What is the humerus?

What it is

• The humerus is the longest and largest bone of the upper extremity; it is divisible into a body and two extremities. Upper Extremity. —The upper extremity consists of a large rounded head joined to the body by a constricted portion called the neck, and two eminences, the greater and lesser tubercles. The Head ( caput humeri ). —The head, nearly hemispherical in form, 54 is directed upward, medialward, and a little backward, and articulates with the glenoid cavity of the scapula.
• The circumference of its articular surface is slightly constricted and is termed the anatomical neck, in contradistinction to a constriction below the tubercles called the surgical neck which is frequently the seat of fracture. Fracture of the anatomical neck rarely occurs.