Humerus (upper arm bone)
The humerus is the long bone of the upper arm in tetrapods. It connects the shoulder and elbow, provides sites for muscle attachment, and is important in movement, clinical diagnosis, and comparative anatomy.
The humerus is the long bone of the upper arm in vertebrate limbs. In humans and other tetrapods it spans between the shoulder girdle and the elbow joint, transmitting forces and serving as an anchor for many muscles. The term is often used in anatomical descriptions of limb structure and development (upper arm, bone, tetrapods).
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Structure and landmarks
Its proximal end features a rounded head that fits into the shoulder socket of the scapula, while the distal end forms articulations with the forearm bones at the elbow. Major surface landmarks used in anatomy and surgery include:
- Head and neck: proximal articular surface and the anatomical and surgical necks.
- Tubercles: greater and lesser tubercles for rotator cuff attachment.
- Shaft: deltoid tuberosity and the radial (spiral) groove for the radial nerve.
- Distal condyles: capitulum and trochlea with medial and lateral epicondyles.
Function and clinical importance
The humerus transmits loads between hand and shoulder and provides attachment for muscles that move the shoulder, elbow, and forearm. Clinically it is notable for several common fracture sites: surgical neck fractures in older adults, midshaft fractures that risk radial nerve damage, and supracondylar fractures in children. Knowledge of its anatomy guides treatment and rehabilitation.
Development, variation and significance
During growth the humerus ossifies from primary and secondary centers and reaches its adult shape in adolescence. Across vertebrates its form reflects lifestyle: robust in digging mammals, modified for flight in birds and bats. In archaeology and medicine the humerus is used for estimates of activity, stature, and sometimes sex, because of its size and muscle attachment patterns.
Further reading
For general overviews and comparative details see anatomy texts and resources (upper arm overview, bone anatomy, tetrapod limb, scapula relations, elbow joint).
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AlegsaOnline.com Humerus (upper arm bone) Leandro Alegsa
URL: https://en.alegsaonline.com/art/45701