Muscle Chart: Extensor-Supinator - Deep Layer

Question 1

Supinator

Origin, Insertion, Innervation, Blood Supply

Answer 1

Origin: Lateral epicondyle of the humerus, radial collateral and annular ligaments, supinator fossa of crest of ulna

Insertion: Lateral, posterior and anterior proximal 1/3 of the radius

Innervation: Deep branch of the radial nerve (C7, C8)

Blood Supply: Recurrent branch of radial artery

Question 2

Supinator Movements

Answer 2

Supinates the forearm

Question 3

Abductor Pollicis Longus (APL)

Origin, Insertion, Innervation, Blood Supply

Answer 3

Origin: Posterior surface of the proximal halves of the ulna and radius and interosseous membrane

Insertion: Base of metacarpal 1

Innervation: Posterior interosseous nerve (C7, C8)

Blood Supply: Common interosseous

Question 4

Abductor Pollicis Longus (APL) Movements

Answer 4

Abducts and extends thumb at CMC joint

Question 5

Extensor Pollicis Brevis (EPB)

Origin, Insertion, Innervation, Blood Supply

Answer 5

Origin: Posterior surface of the distal third of radius and interosseous membrane

Insertion: Dorsal aspect of the base of proximal phalanx of the thumb

Innervation: Posterior interosseous nerve (C7, C8)

Blood Supply: Common interosseous

Question 6

Extensor Pollicis Brevis (EPB) Movements

Answer 6

Extends the proximal phalanx, MCP and CMC joint of thumb

Question 7

Extensor Pollicis Longus (EPL)

Origin, Insertion, Innervation, Blood Supply

Answer 7

Origin: Posterior surface of the middle third of ulna and interosseous membrane

Insertion: Dorsal aspect of the base of distal phalanx of thumb

Innervation: Posterior interosseous nerve (C7, C8)

Blood Supply: Common interosseous artery

Question 8

Extensor Pollicis Longus (EPL) Movements

Answer 8

Extends distal phalanx, IP, CMC, and MCP joint of thumb

Question 9

Extensor Indicis (EI)

Origin, Insertion, Innervation, Blood Supply

Answer 9

Origin: Posterior distal ulna and interosseous membrane

Insertion: Tendons of extensor digitorum (2nd digit)

Innervation: Posterior interosseous nerve (C7, C8)

Blood Supply: Common interosseous artery

Question 10

Extensor Indicis (EI) Movements

Answer 10

Extends the 2nd digit, helps extend hand and wrist