Synovial Joints (6)

Medial Meniscus

-AKA articular discs. -two fribrocartilage discs between tibial and femoral condyles help compensate for the irregular shapes of bones and circulate synovial fluid.

Hinge Joints

-AKA ginglymus joint. -the convex surface of the bone fits into the concave surface of another bone. -produce an angular opening and closing motion. -uniaxial (monaxial) because they typically allow motion around a single axis. -permit only flexion and extension.

Pivot Joint

-AKA trochoid joint. -the rounded or pointed surface of the bone articulates with a ring formed partly by another bone and partly by a ligament. -Isuniaxial because it allows rotation only around its own longitudinal axis.

Factors affecting ROM: Hormones

-Joint flexibility may also be affected by hormones. For example, relaxin, a hormone produced by the placenta and ovaries, increases the flexibility of the fibrocartilage of the pubic symphysis and loosens the ligaments between the sacrum, hip bone, and coccyx toward the end of pregnancy. These changes permit expansion of the pelvic outlet, which assists in delivery of the baby.

Factors affecting ROM: Disuse

-Movement at a joint may be restricted if a joint has not been used for an extended period. Disuse may result in decreased amounts of synovial fluid, diminished flexibility of ligaments and tendons, and muscular atrophy, a reduction in size or wasting of a muscle.

Factors affecting ROM: arrangement and tension of the muscles

-Muscle tension reinforces the restraint placed on a joint by its ligaments, and thus restricts movement.

Factors affecting ROM: Strength and tension (tautness) of the joint ligaments.

-The different components of a fibrous capsule are tense or taut only when the joint is in certain positions. -Tense ligaments restrict the range of motion and also direct the movement of the articulating bones.

Factors affecting ROM: Contact of Soft Parts

-The point at which one body surface contacts another may limit mobility. Joint movement may also be restricted by the presence of adipose tissue.

Ball-and-socket joint or spheroid joint.

-a ball-like surface of a bone fitting into a depression of another bone. -triaxial (multiaxial) permiting movements around 3 axes felxion-extension and abduction-adduction, and rotation.

Tibial collateral ligament

-broad, flat ligament on the medial surface of the joint that extends from the medial condyle of the femur to the medial condyle of the tibia.

Posterior cruciate ligament (PCL)

-extends anteriorly and medially from a depression on the posterior intercondylar area of the tibia and lateral meniscus to the anterior part of the lateral surface of the medial condyle of the femur.

anterior cruciate ligament (ACL)

-extends posteriorly and laterally from a point anterior to the intercondylar area of the tibia to the posterior part of the medial surface of the lateral condyle of the femur.

Factors affecting Range of Motion (ROM) : Structure or shape of the articulating bones

-how closely they can fit together. An interlocking fit allows rotational movement.

examples of hinge joints

-knee, elbow, ankle, and interphalangeal joints

Knee Joint (tibiofemoral joint)

-largest, most complex joint of the body. -modified hinge joint because its primary movement is a uniaxial hinge movement. -consists of 3 joints within a synovial cavity.

Lateral Meniscus

-nearly circular piece of fibrocartilage. attached anteriorly to the intercondylar eminence of the tibia, and laterally and posteriorly to the anterior cruciate ligament.

Synovial Joints

-similar characteristics. -shapes of artciulating surfaces vary. -many different movements. -6 categories of synovial joints based on the types of movement: plane, hinge, pivot, condyloid, saddle, and ball-and-socket.

Fibular collateral ligament

-strong, rounded ligament on the lateral surface of the joint. -extends from the lateral condyle of the femur to the lateral side of the head of the fibula. -strengthens the lateral aspect of the joint.

Saddle Joint or sellar joint

-the articular surface of one bone is saddle- shaped, and hte articular surface of the other bone fits in the "saddle". -biaxial (felxion-extension and abduction-adduction) plus limited circumduction.

planar joint

-the articulating surfaces of bones in a plane joint, also called planar joint. -flat, or slightly curved. -permit back-and-fourth and side-to-side movements between the flat surfaces of the bones. -may also rotate against one another. -biaxial- moves in two axes. -triaxial- movement in 3 axes. joints that rotate in addition to sliding.

Condyloid or ellipsoidal joint

-the convex oval-shaped projection of one bone fits into the oval- shaped depression of another bone. -biaxial because it permits movement around 2 axis. (felxion-extension and abduction-adduction) -limited circumduction (isolated movement)

what are the 3 joints within a synovial cavity that make up the knee joint?

1. Laterally: tibiofemoral joint. 2. Medially: tibiofemoral joint. 3. intermediate: patellofemoral joint.

Examples of pivot joints

atlanto-axial joint, and radioulnar joints.

example of saddle joint or sellar joint.

carpometacarpal joint

examples of planar joints

intercarpal joints (between carpal bones and the wrist) intertarsal joints (between tarsal bones and ankle) sternoclavicular joints (between manubrim and clavicle)

examples of condyloid or ellipsoidal joints

radiocarpal (wrist). metacarpophalangeal (between metacarpals and proximal phalanges)

examples of ball and socket joints

shoulder and hip joints.