Joints in Depth

Question 1

The Knee

Answer 1

Largest and most complex joint

Usually acts as a hinge but can rotate slightly

Technically 2 condyloid joints (bicondyloid); both femur and tibia have 2 condylar surfaces
–lateral and medial

Question 2

The Knee: Ligaments

Answer 2

Has strong ligaments to help keep the knee from moving in the wrong way (i.e.: hyperextension)

• -Lateral (fibular) Collateral Ligament (LCL)
• -Medial (tibial) Collateral Ligament (MCL)
• -Anterior Cruciate Ligament (ACL)
• -Posterior Cruciate Ligament (PCL)

Question 3

The Knee: Bursa

Answer 3

Note: about 12 bursa in knee joint to help reduce friction between articulating elements (tibia/femur, femur/patella)

• -Suprapatellar Bursa
• -Sub-q Prepatellar Bursa
• -Deep Infrapatellar Bursa

Question 4

The Knee: Menisci

Answer 4

In addition to ligaments, menisci of fibrocartilage (aka articular discs) help even out the weight distribution and stabilize the joint. They also prevent side-to-side rocking the femur on the tibia

Anterior View of Knee:

• -Medial Meniscus
• -Lateral Meniscus

Superior View of Knee:

• -Medial Meniscus
• -Lateral Meniscus
• -Posterior Cruciate Ligament (PCL)
• -Anterior Cruciate Ligament (ACL)

Question 5

The Knee: “The Unhappy Triad”

Answer 5

Common injury in athletes, knee is hit from side while foot is planted

• -lateral blow, forcing knee medially without moving femur/foot
• -think soccer injury…

Result is a combination of multiple torn/damaged ligaments and damage to menisci

Question 6

TMJ

Answer 6

Divided by articular disc (meniscus) into superior and inferior compartments

Superior compartment allows gliding

Inferior compartment is a hinge

Movement is back and forth (opening and closing mouth)

Movement is side to side

Question 7

Glenohumeral Joint

Answer 7

Ball and socket joint: highly mobile, not stable (glenoid cavity not very deep)

Dislocates relatively easily

Question 8

Hip Joint

Answer 8

Ball and socket joint: less mobility, very stable

Deep acetabulum for head of femur

Ligamentum tere extends from acetabulum to fovea captius (on head of femur) - may add stability

Question 9

Elbow Joint

Answer 9

Hinge joint (humerus/ulna) but annular ligament forms pivot at proximal radioulnar joint

Question 10

Rheumatoid Arthritis (RA)

Answer 10

Autoimmune disease

S and S: pain, stiffness, swelling

Begins w/ inflamm of synovial membrane, joint swells

Chronic inflamm of the joint capsule deteriorates the CT around the joint

Question 11

Arthritis in Knee

Answer 11

Most common: osteoarthritis - affects articular cartilages

“Wear and tear”

Pain, stiffness, swelling

Extreme solution: replacement