Week 1: Joint Structure and Function

Question 1

What are the components of a synarthroses joint?

Answer 1

They have essentially no movement.

Function to bind and transfer forces between bones.

Question 2

Describe a diarthroses joint.

Answer 2

A joint that allows for moderate to extensive motion. They have a synovial fluid-filled cavity.

EX: GH Joint

Question 3

What are the elements that are always associated with synovial joints?

Answer 3

1. Synovial fluid
2. Articular cartilage
3. Joint capsule
4. Synovial membrane
5. Ligaments
6. Blood vessels
7. Sensory nerves

Question 4

What are other features that are sometimes noted in synovial joints?

Answer 4

1. Intra-articular disc = increase congruency and improve force dispersion
2. Peripheral labrum = deepen concave joint and support attachment of joint capsule
3. Fat pads = reinforce internal aspects of capsule and fill non-articulating joint spaces.
4. Bursa = extension of synovial membrane; absorb force and protect CT
5. Synovial plica = overlapped pleats of tissue

Question 5

What are the 3 functions of joints?

Answer 5

1. Allow for motion
2. Bear body weight
3. Provide stability

Question 6

What are the 7 types of synovial joints?

Answer 6

1. Hinge
2. Pivot
3. Ellipsoid
4. Ball and Socket
5. Plane joint
6. Saddle joint
7. Condyloid joint

Question 7

What is an instantaneous axis of rotation?

Answer 7

Axis of rotation for a specific arc of motion.

Question 8

Define what connective tissue (CT) forms. What are the three different components of CT?

Answer 8

Connective tissue forms capsules, ligaments, tendons, articular cartilage, and fibrocartilage

Components:

1. Fibrous protein = collagen & elastin
2. Ground substance = water, solutes, glycosaminoglycans
3. Cells = fibroblast and chondrocytes

Question 9

What are the 3 different types of periarticular connective tissue?

Answer 9

1. Dense connective tissue
2. Articular cartilage
3. Fibrocartilage

Question 10

What are some examples of dense connective tissue?

Answer 10

Ligaments, fibrous layer of joint capsules, and tendons

Question 11

Describe dense irregular connective tissue.

Answer 11

Irregular = irregular and haphazard orientation of collagen within ground substance.
Best suited to resist tensile force in multiple directions.

EX: joint capsule

Question 12

Describe dense regular connective tissue

Answer 12

Regular = more orderly/near parallel orientation of collagen fibers.

EX: Ligaments and tendons

Question 13

What are the primary functions of dense connective tissue?

Answer 13

Resist tension!
Ligaments and joint capsules protect and bind the joint.
Tendons transfer forces b/w muscle and bone.

*Limited blood supply

Question 14

What is the primary function of articular cartilage?

Answer 14

Distributes and absorbs joint forces and reduces joint friction.

*Receives nutrition with compression!

Question 15

How is articular cartilage classified?

Answer 15

Avascular and aneural

Question 16

What are some examples of fibrocatilage?

Answer 16

Menisci, labrum, and disc

Question 17

What is fibrocartilage made of?

Answer 17

A mixture of dense and articular cartilage

Question 18

What is fibrocartilage main function?

Answer 18

Supports and mechanically stabilizes joints, dissipates loads across multiple planes, and guides complex arthrokinematics.

*Aneural and limited blood supply

Question 19

What does bone consist of?

Answer 19

Type 1 collagen, osteoblast, and hard ground substance

Question 20

What is the primary function of bone?

Answer 20

Rigid support to the body and systems of levers for muscles.
Can accept tremendous compressive loads.

*Richly vascularized and innervated.

Question 21

What is compact bone and cancellous bone?

Answer 21

Compact = outer cortex of long bones

Cancellous bone = end of long bones with thinner layer of compact bone surrounded by a network of cancellous bone.

Question 22

What does Wolff’s Law state?

Answer 22

“Bone is laid down in areas of high stress and reabsorbed in areas of low stress.”

Question 23

What are 3 different effects of immobalization?

Answer 23

1. Immobilized joint will demonstrate changes in structure and function of connective tissues if immobilized for prolonged time.
2. Rate of decline is dependent on metabolic activity of the tissue.
3. Rapid loss of strength occurs with prolonged reduced loading and recovery is slower.