Chapter 9 (2)

• Range of motion (ROM) means the degrees through which a joint can move. It is an aspect of joint performance and a physical assessment of a patient’s joint flexibility.
• ROM is determined by (1)the structure of the articular surfaces (2)the strength and tautness of ligaments and joint capsules AND (3)the action of the muscles and tendons. Muscle tone means the state of tension maintained in resting muscles.
• In axes of rotation, a moving bone has a relatively stationary axis of rotation that passes through the bone in a direction perpendicular to the plane of movement. A multiaxial joint is the shoulder joint and it has three degrees of freedom or axes of rotation. Other joints are monoaxial or biaxial.
• Six classes of synovial joints are; ball-and-socket, condylar, saddle, plane, hinge, and pivot.
• (1)Ball-and-socket joints are smooth, hemispherical heads that fit within a cup-like socket. It is the only multiaxial joint in the body e.g. in the shoulder and hip. (2)Condylar (ellipsoid) joints are the oval convex surfaces of one bone that fit into a complementary-shaped depression on the other. Biaxial joints are movement in two planes. e.g. radiocarpal joint, metacarpophalangeal joints.
• Saddle joints mean that both bones have an articular surface that is shaped like a saddle, one concave, the other convex. They are biaxial joints, e.g. the trapeziometacarpal (opposable thumb), and sternoclavicular joint. Plane (gliding) joints are flat articular surfaces, where bones slide over each other. They are usually biaxial joints, e.g. between the carpal bones of the wrist, between the tarsal bones of the ankle, and also between the articular processes of vertebrae.
• With Hinge joints there is one bone with a convex surface that fits into a concave depression of another bone. Here, monoaxial joints move freely in one plane, e.g. elbow, knee, joints within fingers, toes. With Pivot joints a bone spins on its longitudinal axis. There are monoaxial joints e.g. the atlantoaxial joint (C1 (atlas) and C2 (axix)), radioulnar joint at the elbow.
• The zero position is the position of a joint when a person is in the standard anatomical position. Here the joint movements are described as deviating from the zero position or returning to it.
• Flexion is the movement that decreases joint angle. It means to bend, and it is common in hinge joints. Extension is a movement that straightens a joint and returns a body part to the zero position. Hyperextension is the extension of a joint beyond the zero position. Flexion and extension occur at nearly all diarthroses and hyperextension is limited to a few.
• Abduction is the movement of a body part in the frontal plane away from the midline of the body. Hyperabduction means to raise the arm over the back or front of the head.
• Adduction is the movement in the frontal plane back toward the midline. Hyperadduction, e.g. crossing fingers, crossing ankles.
• Elevation is the movement that raises a body part vertically in the frontal plane. Depression is the movement that lowers a body part in the same plane.
• Protraction is the anterior movement of a body part in the transverse (horizontal) plane. Retraction is the posterior movement.
• Circumduction is when one end of an appendage remains stationary while the other end makes a circular motion. Example: an artist circumducts the upper limb when painting a circle on a canvas.
• Rotation is the movement in which a bone spins on its longitudinal axis, e.g. the rotation of trunk, thigh, head, or arm. Medial (internal) rotation turns the bone inward while Lateral (external) rotation turns the bone outward.
• Supination means forearm movement that turns palm to face anteriorly or upward. The forearm is supinated in an anatomical position and in this position, the radius is parallel to the ulna. Pronation means forearm movement that turns palm to face either posteriorly or downward in this position the head of the radius spins and it crosses the stationary ulna like an X.
• Flexion means forward-bending movements at the waist or neck. Extension straightens the trunk or neck. Hyperextension means bending over backward. Lateral flexion means tilting the head or trunk to the right or left at the midline.
• The lateral excursion is the right or left movement of the mandible from the zero position. The medial excursion is the movement of the mandible back to the median, zero position, e.g. the side-to-side grinding during chewing. Protraction means retraction. Elevation means depression.
• Radial flexion is the tilting of the hand toward the thumb. Ulnar flexion is the tilting of the hand toward the little finger. Abduction vs. adduction ofthe fingers is spreading them apart vs. bringing them together. Flexion vs. extension of fingers curling vs. straightening them.
• Palmar abduction means moving the thumb away from the hand and pointing it anteriorly. Radial abduction is the moving thumb away from the index finger (90°). Flexion of the thumb means the tip of the thumb is directed toward the palm. Extension of the thumb is the straightening of the thumb. Opposition is the moving of the thumb to touch the tip of a finger. Reposition is the return of the thumb to the zero position.