ANATOMY Dr . Saja Majid

Skeletal system

The skeletal system includes connective tissues such as bone, cartilage, tendons, and ligaments. These tissues are combined with the various types of muscle tissue to form the Musculo-Skeletal System

1- Bone itself has five functions, including: • Support of the body. • Protection of soft organs. • Movement due to attached skeletal muscles. • Storage of minerals and fats. • Blood cell formation) Haematopoiesis).

2- Cartilage serves as the fetal template for bone formation, and covers the ends of bone most especially at the joints, or points of articulation. 3-Tendons connect muscles to bone. 4-Ligaments connect bone to bone.

Bone Biology : 1-Bone is composed of organic material (mostly collagen, a spongy protein), within an inorganic matrix called hydroxyapatite (mostly calcium and potassium).

2-Bone tissue consists of three specialized cell types, osteoblasts, osteocytes and osteoclasts a.Osteoblasts are bone-forming cells, which line the surface of a bone’s structure. b. Osteocytes are bone cells and are found within the bone’s structure. c. Osteoclasts are cells that resorb bone trough a degradation process.

3-Two basic types of bone tissue: a- Compact bone(Homogeneous). b-Spongy bone( Small needle-like pieces of bone , Many open spaces).

1-There are approximately 206 bones in the human body. Bone Anatomy : 1-There are approximately 206 bones in the human body.

2-They can be classified into four main classes: a. Long bones: main components of limbs, include the femur, humerus , radius and ulna, tibia and fibula. b. Short Bones: include metacarpals of hands and metatarsals of feet. c. Flat Bones: includes cranial bones, in nominates and scapula, offer protection and large muscle attachments. d. Irregular Bones: includes vertebra, carpals (hand) and tarsals (feet), many of the cranial bones.

3-The skeleton can also be divided into two parts, the axial skeleton, and the appendicular skeleton. a. The axial skeleton includes the skull or cranium, the vertebral column, and the ribs.

1.The pectoral girdle includes the scapula and b. The appendicular skeleton includes the pelvic and pectoral girdles, as well as the upper and lower limb bones. 1.The pectoral girdle includes the scapula and clavicle, and forms the shoulder. 2. The pelvic girdle includes innominate or hip bones. 3. The upper limbs include the humerus, radius, ulna , carpals, metacarpals, and hand phalanges. 4. The lower limbs include the femur, tibia, fibula , patella, tarsals, metatarsals and foot

Gross Anatomy of a Long Bone : 1- Diaphysis ( shaft , composed of compact bone ). 2-Epiphysis (Ends of the bone , Composed mostly of spongy bone ). 3-Periosteum (Outside covering the diaphysis , Fibrous connective tissue membrane). 4- Sharpey’s fibers (Secure periosteum to underlying bone ). 5- Arteries (Supply bone cells with nutrients).

Bone Growth : - New cartilage is continuously formed. - Epiphyseal plates allow for growth of long bone during childhood. - New cartilage is continuously formed. - Older cartilage becomes ossified. - Cartilage is broken down. - Bone replaces cartilage.

Changes in the Human Skeleton : - In embryos, the skeleton is primarily hyaline cartilage - During development, much of this cartilage is replaced by bone Cartilage remains in isolated areas ( Bridge of the nose , Joints , and Parts of ribs)