Head & Spine
This spinal curvature type is present at birth and functions primarily to protect vital organs.
What is the primary (kyphotic) curvature?
The sacroiliac joints connect which two major skeletal structures and serve what biomechanical purpose?
What are the spine and pelvic girdle, transmitting load and force between upper and lower body?
The tibiofemoral joint is described as a modified hinge joint. Explain why it is not a true hinge.
Because it allows rotational movement (medial/lateral) in addition to flexion/extension.
Describe the difference between open-chain and closed-chain movement using an example from the lower limb.
Open-chain: leg extension machine (foot free); Closed-chain: squat (foot fixed, body moves).
A herniated disc most often occurs under which type of spinal load, and why is the annulus fibrosus vulnerable?
During torsional or flexion-compression forces, the fibrocartilaginous lamellae are stressed asymmetrically, allowing nucleus pulposus extrusion.
The angle of the facet joints determines each spinal region’s primary movement. Which plane are the thoracic facets oriented in, and what motion does this favor?
What is the frontal plane, favoring lateral flexion?
During gait, the pelvis alternates between right and left rotation. This motion primarily occurs around which axis and in which plane?
What is the superoinferior axis in the transverse plane?
During the “screw-home mechanism” of knee extension, the tibia performs what rotation relative to the femur, and which structure restrains excessive motion?
The tibia laterally rotates, restrained by the ACL.
The rectus femoris and hamstrings are both two-joint muscles. Compare their concentric actions at the hip and knee.
Rectus femoris: hip flexion & knee extension; Hamstrings: hip extension & knee flexion.
Chronic low back pain is often linked to insufficient control of this movement pattern at the lumbosacral joint.
What is anterior/posterior pelvic tilt instability or poor lumbopelvic rhythm?
During forward trunk flexion, which muscle group contracts eccentrically to control the motion against gravity?
What are the spinal extensors (erector spinae and transversospinales)?
Which hip motion is mechanically linked to posterior pelvic tilt, and why do they often occur together in functional movement?
What is hip extension, which accompanies posterior tilt to maintain trunk alignment during motion such as standing up?
The plantar fascia tightens during toe-off to stabilize the arch. This mechanism is called what, and which joint does it primarily affect?
What is the windlass mechanism, affecting the metatarsophalangeal joints?
During a vertical jump landing, which type of muscle contraction absorbs impact at the hip and knee, and which muscles are involved?
What is eccentric contraction of the gluteus maximus and quadriceps?
In scoliosis, the spine deviates in this plane, but a rotational component also occurs in which other plane?
What is the transverse plane?
The atlantoaxial joint allows approximately 40–45° of rotation. Describe the arthrokinematic motion occurring between the atlas and axis during this rotation.
What is the pivoting of the atlas (C1) around the dens of the axis (C2)?
The gluteus medius prevents this deviation during single-leg stance by stabilizing the pelvis in the frontal plane.
What is contralateral pelvic drop (Trendelenburg sign)?
The talocrural joint allows dorsiflexion and plantarflexion. Identify the specific bones articulating to form this joint and classify its movement type.
What are the tibia, fibula, and talus, forming a uniaxial synovial hinge joint?
The transversus abdominis has been debated as the “core stabilizer.” Based on biomechanical consensus, why is this view incomplete?
Because spinal stability results from coordinated activation of multiple trunk muscles, not one isolated muscle.
In Duchenne muscular dystrophy, respiratory insufficiency occurs because which specific type of breathing muscles become replaced by adipose tissue?
What are the secondary muscles of forced inspiration and expiration (pectoralis major, abdominals)?
In an exaggerated posterior pelvic tilt, what happens to the lumbar spine curvature, and which muscle groups are primarily responsible for the movement?
The lumbar spine flexes, driven by abdominals (rectus abdominis and obliques) concentrically and spinal extensors eccentrically.
The adductor magnus is unique among the adductors because of its additional function in the sagittal plane. What is that action, and why does it occur?
It performs hip extension because of its posterior fiber orientation and attachment on the ischial tuberosity.
During an inversion ankle sprain, which ligament group is most commonly injured, and why are eversion injuries less frequent?
What are the lateral ligaments (especially the anterior talofibular ligament); eversion injuries are rarer because the deltoid ligament is stronger and the fibula extends farther distally.
In a hanging leg raise, which primary muscle acts concentrically to flex the hip, and which acts isometrically to stabilize the spine?
What are the iliopsoas (concentric) and abdominals (isometric)?
Describe the mechanical reason why an anterior cruciate ligament (ACL) tear often coincides with medial meniscus injury.
Because the medial meniscus is more firmly attached to the MCL, rotational or valgus stress that tears the ACL also compresses/shears the medial meniscus.