Study Notes on Long Bone Anatomy

Long bones, such as the femur, function to transmit forces along their shaft and possess a rich blood supply.
The structural organization includes both compact and spongy bone, as demonstrated in Module 4.14.

Epiphysis
- Pronunciation: (e-PIF-i-sis)
- Description: Expanded area at each end of the bone.
- Composition: Primarily made up of spongy bone, also termed trabecular bone (pronunciation: tra-bek-YÜ-lar).
- Structure: Spongy bone consists of an open network of struts and plates that resemble latticework with a thin exterior covering of compact bone.
- Functional Role: At the proximal epiphysis, spongy bone assists in channeling and directing body weight into the compact bone of the diaphysis. It also aids in distributing body weight across the articular surface at the knee through the spongy bone of the distal epiphysis.
Metaphysis
- Pronunciation: (me-TAF-i-sis)
- Definition: A narrow zone that connects the epiphysis to the shaft of the bone, playing a crucial role in bone growth.
Diaphysis
- Description: The long cylindrical shaft of the bone.
- Composition: It consists mainly of relatively dense compact bone, which forms a sturdy protective wall around a central medullary cavity.

Definition: Also known as the marrow cavity, it is a hollow space within the diaphysis.
Function: The medullary cavity does not compromise the bone's strength, as it is situated centrally where it is not subject to compressive or tensile forces.
Contents:
- Red Bone Marrow: Highly vascularized tissue involved in producing blood cells.
- Yellow Bone Marrow: Comprised of adipose tissue, serves as an energy reserve.

Compression Forces: Act primarily on the medial side of the shaft, contributing to resistance against body weight.
Tension Forces: Applied on the lateral side of the shaft, helping maintain structural integrity under load.

A. List the major parts of a long bone.
B. Describe the function of the medullary cavity.