Summarizing Joints and Skeletal Movement

Summary

The structural classification of joints divides them into bony, fibrous, cartilaginous, and synovial joints. The bones of fibrous joints are held together by fibrous connective tissue; the three types of fibrous joints are sutures, syndesomes, and gomphoses. Cartilaginous joints are joints in which the bones are connected by cartilage; the two types of cartilaginous joints are synchondroses and symphyses.

Synovial joints are joints that have a space between the adjoining bones. The functional classification divides joints into three categories: synarthroses, amphiarthroses, and diarthroses. The movement of synovial joints can be classified as one of four different types: gliding, angular, rotational, or special movement. Gliding movements occur as relatively flat bone surfaces move past each other. Angular movements are produced when the angle between the bones of a joint changes.

Rotational movement is the movement of a bone as it rotates around its own longitudinal axis. Special movements include inversion, eversion, protraction, retraction, elevation, depression, dorsiflexion, plantar flexion, supination, pronation, and opposition. Synovial joints are also classified into six different categories on the basis of the shape and structure of the joint: planar, hinge, pivot, condyloid, saddle, and ball-and-socket.

Glossary

abduction

when a bone moves away from the midline of the body

adduction

movement of the limbs inward after abduction

amphiarthrosis

joint that allows slight movement; includes syndesmoses and symphyses

angular movement

produced when the angle between the bones of a joint changes

ball-and-socket joint

joint with a rounded, ball-like end of one bone fitting into a cuplike socket of another bone

cartilaginous joint

joint in which the bones are connected by cartilage

circumduction

movement of a limb in a circular motion.

condyloid joint

oval-shaped end of one bone fitting into a similarly oval-shaped hollow of another bone

depression

movement downward of a bone, such as after the shoulders are shrugged and the scapulae return to their normal position from an elevated position; opposite of elevation

diarthrosis

joint that allows for free movement of the joint; found in synovial joints

dorsiflexion

bending at the ankle such that the toes are lifted toward the knee

elevation

movement of a bone upward, such as when the shoulders are shrugged, lifting the scapulae

eversion

movement of the sole of the foot outward, away from the midline of the body; opposite of inversion

extension

movement in which the angle between the bones of a joint increases; opposite of flexion

fibrous joint

joint held together by fibrous connective tissue

flexion

movement in which the angle between the bones decreases; opposite of extension

gliding movement

when relatively flat bone surfaces move past each other

gomphosis

the joint in which the tooth fits into the socket like a peg

hinge joint

slightly rounded end of one bone fits into the slightly hollow end of the other bone

hyperextension

extension past the regular anatomical position

inversion

soles of the feet moving inward, toward the midline of the body

joint

point at which two or more bones meet

lateral rotation

rotation away from the midline of the body

medial rotation

rotation toward the midline of the body

opposition

movement of the thumb toward the fingers of the same hand, making it possible to grasp and hold objects

plantar flexion

bending at the ankle such that the heel is lifted, such as when standing on the toes

planar joint

joint with bones whose articulating surfaces are flat

pivot joint

joint with the rounded end of one bone fitting into a ring formed by the other bone

pronation

movement in which the palm faces backward

protraction

anterior movement of a bone in the horizontal plane

retraction

movement in which a joint moves back into position after protraction

rotational movement

movement of a bone as it rotates around its own longitudinal axis

saddle joint

joint with concave and convex portions that fit together; named because the ends of each bone resemble a saddle

supination

movement of the radius and ulna bones of the forearm so that the palm faces forward

suture

short fiber of connective tissue that holds the skull bones tightly in place; found only in the skull

synarthrosis

joint that is immovable

symphysis

hyaline cartilage covers the end of the bone, but the connection between bones occurs through fibrocartilage; symphyses are found at the joints between vertebrae

synchondrosis

bones joined by hyaline cartilage; synchondroses are found in the epiphyseal plates of growing bones in children

syndesmosis

joint in which the bones are connected by a band of connective tissue, allowing for more movement than in a suture

synovial joint

only joint that has a space between the adjoining bones