Gross Anatomy of a Long Bone

Flashcards covering the gross anatomy of a long bone, including its regions, coverings, internal structures, cellular components, and vascular access.

What is the most common bone shape in the body?

Long bones are the most common bone shape in the body.

What is the diaphysis of a long bone?

The elongated, usually cylindrical shaft of a long bone that provides leverage and major weight support.

How are compact bone and spongy bone arranged within the diaphysis?

Compact bone forms the external component of the diaphysis, while spongy bone extends internally from it in the form of spicules (thin, needlelike structures).

What is the medullary cavity, and how does its contents differ between children and adults?

The medullary cavity is the cylindrical hollow space within the diaphysis. In children, it contains red bone marrow, which is replaced by yellow bone marrow in adults.

How does Learning Strategy 7.1 compare a long bone to a barbell?

The barbell's rounded ends represent the epiphyses, and its cylindrical handle represents the diaphysis.

What is an epiphysis, and how are the proximal and distal epiphyses distinguished?

An epiphysis is an expanded, knobby region at each end of a long bone. The proximal epiphysis is closest to the body trunk, whereas the distal epiphysis is farthest from the trunk.

What is the structural composition and functional role of spongy bone within an epiphysis?

An epiphysis contains an inner region of spongy bone surrounded by a thin outer layer of compact bone. The spongy bone functions to resist stress applied from many directions.

What is articular cartilage and what are its main functions?

Articular cartilage is a thin layer of hyaline cartilage covering the joint surface of an epiphysis. It helps reduce friction and absorb shock in movable joints.

What is the metaphysis of a long bone?

The metaphysis is the region where a long bone widens and transfers forces between the diaphysis and the epiphysis.

What is the epiphyseal plate, and where is it located?

The epiphyseal plate (growth plate) is a thin layer of hyaline cartilage located in the metaphysis of a growing juvenile skeleton that allows for continued growth in bone length.

What is the epiphyseal line?

The epiphyseal line is a thin, defined area of compact bone in adults that remains as a remnant of the epiphyseal plate.

What membrane lines the internal surfaces and medullary cavity of a long bone?

The endosteum lines the internal medullary cavity of a long bone.

Which cell types are found in the endosteum as illustrated in Figure 7.3b?

Osteocytes, osteoclasts, osteoblasts, and osteoprogenitor cells.

What membrane covers the external surface of the long bone shaft, and what are its two layers?

The periosteum lines the external surface of the bone shaft. It consists of an outer fibrous layer and an inner cellular layer (containing osteoblasts and progenitor cells).

What structure anchors the periosteum to the underlying bone?

Perforating fibers anchor the periosteum to the bone.

How does the main arterial blood supply enter the diaphysis of a long bone?

Via a nutrient artery that passes through a nutrient foramen in the diaphysis.