Lecture 2-3 Skeletal System & Joints PDF

Lecture 2 Skeletal System& joints By Dr/Maram Mofreh Mahrous Lecturer of Anatomy & Embryology Faculty of Medicine Tanta University Rules  ILOs Define skeletal system components Identify type of bones according to : -Form...

Lecture 2 Skeletal System& joints By Dr/Maram Mofreh Mahrous Lecturer of Anatomy & Embryology Faculty of Medicine Tanta University Rules  ILOs Define skeletal system components Identify type of bones according to : -Form -Development -Shape Mention types of joints Describe each type of joints  Skeletal system The skeleton composed of: cartilage & bones  Cartilage Softer and less rigid than bone. It forms the temporary skeleton of the developing fetus and gradually replaced by bone. Cartilage is retained throughout life in certain sites of body as: external ear costal cartilage air passages articular surfaces of most bones.  Bone Hard living tissue consists of osteocytes, fibers and matrix with calcification of its extracellular matrix.  Types of bone According to : Form Development Shape Site in body Forms of bone Compact (ivory): hard dense bone forms the outer layer of all bones and shafts of long bones. Spongy (cancellous):looks like a sponge found inside the hard bone and ends of long bones. Development of bones: Membranous ossification: occurs in bones required urgently for support or protection of essential organs as those of the vault of skull. Cartilagenous ossification: at 1st a model of the future bone is formed in a cartilage then ossified into 2 steps. Shapes of bones: Long bones: typical of the limbs, has shaft and 2 expanded ends like: femur, tibia, humerus ,radius , ulna. Short bones: subjected to pressure as carpal and tarsal bones. Flat bones: like vault of skull, ribs, sternum and scapula. Irregular bones: not assigned to previous groups as vertebrae. Pneumatic bone: contain air spaces (sinuses) as frontal & maxillary bones Sesamoid bone: small bones deposited in muscle tendons as patella.  Parts of Skeleton Axial skeleton Appendicular skeleton (80 bones) (126 bones)  Upper limb (64 bones): Skull (28) Shoulder girdle (2 clavicle &2 scapula= 4) Hyoid (1) Arm bones (2 humerus ) Vertebrae (26) Forearm bones (2 radius & 2 ulna=4) Wrist bones (8 carpal bones= 16) Sternum (1) Hand bones (5 metacarpals =10) Ribs (24) Fingers bones (14 phalanges =28)  Lower limb (62 bones): Pelvic girdle (2 hip bones) Thigh bone (2 femur) Knee (2 patella) Leg (2 tibia & 2 fibula=4) Ankle (7 tarsal bones = 14) Foot bones (5 metacarpals=10) Toe bones (14 phalanges=28)  Function of skeleton Supports the body Give shape to body Allow movement Blood formation by bone marrow Store of calcium and phosphorus Protection of vital organs as cranium for brain and vertebral column for spinal cord.  Bone Markings in practical Elevations: Linear / rounded / pointed Depressions Elongated / rounded / on edge Perforations Foramen / meatus / canal Heads Condyles / trochlea  Joints A joint: is the site where two or more bones are articulated together. 1- Fibrous joint: The bony surfaces are joined by fibrous tissue. The bones are fixed together or a very little movement is allowed. They are 3 Types:  Sutures: limited to flat bones of the skull where the margins of bones are serrated and articulate with each other.  Syndesmosis: Opposed bony surfaces are connected by interosseous ligament: inf. tibio-fibular joint. Gomphosis: peg & socket joint, restricted to the fixation of teeth in the mandible and maxilla. 2-Cartilagenous joints: The bones united by intervening cartilage  1ry cartilagenous joint: bones are connected by hyaline cartilage. -Movement: No movement. -Fate: Temporary (ossifies). -Site: between epiphysis and diaphysis of long bones  2ry cartilagenous joint: bones connected by a disc of fibrocartilage. -Movement: limited degree of movement -Fate: permnant (no ossify) -Site: in midline of body as parts of sternum, symphysis pubis. 3-Synovial joint: Bones involved are linked by fibrous capsule which is lined by synovial membrane.  Movement: Freely mobile.  Charactersistics of synovial joint: -The articular surfaces are in contact but not in continuity and covered by hyaline cartilage and there is a joint cavity. -Hyaline cartilage decreases the friction. -The joint is surrounded by a strong fibrous capsule. -The capsule is lined by synovial membrane that secretes synovial fluid for lubrication.  Classification of synovial joint 1-Plane synovial joint Simple sliding movement (intercarpal & inter metacarpals) 2-Uniaxial synovial joint Hinge joint: transverse axis (Elbow joint ) Pivot joint: vertical axis ( atlanto-axial joint) (Saying No) 3- Biaxial synovial joint -Condyloid: biconcave surface articulate with biconvex one (metacarpo-phalangeal joints) -Ellipsoid: Elliptical biconcave surface articulate with elliptical biconvex one (wrist joint) -Saddle: the articulating surfaces are concavo-convex and convexo-concave (carpo-metacarpal joint of thumb).  Stability of the Joint Depend on : Shape and size of articular surfaces Ligaments Surrounding muscles  Summary  Difference between cartilage & bone  Classification of bones according to: form, development & shape  Parts and function of skeleton  Types of joints  Characteristics and classification of synovial joint  Stability of joint  Questions -What type of joint is at the base of the thumb? A. Hinge joint B. Pivot joint C. Saddle joint D. Ball and socket joint -Which of the following is retained cartilage throughout life? A. Inner ear B. Costal cartilage C. Food passages D. Shafts of long bone -All are examples of long bone EXCEPT a. humerus b. Scapula c. Ulna d. Tibia References