The upper arm bone
Humerus · humerus
The single long bone of your upper arm, from shoulder to elbow.
What it does
The humerus links the shoulder to the elbow. Its rounded head fits into a shallow socket on the shoulder blade, giving your arm its huge range of movement. Muscles that lift, rotate and bend the arm attach along its length, and its lower end forms the hinge of the elbow.
Surprising fact
The "funny bone" pun works because of the humerus. The tingle you feel when you knock your elbow comes from a nerve sliding over the lower end of this bone, which sounds like "humorous".
Why it matters
The shallow shoulder socket trades stability for movement, which is why shoulders dislocate more often than any other major joint. A fall on an outstretched hand can also break the humerus just below the shoulder.
Nearby
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Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.