4.9 Critical joints discussed in this course

4.9.1 The hip

@Bartel2006

  • The hip is a synovial ball and socket joint.
  • The head of the femur rotates relative to the acetabulum of the pelvis
  • Contact can (sometimes) be modeled as a single force acting through the center of the joint
    • This approximation isn’t perfect

@Bartel2006

  • Modeling the hip
    • We might model the femoral diaphysis as a hollow circular beam
    • The metaphysis can be modeled as an elastic or rigid link, or modeled using FEA if detailed outcome is desired
    • Contact in the ball and socket leads to complex load distributions

@Bartel2006

  • Muscle attachments to the greater and lesser trochanters and bony ridges such as the linea aspera
    • These allow for a greater moment arm for the muscles

4.9.2 The knee

@Blausen2014

  • A bicondylar synovial joint which allows the femur and tibia to rotate, twist, and slide relative to each other
  • Each motion is necessary… otherwise abnormal forces develop and cause rapid deterioration of the joint

@Bartel2006

  • Important structures include:
    • Medial collateral ligament (MCL)
    • Lateral collateral ligament (LCL)
    • Quadriceps tendon
    • Patellar ligament
    • Anterior Cruciate ligament (ACL)
    • Posterior Cruciate Ligament (PCL)
    • Menisci (two crescent-shaped pads that help distribute the loads from the femoral condyles to the tibial plateaus)
  • ACL and PCL are within the knee joint capsule and pass through the notch between the condyles, the others are outside the capsule

4.9.3 Spine

@Bartel2006

@Bartel2006 @Bartel2006

OpenStax College CCSA3.0

  • “Cartilaginous” type joint

  • Connective tissue is a fibrocartilage structure called the Intervertebral disc

  • Healthy disk acts like a tire… needs to have sufficient fluid inside.

    • Aging causes the gel-like fluid to solidify with negative consequences
    • Largest avascular tissue in the body

4.9.4 Anterior portion of the intervertebral joint

  • Pedicles and laminae form an arch – the vertebral foramen (hole) for the spinal cord

Jmarchn CCSA3.0 Anatomist90 CCSA3.0

Dr.foksha CCSA4.0

  • Adjacent vertebrae are connected through articulating joints (called facets) that constrain the motion between the vertebrae and limit twisting and extension of the spinal column
  • The structure supports the upper body and protects the spinal cord.

4.9.5 Vertebral attachments

OpenStax College CCSA3.0

  • Back muscles attach \(\approx 5\)cm posterior to the center of the vertebral body
  • Center of sagittal bending is approximately within the disk

Latissimus dorsi

Anatomography CCSA2.1 Japan

@Bartel2006