VH Dissector: Upper Limb: Anterior Forearm

Add the Pronator Quadratus muscle. 

Origin - Distal 1/4th of the anterior surface of the ulna

Insertion - Distal 1/4th of the anterior surface of the radius

Innervation - Anterior Interosseous Nerve from Median Nerve

Action - Pronates the hand

Add the Flexor Pollicus Longus muscle has two heads of origin; Radial Head and Humeral Head.

Origin - Anterior surface of the radius; it also arises from the interosseous membrane.

Insertion - Base of the distal phalanx of the thumb

Innervation - Anterior Interosseous Nerve from Median Nerve 

Action - Flexion of the distal phalanx of the thumb and aids in thumb flexion

Add the Flexor Digitorum Profundus muscle.

Origin - Proximal 3/4ths of the anterior and medial aspects of the ulna and the ulnar half of the interosseous membrane

Insertion - Four long tendons at the base of the distal phalanx’s of the 4 medial fingers

Innervation - Lateral Part from Anterior Interosseous Nerve form Median Nerve and Medial Part from Ulnar Nerve 

Action - Finger flexion at the distal interphalangeal joints, also aids in hand flexion at the wrist

Add the Flexor Digitorum Superficialis muscle has two heads of origin; HumeroUlnar Head and Radial

Origin - HumeroUlnar Head- medial epicondyle of the humerus, ulnar collateral ligament, and coronoid process of the ulna; Radial Head- anterior surface of the radius just distal to the radial tuberosity

Insertion - Four long tendons into the middle phalanx of each of the 4 most medial fingers (2 through 5).

Innervation - Median Nerve (C7, C8, T1)

Action - Finger flexion at the metacarpophalangeal joints and proximal interphalangeal joints, also aids in hand flexion at the wrist

Add the Flexor Carpi Ulnaris muscle has two heads of origin; Humeral Head and Ulnar Head

Origin - Humeral Head- medial epicondyle of the humerus, Ulnar Head- medial margin of the olecranon and the posterior border of the ulna

Insertion - Pisiform bone. Halmus (Hook) of the Hamate Bone, 5th Metacarpal. The tendon the the flexor carpi ulnaris is a good guide to the ulnar nerve and artery, which are on its lateral side.

Innervation - Ulnar Nerve 

Action - Flexes hand at the wrist and ulnar deviation of the wrist

The Palmaris Longus muscle is absent in approximately 20% of the population. It is absent in this 3D cadaver.

Origin - Medial epicondyle of the humerus

Insertion - Anterior flexor retinaculum and palmar aponeurosis

Innervation - Median Nerve

Action - Flexes the hand at the wrist and tightens the palmar aponeurosis

Add the Flexor Carpi Radialis muscle.

Origin - Medial epicondyle of the humerus

Insertion - Base of the 2nd metacarpal. The tendon of the flexor carpi radialis can be used as a guide to the radial artery which lies just lateral to it.

Innervation - Median Nerve 

Action - Flexes the hand at the wrist and radial deviation of wrist

Add the Pronator Teres muscle has two heads of origin: Humeral Head and Ulnar Head

Origin - Humeral Head- medial epicondyle of humerus Ulnar Head- coronoid process of the ulna

Insertion - Middle lateral surface of the radius

Innervation - Median Nerve

Action - Pronates and flexes forearm

Add the Median Nerve It enters the forearm with the brachial artery; lies on the surface of the brachialis muscle; passes between the two heads of the pronator teres muscle. Near the wrist the median nerve becomes superficial by passing between the tendons of the flexor digitorum superficialis and flexor carpi radialis muscles. The branches of the median nerve (no branches in the arm):

The Articular branches to the elbow joint.

The Muscular branches to pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis.

The Anterior Interosseous Branch arises in the distal part of the cubital fossa; passes inferiorly on the interosseous membrane with the anterior interosseous branch of the ulnar artery. The anterior interosseous nerve runs between the flexor digitorum profundus and the flexor pollicis longus to reach the pronator quadratus, supplying flexor pollicis longus, pronator quadratus, and the lateral half of the flexor digitorum profundus muscle. It passes deep to the pronator quadratus and ends by supplying the wrist joint.

The Palmar Cutaneous Branch arises just proximal to the flexor retinaculum and becomes cutaneous between the tendons of the palmaris longus and the flexor carpi radialis muscle; supplies the skin of the lateral palm.

Any lesion that significantly reduces the size of the carpal tunnel may cause compression of the median nerve indicated by paresthesia (tingling), anesthesia (loss of tactile sensation), or hypoesthesia (diminished sensation). In cases of severe compression of the median nerve, there may be atrophy of the thenar muscles. To relieve symptoms of the carpal tunnel syndrome, transection of the flexor retinaculum (transverse carpal ligament) may be necessary.

Add the Ulnar Nerve which passes posterior to the medial epicondyle of the humerus, the ulnar nerve enters the forearm by passing between the two heads of the flexor carpi ulnaris muscle. It descends deep to this muscle on the flexor digitorum profundus where it accompanies the ulnar artery near the middle of the forearm. It becomes relatively superficial in the distal part of the forearm. Near the pisiform bone it pierces the deep fascia and passes superficial to the flexor retinaculum. The branches of the ulnar nerve are:

The Articular branches to the elbow joint. 

The Muscular branches to supply flexor carpi ulnaris and the medial half of the flexor digitorum profundus.

The Superficial branch (palmar cutaneous branch) supplies the skin of the medial palm and medial 1 ½ digits.

The Dorsal cutaneous branch supplies the posterior surface of the medial part of the hand and medial 1 ½ digits.

Ulnar Nerve Injury may result in extensive motor and sensory loss to the hand. Patients may have difficulty in making a fist due to inability to flex their fourth and fifth digits at the distal interphalangeal joints. The appearance of the hand is then known as claw hand.

Add the Radial Artery which begins in the cubital fossa, just medial to the biceps tendon at the level of the neck of the radius. The course of the radial artery in the forearm can be represented by a line connecting the midpoint of the cubital fossa to a point just medial to the tip of the styloid process of the radius. The radial artery crosses the floor of the anatomical snuff box. The radial artery ends by completing the deep palmar arch in conjunction with the ulnar artery. The branches of the radial artery are:

The Radial recurrent artery arises from the lateral side of the radial artery and ascends between the brachioradialis and brachialis muscles, supplies these muscles and anastomoses with the radial collateral artery to participate in the anastomosis around the elbow.

The  Muscular branches that supply muscles on the lateral side of the forearm. (Not identified in ths 3D Cadaver)

The Superficial Palmar Arch that anastomoses with the terminal part of the ulnar artery. The superficial palmar branch supplies the thenar muscles

The Deep Palmar Arch that runs across the wrist deep to the flexor tendons to anastomoses with the deep branch of the ulnar artery.

Add the Ulnar Artery makes a gentle curve as it passes from the cubital fossa to the medial side of the forearm. The ulnar artery passes with the median nerve between the ulnar and radial heads of the flexor digitorum superficialis. In the distal 2/3rds of the forearm, the ulnar artery lies lateral to the ulnar nerve. At the wrist the ulnar artery and nerve lie lateral to the tendon of the flexor carpi ulnaris. The branches of the Ulnar artery are:

The Anterior ulnar recurrent artery that arises just inferior to the elbow and runs between the brachialis and pronator teres supplying these muscles, anastomoses with the inferior ulnar collateral artery, participating in the anastomoses of the elbow. (Not identified in ths 3D Cadaver)

The Posterior ulnar recurrent artery that arises distal to the anterior ulnar recurrent, passes posterior to the medial epicondyle to anatomoses with the superior ulnar collateral artery and participate in the elbow anastomoses. (Not identified in ths 3D Cadaver)

The Common interosseous artery that arises in the cubital fossa and divides into the anterior and posterior interosseous arteries. (Not identified in ths 3D Cadaver)

The Muscular branches that supply muscles on the medial side of the forearm. (Not identified in ths 3D Cadaver)

Participates in both the superficial and deep palmar arches.