Presentation on theme: "BONES. Functions 1.Provides framework for form and shape of the body (Prevents soft tissue from collapsing) 2.Provide points of attachment for muscles."— Presentation transcript:
Functions 1.Provides framework for form and shape of the body (Prevents soft tissue from collapsing) 2.Provide points of attachment for muscles (Articulation: allowing bone movement relative to one another) 3.Protection of vital organs 4.Storage areas for mineral salts and fats (Ca, P, Na, K) 5.Blood Cell production
Macroscopic Structure Diaphysis is a hollow cylinder of compact bone containing yellow bone marrow (fat storage) in the centre Epiphyses contain spongy (cancellous bone) in centre. Large spaces in spongy bone are often filled with red bone marrow. (Red blood cell production) Periosteum: dense white fibrous covering Articular Cartilage: cartilage covering each epiphysis.
Microscopic Structure Bone is a connective tissue (cells separated by large amounts of non-cellular matrix) with inorganic salt deposits. (increase strength / rigidity) Composed of bones cells (osteocytes) 1.Haversian System/ Osteons (compact bone): Projections from bone cells enter canaliculi and make contact with adjacent cells (Material transfer) Haversian/Central canal contains at least one blood capillary. (may also contain nerves / lymph capillary) Haversian system runs parallel to long axis of bone (adds strength) Lamellae: layers of bony matrix Lacunae: pockets (spaces) between lamellae
Microscopic Structure 2. Trabeculae (spongy bone): Irregular arrangement of thin, bony plates. Contains bone cells but not in concentric layers Nerves and blood vessels pass through irregular spaces in matrix
Microscopic Structure A connective tissue Perichondrium: fibrous protective layer Only external blood vessels (in perichondrium), relies on diffusion through matrix. Consists of protein fibres (Collagen) which are embedded in Protein-carb complex (chondrin). Chondroblasts: immature cartilage cells in the spaces in the matrix (produce matrix which will eventually surround it) Chondrocytes: mature cartilage cells which are inside a pocket (lacunae) surrounded by chondrin
CLASSIFICATOIN Three types (based on thickness of fibres in matrix) 1.Hyaline: Very fine and very dense for strength. E.g. larynx (part), trachea, bronchi, articular cartilage, nose (part). 2.Elastic: medium thickness with elastic properties. E.g. ear, larynx (part), epiglottis, nose (part) 3.Fibrocartilage: thick and less dense, allowing for slight compression ideal for areas which withstand high pressure. E.g intervertebral discs, knee & pelvic joint.
1.Fixed (Fibrous joints) No movement occurs between the bones involved. Held in place by fibrous connective tissue On impact bone fracture rather that joint damage. E.g. skull, teeth/jaw 2. Slightly movable (cartilaginous joints) Allows very limited movement Held in place by fibrous cartilage eg symphysis pubis, vertebrae joints, joints between ribs and sternum 3. Freely movable (synovial joints) Amount of movement is limited only by ligaments, muscles, tendons and adjoining bones. Highly mobile but equally weak
Ball-and-socket joints Spherical head of one bone fits into cup-like head of another Only occur in two places: shoulder (humerus/scapula) & hip (femur/pelvis) Hinge Joint Allows movement in one plane only. Convex surface of one bone fits into concave surface of another E.g. elbow (ulna/Humerus), wrist (radius/carpals), knee (femur/tibia), ankle (tibia/tarsals), fingers & toes (phalanges)
Pivot Joint Rounded, pointed or conical end of one bone articulates with a ring (part bone, part ligament) E.g. 1 st vertebrae (head) / 2 nd vertebrae & radius / ulna Gliding Joint Gliding movement in any direction (back/forth, side/side), limited only by ligaments or bony processes. E.g. carpals, tarsals, sternum/clavicle, scapula/clavicle
Saddle joint Two saddle shaped joints Allows side/side and back/forth movements e.g. thumb (carpal/metacarpal) Condyloid (ellipsoid) joint Slightly convex fits with slightly concave Allows side/side or back/forth movements e.g. radius/carpal, metacarpal/phalanges, metatarsals/phalanges
STRUCTURE OFA SYNOVIAL JOINT Capsule: surrounding and enclosing the joint (2 layers): 1) fibrous capsule (outer layer), dense, fibrous connective tissue attached to periosteum. Flexibility allows movement but strength prevents dislocation 2) Synovial membrane (inner layer), vascular, loose connective tissue Synovial Fluid (0.5mL): Secreted by synovial membrane, fills synovial cavity. Lubricates, nourishes & contains phagocytic cells.
STRUCTURE OFA SYNOVIAL JOINT Articular Cartilage: provides smooth surface for movement Articular Discs: (in knee - Menisci/meniscus) fibrocartilage extending inward from articular Capsule. Divide synovial cavities into two cavities. Bursae: little sacs of synovial fluid. Prevent friction between a bone and a ligament/tendon/skin Accessory Ligaments: hold bones together
Factors keeping bones together: fit of articulating bones Strength of bone ligaments Tension by surrounding muscles
Movement of a Joint: Flexion: (bending) decreases angle between articulating bones Extension: (Straightening) increases angle between articulating bones Abduction: movement away from the body Adduction: movement towards from the body Rotation: Movement of a bone around its long axis.