Muscles Of Hand

Question 0

Abductor pollicis brevis Origin? Insertion? Innervation? Action?

Answer 0

O: Flexor retinaculum and tubercles of scaphoid and trapezium

I: Lateral side of base of proximal phalanx of thumb

Innervation: Median nerve (C8 and T1)

Action: Abducts thumb; helps oppose it

Question 1

Opponens pollicis Origin? Insertion? Innervation? Action?

Answer 1

O: Flexor retinaculum and tubercles of scaphoid and trapezium

I: Lateral side of 1st metacarpal

Innervation: Median nerve (C8 and T1)

Action: To oppose thumb, it draws 1st metacarpal medially to center of palm and rotates it medially

Question 2

Flexor pollicis brevis Origin? Insertion? Innervation? Action?

Answer 2

O: Flexor retinaculum and tubercles of scaphoid and trapezium

I: Lateral side of base of proximal phalanx of thumb

Innervation: Median nerve (C8 and T1)

Action: Flexes thumb

Question 3

Abductor digiti minimi Origin? Insertion? Innervation? Action?

Answer 3

O: Pisiform

I: Medial side of base of proximal phalanx of 5th finger

Innervation: Deep branch of ulnar nerve (C8 and T1)

Action: Abducts 5th finger; assists in flexion of its proximal phalanx

Question 4

Flexor digiti minimi brevis Origin? Insertion? Innervation? Action?

Answer 4

O: Hook of hamate and flexor retinaculum

I: Medial side of base of proximal phalanx of 5th finger

Innervation: Deep branch of ulnar nerve (C8 and T1)

Action: Flexes proximal phalanx of 5th finger

Question 5

Opponens digiti minimi Origin? Insertion? Innervation? Action?

Answer 5

O: Hook of hamate and flexor retinaculum

I: Medial border of 5th metacarpal

Innervation: Deep branch of ulnar nerve (C8 and T1)

Action: Draws 5th metacarpal anterior and rotates it, bringing 5th finger into opposition with thumb

Question 6

Lumbricals (1 and 2) Origin? Insertion? Innervation? Action?

Answer 6

O: Lateral 2 tendons of flexor digitorum profundus (unipennate)

I: Lateral sides of extensor expansions of 2nd-5th fingers

Innervation: Median nerve (C8 and T1)

Action: Flex metacarpophalangeal joints; extend interphalangeal joints of 2-5 fingers

Question 7

Lumbricals (3 and 4) Origin? Insertion? Innervation? Action?

Answer 7

O: Medial 3 tendons of flexor digitorum profundus (bipennate)

I: Lateral sides of extensor expansions of 2-5th fingers

Innervation: Deep branch of ulnar nerve (C8 and T1)

Action: Flex metacarpophalangeal joints; extend interphalangeal joints of 2-5th fingers

Question 8

Dorsal interossei 1-4 Origin? Insertion? Innervation? Action?

Answer 8

O: Adjacent sides of two metacarpals (bipennate)

I: Bases of proximal phalanges; extensor expansions of 2-4th fingers

Innervation: Deep branch of ulnar nerve (C8 and T1)

Action: Abduct 2-4th fingers from axial line; act with lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joints

Question 9

Palmar interossei 1-3 Origin? Insertion? Innervation? Action?

Answer 9

O: Palmar surfaces of 2nd, 4th, and 5th metacarpals (unipennate)

I: Bases of proximal phalanges; extensor expansions of 2nd, 4th and 5th fingers

Innervation: Deep branch of ulnar nerve (C8 and T1)

Action: Adduct 2nd, 4th and 5th fingers toward axial line; assist lumbricals in flexing metacarpophalangeal joints and extending interphalangeal joints