Module 9: Biomechanics of the Lower Extremity Flashcards
Name the bones that form the pelvic girdle.
Sacrum, ilium, pubis, ischium
Name the bones that form the lower limb.
Femur, patella, tibia, fibula, tarsals, metatarsals, phalanges
What are the functions of the pelvic girdle?
Support the body (weight bearing/posture)
Allow for locomotion
Name the joints of the pelvic girdle.
Sacroiliac joint and symphysis pubis
Name the axis and planes of movement that are possible in the hip joint.
Anteroposterior axis | Frontal plane | Abduction/adduction
Frontal axis | Sagittal plane | Flexion/extension
Vertical axis | Transverse plane | Rotation/circumduction
What type of joint is the pubic symphysis?
Cartilaginous, amphiarthrosis, little to no movement
What type of joint is the sacroiliac joint?
Synovial plane joint
Describe the movement of nutation of sacrum and when it occurs
A forward tilt of the sacral base with the apex moving posteriorly, occurring during lumbar flexion and weight-bearing activities
Describe the movement of counternutation of the sacrum and when it occurs.
A backward tilt of the sacral base with the apex moving forward, occurring during lumbar extension and hip extension.
What are the pelvic movements?
The pelvic girdle moves as a unit to facilitate the positioning and function of the hip joint and vertebrae. Movements include anterior and posterior pelvic tilts
Describe the movement of anterior pelvic tilt and which muscles are responsible for this movement.
The ASIS moves downward and the PSIS moves upward. This movement is produced by the hip flexors (iliopsoas = iliacus + psoas)
Describe the movement of posterior pelvic tilt and which muscles are responsible for this movement?
The ASIS moves upward and the PSIS moves downward. This movement is produced by the hip extensors (gluteus maximus)
List 2 differences between the hip and shoulder joint that impact the stability of the joints.
The hip joint has a deeper socket (acetabulum) enhancing stability
The femoral head has more contact with its acetabulum (~70%), while the shoulder has less, enhancing mobility
List 2 similarities between the hip and shoulder joint.
Both have a labrum (fibrocartilage that deepens the joint socket) and gravity aids in coaptation, or stability, especially when upright
What is the function of the labrum in the hip joint?
Increase joint congruency, stabilizing the hip by providing a more secure fit for the femoral head within the acetabulum.
What effect does unilateral movement of the lower limb in the sagittal plane have on the pelvis?
Causes pelvic rotation towards the stepping leg to facilitate fluid and balanced walking