General Anatomy Skeletal System PDF

General Anatomy Skeletal system Dr. Abdullah Bashir 1  Objectives By the end of this lecture the attendant will be able to : 1. Describe the structure of bones 2. list the function of bones and periosteum. 3. List the arteries that supplies the bone 4....

General Anatomy Skeletal system Dr. Abdullah Bashir 1  Objectives By the end of this lecture the attendant will be able to : 1. Describe the structure of bones 2. list the function of bones and periosteum. 3. List the arteries that supplies the bone 4. List the components of skeleton 5. Identify the names of bones 6. Discuss the types of cartilages 2  Introduction Osteology: The branch of anatomy that deals with the structure and function of bones. skeleton: is a complex structures of bones and cartilages which connected together through ligaments and joints Bones are rigid organs that make up the skeletal structure 3  The Skeletal System Cells (Osteocytes) Tissues (Osseous Tissue) Organs = Bones System (Skeletal) 4  The Skeletal System 206 distinct bones in adults. 15% of body weight 5  Skeletal system The skeletal system is formed of bones and cartilages which connected together through ligaments and joints 6  Bones have five basic functions 1. Protection – serves to protect the vital organs (heart, brain, and spinal cord....... ). 2. Transmits and Support of the body weight and organs. 3. Attachment of muscles and forms the joints (Movement) 4. Blood cell production. (Hemopoiesis) 5. Storage – serves as storage for calcium, phosphorous, potassium, sodium, and other minerals. 7  Bone Is a type of dense connective tissue. - It is living and highly vascular. - It is composed of cells “osteocytes” and matrix. - It is covered by a strong fibrous connective tissue membrane called periosteum. - It is lined by endosteum. 8  Classification of Bones Acording to : Position: Axial and Appendicular Shape: long, short, flat, irregular Structure: compact or spongy Development (ossification): membranous or cartilagenous. 9 Classification of Bones on the Basis of Shape 1. Long bones: Typically longer than wide. Have a shaft with heads at both ends. Examples: Femur, humerus. Gross Structure of a Long Bone Each long bone has: A shaft called the „diaphysis‟ Two expanded ends called the „epiphyses‟ The region at the junction of diaphysis and epiphysis is called „metaphysis. 10  Diaphysis (Shaft): Composed of compact bone. Covered on its external surface by a fibrous connective tissue membrane called the periosteum. It has a cavity called the marrow cavity. The central medullary cavity filled with bone marrow. 11  Epiphyses: Each epiphysis is composed of spongy bone, lined by a thin layer of compact bone. The articular surface is covered by a layer of hyaline cartilage. Metaphysis It contains a thin plate of cartilage called the epiphyseal plate that is responsible for the lengthwise growth of the long bones. 12  Epiphysial Plate of Cartilage - Is a hyaline cartilage plate, - Also known as growth plate - It located at metaphysis between epiphysis and diaphysis. - Proliferation of cells in this cartilaginous plate is responsible for longitudinal bone growth in children and adolescents. - The growth cartilage is nourished by both the epiphysial and metaphysial arteries. 13 Long bone 14  Periosteum: It covers the surface of the bone (except the articular part). Function: 1. Protects the bone. 2. Gives attachment to muscles. 3. Growth of long bone in width 4. Carries blood vessels and nerves to bone. 15  Long bones Examples: typical long bones like humerus, radius, ulna, femur, tibia and fibula. Modified long bones have no medullary cavity like clavicle 16  2. Short bones: They are cuboidal in shape. They are found in the hand and foot e.g. carpal and tarsal bones. 3. Flat bones: They are thin and flattened. Examples: Skull, ribs, sternum and scapula. 4. Irregular bones: They are irregular in shape. Example: Vertebrae and hip bone 5. Pneumatic bones: Certain irregular bones contain large air spaces lined by epithelium Examples: maxilla, sphenoid, ethmoid. 6. Sesamoid bones: are found embedded within certain tendons. Example: patella. 17 Classification of Bones on the Basis of Structure: Macroscopically, Two basic types of bone tissue: 1. Compact bone (dense bone). 2. Spongy bone (cancellous bone). 18 Most bones contain both types: Compact bone is dense, hard, and forms the protective exterior portion of all bones. Spongy bone is inside the compact bone and is very porous (full of tiny holes). Spongy bone found in most bones. 19 Irregular bone 20 21 Classification according to their ossification 1. Intracartilagenous ossification (Cartilagenous bone): In most of long bones. Mesenchyme cartilage bone 2. Intramembranous ossification (membranous bone): In flat bones (skull cap, scapula) (Rapid ossification for protection. Mesenchymal tissue transformed into bone without cartilage formation. Mesenchyme bone 22  Blood supply of bones 1. Nutrient artery and vein: a single pair of large blood vessels enters the diaphysis through the nutrient foramen 3. Periosteal vessels : provide blood to superficial osteons 3. Epiphyseal vessels : usually arise from articular branches supplying the joint 2. Metaphyseal vessels: supply the epiphyseal cartilage where bone growth occurs 23 24  Cartilage Cartilage is a connective tissue composed of cells (chondrocytes) and fibers (collagen or yellow elastic) embedded in a firm, gel-like matrix. It is much more elastic than bone. General Features 1. no blood vessels or lymphatics. The nutrition of cells diffuses through the matrix. 2. no nerves, insensitive. 3. Cartilage is surrounded by a fibrous membrane, called perichondrium, which is similar to periosteum in structure and function. The articular cartilage has no perichondrium, 4. When cartilage calcifies, the chondrocytes die and the cartilage 25 is replaced by bone like tissue.  Differences between bone and cartilage Bone is hard. Bone has rich nerve supply. It is vascular in nature, Bone marrow is present Cartilage is firm. It does not have nerve supply. It is avascular in nature, Bone marrow is absent 26  Types of Cartilage Three types of cartilage: 1. Hyaline cartilage (Most abundant kind)Associated with synovial joints in the articular cartilages of long bones, sternum. 2. Fibrocartilage Has collagen fibers: Intervertebral discs, pubic symphysis. 3. Elastic cartilage Has elastic fibers respiratory tubing trachea and bronchi, Ear In the pinna, external auditory meatus, Eustachian tube. Epiglottis. 27  Function of cartilage 1. Support soft tissue. 2. Provide a smooth, gliding surface for bone articulations at joints. 3. Enable the development and growth of long bones. 4. Cushioning and shock absorption: Cartilage acts as a cushion between bones in joints, reducing friction and absorbing shock during movement 28  Skeletal System In the skeleton of the adult there are 206 distinct bones, as follows : 1- Axial Skeleton (80) - Skull 22 - Vertebral column 26 - Hyoid bone 1 - Auditory ossicles 6 - Ribs and sternum 25 2-Appendicular Skeleton (126) - Upper extremities 64 - Lower extremities 62 — 29 Total 206 Axial Skeleton 30 Vertebral column 31 Sacrum 32 Appendicular Skeleton 33 Clavicle 34 Scapula 35 Humerus 36 Radus Ulna 37 Hand bones 38 Hip bone 39 Femur 40 Patella 41 Fibula Tibia 42 43 Foot bones 44  Summary Describe the structure of bones. list the function of bones and periosteum. List the arteries that supplies the bone. List the components of skeleton. Identify the names of bones. Discuss the types of cartilages. 45 Recommended Learning Resources Gray's Anatomy for Students, Drake et al., 4th edition, 2020. 46 Thank Any ? You 47