Antebrachial fascia

The antebrachial fascia or deep fascia of the forearm is a thick connective tissue fascia investing the muscles of the forearm. It also formes the lateral intermuscular septum which divides the forearm muscle into the two following compartments of the forearm together with the radius, ulna and interosseous membrane:

• anterior compartment
• posterior compartment

Summary

• location: forearm
• blood supply: radial and ulnar artery
• innervation: branches of the median, radial, ulnar nerves
• relations: brachial facia, lacertus fibrosus, transverse and dorsal carpal ligaments, palmaris longus muscle

Gross anatomy

The antebrachial fascia envelopes the forearm from the elbow to the wrist. The antebrachial fascia is thicker on its dorsal aspect and distally than on the volar side and proximally ².

Besides the lateral intermuscular septum, which divides the muscles of the forearm together with the radius, ulna and interosseous membrane into an anterior and posterior compartment, it forms several intermuscular septa enclosing the different forearm muscles.

Proximally the antebrachial fascia is connected to the olecranon and the proximal ulna. On the inside of the elbow, the antebrachial fascia features an opening for the connection of the superficial and deep veins of the forearm ².

Distally and volar it is continuous with the transverse carpal ligament forming a sheath for the palmaris longus muscle which inserts to the palmar aponeurosis ². On the dorsal side, it is continuous with the dorsal carpal ligament.

Function

The antebrachial fascia ensheathes the muscles of the forearm separating extensor and flexor muscle groups together with the radius, ulna and interosseous membrane.

It serves as an insertion site for the bicipital aponeurosis (lacertus fibrosus) and to the triceps tendon ²  and serves as a site of origin for the forearm muscles including extensor carpi ulnaris and extensor digiti minimi muscles ².

Attachments

Musculotendinous

Musculotendinous attachments of the antebrachial fascia include the following ²:

• brachial fascia
• lacertus fibrosus
• triceps tendon
• extensor carpi ulnaris
• extensor digiti minimi
• transverse carpal ligament
• dorsal carpal ligament

Ligamentous

Ligamentous or bony attachments of the crural fascia are:

• olecranon
• ulna

Boundaries

The antebrachial fascia borders and is continuous to the following structures ^1,2:

• proximal: brachial fascia, lacertus fibrosus, olecranon
• distal: palmar (transverse) and dorsal carpal ligaments
• anterior: palmaris longus
• posterior: ulna

Arterial supply

The antebrachial fascia receives blood from the branches of the radial and ulnar arteries including the superficial palmar arch.

Innervation

The antebrachial fascia is richly innervated containing free nerve endings, Pacini and Ruffini corpuscles ³ from branches of the median, ulnar and radial nerves.

Histology

The antebrachial fascia appears as an irregular mesh essentially consisting of collagen fibre bundles intermixed with many elastic fibres ⁴ with internal and external layers showing characteristics of epimysial fasciae and an aponeurosis-like median layer consisting of layers of parallel undulating collagen fibre bundles ^4,5.

Radiographic features

Ultrasound

The antebrachial fascia appears as a thick hyperechoic lamina of connective tissue on ultrasound.

Related pathology

The antebrachial fascia or deep fascia of the forearm is related to the following pathologies ^6,7:

• acute compartment syndrome
• chronic exertional compartment syndrome
• nerve compression syndromes of the forearm
  • cubital tunnel syndrome
  • pronator teres syndrome