CHAPTER IV PDL 101 HUMAN ANATOMY & PHYSIOLOGY

Transcription

1 CHAPTER IV PDL 101 HUMAN ANATOMY & PHYSIOLOGY Ms. K. GOWRI. M.Pharm., Lecturer.

2 BONES AND JOINTS Structure and function of bone(skeleton): Bone is a strong and durable type of connective tissue. It consists of water (25%), organic costituents including osteoid and bone cell (25%), inorganic mainly cal.phosphate (50%). Structure: Bones are classified as long, short, irregular, flat and sesamoid General structure of bone These have a diaphysis or shaft and two epiphyses or extremeties. The diaphysis is composed of compact bone with a central medullary canal, containing fatty yellow bone marrow.

3 The epiphyses and diaphysis are separated by epiphyseal cartilages which ossify when growth is complete. Long bones are almost covered by a vascular membrane, the preiosteum Outer layer fibrous and Inner layer osteogenic containing osteoblasts,osteoclasts which are involved in maintenance and remodeling of bones. Hyaline cartilage replaces periosteum on the articular surfaces of bones forming synovial joints. Structure of short, flat, irregular & seasmoid bone They have a relatively thin outer layer of compound bone with cancellous bone inside containing. red bone marrow

4 microscopic structure of bone COMPACTBONE: To the naked eye compound bone appears solid,but on microscopic examination large number of haversian system and osteans are seen. These consists of central haversian canal,containing blood & lymph vessels &nerves, surrounded by concentric rings or plates of bones. Lacunae: Tiny spaces containing tissue fluid & spider shaped osteocytes. CARCELLOUS BONE: To the naked eye this bone looks like a honey comb. microscopic examination reveals a frame work formed from the trabeculae(means little beams)which consists a few lamelle & osteocytes inter connected by canalliculi. BONE CELLS:

5 The cells responsible for nbone formation are called osteoblast. Osteoblast & condrocytes develop from the same parent fibrous tissue cells. FACTORS AFFECTING HEALING OF FRACTURES OSTEOBLAST: These are bone forming cells secreting collagen & other constituents of bone tissue. They are present In deeper layers of periosteium. In the centers of ossification of immature bones. At the end of diaphysis adjacent to epiphysial cartillages of long bones. At the site of fracture. OSTEOCYTES:

6 Osteoblast become trapped & remain isolated in the lacunae.they stop forming a new bone at this stage called osteocytes. OSTEOCLASTS: Function is resorption of bone to maintain the optimum shape. this takes at bone surfaces. Under the periosteiumto maintain shape of bones during growth & to remove excess callus formed dueing healing. Round the walls of the medullary canal during growth & to canalise calllus during healing. A fine balnce of osteoblast & osteoclast activity maintains normal bone structure & functions. FUNCTIONS OF BONES: Provide the frame work of the body. Give attachment to muscles & tendons.

7 Permit movement of the body as a whole & of parts of the body. Form boundaries of the cranial, thoracic & pelvic cavities contain red bone marrow in which blood cells develop. Provide reservoir of minerals, especially calcium phosphate. JOINTS Joint is the site at which any two or more bones articulate or come together. Some some joints have no movement(fibrous), some only slight movement(cartilagenous) & some are freely movable(synovial). TYPES OF JOINTS: 1.FIBROUS or fixed joints: These immovable joints have fibrous tissue between the bones.

8 ex: Joints between the bones of the skull & those between the maxille, mandible & teeth. 2.CARTILEGINOUS or slightly movable joints: There is a pad of fibrocartilage between the ends of the bones that form the joint which allows for very slight movement where the pad of cartilage is compressed. 3.SYNOVIAL or freely movable joints: This joints have characterstic features that enable a wide range of movements. Classified according to the range of movement possible or to the shape of the articulating parts of the bone involved. a)ball & SOCKET: Ball or head of one bone articulates with the socket of another & the shape of the bone allows for a wide range of movement.

9 ex: Shoulder & hip. b)hinge JOINT: Allow the ovement of flexion & extension only. They are the elbow,knee,ankle joints between the atlas & occipetal bone. c)gliding JOINTS: Articulating surfaces glide over each other. ex: Sterno clavicular joints, joints between the carpel bones, & those between tarsal bones. d)pivot JOINTS : Movement is round one axis. ex: Proximal & distal radio lunar joints & joint between the atlas & odontoid process of the axis. e)condyloid & SADDLE JOINTS: Movements take place round two axes, permitting flexion, extaension,abduction.

10 ex: The wrist, temporo mandibular, metacarpal phallinges. DIFFERENT TYPES OF JOINTS ARE: Shoulder joint Elbow joint Proximal and distal radioulnar joints Wrist joint Joints of the hands and fingers Hip joint Knee joint. Disorders of joint: Inflammatory diseases of joints arthritis Two main types of arthritis 1. osteoarthritis 2. rheumatoid arthritis In osteoarthritis type of diseases is degenerative

11 tissue affected articular cartilage age of onset late middle age joints affected weight earing eg: Hip, knee, of ten only a single joint. In Rheumatoid arthritis: Type of disease inflammatory and auto immune Tissue affected synovial membrane Age of onset any age, mainly yrs, occasionally children. Joint affected small eg: hands, feet, often, many joints. Other types of polyarthritis: This group of autoimmune inflammatory arthritic diseases has many characteristics similar to rheumatoid arthritis: ankylosing spondylitis pscriatic arthritis

12 reiter's syndrome rheumatic fever. Traumatic injury to joints: Sprains, strains and dislocations these damage the soft tissue, tendons and ligaments round the joint without penetrating the joint capsule. In disslocations, additional damage to intracapsular structures by stretching. Gout: This condition is more prevalent in males then in females. caused by deposition of sodium ureate crystals in joints and tendons. It occurs in people whose blood uric acid is high. Carpal tunnel syndrome:

13 Occurs when the median nerve is compressed in the wrist as it passes through carpal tunnel. common in women between the age of yrs.