Biology XI: 20 Locomotion & Movement(4 Joints)

Joints & Disorders of Musculo-Skeletal System Joints Points of contact between bones or between bones and cartilages Joints act as fulcrum used to carry out movement by force generated through muscles. Classification of joints depending upon structure: Fibrous joints Cartilaginous joints Synovial joints Bones fuse end to end with the help of dense fibrous connective tissues. Bones are joined together with the help of cartilages. Bones are not joined together directly, but fluid-filled synovial cavity is present between articulating surfaces of two bones. Do not allow any movement Permit limited movement Show maximum movement Example − Skull bones fuse end to end with the help of dense fibrous connective tissues called sutures to form cranium. Example − Joints between adjacent vertebrae Example − Ball and socket joint       Types of Synovial joints Synovial joint − five types: Ball and socket jointAllows free movementFound between humerus and pectoral girdle, femur and acetabulum Hinge jointAllows movement in one planeExample: knee joint, elbow joint Pivot jointOne bone rotates over other.Found between atlas and axis Gliding jointAllows only gliding and sliding movementFound between carpals and wrist Saddle jointThis type of joints allows back and forth and side to side motion, but only limited rotation.Found between carpal and metacarpal of thumb Disorders of Muscular and Skeletal Systems Myasthenia Gravis Autoimmune disorder affecting neuromuscular function Leads to fatigue, weakening, and skeletal muscle paralysis Muscular Dystrophy Genetic disorder leading to degeneration of skeletal muscle Tetany Low calcium concentration in body fluid Rapid spasms in muscle Arthritis Inflammation of joints Osteoporosis Age related disorder associated with decreased estrogen levels Decreased bone mass and increased chances of fractures Gout Accumulation of uric acid crystals Inflammation of joints