Class 13 - Joints

Question 1

Joint (articulation)

Answer 1

Any point where two bones meet, whether or not the bones are moveable at that interface

Question 2

Arthrology

Answer 2

Science of joint structure, function, and dysfunction

Question 3

Kinesiology

Answer 3

The study of musculoskeletal movement

Question 4

Bony joint (synostosis) + example

Answer 4

An immobile joint formed when the gap between bones ossifies, and the bones become essentially one single bone

Example: left and right frontal and mandibular bones fuse in infants

Can occur in either fibrous or cartilaginous joint

Question 5

Fibrous joints (synarthrosis) + 3 types

Answer 5

Adjacent bones are bound by collagen fibers that emerge from one bone and penetrate into the other.

1. Sutures
2. Gomphoses
3. Syndesmoses

Question 6

Sutures + 3 types

Answer 6

Immobile or slightly mobile fibrous joints in which short collagen fibers bind the bones of the skull to each other

1. Serrate suture
2. Lap (squamous) suture
3. Plane (butt) suture

Question 7

Serrate suture + 3 examples

Answer 7

Interlocking wavy lines

Examples: coronal, sagittal, and lambdoid sutures.

Question 8

Lap (squamous) suture + 2 examples

Answer 8

Overlapping beveled edges.

Examples: temporal and parietal bones

Question 9

Plane (butt) suture + example

Answer 9

Straight non-overlapping edges

Palatine processes of the maxillae.

Question 10

Gomphosis

Answer 10

Attachment of a tooth in its socket.

Held in place by fibrous periodontal ligament.
Collagen fibers attach tooth to jawbone, allowing tooth to move slightly

Question 11

Syndesmosis + 2 examples

Answer 11

A fibrous joint at which two bones are bound by long collagen fibers

Separation of bones and long fibers = more mobile joint

1. Mobile example: Interosseus membrane of ulna and radius
2. Less mobile: joint between tibia and fibula

Question 12

Cartilaginous joints (amphiarthrosis) + 2 types

Answer 12

Two bones linked by cartilage.

1. Synchondroses
2. Symphyses

Question 13

Synchondrosis + 2 examples

Answer 13

Type of cartilaginous joint. Bones joined by HYALINE cartilage.

1. Temporary joint between epiphysis and diaphysis in child formed by epiphyseal plate cartilage
2. First rib attached to sternum

Question 14

Symphysis + 2 examples

Answer 14

Type of cartilaginous joint. Two bones joined by FIBROCARTILAGE

1. Interpubic disc of pubic symphysis
2. Bones of vertebrae joined by intervertebral discs.

Question 15

Synovial joint (diarthrosis)

Answer 15

Joint in which two bones are separated by a joint cavity.

Most freely mobile, structurally complex, and likely to develop dysfunction.

Question 16

Structure of synovial joints (5)

Answer 16

1. Articular cartilage - layer of hyaline cartilage covering the facing bone surfaces
2. Joint (articular) cavity - separates articular surfaces
3. Synovial fluid - lubricant, nourishes articular cartilage/removes waste
4. Joint (articular) capsule - connective tissue enclosing the cavity and retaining fluid.
5. Articular disc OR meniscus

Question 17

Joint capsule 3 features

Answer 17

1. Outer fibrous capsule - continuous with periosteum of adjoining bones
2. Inner synovial membrane - composed of fibroblast-like cells which secrete synovial fluid, and macrophages which remove debris
3. Lamellar corpuscles - sensory receptors which enable the brain to monitor limb movements

Question 18

Synovial joints: Articular disc vs meniscus + examples

Answer 18

1. Articular disc - fibrocartilage pad crosses the entire joint capsule

Example: TMJ jaw joint, joints of clavicle, between ulna and carpal bones

2. Meniscus - crescent-moon shaped pad, does not cross joint entirely. Absorbs shock and pressure, stabilizes bones in joint

Example: found in knee.

Question 19

Accessory structures associated with synovial joints (4)

Answer 19

1. Tendon - collagenous tissue attaching muscle to bone
2. Ligament - collagenous tissue attaching one bone to another
3. Bursa - fibrous sac filled with synovial fluid.
4. Tendon (synovial) sheath - elongated cylindrical bursa wrapped around a tendon; abundant in hand and foot

Question 20

Synovial joint accessory: Bursa + 3 functions

Answer 20

Fibrous sac filled with synovial fluid; located between muscles, where tendons pass over bone, or between bone and skin

1. Cushions muscles
2. Helps tendons slide more easily over joints
3. Modifies direction of tendon pull

Question 21

How exercise affects articular cartilage (3)

Answer 21

1. Warms synovial fluid—>more easily absorbed by cartilage—>swell into cushion
2. Protects cartilage from wear and tear
3. Repetitive compression squeezes out fluid and metabolic waste, sucks in synovial fluid/oxygen/nutrients to chondrocytes.

Question 22

Range of motion + 3 determining factors

Answer 22

Degree through which a joint can move.

1. Structure of articular surfaces - (elbow: olecranon of ulna in olecranon fossa of humerous restricts movement)
2. Strength and tautness of ligaments and joint capsules
3. Action of muscles and tendons - nervous system maintains joint position and muscle tone (tension)

Question 23

Axes of rotation + 3 main types for joints

Answer 23

Passes through bone in direction perpendicular to plane of movement

1. Multiaxial joint
2. Biaxial
3. Monoaxial

Question 24

6 types of synovial joints

Answer 24

1. Ball and socket - Multiaxial
2. Condylar - Biaxial
3. Saddle - Biaxial
4. Plane - Biaxial
5. Hinge - Monoaxial
6. Pivot - Monoaxial

Question 25

Ball-and-socket joint + 2 examples

Answer 25

Multiaxial. Smooth, hemispheric head fits within cup-like socket. Examples: shoulder, hip

Question 26

Condylar joints + example

Answer 26

Biaxial. Allow significant movement in two planes. Oval convex surface of one bone fits into a complementary shaped depression on the other Examples: radius and scaphoid, metacarpophalangeal joints, atlas and occipital bone

Question 27

Saddle joints + example

Answer 27

Biaxial. Both bones have an articular surface shaped like a saddle, one concave, the other convex Examples: trapeziometacarpal (thumb)

Question 28

Plane joints + 2 examples

Answer 28

Biaxial. Flat, articular surfaces. Bones slide over each other. Examples: Between carpal and tarsal bones, between articular processes of vertebrae

Question 29

Hinge joints + example

Answer 29

Monoaxial. Allow angular movement. One bone with convex surface fits into concave depression of another bone. Examples: Elbow, knee, between phalanges

Question 30

Pivot joints + 2 examples

Answer 30

Monoaxial. Bone spins on its longitudinal axis. Examples: altantoaxial joint, radioulnar (elbow) joint

Question 31

Flexion, extension, hyperextension

Answer 31

Flexion - decreases joint angle Extension - straightens joint/returns body part to zero position Hyperextension - extension of a joint behind zero position

Question 32

Abduction/hyperabduction, adduction/hyperadduction

Answer 32

Abduction - movement of body part in frontal plane away from midline Hyperabduction - raise arm over back or front of head Adduction - movement in frontal plane back toward midline Hyperadduction - crossing fingers, crossing ankles

Question 33

Elevation, depression

Answer 33

Elevation - movement raises body part vertically in frontal plane (e.g. shrugging shoulders) Depression - lowers body part in same plane

Question 34

Protraction, retraction

Answer 34

Protraction - anterior movement of a body part in the transverse (horizontal) plane Retraction - posterior movement

Question 35

Circumduction

Answer 35

One end of an appendage remains stationary while other end makes circular motion (e.g. painting a circle)

Question 36

Rotation + 2 types

Answer 36

Rotation - bone spins on its longitudinal axis 1. Medial rotation - turns bone inward 2. Lateral rotation - turns bone outward.

Question 37

Supination, pronation

Answer 37

Forearm movements. Supination - palm turns to face anteriorly or upward (as in anatomical position) Pronation - palm turns to face posteriorly or downward (radius + ulna cross)

Question 38

Special movements of head and trunk (4)

Answer 38

1. Flexion - Forward bending movements at the waist or neck 2. Extension - Straightens trunk or neck. 3. Hyperextension - Bending over backward 4. Lateral flexion - Tilting head or trunk to right/left at the midline.

Question 39

Special movements of the hand (4)

Answer 39

1. Flexion - hand moves anteriorly 2. Extension - hand moved posteriorly 3. Radial flexion - hand tilts toward thumb 4. Ulnar flexion - hand tilts toward pinky finger

Question 40

Special movements of the digits (4)

Answer 40

1. Flexion - curling the fingers 2. Extension - straightening the fingers 3. Abduction - spreading fingers apart 4. Adduction - bringing fingers together again

Question 41

Special movements of the thumb (4)

Answer 41

1. Radial abduction - thumb moves away from hand, staying in plane of hand 2. Palmar abduction - thumb moves away from the plane of hand to point anteriorly 3. Opposition - thumb moves to approach tip of another finger 4. Reposition - Return of thumb to zero position

Question 42

Special movements of the foot (4)

Answer 42

1. Dorsiflexion - elevating toes of foot forward (heel strike) 2. Plantar flexion - extending foot so toes point downward (tip-toe) 3. Inversion - soles turn in medially 4. Eversion - Soles turn out laterally NOTE: feet can also pronate and supinate but they are complex combined movements

Question 43

Special movements of the mandible (4)

Answer 43

1. Protraction - out and forward 2. Retraction - pull back to neutral 4. Elevation/depression - opening and closing mouth 5. Lateral/medial excursion