Humerus

humerus anatomy muscles actions
Humerus
The humerus articulates with the scapula at the shoulder
joint and with the radius and ulna at the elbow joint. The
upper end of the humerus has a head (Fig. 9.9), which
forms about one third of a sphere and articulates with the
glenoid cavity of the scapula. Immediately below the headis the anatomic neck. Below the neck are the greater and
lesser tuberosities, separated from each other by the bicipital
groove. Where the upper end of the humerus joins the
shaft is a narrow surgical neck. About halfway down the
lateral aspect of the shaft is a roughened elevation called
the deltoid tuberosity. Behind and below the tuberosity
is a spiral groove, which accommodates the radial nerve
(Fig. 9.9).
The lower end of the humerus possesses the medial
and lateral epicondyles for the attachment of muscles and
ligaments, the rounded capitulum for articulation with
the head of the radius, and the pulley-shaped trochlea for
articulation with the trochlear notch of the ulna (Fig. 9.9).
Above the capitulum is the radial fossa, which receives
the head of the radius when the elbow is flexed. Above the
trochlea anteriorly is the coronoid fossa, which during
the same movement receives the coronoid process of the
ulna. Above the trochlea posteriorly is the olecranon fossa,
which receives the olecranon process of the ulna when the
elbow joint is extended