Skeletal System (PDF)

# The Skeletal System ## The Skeletal System The skeletal system contain 206 separated bone. The skeletal system includes the bones of the skeleton and the cartilages, joints, ligaments, and other connective tissues that stabilize or connect them. ### Functions of the Skeletal System This syste...

# The Skeletal System ## The Skeletal System The skeletal system contain 206 separated bone. The skeletal system includes the bones of the skeleton and the cartilages, joints, ligaments, and other connective tissues that stabilize or connect them. ### Functions of the Skeletal System This system has five primary functions: 1. **Support:** It provides structural support for the entire body. 2. **Storage:** Bones store calcium and phosphate. In addition, bones store energy reserves as lipids in areas filled with yellow marrow. 3. **Blood Cell Production:** Red blood cells, white blood cells, and other blood elements are produced within the bone marrow. 4. **Protection:** Soft tissues and organs are often surrounded by skeletal elements. ## The Structure of Bone The bone is a supporting connective tissue that contains specialized cells and a matrix consisting of extracellular protein fiber and ground substance. ### Bone Shapes The bones have four general shapes: - **Long:** (femur) - **Short:** (ankle, carpal) - **Flat:** (frontal cranium, sternum) - **Irregular:** (vertebra) - **Sesamoid:** (patella) ### Bone Structures Two types of bone structure exist: - **Compact bone (solid):** - **Spongy bone (cancellous):** A network of bone rods separated by space. - Bone marrow (also known as myeloid tissue). ## The Cells in Bone - **Osteocytes** - **Osteoclasts** - **Osteoblasts** ## Requirements for Normal Bone Growth and Maintenance - Calcium and phosphate salts: The body must be able to absorb and transport these minerals to sites of bone formation. - Vitamins D3, A, C. - Hormones including growth hormone, thyroid hormone, sex hormone, parathyroid hormone, calcitonin hormone. ## Injury and Repair of Bone Bone fractures develop when bones are subjected to extreme loads. Bone will heal even after they have been severely damaged by 4 steps, if the periosteum & edosteum are survive: 1. **Formation of fracture hematoma.** 2. **Formation of internal and external callus.** 3. **Osteoblasts replace the new central cartilage of external callus with spongy bone.** 4. **The remodeling process of spongy bone at the site of fracture, which may continue over a period of 4 months to well over a year.** ## Skeletal Divisions The skeletal system consists of 206 separated bones and divided in: 1. **Axial divisions.** 2. **Appendicular divisions.** ### Axial Divisions The axial skeleton forms the longitudinal axis of the body, containing 80 bones: 1. **Skull:** (22 bones) +7 associated bone (auditory ossicles, hyoid bone) 2. **Thoracic cage:** (24 ribs, and the sternum). 3. **Vertebral column:** (26 bones) ### Appendicular Divisions The appendicular skeleton includes the bones of limbs and those of pectoral & pelvic girdles, which attach limbs to the trunk: - **There are 126 appendicular bones:** - 32 bones for each upper limb. - 31 bones for each lower limb. ### Axial Division Function: 1. It creates a framework that supports and protects organ systems in the brain and spinal cavities, and ventral body cavities. 2. It provides an extensive surface for the attachment muscles. ## The Skull The skull is made up of 22 bones divided in: - 8 bones form the cranium. - 14 bones are associated with the face. ### Cranium Bones The cranium bones consist of (8 bones): 1. **Frontal bone:** forms the forehead. 2. **Parietal bone:** forms the both sides and upper walls of the cranium. 3. **Temporal bone:** forms the both sides and base of cranium and contains the auditory system. 4. **Occipital bone:** forms the back and base of the cranium. They connect together by immovable sutures. ### Facial Bones The facial bones (14 bones): 1. **Maxillae:** form the upper jaw. 2. **Mandible:** form the lower jaw. ## Appendicular Division ### Upper Limbs The upper limbs consist from: 1. **Pectoral girdle:** contains clavicle and scapula bones. 2. **Limb bones:** in each limb exist: humerus, radius, ulna, (8) carpal bones, (5) metacarpal bones, (14) phalanges (proximal, middle, distal). ### Lower Limbs The lower limbs consist from: 1. **Pelvic girdle:** consist from coxal (hip) bone. 2. **Limb bones:** in each limb exist: femur, tibia, fibula, (7) tarsal bones, (5) metatarsal bones, (14) phalanges (proximal, middle, distal), patella. The image attached depicts the skeletal system, showing the axial and appendicular skeletons. * Figure 2 labels the axial skeleton: skull, hyoid bone, vertebral column, ribs. * Figure 1 labels the appendicular skeleton: shoulder girdle, arm, hand, pelvic girdle, leg, foot.