GA Forearm Muscles, Vasculature and Innervation

Question 1

Muscles of Forearm

Answer 1

flexors and pronators are in the anterior compartment
-served by median n. and branches
-supplied by radial and ulnar arteries
extensors and supinators are in the posterior compartment
-innervated by radial nerve and branches

Question 2

Superficial Flexor Compartment

Answer 2

Pronator teres muscle
Flexor Carpi Radialis muscle
Palmaris longus muscle
Flexor Carpi Ulnaris muscle

Question 3

Intermediate Flexor Compartment

Answer 3

Flexor Digitorum superficialis Muscle

Question 4

Depp Flexor Compartment

Answer 4

Flexor Digitorum profundus muscle
Flexor Pollici longus muscle
Pronator quadratus muscle

Question 5

Pronator Teres Muscle

Answer 5

most lateral of the forearm flexors
O- Ulnar head - coronoid process
Humeral head - medial epicondyle via common flexor tendon
I - Middle of convexity of lateral surface of radius
A - Pronation and flexion of forearm
N - Median n. (C6,C7)

Question 6

Flexor Carpi Radialis Muscle

Answer 6

medial to pronator teres, tendon does not pass thru carpal tunnel, Radial a. lies just lateral to this muscle
O- Medial epicondyle via common flexor tendon
I - Base of 2nd metacarpal
A - Flexion and radial deviation of the hand
N - Median n. (C6,C7)

Question 7

Palmaris Longus muscle

Answer 7

absent in one or both sides of people, passes superficial to flexor retinaculum, tendon lies deep and slightly medial to median n. at wrist
O- medial epicondyle via common flexor tendon
I - Distal 1/2 flexor retinaculum and apex of palmar aporneurosis
A - Flexion of hand at wrist and tenses palmar aponeurosis
N - Median n. (C7,C8)

Question 8

Flexor Carpi Ulnaris muscle

Answer 8

most medial of superficial flexors, tendon is guide to ulnar n. and a. on lateral side at wrist
O - Humeral head - medial epicondyle via common flexor tendon
Ulnar head - Olecranon and posterior border via aperneurosis
I - Pisiform, hook of hamate and 5th metacarpal
A - Flexion and ulnar deviation of hand
N - Ulnar n. (C7,C8)

Question 9

Flexor Digitorum Superficialis muscle

Answer 9

median n. and ulnar n. enter forearm by passing b/w its two heads, gives rise to 4 tendons at wrist
O - Humeroulnar head - medial epicondyle via common flexor tendon and coronoid process
Radial head - superior 1/2 anterior border
I - Shafts of middle phalanges of medial 4 digits via split tendon
A - flexion of PIP’s; strong flexion of MP’s; flexion of wrist
N - Median n. (C7,C8,T1)

Question 10

Flexor Digitorum Profundus muscle

Answer 10

only muscle that can flex DIP’s, gives rise to 4 tendons at wrist
O - medial and lateral halves: proximal 3/4 medial and anterior surfaces of ulna and interosseous membrane
I - Medial half - Basses of phalanges of 4th and 5th digits
Lateral half - Basses of phalanges of 2nd and 3rd digits
A - Medial half - Flexes DIP’s of 4th and 5th
Lateral half - Flexes DIP’s of 3rd and 2nd
N - Medial half - Ulnar n. (C8,T1)
Lateral half - A.I.N. (C8,T1)

Question 11

Flexor Pollicis Longus muscle

Answer 11

lies lateral to FDP, passes thru the carpal tunnel
O - Anterior surface of radius and adjacent interosseous membrane
I - base of distal phalanx of thumb
A - Flexion of thumb; flexion of wrist
N - A.I.N. (C8,T1)

Question 12

Pronator Quadratus muscle

Answer 12

deepest muscle in anterior forearm, costal distal radius, ulna and interosseous membrane, A.I.A. and A.I.N. pass deep to this muscle
O - Distal 1/4 of anterior surface of ulna
I - Distal 1/4 of anterior surface of radius
A - Prime mover for forearm pronation; deep fibers bind radius and ulna together
N - A.I.N. (C8,T1)

Question 13

Superficial Extensor Compartment

Answer 13

Brachioradialis muscle
Extensor Carpi Radialis longus muscle
Extensor Carpi Radialis brevis muscle
Extensor Digitorum Muscle
Extensor Digiti Minimi muscle
Extensor Carpi Ulnaris muscle

Question 14

Depp Extensor Compartment

Answer 14

Supinator Muscle

Extensor Indicis muscle

Question 15

Outcropping Extensor Muscle

Answer 15

Abductor Pollicis Longus muscle
Extensor Pollicis Longus muscle
Extensor Pollicis Brevis muscle

Question 16

Brachioradialis muscle

Answer 16

lies on anterolateral surface of forearm, forms lateral border of cubital fossa, functionally a flexor, but is innervated by radial nerve, overlies radial n. and a. proximally, does not cross wrist joint
O - Proximal 2/3 of lateral supracondylar ridge
I - Lateral surface of distal end of radius proximal to styloid process
A - Forearm flexion (maximal in mid-pronated/mid-supinated position)
N - Radial n. (C5,C6,C7)

Question 17

Extensor Carpi Radialis Longus muscle

Answer 17

partially overlapped nu brachioradialis m., distal tendon is crossed over by Abductor Pollicis longus and Extensor Pollicis brevis
O - Lateral supracondylar ridge
I - Dorsal aspect, base of 2nd metacarpal
A - Ext. and radial deviation of wrist
N - Radial n. (C6,C7)

Question 18

Extensor Carpi Radialis Brevis muscle

Answer 18

shorter that ECRL because it arises distally
O - Lateral epicondyle of humerus via common extensor tendon
I - Dorsal aspect, base of 3rd metacarpal
A - Ext. and radial deviation of wrist
N - Deep branch of radial n. (C7,C8)

Question 19

Extensor Digitorum Muscle

Answer 19

principle extonsor of medial 4 digits, tendons spread out on dorsum of hand as they pass the digits
O - Lateral epicondyle via common extensor tendon
I - Extensor expansion of medial 4 digits
A - Ext. of medial 4 digits primarily at metaphalanges, secondarily at intermediate phalanges, ext of wrist
N - Deep branch of radial n. (C7,C8)

Question 20

Extensor Digiti Minimi muscle

Answer 20

partially detached part of extensor digitorum m.
O - Lateral epicondyle via common extensor tendon
I - Extensor expansion of 5th digit
A - Extension of 5th digit primarily at metaphalange, secondarily at Intermediate phalanges, assists with wrist ext.
N - Deep branch of radial n. (C7,C8)

Question 21

Extensor Carpi Ulnaris muscle

Answer 21

located on medial border of forearm, has humeral and ulnar heads
O - Lateral epicondyle via common extensor tendon, posterior border of ulna via shared aponeurosis
I - Dorsal aspect, base of 5th metacarpal
A - Ext and ulnar deviation of wrist
N - Deep branch of radial n. (C7,C8)

Question 22

Supinator muscle

Answer 22

helps form floor of cubital fossa
O - Lateral epicondyle, radial collateral and anular ligaments, supinator fossa, crest of ulna
I - Lateral, posterior, and anterior surfaces of proximal 1/3 or radius
A - Supination of forearm, especially slow, unopposed with extended forearm
N - Deep branch of radial n. (C7,C8)

Question 23

Extensor Indicis muscle

Answer 23

part of deep extensor group, lies medial and alongside Extensor pollicis longs, confers independence to index finger
O - Posterior surface of distal 1/3 ulna and interosseous membrane
I - Extensor expansion of 2nd digit; assits with wrist extension
A - Extension of 2nd digit (independent extension)
N - P. I. N. (C7,C8)

Question 24

Abductor Pollicis Longus muscle

Answer 24

lies just distal to supinator muscle, tendon and belly may be split into 2, forms one border of the snuffbox
O - Posterior surface of proximal halves of ulna, radius and interosseous membrane
I - Base of 1st metacarpal
A - ABD of thumb, ext. of CM
N - P.I.N. (C7,C8)

Question 25

Extensor Pollicis Brevis muscle

Answer 25

tendon lies parallel and immediately medial to APL but extends further, forms one border of anatomical snuffbox
O - Posterior surface distal 1/3 of radius of interosseous membrane
I - dorsal aspect, base of proximal phalanx of thumb
A - Extension of proximal phalanx of thumb at MP, ext. of CM, assists with ext. and radial deviation
N - P.I.N. (C7,C8)

Question 26

Extensor Pollicis Longus muscle

Answer 26

tendon passes medial to the dorsal tubercle of radius, form one border of the anatomical snuffbox
O - Posterior surface middle 1/3 of ulna and interosseous membrane
I - Dorsal aspect, base of distal phalanx of thumb
A - Extension of distal phalanx at IP, ext. of MP’s and CM’s
N - P.I.N. (C7,C8)