Skeletal system Types of bones Characteristics of bone

Skeletal system Types of bones

Characteristics of bone types Bone type example characteristics • Flat • Like plates of armor, flat bones protect soft tissues of the brains and organs in the thorax • Long Skull, shoulder blades, ribs, sternum, pelvic bones Arms and legs • Like steel beams, these weightbearing bones provide structural support • Short Wrists, ankles • • Irregular Vertebral column, kneepcaps Short bones look like blocks and allow a wider range of movement than larger bones • Irregular bones have a variety of shapes and usually have projections that muscles, tendons, and ligaments can attach to.

Flat Bones

Long bones

Short bones

Irregular bones

Sesamoid bones • Though not universally recognized, sesamoid bones are usually small and rounded like the patella.

Joint Types • Every bone in the body forms a joint with another bone except the hyoid bone. • Synarthroses: Joints that do not move. The sutures between the different bones in the cranium do not move. • Amphiarthroses: Slightly moveable joints connected by fibrous cartilage. Examples are the intervertrebral disks join each vertebrae and allow slight movement. • Diarthroses: A. K. A. synovial joints, diarthroses are held together by ligaments and are freely moveable.

Types of synovial joints • Name: Ball-and-socket joint • Description: The ball shaped head of one bone fits into a depression (socket) in another bone. • Movement: Circular movements; joints can move in all planes, and rotation is possible. • Example: Shoulder, hip

Types of synovial joints • Name: Condyloid joint • Description: Oval-shaped condyle of one bone fits into oval-shaped cavity of another bone • Movement: Can move in different planes but cannot rotate • Example: Knuckles (joints between metacarpals and phalanges)

Types of synovial joints • Name: Gliding joint • Description: Flat or slightly curved surfaces join • Movement: Sliding or twisting in different planes • Example: Joints between carpal bones (wrist) and between tarsal bones (ankle), Sternoclavicular joint.

Types of synovial joints • Name: Hinge joint • Description: Convex surface joins with concave surface • Movement: Up and down motion in one plane • Example: Elbow, Knee

Types of synovial joints • Name: Pivot joint • Description: Cylindershaped projection on one bone is surrounded by a ring of another bone and ligament • Movement: Rotation is only movement possible • Example: Joint between radius and ulna at elbow and joint between atlas and axis at top of vertebral column

Types of synovial joints • Name: Saddle joint • Description: Each bone is saddle shaped and fits into the saddle-shaped region of the opposite bone • Movement: Many movements are possible • Example: Joints between carpal and metacarpal bones of the thumb

Movements • Joints can produce two basic types of movement, angular and circular. • Angular movements make the angle formed by two bones larger or smaller, examples: • Abduction: Moving a body part away from the midline • Adduction: Moving a body part toward the midline • Extension: Making the angle larger (hyperextension occurs when the body part passes 180 degrees) • Flexion: Making the angle smaller.

Movements Circular movements : Circumduction: movement of a body part in circles Depression: downward movement of a body part Elevation: upward movement of a body part Eversion: only happens in feet, when sole of foot is facing outward • Inversion: only happens in feet, when sole of foot is facing inward • Rotation: movement of a body part around its own axis • Supination/pronation: rotating forearm to make palm face up/down. • • •

Movements • Angular movements: • Dorsiflexion: Movement at the ankle that brings the foot closer to the shin • Plantarflexion: Movement at the ankle that brings the foot farther from the shin • Protraction: Moving a body part forward • Retraction: Moving a body part backwards