Membrane bone

Membrane bone or intramembranous bone is a type of bone that forms directly within mesenchyme tissue, which is characterized by its ability to differentiate into various types of tissues. This process of bone formation is known as intramembranous ossification. Membrane bones are primarily found in the skull and clavicle (collarbone), providing protection for the brain and internal organs.

Formation

The formation of membrane bone begins with the condensation of mesenchyme tissue into a soft sheet permeated with blood vessels. Osteoblasts, bone-forming cells, differentiate within this mesenchyme sheet and begin to secrete osteoid, the organic component of bone matrix. The osteoid then mineralizes to form bone. This process does not involve a cartilage model, unlike endochondral ossification, the other main method of bone formation.

Function

Membrane bones play a crucial role in the protection of vital organs. The skull, for instance, is primarily composed of membrane bones and serves to protect the brain. The clavicle, another membrane bone, provides support for the shoulder and upper limb.

Clinical significance

Abnormalities in the formation of membrane bones can lead to various medical conditions. For example, craniosynostosis is a condition where the sutures in the skull fuse prematurely, affecting the shape and growth of the skull. This condition can lead to increased intracranial pressure and developmental delays.

See also

• Endochondral ossification
• Osteoblast
• Osteoid
• Craniosynostosis