Forearm- Posterior Muscles

Question 1

Superficial forearm posterior muscles

Answer 1

Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris

Question 2

Which nerve innervates the superficial muscles of the posterior forearm?

Answer 2

radial

Question 3

Extensor carpi radialis longus

Answer 3

• Originates on the lateral side of the humerus (specifically, from the supracondylar ridge)
• Inserts on the base of metacarpal II.
• Extends and abducts the hand.
N: c5-c8--> radial n
BV:  radial artery

Question 4

Which superficial extensor of the posterior forearm doesn’t originate on the lateral epicondyle of the humerus

Answer 4

Extensor carpi radialis longus

Question 5

Extensor carpi radialis brevis

Answer 5

• Inserts on the base of metacarpal III; it extends and abducts the hand.
N: C5-C8–> radial N
BV: Radial artery, profunda brachii–> radial collateral branch

Question 6

Extensor digitorum

Answer 6

gives rise to the extensor tendons, which has lateral and central bands:
• Lateral bands of the tendons insert on the bases of the distal phalanges of digits 2-5.
• Central bands of the tendons insert on the middle phalanges of digits 2-5.
• Extensor digitorum extends digits 2-5 and the hand.
N: deep radial–> posterior interosseous N
BV: posterior interosseous artery & radial recurrent artery

Question 7

Extensor digiti minimi

Answer 7

inserts into the extensor expansion on the middle phalanx of digit 5
• It extends this digit 5 (along with extensor digitorum).
N: Radial –> posterior interosseous N
BV: radial recurrent, anter interosseous, post interosseous artery

Question 8

Extensor carpi ulnaris

Answer 8

• Inserts on the base of metacarpal V
• It extends and adducts the hand.
Ulnar bv
Radial n–> posterior interosseuous

Question 9

Posterior forearm deep muscles

Answer 9

Supinator
Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus
Extensor indicis

Question 10

Supinator

Answer 10

The deep head originates on the ulna (specifically, the supinator crest) and wraps around the radius.
• The superficial head originates on the lateral epicondyle of the humerus (and from the radial collateral and annular
ligaments).
• Both heads insert together on the proximal lateral radius.
• Supinator supinates the forearm.

Question 11

Abductor pollicis longus

Answer 11

• Originates on the middle third of the posterior radius and ulna (and the interosseous membrane).
• Inserts on metacarpal one (on the lateral side of its base).
• Abducts the thumb and hand

Question 12

Extensor pollicis brevis

Answer 12

Originates on the radius and interosseous membrane.
• Inserts via a tendon at the base of the proximal phalanx of the thumb.
• Extends the thumb and abducts the hand.

Question 13

Extensor pollicis longus

Answer 13

• Originates on the ulna and interosseous membrane.
• Inserts via a tendon on the base of the distal phalanx of the thumb.
• Extends the thumb and abducts the hand.

Question 14

Extensor indicis

Answer 14

Originates on the distal ulna and interosseous membrane.

Question 15

Which muscle is the only muscle to inser in the forearm and act upon it

Answer 15

Supinator

Question 16

Which muscle is the only one that acts on digit 2

Answer 16

extensor indicis

Question 17

Anatomical snuffbox borders

Answer 17

anteriorly by the abductor pollicis longus and extensor

pollicis brevis tendons anteriorly and the tendon of extensor pollicis longus posteriorly.

Question 18

Contents of the anatomical snuffbox

Answer 18

The radial artery, the scaphoid, and trapezium lie within the boundaries of the anatomical snuffbox; pain in the
anatomical snuffbox can be indicative of a fractured scaphoid