PAS Anatomy & Physiology of Posture 3 — Questions and Answers
Question 1: The quadratus lumborum muscle originates on the iliac crest and inserts primarily on which structure?
- Sacrum
- 12th rib and lumbar transverse processes (Correct answer)
- Lumbar spinous processes
- Thoracolumbar fascia only
Correct answer: 12th rib and lumbar transverse processes
The quadratus lumborum attaches to the 12th rib and the transverse processes of L1–L4, enabling lateral flexion, hip hiking, and spinal stabilization.
Question 2: Which type of muscle fiber is primarily responsible for maintaining static postural tone?
- Type II-b (fast-twitch glycolytic)
- Type II-a (fast-twitch oxidative)
- Type I (slow-twitch oxidative) (Correct answer)
- Type III (intermediate)
Correct answer: Type I (slow-twitch oxidative)
Type I slow-twitch fibers are highly fatigue-resistant and oxidative, making them ideal for sustained postural stabilization.
Question 3: Overpronation of the foot most commonly leads to which compensatory postural change at the knee?
- Knee valgus (inward collapse) (Correct answer)
- Knee varus (bowing outward)
- Knee hyperextension
- Lateral tibial rotation
Correct answer: Knee valgus (inward collapse)
Excessive pronation causes medial tibial rotation which drives the knee into a valgus position, disrupting alignment from the foot to the hip.
Question 4: The thoracolumbar fascia is important for postural stability because it:
- Limits thoracic kyphosis by connecting ribs to vertebrae
- Transfers force between the lower extremities, spine, and upper extremities (Correct answer)
- Directly attaches the diaphragm to the lumbar spine
- Prevents lateral bending of the cervical spine
Correct answer: Transfers force between the lower extremities, spine, and upper extremities
The thoracolumbar fascia acts as a key force-transfer structure connecting the gluteus maximus, latissimus dorsi, and spinal extensors, integrating trunk and limb movement.
Question 5: Which postural pattern is characterized by a forward-shifted thorax over a posteriorly tilted pelvis?
- Lordotic posture
- Kyphotic-lordotic posture
- Sway-back posture (Correct answer)
- Military posture
Correct answer: Sway-back posture
Sway-back posture involves anterior displacement of the thorax and hips forward, with the pelvis posteriorly tilted and knees hyperextended.
Question 6: Which plane of the body divides it into anterior and posterior halves?
- Sagittal plane
- Frontal (coronal) plane (Correct answer)
- Transverse plane
- Oblique plane
Correct answer: Frontal (coronal) plane
The frontal (coronal) plane divides the body into anterior and posterior sections and is used to assess lateral deviations such as scoliosis.
Question 7: The gastrocnemius muscle crosses how many joints, and what postural impact does its tightness have?
- One joint; limits knee extension
- Two joints; limits dorsiflexion and may promote knee flexion (Correct answer)
- Two joints; limits plantar flexion and pronation
- One joint; causes foot supination
Correct answer: Two joints; limits dorsiflexion and may promote knee flexion
The gastrocnemius crosses both the ankle and knee; tightness restricts ankle dorsiflexion and can contribute to compensatory pronation or knee flexion.
PAS Anatomy & Physiology of Posture 3
The quadratus lumborum muscle originates on the iliac crest and inserts primarily on which structure?