The sacrum forms a base for the spine and the back part of the pelvis. The L5 vertebrae rests on the sacrum, a large bone made up of several smaller vertebrae-like bones which have fused together. The foramina are openings for the nerve roots to pass out of the spinal canal and for blood vessels to pass into the canal. The vertebrae, discs, and ligaments are able to maintain the correct alignment and consequently protect the spinal cord against all but the most violent injury.īetween each adjoining vertebrae on each side of the spinal canal are openings called foramina. Although the ligaments will stretch to permit limited movement, they are rigid enough to maintain alignment of the spinal canal as it passes through each vertebrae. Strong ligaments bind the vertebrae together. passage ways for blood vessels and nerves. Facial Bones (14) There are numerous holes in the skull called.
Cranial bones (18) The bones that form the underlying structure of the face are reffered to as the. Between vertebral bodies are small fibrocartilage cushions called discs. The bones that surround and protect the brain are referred to as the. Red marrow functions in the formation of red blood cells, white blood cells and blood platelets.The manner in which the vertebrae are stacked is shown here. In adults, red marrow is limited to the spongy bone in the skull, ribs, sternum, clavicles, vertebrae and pelvis. With age, it is largely replaced by yellow marrow for fat storage. The facial bones protect the front of the head, and most of the bones of the skull are joined together by immovable joints called sutures. In infants, red marrow is found in the bone cavities. Its a tough, fibrous layer called the dura mater, or usually just. The outermost covering is just inside the skull. Hematopoiesis, the formation of blood cells, mostly takes place in the red marrow of the bones. These layers cover and protect the brain. The dynamic process of releasing and storing calcium goes on almost continuously. When blood calcium levels are increased, the excess calcium is stored in the bone matrix. When blood calcium levels decrease below normal, calcium is released from the bones so that there will be an adequate supply for metabolic needs. The intercellular matrix of bone contains large amounts of calcium salts, the most important being calcium phosphate. Vertebrae surround and protect the spinal cord and bones of the rib cage help protect the heart and lungs of the thorax.īones work together with muscles as simple mechanical lever systems to produce body movement.īones contain more calcium than any other organ. The cranium (skull) is the skeletal structure of the head that supports the face and protects the brain.It is subdivided into the facial bones and the brain case, or cranial vault (Figure 7.3).The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws. The fused bones of the cranium surround the brain to make it less vulnerable to injury. The skeleton also protects the soft body parts. The large bones of the lower limbs support the trunk when standing. The skeleton supports the body against the pull of gravity. Together, the cranium and bones that protect the face are called the skull.
They contain active tissues that consume nutrients, require a blood supply and change shape or remodel in response to variations in mechanical stress.īones provide a rigid framework, known as the skeleton, that support and protect the soft organs of the body. The cranium protects the brain from injury. This likely has huge implications for conditions like dementia and Alzheimer’s disease because these diseases have an inflammatory component. The living bones in our bodies use oxygen and give off waste products in metabolism. Cells in the skull’s bone marrow are surveilling the cerebrospinal fluid that exits the brain through the skull channels we discovered earlier, says Nahrendorf. The human skeletal system consists of bones, cartilage, ligaments and tendons and accounts for about 20 percent of the body weight. They rely on a sturdy internal frame that is centered on a prominent spine. Humans are vertebrates, animals having a vertabral column or backbone. Acknowledgements Introduction to the Skeletal System
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