L13_The Forearm and Hand (2)

Question 1

Muscles of the superficial layer of the posterior compartment of the forearm

Extensor carpi ulnaris (origin, insertion, functions, innervation)

Answer 1

Origin: Lateral epicondyle of the humerus

Insertion: Metacarpal V

Functions: extension and adduction (ulnar deviation) of the hand at the wrist

Innervation: Deep radial nerve (C7-C8)

Question 2

Muscles of the superficial layer of the posterior compartment of the forearm

Extensor Digitorum (origin, insertion, functions, innervation)

Answer 2

Origin: lateral epicondyle of the humerus

Insertion: 4 tendons inserting on middle and distal phalanges II-V via “extensor hoods”

Functions: Extension of the hand at the wrist, MCP and IP joints

Innervation: deep radial nerve (C7-C8)

Question 3

Muscles of the superficial layer of the posterior compartment of the forearm

Extensor Carpi Radialis Longus (origin, insertion, functions, innervation)

Answer 3

Origin: lateral supracondylar ridge of the humerus

Insertion: Base of metacarpal II

Functions: Extension and abduction (radial deviation) of the hand at the wrist

Innervation: Radial nerve (C6-C7)

Question 4

Muscles of the deep layer of the posterior compartment of the forearm

Extensor Pollicis Longus (origin, insertion, functions, innervation)

Answer 4

Origin: Interosseous membrane and posterolateral surface of the ulna

Insertion: Base of 1st distal phalanx of digit I

Functions: Extends the thumb at the IP joints

Innervation: Deep radial nerve (C7-C8)

Question 5

Tell me the broders of the “anatomical snuff box”

Answer 5

Question 6

Muscles of the deep layer of the posterior compartment of the forearm

Extensor indicis (origin, insertion, functions, innervation)

Answer 6

Origin: Interosseous membrane and posterolateral surface of the ulna

Insertion: joins tendon IIof extensor digitorum, extensor expansion

functions: extends index finger at MCP and IP joints digit II

Innervation: deep radial nerve (C7-C8)

Question 7

Explain the trajectory of the arteries in the anterior and posterior forearm

Answer 7

1- The brachial artery splits into the ulnar and the radial artery

Radial artery (supplies antero-lateral and postero-lateral muscles) -> travels posterior to the thumb

Ulnar artery (supplies antero-medial and postero-medial muscles)

2- The common interosseous artery devides itself from the ulnar artery

3- The common interosseous artery splits into the anterior and posterior interosseous artery

Anterior interosseous artery (supplies deep muscles of anterior compartment) -> travels with the anterior interosseous nerve

Posterior interosseous artery (supplies deep muscles of posterior compartment)

Question 8

Give my the location and the function of the extensor retinaculum

Answer 8

Location: on the posterior side of the wrist

function: holding all of the posterior tendons together to keep them in place when movinf the wrist

Question 9

Location and innervation of the deep radial nerve

Answer 9

Location: divides from the radial nerve just below the lateral epicondyle and pierces through the supinator muscle (DEEP)

Innervation deep: gives innervation to the posterior/extensor compartment of the forearm (extensor digitorum, extensor carpi ulnaris, extensor digiti minimi, supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis)

Question 10

Tell me the myotomes of the upper limb so far (10)

Answer 10

Question 11

Muscles of the superficial layer of the posterior compartment of the forearm

Anconeus (origin, insertion, functions, innervation)

Answer 11

Origin: lateral epicondyle of the humerus

Insertion: lateral side of the olecranon and the upper 1/4 of the ulna

Functions: extends the forearm at the elbow

Innervation: Radial nerve (C7-T1)

Question 12

Muscles of the superficial layer of the posterior compartment of the forearm

Brachioradialis (origin, insertion, functions, innervation)

Answer 12

origin: lateral supracondylar ridge of the humerus

Insertion: Styloid process of the radius

Functions: flexion of the forearm at the elbow

Innervation: Radial nerve (C5-C7)

Question 13

Content of the anatomical snuff box

Answer 13

• Radial artery
• Branches from superficial radial nerve

Question 14

Muscles of the deep layer of the posterior compartment of the forearm

Extensor Pollicis Brevis (origin, insertion, functions, innervation)

Answer 14

Origin: Interosseous membrane and posterior surface of distal radius

Insertion: Base of the 1st proximal phalanx of digit I

Functions: extends the thumb at the MCP joint

Innervation: deep radial nerve (C7-C8)

Brevis tendon between 2 longus tendons

Question 15

Muscles of the superficial layer of the posterior compartment of the forearm

Extensor Carpi Radialis Brevis (origin, insertion, functions, innervation)

Answer 15

Origin: Lateral epicondyle of the humerus

Insertion: Base of metacarpals II-III

Functions: Extension and abduction (radial deviation) of the hand at the wrist

Innervation: Radial nerve (C7-C8)

Question 16

Muscles of the deep layer of the posterior compartment of the forearm

Abductor Pollicis Longus (origin, insertion, functions, innervation)

Answer 16

Origin: Posterior surface of the radius, interosseous membrane and posterolateral ulna

Insertion: Radial side of the base of the 1st metacarpal

Functions: abducts and extends the thumb at CMC joint

Innervation: Deep Radial nerve

Question 17

Location and innervation of the superficial radial nerve

Answer 17

Location: divides from the radial nerve and travels deep to brachioradialis muscle, the branches also travel superficial to the snuff box

Innervation: Sensory innervation along the posterolateral forearm

Question 18

Muscles of the deep layer of the posterior compartment of the forearm

Supinator (origin, insertion, functions, innervation)

Answer 18

Origin: Lateral epicondyle of the humerus

Insertion: lateral side of the proximal radius

Function: supination of the forearm

Innervation: deep radial nerve (C7-C8)