Bones - Skeleton

Early Life During development of the embryo, the human skeleton is made up of cartilage and fibrous membranes, but most of these early supports are soon replaced by bone. Think about the body position in utero during development, and the first few years of child’s life.

Most bones stop growing during adolescence. Some facial bones, especially those of the nose and lower jaw, continue to grow almost to no end throughout life. (example of change of facial structure in elderly)

Skeleton divided into the axial and appendicular Together comprise 206 bones in the human body

axial skeleton These bones form the vertical axis of the body. They function in protection and support of the body and body parts. skull bones vertebral column rib cage

Axial Skeleton

Appendicular Skeleton These bones comprise the upper and lower limbs of the body, and the bones that connect limbs to the axial skeleton. They function in movement. clavicles pelvis Arms and hands Legs and feet

Appendicular Skeleton

Function of Bones -Protection of vital organs -Support & maintenance of posture -Providing attachment points for muscles -Storage & release of minerals (calcium & phosphorus) -Blood cell production (haemopoiesis) -Storage of energy (lipids in yellow bone marrow)

bone classifications (types) Long bones: longer than they are wide; have a shaft with 2 ends. Movement bones: including femur, metatarsals & clavicle Short bones: small & cube-shaped. Include carpals & tarsals Flat bones: thin, flat and often curved. Including the sternum, scapula, ribs and skull bones Irregular bones: have specialized & complicated shapes, including sacrum, coccyx & vertebrae

Bone classifications

Bone Textures Bones are made up of 2 layers that differ in texture and function: - Compact bone: external layer of the bone that is very dense, filled with passageways for nerves, blood vessels, and lymphatic vessels. - Cancellous bone: internal layer of the bone that looks spongy; has an irregular latticework structure.

Long Bone: structure Long bones are mainly comprised of a shaft, 2 ends and membranes. Diaphysis: the shaft; constructed of compact bone and envelopes a marrow cavity. In adults, this cavity stores yellow marrow (fat) Epiphyses: the bone ends of a long bone; constructed of compact bone externally and spongy bone internally. Blood cell production occurs here

Con’t Articular Cartilage: thin layer of cartilage covering the ends of the bone where joints are formed. They reduce friction & absorb shock - Periosteum; thin shiny white membrane; important for bone growth, repair, nutrition and attachment of ligaments/tendons. - Medullary Cavity: space within the diaphysis where yellow bone marrow is stored. -Nutrient Foramen: where blood vessels pass into the bone.

Diagram of Long Bone

Vertebral column 33 Vertebrae in the body Strong and flexible Cervical: 7 vertebrae; the smallest & have the most movement Thoracic: 12 vertebrae; less mobile due to the ribs attached to them Lumbar: 5 vertebrae; biggest & strongest; weight bearing Sacral: 5 vertebrae (fused); transmit weight to the legs/pelvis Coccygeal: 4 vertebrae (fused)

Vertebrae

The vertebral foramen; (hole) in each vertebrae line up to house the spinal cord. -Intervertebral discs: located between the body of each vertebrae; fibrocartilage on the outside & gel like in the middle; give the vertebral column flexibility; shock absorbers

Spinal column 4 curves of the spine increase strength, help maintain upright balance & absorb shock

Sources “Human Anatomy & Physiology, Pearson International Edition, Eighth Edition.” Marieb and Hoehn McGraw-Hill Companies. National Library of Medicine and International Osteoporosis Foundation. Nucleus Communications, Inc Visual Dictionary Online.