Medial Border of the Forearm

Description

Running along the ulnar side of the antebrachium, the medial border is defined by the subcutaneous crest of the ulna from the region of the olecranon proximally toward the ulnar head and styloid process distally. Anterior to this margin the flexor compartment forms a gentle convexity, with the flexor carpi ulnaris belly and tendon shaping the surface as they course toward the pisiform. Posteriorly, the extensor carpi ulnaris contour sits just lateral to the ulnar border, so the edge reads as a clean line between flexor and extensor masses in anatomical position. Palpation of this border is a standard orientation point in upper-limb examination because the ulna is the more consistently subcutaneous forearm bone, unlike the radius which is masked by the brachioradialis and extensor mass proximally. A tender step-off along the ulnar crest raises concern for an isolated ulnar shaft fracture (the classic nightstick mechanism), while a prominent distal ulna can signal distal radioulnar joint instability after a distal radius fracture. Clinically, this medial surface also frames the course of the ulnar neurovascular bundle in the proximal forearm (deep to flexor carpi ulnaris after passing the cubital tunnel), a relationship that matters in ulnar neuropathy and in surgical approaches that split or retract FCU. Surface anatomy teaching benefits from a realistic, neutral-standing figure, letting you relate the medial forearm border to adjacent landmarks, the medial epicondyle region, and the wrist-level ulnar styloid in one continuous line. Suitable for gross anatomy and physical diagnosis courses, orthopedics and hand surgery chapters discussing ulna shaft fractures or DRUJ pathology, and patient-facing materials explaining where clinicians palpate along the ulnar side of the forearm. Anatomical accuracy verified by SciePro's Medical Advisory Board.