Antebrachial fascia !
The antebrachial fascia is the sleeve around the forearm muscles; it forms compartments where swelling can cause compartment syndrome.
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What it is
The sleeve of deep fascia around the forearm muscles.
What it does
Forms the forearm compartments; swelling inside them can cause compartment syndrome.
Key facts
- Where
- Deep fascia of the forearm; thickens into the retinacula at the wrist
- Function
- Encloses the forearm compartments (tight in compartment syndrome)
Relations
- Contents
- Volar: superficial layer (pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris), FDS, then FDP, FPL and pronator quadratus, with the median and ulnar nerves; dorsal: extensors and the posterior interosseous nerve
- Superficial
- Cephalic, basilic and median forearm veins; the lateral forearm skin nerve and medial forearm skin nerve
- Deep
- Septa from its deep surface reach the radius and ulna; behind, it is fixed along the subcutaneous border of the ulna
- Above
- Continuous with the brachial fascia; strengthened at the elbow by the bicipital aponeurosis
- Below
- Thickens into the extensor retinaculum behind and the palmar carpal ligament in front, over the flexor retinaculum
How to find it
Its posterior attachment follows the subcutaneous border of the ulna, felt as a continuous ridge from the olecranon to the ulnar styloid. The mobile wad can be pinched between thumb and fingers on the lateral side of the forearm below the elbow.
On imaging
On ultrasound a bright line, and on MRI a thin dark line, wrapping the forearm compartments and thickening at the wrist into the retinacula. In compartment syndrome after a forearm fracture, the radiograph shows the fracture but the diagnosis rests on examination and compartment pressure; imaging must not delay fasciotomy. CT or MRI shows gas or fluid along the fascia in necrotising fasciitis.
Common problems
- Compartment syndrome: after a fracture, crush or tight cast, pressure builds in a forearm compartment and starves muscles and nerves.
- Warning signs: pain out of proportion, especially when the fingers are stretched; tight, swollen forearm.
How it is diagnosed
An emergency diagnosis from the exam, sometimes with a compartment pressure measurement.
Treatment
- Loosening casts and dressings right away.
- Emergency fasciotomy (opening the fascia) to relieve the pressure.
Clinical notes
- Volar fasciotomy: a curving incision from above the elbow to the palm releases the bicipital aponeurosis, the volar compartment and the carpal tunnel; a straight dorsal incision releases the dorsal compartment and mobile wad if needed
- Causes include supracondylar and forearm fractures, crush, reperfusion after arterial repair, infiltrated intravenous fluid and tight casts
- Chronic exertional compartment syndrome of the forearm is described in motorcycle riders and rowers
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
What are the three compartments enclosed by the antebrachial fascia?
Volar (flexors and pronators), dorsal (extensors) and the mobile wad (brachioradialis, ECRL, ECRB).
What is Volkmann ischaemic contracture?
Untreated forearm compartment syndrome scars the deep flexors, leaving a flexed wrist and clawed fingers; classically after a child's supracondylar fracture.
What pressure threshold is commonly used for forearm fasciotomy?
A gap of under 30 mmHg between diastolic pressure and compartment pressure.
What are the warning signs of forearm compartment syndrome?
Pain out of proportion, especially when the fingers are stretched, and a tight, swollen forearm.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- fascia antebrachii TA2 2544
- Official Spanish (DeCS)
- Fascia del antebrazo
- English (TA2)
- Antebrachial fascia
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Forearm Compartments.
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Representative model, for educational purposes only.
