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Physiology & Rehabilitation MCQs

Practice Set 21 of 26

This practice set contains high-yield board review questions covering key concepts in Physiology & Rehabilitation. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 401

Topic: Physiology & Rehabilitation

A marathon runner sustains an overuse injury to the soleus muscle. Compared to the gastrocnemius, the soleus relies predominantly on a specific muscle fiber type. Which of the following describes the physiological characteristics of the predominant muscle fibers in the soleus?

. Fast twitch, high glycogen content, anaerobic metabolism
. Slow twitch, rich in mitochondria, aerobic metabolism
. Fast twitch, high oxidative capacity, aerobic metabolism
. Slow twitch, low myoglobin content, anaerobic metabolism
. Intermediate twitch, high glycolytic capacity, low mitochondria

Correct Answer & Explanation

. Slow twitch, rich in mitochondria, aerobic metabolism

Explanation

The soleus is primarily composed of Type I (slow-twitch) muscle fibers, which are uniquely designed for sustained postural control and endurance. These fibers rely heavily on aerobic metabolism, meaning they are rich in mitochondria, oxidative enzymes, and myoglobin (giving them a red appearance) and possess a high resistance to fatigue.

Question 402

Topic: Physiology & Rehabilitation

Which of the following physiological characteristics is most strongly associated with Type I (slow-twitch) muscle fibers?

. Anaerobic glycolysis metabolism
. Rapid rate of fatigue
. High concentration of myoglobin and mitochondria
. Large motor neuron size
. Low capillary density

Correct Answer & Explanation

. High concentration of myoglobin and mitochondria

Explanation

Type I muscle fibers are "slow-twitch" and optimized for prolonged, aerobic endurance activities. To support oxidative metabolism, they inherently contain high concentrations of mitochondria and myoglobin, along with an extensive capillary network.

Question 403

Topic: Physiology & Rehabilitation

During the normal human gait cycle, eccentric muscle contraction is vital for shock absorption and controlled deceleration. In which phase of the gait cycle does the tibialis anterior reach its peak electromyographic (EMG) activity?

. Mid-stance
. Terminal stance
. Pre-swing
. Initial contact (heel strike)
. Mid-swing

Correct Answer & Explanation

. Initial contact (heel strike)

Explanation

The tibialis anterior reaches peak EMG activity during initial contact (heel strike). It contracts eccentrically to prevent foot slap by slowly lowering the foot to the ground as the limb accepts weight.

Question 404

Topic: Physiology & Rehabilitation

Skeletal muscle function is dictated by the type of contraction performed. Which type of muscle contraction is defined by muscle lengthening under tension and is capable of generating the greatest maximal force?

. Isotonic concentric contraction
. Isometric contraction
. Isokinetic concentric contraction
. Eccentric contraction
. Plyometric concentric contraction

Correct Answer & Explanation

. Eccentric contraction

Explanation

An eccentric contraction occurs when a muscle generates tension while lengthening, acting as a brake to decelerate joint motion. Eccentric contractions can generate significantly higher maximal forces than isometric or concentric contractions and are primarily responsible for delayed-onset muscle soreness (DOMS).

Question 405

Topic: Physiology & Rehabilitation

During physical rehabilitation, a patient undergoes muscle contraction exercises where the muscle actively lengthens while under tension to decelerate a joint. Which type of muscle contraction is being performed?

. Concentric contraction
. Isometric contraction
. Isokinetic contraction
. Eccentric contraction
. Plyometric contraction

Correct Answer & Explanation

. Eccentric contraction

Explanation

An eccentric contraction occurs when a muscle lengthens while developing active tension, typically acting as a decelerator. Eccentric contractions generate the highest absolute forces and are most often associated with delayed onset muscle soreness (DOMS).

Question 406

Topic: Physiology & Rehabilitation

Skeletal muscle fibers are broadly classified based on their metabolic properties and fatigue resistance. Type I muscle fibers are uniquely characterized by which of the following properties?

. Slow-twitch mechanism, high mitochondrial density, predominantly aerobic metabolism
. Fast-twitch mechanism, low myoglobin content, primarily glycolytic metabolism
. Fast-twitch mechanism, high glycogen content, primarily anaerobic metabolism
. Intermediate-twitch mechanism, specialized exclusively for maximal burst strength
. Absence of myoglobin, reliance on lactic acid production for endurance

Correct Answer & Explanation

. Slow-twitch mechanism, high mitochondrial density, predominantly aerobic metabolism

Explanation

Type I fibers are 'slow-twitch' oxidative fibers highly adapted for endurance and posture maintenance. They rely on aerobic metabolism and are rich in mitochondria, capillary density, and myoglobin, which gives them a distinct red appearance.

Question 407

Topic: Physiology & Rehabilitation

A marathon runner sustains a gastrocnemius strain. The predominantly active muscle fibers in this athlete's gastrocnemius during a long-distance run rely on oxidative metabolism. Which of the following is a characteristic of these specific muscle fibers?

. High glycogen content
. Rapid fatigue rate
. Low mitochondrial density
. High myoglobin content
. Fast twitch response

Correct Answer & Explanation

. High myoglobin content

Explanation

Endurance athletes utilize predominantly Type I (slow-twitch) muscle fibers, which rely heavily on oxidative metabolism. These fibers are characterized by high myoglobin content (giving them a red color), high mitochondrial density, and a high resistance to fatigue.

Question 408

Topic: Physiology & Rehabilitation

In the evaluation of medial compartment osteoarthritis of the knee, which dynamic gait parameter is most closely correlated with disease severity and progression?

. Peak knee flexion angle
. External knee adduction moment
. Internal knee extension moment
. Ankle dorsiflexion angle
. Hip internal rotation moment

Correct Answer & Explanation

. External knee adduction moment

Explanation

The external knee adduction moment (KAM) during the stance phase of gait is an established surrogate measure of dynamic medial compartment loading. High KAM is strongly associated with the progression of medial knee osteoarthritis.

Question 409

Topic: Physiology & Rehabilitation

A patient with an expanding cervical syringomyelia will most likely present with which of the following classic early neurological deficits?

. Loss of proprioception and vibratory sense in the feet
. Loss of pain and temperature sensation in a cape-like distribution over the shoulders
. Spastic paraparesis of the lower extremities
. Flaccid paralysis of the upper and lower extremities
. Intention tremor and dysmetria

Correct Answer & Explanation

. Loss of pain and temperature sensation in a cape-like distribution over the shoulders

Explanation

The expanding syrinx compresses the decussating fibers of the spinothalamic tract in the anterior white commissure of the spinal cord. This typically causes a bilateral loss of pain and temperature sensation in a cape-like distribution over the arms and shoulders.

Question 410

Topic: Physiology & Rehabilitation

A 14-year-old female presents with a rapidly progressive left thoracic scoliosis. Neurological examination reveals a cape-like distribution of decreased pain and temperature sensation over her shoulders and arms, but intact proprioception and light touch. What is the precise anatomical location of the lesion causing her sensory deficit?

. Dorsal columns
. Spinothalamic tract
. Anterior white commissure
. Corticospinal tract
. Anterior horn cells

Correct Answer & Explanation

. Anterior white commissure

Explanation

The patient has syringomyelia, which typically expands centrally from the ependymal canal. It first compresses the crossing spinothalamic fibers in the anterior white commissure, leading to dissociated sensory loss (loss of pain/temperature with preserved proprioception/touch).

Question 411

Topic: Physiology & Rehabilitation

A 45-year-old male presents with painless swelling, severe destruction, and dislocation of his right shoulder joint. Radiographs show a disorganized, fragmented joint with significant bony debris. He has a history of a cervical spinal cord injury resulting in a progressive fluid collection within the cord. This shoulder pathology is most directly mediated by the loss of which of the following?

. Autonomic sympathetic tone
. Deep pain and proprioceptive sensation
. Motor innervation to the rotator cuff
. Vascular supply to the humeral head
. Synovial fluid production

Correct Answer & Explanation

. Deep pain and proprioceptive sensation

Explanation

The patient has a Charcot joint (neuropathic arthropathy) of the shoulder due to syringomyelia. The loss of deep pain and proprioception removes protective joint reflexes, leading to repetitive microtrauma and severe joint destruction.

Question 412

Topic: Physiology & Rehabilitation

A 30-year-old woman with a known history of syringomyelia presents to the clinic with a cape-like distribution of sensory loss over her shoulders. Which specific sensory modalities are typically lost FIRST in this condition?

. Proprioception and vibratory sense
. Pain and temperature
. Fine touch and two-point discrimination
. Deep pressure and joint position
. Light touch and stereognosis

Correct Answer & Explanation

. Pain and temperature

Explanation

A syrinx typically expands centrally in the spinal cord, first compressing the crossing spinothalamic tracts at the anterior white commissure. This results in the classic dissociated sensory loss of pain and temperature.

Question 413

Topic: Physiology & Rehabilitation

A patient with syringomyelia presents with characteristic neurologic deficits in the upper extremities. Which of the following physical exam findings is most classically associated with a central cord syrinx?

. Loss of proprioception and vibration sense with preserved pain sensation
. Bilateral flaccid paralysis of the lower extremities
. Cape-like distribution of decreased pain and temperature sensation
. Unilateral loss of motor function and contralateral loss of pain
. Hyperreflexia and spasticity in the upper extremities

Correct Answer & Explanation

. Cape-like distribution of decreased pain and temperature sensation

Explanation

A syrinx typically expands from the central canal, first damaging the crossing spinothalamic fibers in the anterior white commissure. This classically produces a "cape-like" distribution of bilateral loss of pain and temperature sensation in the upper extremities and neck, while preserving light touch and proprioception.

Question 414

Topic: Physiology & Rehabilitation

During a normal gait cycle, maximal electromyographic activity of the ankle dorsiflexors (e.g., anterior tibialis) occurs during which phase?

. Initial contact to loading response
. Mid-stance
. Terminal stance
. Pre-swing
. Initial swing

Correct Answer & Explanation

. Initial contact to loading response

Explanation

The anterior tibialis contracts eccentrically from initial contact to the loading response to smoothly lower the foot to the ground and prevent 'foot slap'. This represents its maximal activity during the gait cycle.

Question 415

Topic: Physiology & Rehabilitation

A 7-year-old child with spastic diplegic cerebral palsy presents with a crouch gait. Which of the following kinematic findings is most characteristic of this pattern?

. Excessive knee extension in stance
. Hip hyperextension in stance
. Increased ankle plantarflexion in stance
. Increased knee flexion in stance phase
. Premature heel rise

Correct Answer & Explanation

. Increased knee flexion in stance phase

Explanation

Crouch gait is characterized by excessive hip and knee flexion and excessive ankle dorsiflexion during the stance phase. This is often due to hamstring/psoas tightness and calf weakness.

Question 416

Topic: Physiology & Rehabilitation

A patient exhibits a compensated Trendelenburg gait. Which kinematic adaptation is most typically observed during the stance phase on the affected side?

. Lateral trunk lean toward the affected side
. Lateral trunk lean away from the affected side
. Increased hip flexion
. Knee hyperextension
. Contralateral pelvic drop

Correct Answer & Explanation

. Lateral trunk lean toward the affected side

Explanation

In a compensated Trendelenburg gait, the patient leans their trunk laterally over the affected hip during stance. This shifts the center of gravity closer to the hip joint center, reducing the moment arm and the demand on the weak abductor muscles.

Question 417

Topic: Physiology & Rehabilitation

A patient with cerebral palsy presents with a stiff-knee gait, visibly dragging the toe during the swing phase. Which of the following is the most common underlying cause?

. Overactivity of the rectus femoris
. Weakness of the triceps surae
. Overactivity of the hamstrings
. Gluteus medius weakness
. Spasticity of the anterior tibialis

Correct Answer & Explanation

. Overactivity of the rectus femoris

Explanation

Stiff-knee gait in CP is primarily caused by overactivity or spasticity of the rectus femoris during the swing phase. This prevents the necessary knee flexion required for foot clearance.

Question 418

Topic: Physiology & Rehabilitation

During normal human walking, the vertical ground reaction force (GRF) exhibits a characteristic pattern. Which of the following best describes this pattern during the stance phase?

. A single distinct peak at mid-stance
. A bimodal 'm-shaped' curve with peaks at loading response and terminal stance
. A linear increase from heel strike to toe-off
. A bimodal curve with peaks at mid-stance and initial swing
. A constant plateau throughout the entire stance phase

Correct Answer & Explanation

. A bimodal 'm-shaped' curve with peaks at loading response and terminal stance

Explanation

The normal vertical ground reaction force is bimodal ('m-shaped'). The first peak corresponds to weight acceptance (loading response), and the second peak corresponds to push-off (terminal stance).

Question 419

Topic: Physiology & Rehabilitation

During computerized gait analysis of a patient with cerebral palsy, the kinematic data reveals severely diminished peak knee flexion during the swing phase. Electromyography (EMG) demonstrates continuous firing of the rectus femoris. What is the most appropriate surgical intervention to address this specific abnormality?

. Rectus femoris transfer to the sartorius or semitendinosus.
. Fractional lengthening of the vastus medialis.
. Distal femoral extension osteotomy.
. Patellar tendon advancement.
. Medial hamstring lengthening.

Correct Answer & Explanation

. Rectus femoris transfer to the sartorius or semitendinosus.

Explanation

Continuous firing of the rectus femoris during the swing phase causes a 'stiff-knee gait' by preventing normal knee flexion. Transferring the rectus femoris distally converts it from a knee extensor to a knee flexor, improving swing-phase clearance.

Question 420

Topic: Physiology & Rehabilitation

During the normal gait cycle, the vertical ground reaction force (vGRF) curve demonstrates a characteristic 'M' shape or two-peak pattern. In which phases of the gait cycle do these two peak vertical forces occur?

. Heel strike and toe-off
. Loading response and terminal stance
. Mid-stance and mid-swing
. Initial contact and mid-stance
. Pre-swing and initial swing

Correct Answer & Explanation

. Loading response and terminal stance

Explanation

The two peaks of the vertical ground reaction force curve occur during loading response (weight acceptance) and terminal stance (push-off). During mid-stance, the vGRF dips as the body's center of mass reaches its highest point.

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