Skeletal system Types of bones

Characteristics of bone types Bone typeexample FlatSkull, shoulder blades, ribs, sternum, pelvic bones LongArms and legs ShortWrists, ankles IrregularVertebral column, kneepcaps characteristics Like plates of armor, flat bones protect soft tissues of the brains and organs in the thorax Like steel beams, these weight- bearing bones provide structural support 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: Cylinder- shaped 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