The anterior (flexor/pronator) compartment of the forearm to hand[muscles]

Question 1

What are the superficial muscles in the anterior of the forearm?

Answer 1

1. Pronator Teres (PT)
2. Flexor carpi radialis (FCR)
3. Palmaris longus (PL) - may not be present in everybody
4. Flexor carpi ulnaris (FCU)

Question 2

What are the origins, insertions and movements of the superficial muscles?

Answer 2

Origin:
PT, FCR, PL, FCU - Common flexor tendon that is attached to the anterior aspect of the medial epicondyle of the humerus

Insertion:
FCR - base of the 2nd metacarpal
FCU - pisiform carpal bone, which is attached to the base of the 5th metacarpal
PL - When present, passes over the flexor retinaculum to insert into the palmar aponeurosis

Movement:
FCR + FCU - flex the wrist
PL - assist with flexion of wrist

Question 3

What are the origins, insertions and movements of the intermediate muscles?

Answer 3

Flexor Digitorum Superficialis (FDS)

Origin: Common flexor tendon
Insertion: Under the flexor retinaculum to the base of the middle phalanx (4 tendons)
Movement: Flex the interphalangeal (IP) joints

Question 4

What are the origins, insertions and movements of the deep muscles?

Answer 4

Flexor digitorum profundus (FDP), Flexor pollicis longus (FPL), Pronator quadratus (PQ)

Origin:
FDP + PQ - ulnar origin
FPL - radial origin

Insertion:
FDP + FPL - pass under flexor retinaculum to the base of the distal phalanx.
PQ - lower end of the radius,

Movement:
FDP + FPL - Flex the IP joints
PQ - Pulls over the ulna in pronatory movements. PT assist PQ when additional speed and power of pronation are required

Question 5

What are the branches of the Median nerve in the arm to hand and what do they innervate?

Answer 5

From proximal:

1. Median nerve (from lateral + medial cord)
2. Anterior interosseous nerve (motor)
3. Palmar cutaneous branch (cutaneous)
4. Recurrent branch (motor, against normal flow)
5. Proper palmar digital nerve (cutaneous)

Median nerve - PT, FDS, FCR, PL
Anterior interosseous nerve - PQ, FPL, lateral half of FDP
Recurrent branch - supplies 5/20 muscles in the hand

Question 6

What are the branches of the Ulnar nerve in the arm to hand and what do they innervate?

Answer 6

From proximal

1. Ulnar nerve (from medial cord)
2. Dorsal cutaneous branch (cutaneous)
3. Palmar cutaneous branch (cutaneous)
4. Deep branch ulnar nerve (motor)
5. Proper palmar digital nerves (cutaneous)

Ulnar nerve - FCU, medial half of FDP
Dorsal cutaneous branch - supplies the posterior side of skin
Deep branch ulnar nerve - supplies most intrinsic muscles on the hand (15/20 muscles)

Question 7

What is the blood supply pathway int he forearm?

Answer 7

From proximal

Brachial artery –> Radial artery + Ulnar artery

Ulnar artery –> common interosseous artery –> Posterior interosseous artery + Anterior interosseous atery

Posterior interosseous artery - muscles require less strength so the vessels are smaller. It supplies the posterior compartment of the forearm

Anterior interosseous artery - muscles require more strength so the vessels are larger