Types of Joints and Bones Mrs. Sheila Taylor

Types of bones There are four major types of bones found in the body. Long – longer than they are wide and work as levers Short – short, cubed shaped, found in the wrist and ankles Flat – broad surfaces for protection and muscle attachment Irregular – bones that don't fit into the other three groups

Irregular bones

Flat bones

The extremes... The largest bone in your body The femur – it is a long bone that makes up the thigh The smallest bones in the body The three bones in the middle ear Incus, malleus, stapes (anvil, hammer, and stirup) Transmit sounds from the eardrum to the inner ear

Synovial joints Most numerous in the body Allows for free movement Parts Articulating cartilage- on the ends of the bones Joint capsule – tubular capsule of dense connective tissue Outer layer is ligaments Inner layer is synovial membrane which secrete fluid into the joint cavity

Extra parts found in some Menisci A flattened shock absorbing pad of fibrocartilage between the bones Bursae Fluid filled sac lined with synovial membrane Not in the main joint cavity Typically located between tendons and underlying bony prominences Aid in movement of the tendon over the bone or other tendons

There are 6 major types of synovial joints Ball and socket Hinge Saddle Pivot Condyloid Gliding

Ball and Socket Description Movement: Ex: Ball head of one bone articulates in the cup- shaped cavity of another one Movement: Movement in all planes and rotation Ex: Shoulder, hip

Ball and socket

Hinge Description Movements: Ex: Convex surface of one bone articulates with the concave surface of another Movements: Flexion and extention Ex: Elbow, joints of phalanges, knee

Hinge

Saddle Description: Movement: Ex: Surfaces have both convex and concave regions, the surface of one bone fits the complementary surface of the another Movement: Variety of movement Ex: Between carpel (trapezium) and metacarpel of the thumb

Saddle

Pivot Description: Movement: Cylindrical surface of one bone articulates with ring of bone and ligament Movement: Rotation around a central axis Ex: joint between the proximal ends of the radius and ulna, as well as tibia and fibula

Pivot

Gliding Description: Movement: Ex: Articulating surfaces ae nearly flat or slightly curved Movement: sliding or twisting Ex: Ankles, wrist, sacroiliac, rib 2-7 and the sternum

Gliding

Condyloid Description: Movement: Ex: Oval-shaped condyle of one bone articulates with ellipitcal cavity of another Movement: Variety of movements on different planes, but no rotation Ex: Between phalanges and metacarpals

Two other types of joints Fibrous – bones are fastened together by a thin layer of dense connective tissue No possible movement Ex: suture between skull bones, joints between the distal ends of the tibia and fibula Cartilaginous- bones are connected by hyaline or fibrocartilage Limited movement Ex: joints between vertebrae bodies, symphysis pubis, first rib and the sternum

Suture, fixed, fibrous

Sometimes a joint is more than one type