Muscles of the Hand

Question 1

Flexor Pollicis Brevis OIFIn

Answer 1

O: Distal border of flexor retinaculum and tubercle of trapezium, anterior surface of trapezoid and capitate bones
I: Base of proximal phalanx of thumb on radial side (with sesamoid bone)
F: Flexes metacarpophalangeal (MCP) joint of thumb
In: Median nerve C8 and T1 to superficial head, ulnar nerve to deep head (C8 and T1)

Question 2

Abductor Pollicis Brevis

Answer 2

O: Flexor retinaculum and the tubercles of scaphoid and trapezium bones
I: Base of proximal phalanx of thumb on radial side
F: Abduction of thumb
In: Median nerve C8 and T1

Question 3

Opponens Pollicis

Answer 3

O: Tubercle of trapezium and flexor retinaculum
I: Anterior and lateral surfaces of shaft of first metacarpal bone
F: Flexes and rotates toward the little finger (opposes) the carpometacarpal joint of thumb
In: Median nerve C8 and T1 and ulnar nerve C8 and T1

Question 4

Adductor Pollicis

Answer 4

O: Anterior surface of distal half of shaft of 3rd metacarpal bone; capitate bone
I: Ulnar side of base of proximal phalanx of the thumb (with sesamoid bone)
F: Adduction of thumb
In: Ulnar nerve C8 and T1

Question 5

Palmaris Brevis

Answer 5

O: Flexor retinaculum and medial aspect of palmar aponeurosis
I: Dermis on ulnar side of the hand
F: Helps with gripping by elevating the hypothenar aspect of the hand
In: Ulnar nerve C8 and T1

Question 6

Abductor Digiti Minimi

Answer 6

O: Pisiform, pisohamate ligament, and tendon of flexor retinaculum
I: Ulnar surface of the base of proximal phalanx and the extensor expansion of little finger
F: Abduction of little finger
In: Ulnar nerve C8 and T1

Question 7

Flexor Digiti Minimi Brevis

Answer 7

O: Convex surface of the hook of hamate bone and flexor retinaculum
I: Ulnar surface of base of proximal phalanx of little finger
F: Flexion of little finger at MCP joint
In: Ulnar nerve C8 and T1

Question 8

Opponens Digiti Minimi

Answer 8

O: Convex surface of hook of hamate and flexor retinaculum with flexor digiti minimi
I: Anterior surface and ulnar border of 5th metacarpal
F: Flexes carpometacarpal joint of little finger and rotates (opposes) this joint towards thumb
In: Ulnar nerve

Question 9

Lumbricals

Answer 9

O: Radial side of flexor digitorum profundus tendon of index and middle finger, third lumbrical from ulnar side of flexor digitorum profundus tendon of middle finger and radial side of flexor digitorum profundus of ring finger, ulnar side of flex. dig. of ring finger and little finger.
I: Radial side of extensor expansion of each finger
F: Weak flexion of metacarpo-phalangeal joints, extension of ICP
In: Median nerve C8 and T1 for first and second lumbricals, ulnar nerve C8 and T1 to third and fourth lumbricals

Question 10

Palmar Interossei

Answer 10

O: Anterior surface of metacarpal bones 1,2,3, and 5 toward the middle finger
I: Base of proximal phalanges and extensor expansion of digits 1,2,4, and 5 on the middle finger side
F: Adduction of digits 1,2,4, and 5 at MCP joints, assists with flexion of MCP, extends at ICP joints
In: Ulnar nerve C8 and T1

Question 11

Dorsal Interossei

Answer 11

O: Each muscle comes from adjacent surfaces of all metacarpal bones
I: Base of proximal phalanges and extensor expansion of digits 2,3, and 4
F: Abduction of digits 2,3, and 4 at the MCP joints, flexion of MCP, extends ICP
In: Ulnar nerve C8 and T1