Upper limb

Brachial and antebrachial fascia, intermuscular septa & bicipital aponeurosis

Fascia brachii, antebrachii et septa intermuscularia

Origin

Investing fascia of arm and forearm, medial/lateral intermuscular septa, and bicipital aponeurosis (lacertus fibrosus)

Insertion

Epicondylar ridges of humerus, ulna, radius, and continuous with wrist retinacula

Function

Encloses anterior and posterior muscular compartments, enhances venous return pump, and protects brachial artery and median nerve

Innervation

Medial/lateral antebrachial cutaneous nerves and fascial mechanoreceptors

Movement & chain

Assists force transmission and compartmental restraint

Palpation

Lacertus fibrosus palpable as tense band across medial cubital fossa during resisted supination/flexion

Clinical

Forearm compartment syndrome (urgent fasciotomy required to prevent Volkmann ischemic contracture); lacertus syndrome (median nerve compression).

Segmental innervation

C5–T1

In clinical practice

Monitoring for 5 P's (Pain, Pallor, Pulselessness, Paresthesia, Paralysis) in forearm trauma; fascial release

Region in the model

Upper limb