Ch3 - Articular System

Question 1

Joints

Answer 1

Are the articulations between bones, and along bones and ligaments, they constitute the articular system.

Question 2

Articulation

Answer 2

Point at which bones connect.

Question 3

Ligaments

Answer 3

Tough, fibrous connective tissues anchoring bone to bone. Sometimes reinforces synovial joints. They can be separate structures (extrinsic) or a thickening of the outer layer of the joint capsule (intrinsic). The collagen fibers of a ligament are typically arranged to counteract multidimensional stresses.

Question 4

3 Classifications of Joints

Answer 4

Synarthrodial, amphiarthrodial, or diarthrodial (synovial)

Question 5

Synarthrodial Joints

Answer 5

Joints that do not move appreciable. Does not contain a articular cavity, synovial membrane, or synovial fluid. Ex: sutures of the skull

Question 6

Amphiarthrodial Joints

Answer 6

Joints move slightly and are held together by ligaments (syndesmosis; eg inferior tibiofibular joint) or fibrocartilage (synchondrosis; eg pubic symphysis). Does not contain a articular cavity, synovial membrane, or synovial fluid.

Question 7

Diarthrodial Joints

Answer 7

AKA Synovial Joints. Most common in the human body. They contain a fibrous articular capsule and an inner synovial membrane that encloses the joint cavity. Has high density of sensory fibers hence proprioceptive feedback such as “pain”. Feedback is important in regulating movement and preventing injury.

Question 8

5 Distinct Features of a Synovial Joint

Answer 8

1. ) Is enclosed by a fibrous joint capsule
2. ) The joint capsule encloses the joint cavity
3. ) The joint cavity is lined with synovial membrane
4. ) Synovial fluid occupies the joint cavity
5. ) The articulating surfaces of the bones are covered with hyaline (transparent) cartilage, which helps absorb shock and reduce friction.

Question 9

Synovial Membrane

Answer 9

Lines the joint cavity and produces synovial fluid which provides constant lubrication during movement to minimize the wearing down of cartilage covering articulating bones.

Question 10

Other Support Structures of Synovial Joints

Answer 10

Articular discs (meniscus of the knee), bursae, or fat pads.

Question 11

“Open Chain” Movement

Answer 11

Occurs when a distal segment of a joint moves in space. Ex: for a knee joint is leg extension exercise on a machine.

Question 12

“Closed Chain” Movement

Answer 12

Occurs when the distal segment of a joint is fixed in space. Ex: for the knee joint is standing barbell squats.

Question 13

“Closed Pack” Postition

Answer 13

When there is both maximal congruency of the joint surfaces and maximal tautness of the joint capsules and ligaments.

Question 14

“Open Pack” Position

Answer 14

“Loose” when there is the least joint congruency and the joint capsules and ligaments are most loose.

Question 15

ROM

Answer 15

“Range of Motion”. The degree of movement within a joint. It can be active or passive. Is quantified using goniometers and inclinometetes and each joint has ROM values that can be used to help guide exercise prescriptions.

Question 16

Passive ROM

Answer 16

It can be achieved by external means

Question 17

Active ROM

Answer 17

Can be reached by voluntary movement from contraction of skeletal muscle.

Question 18

Hypermobile ROM

Answer 18

Joints with excessive range of motion

Question 19

Hypomobile ROM

Answer 19

Joints with restricted range of motion

Question 20

Multiple Joint Movements

Answer 20

Movement at one joint may influence the extent of movement at an adjacent joint because muscles and other soft tissues often cross multiple joints. Ex: finger flexion decreases in the presence of wrist flexion because muscles that flex both wrist and fingers cross multiple joints.

Question 21

Joint Stability

Answer 21

Its resistance to displacement. Not all joints have the same degree of stability. In general, ROM is gained at the expense of stability.

Question 22

5 Factors that Account for Joint Stability

Answer 22

1. ) Ligaments check normal movement and resist excessive movement.
2. ) Muscles and tendons that span a joint also enhance stability, particularly when the bony structure alone contributes little stability (ex: shoulder)
3. ) Fascia contributes to joint stability (ex: iliotibial bond of the tensor fasciae latae).
4. ) Atmospheric pressure creates greater force outside of the joint than normal internal pressure exerts within the joint cavity (the seduction created by this pressure is an important factor in aiding joint stability)
5. ) The bony structure of a joint is an important contributor to joint stability )ex: limitation of elbow extension by the olecranon process of the ulna).