Chapter 9 (Joints IV) Flashcards
Factors Affecting Contact and Range for Motion at Synovial Joints
Range of motion (ROM)
Factors contribute to keeping the articular surfaces in contact and affect range of motion:
• Structure or shape of the articulating bones
• Strength and tension of the joint ligaments
• Arrangement and tension of the muscles
• Contact of soft parts
• Hormones
• Disuse
Structure or shape of the articulating bones
Shape of bones determines how closely they fit together.
Strength and tension of the joint ligaments
Ligaments are tense when the joint is in certain positions.
Tense ligaments restrict the range of motion.
Arrangement and tension of the muscles
Muscle tension reinforces the restraint placed on a joint by its ligaments, and thus restricts movement.
Contact of soft parts.
The point at which one body surface contacts another may limit mobility.
Movement be restricted by the presence of adipose tissue.
Hormones
Flexibility may also be affected by hormones.
Relaxin increases the flexibility of the pubic symphysis and loosens the ligaments between the sacrum and hip bone toward the end of pregnancy.
Disuse
Movement may be restricted if a joint has not been used for an extended period.
Selected Joints of the Body
Temporomandibular joint Shoulder joint Elbow joint Hip joint Knee joint
Temporomandibular joint
Combined hinge and planar joint formed by the mandible and the temporal bone.
Only movable joint between skull bones.
Only the mandible moves.
Shoulder joint
Ball-and-socket joint formed by the head of the humerus and the scapula.
More freedom of movement than any other joint of the body.
Elbow joint
Hinge joint formed by the humerus, the ulna, and the radius.
Hip joint
Ball-and-socket joint formed by the femur and the hip bone.
Knee joint
Largest and most complex joint of the body
Modified hinge joint
