Joint Anatomy, Biomechanics, and Range of Motion

Comprehensive vocabulary flashcards covering joint structure, factors affecting range of motion, anatomical movements, joint pathologies, and surgical replacements from the lecture.

Range of Motion (ROM)

The amount of movement achieved in a particular joint or series of joints that results in an angle change between bones, measured in degrees of a circle ($360^\circ$) and classified clinically as a measurable sign.

Osteophytes

Bone spurs formed when the body lays down excess bone to stabilize a degenerating joint, altering joint architecture and restricting range of motion.

Hypermobile Joint

A joint that can move beyond its normal range of motion due to anatomical variations—such as a shorter process, deeper fossa, or ligamentous laxity—often colloquially mischaracterized as being double-jointed.

Relaxin

A hormone secreted into the bloodstream late in the third trimester of pregnancy that creates ligamentous laxity throughout the body to loosen the pelvic ligaments between the sacrum and the os coxa.

Biomechanics

The structural configuration of the human body and the mechanical forces applied to it, which shifts the center of gravity in front of the hips during pregnancy.

Gliding Movements

Back-and-forth and side-to-side movements occurring between relatively flat bone surfaces, as demonstrated by the carpal bones of the wrist.

Angular Movements

Movements that produce an increase or decrease in the angle between articulating bones relative to standard anatomical position.

Rotational Movements

Movements wherein a bone revolves around its own longitudinal axis, such as the motion occurring at the atlantoaxial joint between C1 and C2.

Flexion

An angular movement that decreases the angle between articulating bones from the starting point of anatomical position.

Extension

An angular movement that increases the angle between articulating bones to return to or straighten toward anatomical position.

Hyperextension

The angular movement of a joint beyond its normal anatomical extension.

Abduction

The angular movement of a body part away from the midline of the body.

Adduction

The angular movement of a body part toward or back to the midline of the body.

Circumduction

The movement of the distal end of a body part in a circle, which differs from rotation about a longitudinal axis.

Elevation

The upward movement of a body part, exemplified by closing the mouth at the mandible or raising the scapula.

Depression

The downward movement of a body part, exemplified by opening the mouth at the mandible or lowering the scapula.

Protraction

The anterior movement of a body part forward along a horizontal plane, such as thrusting the mandible forward.

Retraction

The movement of a protracted body part back to its original anatomical position.

Inversion

The special movement of the foot and ankle turning the plantar surface medially toward the midline.

Eversion

The special movement of the foot and ankle turning the plantar surface laterally away from the midline.

Potts Fracture

A fracture occurring at the distal end of the fibula, commonly caused during severe eversion sprains when the talus impacts the lateral malleolus.

Dorsiflexion

The upward flexion of the foot at the ankle joint toward the dorsum (top) of the foot, such as when standing on the heels.

Plantar Flexion

The downward flexion of the foot at the ankle joint toward the plantar surface, such as when pointing the toes or standing on the toes.

Supination

Movement of the forearm where the radius rotates relative to the ulna to turn the palm upward or forward into anatomical position.

Pronation

Movement of the forearm where the radius rotates around the ulna to turn the palm downward or backward.

Opposition

The specialized movement of the opposable thumb across the palm that enables contact with the fingertips for grasping objects.

Temporomandibular Joint

A combined hinge and planar joint between the condylar process of the mandible and the mandibular fossa of the temporal bone, equipped with an articular disc.

Subacromial Bursa

A fluid-filled cushioning structure positioned beneath the acromion process to buffer the humeral head; when inflamed, it impinges during abduction, causing pain and restricted overhead motion.

Glenoid Labrum

A cartilaginous ridge encircling the perimeter of the shallow glenoid cavity to increase socket depth and stability without bony motion restriction.

Frozen Shoulder

A condition characterized by severe loss of joint motion and stiffness in the shoulder, typically precipitated by muscular imbalances, spasms, or prolonged underuse and disuse.

Ulnar Collateral Ligament

A stabilizing ligament of the elbow vulnerable to tears from unnatural side-to-side forces during high-velocity activities such as baseball pitching.

Biceps Brachii Tendon Rupture

An injury where the tendon of the biceps brachii tears—most frequently at its distal insertion on the radial tuberosity—causing the muscle to retract and ball up.

Ligament of the Head of the Femur

A ligament attaching inside the fovea capitis of the femur that assists in anchoring the femoral head into the acetabulum.

Versed

A sedative agent utilized in twilight anesthesia (such as during knee replacement surgeries) to produce profound relaxation and retrograde memory loss.

Partial Hip Replacement

A surgical arthroplasty procedure in which only the femoral head is replaced.

Complete Hip Replacement

A surgical arthroplasty procedure that involves replacing both the femoral head and reshaping the socket to fit an artificial acetabular component.