Humerus

The humerus is a long tubular bone. There is a body of the humerus (corpus humeri) and two ends: upper and lower. The upper end (proximal) is thickened and forms the spherical head of the humerus (caput humeri). The head is directed medially and slightly backward. Along the edge of the head there is a groove - the anatomical neck (collum anatomicum). Immediately behind the anatomical neck there are two tubercles. The greater tubercle (tuberculum maius) lies laterally, and the lesser tubercle (tuberculum minus) is located in front of the greater. A ridge runs downward from each tubercle: the ridge of the greater tubercle (crista tuberculi majoris) and the ridge of the lesser tubercle (crista tuberculi minoris). Between the tubercles and between the ridges is the intertubercular groove (sulcus intertubercularis), intended for the tendon of the long head of the biceps brachii.

The narrowest point between the head of the humerus and its body is called the surgical neck (collum chirurgicum). The body of the humerus is cylindrical in its upper section and becomes triangular downwards. At this level, the posterior surface (facies posterior), medial anterior surface (facies anterior medialis) and lateral anterior surface (facies anterior lateralis) are distinguished. Slightly above the middle of the body of the bone, on its lateral anterior surface, is the deltoid tuberosity (tuberositas deltoidea), to which the deltoid muscle is attached. Below the deltoid tuberosity, the groove of the radial nerve (sulcus nervi radialis) spirals along the posterior surface of the bone. It begins at the medial edge of the bone, bends around the bone from behind and ends at the lateral edge below. The lower end of the humerus is widened, slightly bent forward and ends in the condyle of the humerus (condylus humeri). The medial part of the condyle forms the trochlea humeri for articulation with the ulna of the forearm. Lateral to the trochlea is the head of the condyle of the humerus (capitulum humeri) for articulation with the radius. In front, above the trochlea of the humerus, the coronoid fossa (fossa coronoidea) is visible, where the coronoid process of the ulna enters during flexion at the elbow joint. Above the head of the condyle of the humerus, there is also a depression - the radial fossa (fossa radialis). Behind, above the trochlea of the humerus, is the fossa of the olecranon process (fossa olecrani).

On the medial and lateral sides of the humerus, elevations are visible above the condyles: the medial epicondyle (epicondylus medialis) and the lateral epicondyle (epicondylus lateralis). On the posterior surface of the medial epicondyle, there is a groove for the ulnar nerve (sulcus nervi ulnaris). Above, this epicondyle passes into the medial supracondylar ridge (crista supracondylars medialis), which forms the medial edge of the bone (margo medialis) in the area of the body of the bone. The lateral epicondyle continues upward into the lateral supracondylar ridge (crista supracondylaris lateralis), which forms the lateral edge of the bone (margo lateralis) on the body of the bone.

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