flexor retinaculum
I - Base of proximal phalanx of thumb
N - Median nerve
N - C8, T1
A - Abduction of thumb

Question 6

Flexor pollicis brevis

Answer 6

O - Flexor retinaculum
I - Base of proximal phalanx of thumb
N - Median nerve
N - C8, T1
A - Flexes metacarpophalangeal joint of thumb

Question 7

Opponens pollicis

Answer 7

O - Flexor retinaculum
I - Shaft of metacarpal bone of thumb
N - Median nerve
N - C8, T1
A - Pulls thumb medially and forward across palm

Question 8

Adductor pollicis

Answer 8

O - Oblique head; 2nd and 3rd metacarpal bones; transverse head; 3rd metacarpal bone
I - Base of proximal phalanx of thumb
N - Deep branch of ulnar nerve
N - C8, T1
A - Adduction of thumb

Question 9

Abductor digiti minimi

Answer 9

O - Pisiform bone
I - Base of proximal phalanx of little finger
N - Deep branch of ulnar nerve
N - C8, T1 
A - Abducts little finger

Question 10

Flexor digiti minimi

Answer 10

O - Flexor retinaculum 
I - Base of proximal phalanx of little finger
N - Deep branch of ulnar nerve
N - C8, T1
A - Flexes little finger

Question 11

Opponens digiti minimi

Answer 11

O - Flexor retinaculum
I - Medial border fifth metacarpal bone
N - Deep ulnar nerve
N - C8, T1
A - Pulls 5th metacarpal forward as in cupping the palm