# Humerus Anatomy > Humerus anatomy for MBBS Anatomy: tubercles, spiral groove, nutrient artery direction and the nerve injuries of each fracture level. - Canonical URL: https://prepelephant.com/topics/mbbs/anatomy/humerus-anatomy - Exam / course: MBBS · Subject: Anatomy - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Humerus Anatomy", PrepElephant, https://prepelephant.com/topics/mbbs/anatomy/humerus-anatomy ## Direct answer The humerus is the longest bone of the upper limb, and its surface records everything that crosses it: the intertubercular sulcus for the long head of biceps, the deltoid tuberosity, and the spiral groove where the radial nerve and profunda brachii artery lie directly against bone. Three injury zones dominate every exam — the surgical neck (axillary nerve with the posterior circumflex humeral artery), the spiral groove (radial nerve, wrist drop), and the supracondylar region of children (brachial artery and median nerve, Volkmann's ischaemic contracture). Its nutrient artery arises from the brachial artery, entering the anteromedial midshaft and pointing downwards, away from the upper growing end. ## What you must remember - **Upper end:** head faces upwards, medially and backwards; greater tubercle receives supraspinatus, infraspinatus and teres minor, lesser tubercle subscapularis; the surgical neck — not the anatomical neck — is the fracture line that strikes the axillary nerve. - **Intertubercular sulcus:** long head of biceps in the floor covered by latissimus dorsi; pectoralis major on the lateral lip, teres major on the medial lip — a favourite attachment-grid viva. - **Shaft:** deltoid tuberosity halfway down laterally (V-shaped for the deltoid); coracobrachialis on the middle third medially; the spiral groove runs obliquely behind the deltoid tuberosity carrying the radial nerve with the profunda brachii. - **Lower end:** capitulum articulates with the radius, trochlea with the ulna; radial and coronoid fossae in front, olecranon fossa behind; the medial epicondyle gives the common flexor origin, and the ulnar nerve grooves its posterior surface. - **Nerve-fracture pairs:** surgical neck — axillary nerve; spiral groove — radial nerve; supracondylar — median nerve and brachial artery; medial epicondyle — ulnar nerve. One bone, four exam questions. - **Blood supply:** nutrient branch of the brachial artery entering the anteromedial surface of the middle third, directed downwards because the humerus grows mainly at its upper end. - **Ossification:** the capitulum centres at about one year, the medial epicondyle at about five with its own centre fusing near twenty — which is why a child's "fracture" at the medial epicondyle may be a normal unfused epiphysis. ## One fall, three nerve lessons A seven-year-old falls on an outstretched hand and arrives holding the elbow: a displaced supracondylar fracture, the distal fragment driven posteriorly, so the brachial artery and median nerve are stretched over the fragment's sharp front. The checklist writes itself — palpate the radial pulse, test thumb-to-pulp opposition and the flexors, and watch for the five Ps of ischaemia, because a missed arterial injury ends in Volkmann's ischaemic contracture, a clawed, fibrosed forearm. Contrast the adult who sleeps drunk on an arm and wakes with a wrist drop: the radial nerve is compressed in the spiral groove, yet elbow extension survives, since the branches to the medial head of triceps leave the nerve before it enters the groove. Same bone, opposite ends of age, and the anatomy predicts both patterns before any radiograph. ## Where the traps sit Examiners love the two necks: the anatomical neck is the marginal line at the head where old people fracture after a fall and the capsule attaches, while the surgical neck below the tubercles is the axillary nerve's territory — test deltoid abduction and sensation over the regimental badge area, and remember that a dislocated shoulder injures the same nerve. The second trap is claiming spiral groove injury kills elbow extension; it does not, for the reason above, and quoting that reason earns the mark. Finally, on a dried bone asked to be sided, three features settle it: the head looks upwards and inwards, the olecranon fossa marks the back, and the spiral groove crosses from medial to lateral behind the deltoid tuberosity. ## Frequently asked questions ### Which nerve and artery are injured in a surgical neck fracture? The axillary nerve with the posterior circumflex humeral artery, both winding around the surgical neck. Test deltoid power and sensation over the upper lateral arm — the regimental badge area. ### Why is elbow extension preserved in radial nerve injury at the spiral groove? Branches to the medial head of triceps arise before the nerve enters the groove, so extension survives while wrist and finger extension are lost. This distinguishes a groove lesion from a posterior cord lesion. ### What complications follow a supracondylar fracture of the humerus? The brachial artery and median nerve lie in front of the distal humerus and are injured by the forward-driving proximal fragment. Untreated arterial compromise leads to compartment syndrome and Volkmann's ischaemic contracture. ### Which nerve lies directly behind the medial epicondyle? The ulnar nerve, in the sulcus behind the epicondyle, where it is palpable and injured by fractures, cubital tunnel compression, or careless tourniquet placement. ### Which way does the nutrient foramen of the humerus point and why? It points downwards on the anteromedial shaft, directed away from the upper growing end. The foramen runs away from the dominant growth plate in every long bone — the humerus grows chiefly from its head.