The humerus is the longest and largest bone of the upper extremity that runs from the shoulder to the elbow.
- It connects the scapula and the lower arm (consisting of the radius and ulna), and consists of three sections.
- The upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities.)
- Its body is cylindrical in its upper portion, and more prismatic below.
- The lower extremity consists of 2 epicondyles, 2 processes (trochlea and capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa).
As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to commonly get fractured, thus often becoming the focus of surgeons.
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).