Skeleton - Horton High School

There are 206 bones in an adult skeleton At birth there are over 300 bones As we mature to about the age of 2 years some bones fuse to make up a single bone and reduce the number to 206.

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Structural support – hold tissues in place Movement – provide levers for muscles to pull and move Protection – ie: ribs protect heart, lungs Mineral Reserve – calcium and phosphorous used in energy production are stored in bone Manufacture of Blood Cells – marrow inside long bones produces new Red blood cells

Axial skeleton is comprised of the skull, vertebrae and rib cage. 80 bones in all. Core muscles anchor here. Appendicular skeleton is comprised of the arm and leg bones plus the shoulder and pelvic girdle bones. 126 bones in all. Muscles for movement insert here.

Bone marrow is found as a yellowish (fat) or red (blood) substance found inside the long bones of the body. It manufactures red blood cells for our blood stream.

Long bone – femur, humerus Short bone – wrist carpal, foot tarsal Irregular bone –vertebrae Sesmoid – patella (floating bone) Flat bone – skull or rib

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True Ribs are connected by cartilage directly to the sternum. There are 7 true ribs. False Ribs are connected to the cartilage of the 7th rib that leads to the sternum. There are 3 false ribs. Floating ribs are located at the inferior level of the rib cage. They are short and do not connect to the sternum (float). There are 2 floating ribs

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Cervical refers to the vertebrae in the neck region at the top of the spine. The first 7 vertebrae are cervical. C1 – C7. Thoracic refers to the vertebrae in the rib area. There are 12, numbers T8 – T19. Lumbar refers to the final 5 vertebrae in the lower back. L20 – L24. Vertebrae protect the spinal cord and allow us flexibility to move

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Our skeleton is constantly replacing old bone cells with new to ensure the integrity and strength of the our frame. The process is known as remodelling. Osteoclasts cells dissolve old bone and Osteoblasts deposit new bone cells. Our skeleton replaces itself completely about every 3 years

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As we age the skeleton loses bone mass. More old bone is dissolved than new bone made to replace it. After the age of 40 we lose more mass than we replace. This results in weaker more frail bone.

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The condition of losing bone density due to aging is called Osteoporosis. The result can lead to brittle bones, posture and joint problems in later years of life. Exercise and diet (calcium rich) along with proper medical attention can reduce the problem as we age.

To slow done the bone loss process we should:  Eat a diet balanced in calcium and vitamin D  Exercise regularly  Regular medical checks for bone density  Avoid excessive alcohol or smoke

Cartilage is not bone but a hard yet flexible material found in the skeleton to provide flexibility, cushioning and to prevent bones from rubbing on bone. Cartilage is very smooth and the surfaces glide over each other. It can be found between most bone articulations (where bones meet). It is found in all moving joints to allow pain free and friction free smooth movement. Cartilage does not have a blood supply so if damaged it does not repair itself very well if at all. It is a common problem in sport joint sprains of knee and shoulder.

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Ligaments are tough strands of connective tissue. They have little give and are found in the joints connecting the bones in place so the joint is stable and only moves in the desired motions. Ligaments join bone to bone.

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When the joint is pushed past its extreme range of motion then the ligaments that hold it in place as well as other soft tissues may tear. This is known as a sprain. It results in swelling, heat, redness and pain. Torn ligaments do not heal easily due to a lack of blood flow to the tissue.

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Long bones are hollow to reduce weight and to allow for blood cell production in the bone marrow housed in its hollow interior.

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Ridges on bones can serve as locations for tendons to attach (tendons connect the skeletal muscles to the skeleton). Ridges can also add strength to the bone

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Tubersosities are bumps found on the bone, spines are projections and grooves run the length of a bone. All of these can serve as attachment locations for the muscle to the bone or places for nerves to locate.

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29 bones in the skull. Many are fused together as in the skull and only a line exists between them outlining the area

We can tell when a person’s skeleton has stopped growing by looking at the growth plates on a long bone. Long bones grow by adding bone at their ends. This plate is found between the shaft and head of the bone. A gap indicates the bone is still growing. A solid line indicates growth has stopped.

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Arthritis is an inflamation around the cartilage surface or a roughening of the surface that causes pain and inflamation around the joint.