Vessels and nerves of the anterior region of the forearm

Radial neurovascular bundle

Located most superficially and laterally. It includes the radial artery (a. radialis) with accompanying veins and the superficial branch of the radial nerve (r. superficialis n. radialis).

Syntopy of the artery:

• Upper third: sandwiched between the brachioradialis muscle (m. brachioradialis) laterally and the pronator teres muscle (m. pronator teres) medially.
• Middle and lower thirds: bounded laterally by the same brachioradialis muscle, and medially by the tendon of the flexor carpi radialis (m. flexor carpi radialis).

Course of elements:

• A. radialis in the lower third gives off the palmar carpal branch (r. carpalis palmaris). Near the wrist, it dives beneath the tendons of the thumb muscles (abductor pollicis longus and extensor pollicis brevis) and passes into the anatomical snuffbox.
• R. superficialis n. radialis is located lateral to the artery. At the border of the middle and lower thirds, it passes laterally beneath the tendon of m. brachioradialis, pierces the fascia, and enters the subcutaneous tissue.

Ulnar neurovascular bundle

Forms at the border of the upper and middle thirds of the forearm from the ulnar artery (a. ulnaris) and the ulnar nerve (n. ulnaris).

Peculiarities of the course:

• In the upper third, the bundle elements run separately. The artery heads medially from the center of the cubital fossa, passing beneath m. pronator teres and the flexor digitorum superficialis. The nerve descends between the heads of the flexor carpi ulnaris.
• Below the upper third, the artery and nerve converge. They descend between the flexor carpi ulnaris (medially) and the flexor digitorum superficialis (laterally).
• Throughout the common course of the bundle, the nerve lies medial to the artery. The entire bundle is located anterior to the flexor digitorum profundus, and near the wrist, anterior to the pronator quadratus.

Important branches of the ulnar artery:

1. Common interosseous artery (a. interossea communis): originates at the upper border of the forearm, dividing into anterior and posterior branches (the latter goes to the dorsum).
2. Dorsal carpal branch (r. carpalis dorsalis): arises at the border of the middle and lower thirds, runs medially beneath the tendon of the flexor carpi ulnaris, emerges subcutaneously on the dorsum of the hand, and participates in the formation of the dorsal carpal network.

Median nerve (n. medianus)

The median nerve is accompanied by a small companion artery (a branch from the anterior interosseous artery). Its position varies depending on the level of the forearm:

• Upper third: passes through the gap between the heads of m. pronator teres. Upon exiting, it crosses the ulnar artery anteriorly.
• Middle third: located in the space between the flexor digitorum superficialis and flexor digitorum profundus. An important detail is that the nerve is firmly fused with the fascia of the posterior surface of the superficial flexor and moves along with this muscle.
• Lower third: the nerve emerges from beneath the muscle belly and lies directly beneath the deep fascia of the forearm within the median sulcus (sulcus medianus). The sulcus is formed by the tendons of the flexor carpi radialis and palmaris longus. Due to this exposed position, the nerve is easily injured in trauma.

Further down, the nerve, along with the tendons, enters the carpal tunnel (canalis carpi).

Class and exam questions

What else to study on this topic

• Boundaries and contents of the anatomical snuffbox
• Topography of the carpal tunnel (canalis carpi) and carpal tunnel syndrome
• Course and branching of the posterior interosseous artery
• Formation and structure of the dorsal carpal network (rete carpale dorsale)

Other topics in the "Upper Extremity" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.