Ch 8 - Joints

Question 1

Definition:

the site where two bones meet (may or may not allow movement)

Answer 1

Joints (articulations)

Question 2

Functional Classification of Joints

Answer 2

1) Synarthoses - no movement
2) Amphiarthroses - some, limited movement
3) Diarthroses - free movement

Question 3

Structural Classification of Joints

(type of tissue that connects bones)

Answer 3

1) Fibrous Joint: bones joined by collagen fibers of connective tissue
2) Cartilaginous Joint: bones joined by cartilage
3) Synovial Joint: (most joints) possess a joint cavity, diarthoses

Question 4

Joint classification

Joint that allows no movement

Answer 4

Synarthroses

Question 5

Joint classification

Joint that allows some, limited movement

Answer 5

Amphiarthroses

Question 6

Joint classification

Joint that allows free movement

Answer 6

Diarthroses

Question 7

Types of Fibrous Joints

Answer 7

1) Sutures - only between bones of skull
2) Syndesmoses - bones connected only by ligaments
3) Gomphoses - joins tooth to alveolar socket

Question 8

Definition

Ossified Sutures in Adulthood

Answer 8

Syntoses

Question 9

Examples of Syndesmoses

Answer 9

Ligament holding together Tibia and Fibula, Ulna and radius

Movement allowed depends on the lengths of the bands of the ligament

Question 10

Ligament Involved in Gomphoses Joints

Answer 10

Periodontal ligament joins tooth to alveolar socket

Very little movement

Question 11

Types of Cartilaginous Joints

Answer 11

1) Synchondroses - Joined by plate of hyaline cartilage
2) Symphyses - joined by fibrocartilage

Question 12

Examples of Synchondroses Joints

Answer 12

1) Epithelial plate in long bones
2) Costal Cartilage

Mostly Synarthroses

Question 13

Examples of Symphyses Joints

Answer 13

1) Intervertebral joints - discs can herniate & press against nerve/muscle
2) Pubic symphysis

Allows for some limited movement and provides support against pressure

Question 14

6 Structures in all Synovial Joints

Answer 14

1) Articular cartilage: hyaline cartilage covering bone ends
2) Joint cavity: small space between articulating bones
3) Articular capsule: two-layered capsule that encloses joint cavity
4) Synovial fluid: slippery fluid occupying space in joint capsule & articular cartilages
5) Reinforcing ligaments: bandlike ligaments that join articulating bones
6) Innervation & vascularization: Joints supplied with sensory nerve fibers and lots of blood

Question 15

What is the function of articular cartilage?

Answer 15

Prevent bones from rubbing against one another; Absorbs synovial fluid when joint in inactive

Question 16

Layers of the Articular Capsule

Answer 16

1) Fibrous Layer - outer layer continuous with perioseum (prevents dislocation)
2) Synovial Membrane - inner layer, lines joint cavity (not at articular cartilage) - produce synovial fluid

Question 17

Function(s) of synovial fluid

Answer 17

1) Protect articular cartilage, bone, and articular capsule from friction
2) Enter and exit articular cartilage depending on movement

When joint is inactive - fluid is viscous, thick, water taken up by articular cartilage, helps hold bones in place
When joint is active - fluid squeezes out of articular cartilage like a sponge into joint cavity, becomes churned up and thinned out - oily/watery - allows bones to slide

Question 18

Why joints need nerve fibers (3)

Answer 18

1) Sensing pain - danger, last warning before break/injury
2) Pressure on the joint - tells CNS how much muscle strength is needed (back off before break/tear)
3) Stretch of joint - tells CNS angle joint is at (back off before break/tear)

Question 19

Structures associated with synovial joints (2)

May or may not be present depending on complexity of the joint

Answer 19

1) Bursae (bag/purse) - sac if synovial fluid to protect structures that may come in contact with bone during joint movement
2) Tendon Sheath - elongated bursae that wraps completely around tendon that is subject to frequent friction (close together)

Ex. Bursae - Glenohumeral joint; bursae exists between head of humerus and muscle
Ex. Tendon Sheath - At wrists and angle as tendons are compacted closely together (forearm/calf wider than wrist/ankle)

Question 20

Factors of Joint Stability (3)

Answer 20

1) Articular Surfaces: better fit = more stable, less flexibility
2) Ligaments: more ligaments = stronger joint, except if ONLY ligaments - weaker
3) Muscle Tone: muscles constantly pull on tendons that wrap around joint - “braces” joint (most important!!)

The more you have of each, the stronger/more stable, but the more stable the joint is, the less flexible it is

Question 21

Types of movements allowed by Synovial Joints

Answer 21

1) Nonaxial movement - flat articular surfaces “plane joint,” gliding
2) Uniaxial movement - flexion/extension OR rotation, hinge/pivot joint
3) Biaxial movement - flexion/extension & a(b/d)duction, condylar/saddle joint
4) Multiaxial movement - Flexion/extension & a(b/d)duction & rotation, ball-and-socket joint

Question 22

Type of joint found in intertarsal/intercarpal joints & movement

Answer 22

Plane Joint - nonaxial, allows for sliding

Question 23

Type of joint found between humerus and ulna & movement

Answer 23

Hinge Joint - uniaxial, allows for flexion/extension

Question 24

Type of joint found between radius and ulna & movement

Answer 24

Pivot Joint - uniaxial, allows for rotation

Question 25

*Type* of joint found at knuckle & movement

Answer 25

**Condylar joint** - biaxial, allows for flexion/extension & a(b/d)duction

Question 26

*Type* of joint found at base of thumb & movement

Answer 26

**Saddle joint** - biaxial, allows for flexion/extension & a(b/d)duction

Question 27

*Type* of joint found at shoulder/hip joint & movement

Answer 27

**Ball-and-socket joint** - Multiaxial, allows for flexion/extension & a(b/d)duction & rotation

Question 28

# Type of joint Temporomandibular joint (TMJ)

Answer 28

*Modified* hinge joint - Articular disc divides synovial cavity into superior and inferior potrions Inferior: allows elevation/depression ## Footnote Superior: allows lateral excursion Inferior: allows elevation/depression

Question 29

Stabilizing the Glenohumeral (shoulder) joint

Answer 29

1) **Reinforcing ligaments** - very thin and loose 2) **Rotator cuff** - 4 muscles (and their tendons) that encircle the joint 3) **Glenoid labrum** - rim of fibrocartilage around glenoid fossa - prevents slipping out of joint ## Footnote Ligaments: coracohumeral ligament & glenohumeral ligaments

Question 30

Stabilizing the Elbow Joint

Answer 30

1) Close fit of trochlea and trochlear notch 2) Muscle and tendon of arm muscles wrap around joint 3) **Ulnar collateral ligament** (medial side) and **radial collateral ligament** (lateral side) prevent lateral movement

Question 31

Stabilizing the Coxal Joint

Answer 31

1) Acetabulum of os coxa has **acetabular labrum** to deepen socket 2) Ligaments of articular capsule (**iliofemoral**, **pubofemoral**, and **ischiofemoral** ligaments) 3) **Ligamentum teres** - ligament of the head of the femur ## Footnote Ligaments of articular capsule named after the bones they connect to - all bones of the os coxa

Question 32

Joints of the Knee

Answer 32

Single joint cavity shared by 3 separate joints: 1) **Femoropatellar joint** - between patella and femur 2) **Tibiofemoral joints** - between femur and tibia (1 medial, 1 lateral)

Question 33

Stabilizing the Knee

Answer 33

1) **Menisci** - thin layer of fibrous cartilage at outer margins of tibiofemoral joints 2) **Extracapsular & capsular ligaments** - prevent hyperextension 3) **Intracapsular ligaments (cruciate ligaments)** - ACL and PCL ## Footnote *Cruciate Ligaments:* **Anterior cruciate ligament** (ACL) - prevents forward sliding of tibia, prevents hyperextion - *attaches anterior of tibia* **Posterior cruciate ligament** (PCL) - prevents backward sliding of tibia and forward sliding of femur - *attaches posterior portion of tibia*

Question 34

Cruciate Ligaments

Answer 34

1) **Anterior cruciate ligament** (ACL) - prevents forward sliding of tibia, prevents hyperextion - *attaches anterior of tibia* 2) **Posterior cruciate ligament** (PCL) - prevents backward sliding of tibia and forward sliding of femur - *attaches posterior portion of tibia*

Question 35

Types of Arthritis

Answer 35

1) **Osteoarthritis** (OA) - exposed bone rubs together, forming bone spurs 2) **Rheumatoid arthritis** (RA) - autoimmune chronic inflammatory disorder

Question 36

Causes and effects of **Osteoarthritis**

Answer 36

Caused by more articular cartilage being destroyed than repaired Effects: exposed bone rubs together, forming *bone spurs* ## Footnote Bone spurs: bone ends deform, restricting movement at the joint

Question 37

Causes and effects of **Rheumatoid Arthritis**

Answer 37

Autoimmune chronic inflammatory disorder - joints of fingers, wrists, ankles, feet most likely to be affected - Flare-ups followed by periods of remission ## Footnote Pain and swelling felt in joints affected by RA during flare ups During periods of remission - no pain/swelling in joints affected by RA

Question 38

Thin layer of fibrous cartilage at outer margins of tibiofemoral joints

Answer 38

Menisci