2e - Joints

Question 1

What is a joint?

Answer 1

A point where two bones articulate together. Mobility of a joint is dependent on the structure.

Question 2

What are the classes of joints?

Answer 2

1) Fibrous
2) Cartilaginous
3) Synovial

Question 3

Fibrous joints:

a) Describe mobility
b) Examples

Answer 3

a) Immovable
b) Sutures (found only in the skull). During development, bones are separated by short collagen fibers. with age, it ossifies and fuses bones.
Distal tibiofibular articulation has short fibers that allow no movement.
Periodontal ligament between tooth and socket.

Question 4

Cartilaginous joints:

a) Describe mobility
b) Examples

Answer 4

a) Slightly moveable
b) Synchondroses (bones united by hyaline cartilage) such as epiphyseal plates and joint between 1st rib and manubrium
Symphyses (bones united by fibrocartilaginous cartilage), such as fibrocartilagnious intervertebral disc

Question 5

Synovial joints:

a) Describe mobility
b) Classes

Answer 5

a) Highly movable
b) Plane
Hinge
Pivot
Condyloid
Saddle
Ball and socket

Question 6

Plane Joints

a) Describe articulation
b) Describe movement
c) Example

Answer 6

a) Flat articular surfaces
b) Short movements in multiple directions
c) Intercarpal bones

Question 7

Hinge Joints

a) Describe articulation
b) Describe movement
c) Example

Answer 7

a) Cylindrical end + trough
b) Uniaxial
c) Elbow

Question 8

Pivot Joints

a) Describe articulation
b) Describe movement
c) Example

Answer 8

a) Round end fits into ring formed by bone and associated ligament
b) Uniaxial
c) Proximal radio-ulnar joint

Question 9

Condyloid Joints

a) Describe articulation
b) Describe movement
c) Example

Answer 9

a) Egg-shaped articular process fits into oval concavity
b) Biaxial movement
c) Metacarpal phalangeal joint

Question 10

Saddle Joints

a) Describe articulation
b) Describe movement
c) Example

Answer 10

a) Concave + convex surface (like a saddle)
b) Biaxial movement
c) First carpometacarpal bone

Question 11

Ball and Socket Joints

a) Describe articulation
b) Describe movement
c) Example

Answer 11

a) Ball head + round socket
b) Multiaxial
c) Shoulder and hip joint

Question 12

Describe the characteristics of a synovial joint.

Answer 12

1) Articular cartilage - surrounds articular surface of bones
2) Articular capsule - surrounds whole joint and ends of bones
3) Synovial fluid - in capsule to lubricate and allow dynamic range of movement
4) Articular disc - found between articular cartilage
5) Intracapsular and extracapsular ligaments

Last two may be present.

Question 13

What causes people to be double-jointed?

Answer 13

The ligaments and capsules of the joints are stretched.

Some individuals suffer from Marfan syndrome (collagen deficiencies) and have hypermobility in all joints.

Question 14

What are bursa?

Answer 14

Bursa are fluid-filled sacs found in some joints, such as the shoulder and knee joint.
They cushion bones and prevent friction of ligaments against bone.

Question 15

Describe important structures of the shoulder joint.

Answer 15

a) There are two bursa: the subacromial (found under the acromion) and subscapular (found under the lateral angle of the scapula).
b) The glenoid labrum is a lip of connective tissue around the glenoid cavity that adds articular surface to the head of the humerus.
c) The coracohumeral ligament (anterior greater tubercle to coracoid process) supports the weight of the limb and the glenohumeral ligaments make up the anterior part of the capsule.
d) Also stabilized by tendons of the rotator cuffs and long head of biceps.

Question 16

Name the ligaments that stabilize the hip joint and their attachments.

Answer 16

Ligamentum teres - head of femur to inferior region of acetabulum (intracapsular)
Iliofemoral - V-shaped from Ilium to greater and lesser trochanter
Pubofemoral - Pubis to femur
Ischiofemoral - Ischium to femur

Question 17

Hip replacements:

a) What does it alleviate?
b) What parts are involved?
c) What does it do?

Answer 17

a) It alleviates arthritis of the hip joint, which involves degeneration of articular surfaces of the bones and hyaline cartilage.
b) Has a plastic socket glued to the acetabulum and a metal femoral shaft implanted into the femur.
c) Reduces pain, restores function, and corrects joint deformity.

Question 18

Describe important structures of the knee joint.

Answer 18

a) Consists of a hinge joint (tibiofibular) and plane joint (patellarfibular).
b) Has three bursa - superior, inferior, and anterior to patella.
c) Has a joint cavity with synovial fluid.
d) Has two menisci (lateral and medial) that allow padding.
e) Intracapsular ligaments include the Anterior Cruxiate Ligament (ACL), going from posterior femur to anterior tibia, and Posterior Cruxiate Ligament (PCL), going from posterior tibia to anterior femur.
f) Extracapsular ligaments include Lateral (fibular) and Medial (tibial) collateral ligaments.

Question 19

What are the purpose of the:

a) ACL?
b) PCL?
c) LCL?
d) MCL?

Answer 19

a) ACL prevents anterior movement of tibia
b) PCL prevents posterior movement of tibia
c) LCL prevents medial movement of tibia
d) MCL prevents lateral movement of tibia