Muscles of Unit 5-7

Name the 6 superficial muscles of the posterior forearm

Brachioradialis m.

Extensor Carpi Radialis Longus m.

Extensor Carpi Radialis Brevis m.

Extensor Digitorum m.

Extensor Minimi m.

Extensor Carpi Ulnaris m. 

Name the 2 muscles of the deep posterior forearm

Supinator m. 

Extensor indicis m. 

Name the 3 outcropping muscles of the deep post. forearm

Abductor pollicis longus m.

Extensor pollicis longus m.

Extensor pollicis brevis m.

Brachioradialis m.

A: Weak elbow flexor (strongest at neutral position), pronation/supination up to neutral position

N: Radial N. (C5,C6,C7)

Extensor carpi radialis longus m.

A: Extends and radially deviates the wrist (active during fist clenching)

N: Radial N. (C6, C7)

Extensor carpi radialis brevis m.

A: Extends and radially deviates the wrist 

N: Deep Branch of the Radial N. (C7, C8)

Extensor digitorum m.

A: Extends digits 2-5 

N: Deep Branch of the Radial N. (C7, C8)

Extensor digit minimi m.

A: Extends 5th digit (pinky)

N: Deep branch of the Radial N. (C7, C8)

Extensor carpi ulnaris m.

A: Extends & ulnarly deviates the wrist (active during fist clenching)

N: Deep Branch of the Radial N. (C7, C8)

Supinator m. 

A: Supinates forearm; rotates radius to turn palm anteriorly or superiorly 

N: Deep Branch of the Radial N. (C7, C8)

Extensor Indicis M.

A: Extends the 2nd digit; assists in wrist extension

N: Post. Interosseous Nerve (C7, C8)

Abductor pollicis longus m.

A: Abducts the thumb and extends it at the CMC jt.

N: Post. interosseous n. (C7, C8)

Extensor pollicis longus m.

A: Extends the distal phalanx of thumb at interphalangeal joint, MCP, and CMC jts.

N: Post. interosseous n. (C7, C8)

Extensor pollicis brevis m.

A: Extends the proximal phalanx of the thumb at MCP, and CMC jts.

N: Post. interosseous n. (C7, C8)

What are the compartments of the hands?

Hypothenar

Thenar

Central - short muscles

Adductor

Interosseous - muscles between the bones

Hypothenar location & muscles

Location: pinky side

Abductor digiti minimi m.

Flexor digiti minimi brevis m.

Opponens digiti minimi m.

Abductor digiti minimi m.

A: Abducts the pinky

N: Deep branch of the ulnar n. (C8, T1)

Flexor digiti minimi m.

A: Flexes the pinky 

N: Deep branch of the ulnar n. (C8, T1)

Opponens digiti minimi m.

A: Opposes pinky toward thumb

N: Deep branch of the ulnar n. (C8, T1)

Thenar location & muscles

Location: Thumb side

Abductor pollicis brevis m.

Flexor polliciis brevis m. [superficial/deep head]

Opponens pollicis m.

Adductor pollicis m. [oblique/transverse heads]

Abductor pollicis brevis m.

A: Abducts thumb; helps oppose it

N: Recurrent branch of the median n. (C8, T1)

Flexor pollicis brevis m.

Superficial head:

• A: Flexes thumb

• N: Recurrent branch of median n. (C8, T1)

Deep head:

• A: Flexes thumb

• N: Deep branch of ulnar n. (C8, T1)

Opponens pollicis brevis m.

A: Opposes thumb toward pinky (forms opposition)

N: Recurrent branch of the median n. (C8, T1)

Adductor pollicis m.

Transverse head:

• A: Adducts thumb

• N: Deep branch of ulnar n. (C8, T1)

Oblique head:

• A: Adducts thumb 

  • N: Deep branch of ulnar n. (C8, T1)

Central compartment - location & short muscles

Location: Central to the palm

Lumbricals - 4 total

Long flexor tendons and tendon sheaths 

• FDS & FDP tendons

Lumbrical m. (4)

1st and 2nd (Digits 2 and 3)

• A: flex MCP jt. and extend IP jt. at digits 2-3

• N: Median n. (C8, T1)

3rd and 4th (Digits 4 and 5)

• A: flex MCP jt. and extend IP jt. at digits 4-5

  • N: Deep branch of ulnar n. (C8, T1)

Proximal attachment: FDP tendon

Interosseous compartment - location & muscles

Location: Between the metacarpal bones 

Interossei muscles - 4 dorsal and 3 palmar 

• movements are relative to the 3rd digit (middle finger)

Dorsal interossei m., 1st-4th

A: Abducts 2nd-4th digits

N: Deep branch of ulnar n. (C8, T1)

DAB

Palmar interossei m., 1st-3rd

A: Adducts digits 2, 4, & 5 toward middle finger

N: Deep branch of ulnar n. (C8, T1)

PAD