Unit 5 Joint Structure and Function

Question 1

How are joints categorized in the body? Give an example of each type of joint.

Answer 1

Fibrous – immovable, fibrous joints, ie. sutures of skull
Cartilaginous – slightly movable, cartilage joints, ie. symphysis pubis; manubriosternal joint
Synovial – freely movable, synovial capsule joints, ie. glenohumeral joint

Question 2

What are the 5 characteristics of a synovial joint and its function?

Answer 2

1) Articular capsule: outer fibrous & inner synovial membrane
2) Synovial cavity: space within articular bones
3) Synovial fluid: fluid within synovial cavity
4) Articular cartilage: hyaline cartilage covering articulating bones
5) Reinforcing ligaments: ligaments within & outside articular capsule

Question 3

Give an example of the 6 types of synovial joints and describe their available movement(s) at that specific joint.

Answer 3

1) Hinge Joint: Flexion, extension, Uniaxial
2) Pivot Joint: Supination, pronation, Uniaxial

3) Condyloid Joint: 4 movements wrist: flexion, extension, RD and UD - Biaxial
4 movements MCP: flexion, extension, adduction and abduction - Biaxial

4) Saddle Joint: Flexion, extension, adduction, abduction and slight rotation, Biaxial
5) Planar Joint: Glides, Non Axial
6) Ball & socket Joint: Free movement in all three axes, Triaxial

Question 4

Define open and close kinetic chain exercises, and give an example of an exercise for each.

Answer 4

Open Kinetic Chain:

• Distal segment free to move (open)
• Proximal segment(s) remain stationary
• Non weight bearing through joint
• Example: leg extension

Closed Kinetic Chain:

• Distal segment fixed (closed)
• Proximal segment(s) move
• Stabilization required through joint; weight bearing
• Example: Squats

Question 5

What is the function of a ligament? (7X)

Answer 5

• A ligament will attach a bone to a bone
• Made up of fibrous connective tissue
• Connective tissue is made up of protein called collagen
• Ligaments are flexible but not elastic
• They are not meant to stretch like muscles (sarcomeres have an elastic quality)
• Flexibility is needed to allow motion at a joint
• Non elasticity prevents excessive motion at joint and thus stabilizes and protects joints

Question 6

Describe scapulohumeral rhythm?

Answer 6

-Relationship between shoulder girdle and shoulder joint movement
-Allows for full upper limb elevation
-Depicts the path of movement of the Glenohumeral joint to the Scapulothoracic joint during shoulder flexion or abduction
◦ 1st 30 degrees of shoulder movement is pure GH
◦ After that, for every 2 degrees of shoulder flexion or abduction, the scapula upwardly rotates 1 degree
◦ Ratio of GH to Scapula motion is 2:1

Question 7

Define close- and open-packed positions. Give an example at the knee joint.

Answer 7

Close-Packed Position:
◦ Joint maximally congruent with each other and ligaments/capsule are taut
◦ Usually at one extreme end of ROM
◦ Example: close packed position of the knee is full extension

Open-Packed Position:
◦ Joint maximally incongruent with each other and parts of ligaments/capsule are lax
◦ Usually somewhere between extreme ends of ROM
◦ Position used when mobilizing joints
◦ Example: open packed position of the knee is mid range flexion

Question 8

Describe a positive Trendelengurg sign, and how should it be interpreted?

Answer 8

-Found in people with weak hip abductors (usually gluteus medius)
-Test: person stands on left foot. If person’s hip shifts down towards lifted leg (R). Then sign is positive for the leg still on the ground (L). This example = +ve Left Trendelenberg Sign