Chapter 50: Elbow & Forearm Anatomy

Elbow & Forearm Anatomy anatomical overview focuses on the elbow and forearm, detailing the complex osseous, soft tissue, and neurovascular structures vital for upper limb movement and function, beginning with the skin's extensive vascular supply derived from muscle perforators, fasciocutaneous networks, and direct cutaneous vessels. The bones include the distal humerus, featuring the specialized articulating surfaces of the capitulum and trochlea, which engage with the radial head and the ulna's trochlear notch, respectively, forming the highly stable humero-ulnar and humero-radial joints. The ulna, positioned medially, features the prominent olecranon and coronoid process, while the lateral bone, the radius, provides a mobile strut, rotating around the ulna to facilitate pronation and supination via the proximal and distal radio-ulnar joints. Crucial stabilizing structures include the strong ulnar (medial) collateral ligamentous complex and the radial (lateral) collateral ligamentous complex, which are essential for coronal plane stability. Longitudinal stability is maintained by the interosseous membrane, a dense collagenous structure connecting the radial and ulnar shafts and restraining the radius from proximal migration, while stability at the wrist's ulnar aspect is reinforced by the Triangular Fibrocartilage Complex (TFCC). Forearm musculature is divided into the anterior (flexor) compartment (superficial and deep groups), and the posterior (extensor) compartment (superficial and deep groups), along with the mobile wad of Henry (Brachioradialis, Extensor carpi radialis longus and brevis). Vascular supply to this region is ensured by extensive periarticular anastomoses formed by branches of the terminal brachial artery (the radial and ulnar arteries), including the recurrent and interosseous arteries, ensuring collateral circulation around the elbow. Innervation is supplied by the median, ulnar, and radial nerves, with their specialized branches, the anterior and posterior interosseous nerves, which are prone to entrapment syndromes like pronator syndrome, cubital tunnel syndrome, and radial tunnel syndrome. Clinically significant injuries detailed include complex fracture-dislocations such as Monteggia, Galeazzi, and Essex–Lopresti injuries, which often involve disruption of the interosseous membrane or the distal radio-ulnar joint, and the potentially devastating condition of forearm compartment syndrome.