Menu

Physiology & Rehabilitation MCQs

Practice Set 11 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 201

Topic: Physiology & Rehabilitation

A 16-year-old male sprinter feels a sudden 'pop' and experiences severe pain in his buttock during a 100-meter dash. Radiographs demonstrate an avulsion fracture of the ischial tuberosity with 3.5 cm of displacement. Which of the following muscles or muscle groups is primarily responsible for the displacement of this fracture?

. Rectus femoris
. Sartorius
. Hamstrings
. Iliopsoas
. Gluteus maximus

Correct Answer & Explanation

. Hamstrings

Explanation

The ischial tuberosity is the anatomic origin of the hamstring muscle complex (long head of the biceps femoris, semitendinosus, and semimembranosus). An avulsion fracture of the ischial tuberosity in a skeletally immature athlete is typically caused by a sudden, forceful eccentric contraction of the hamstrings. The rectus femoris originates at the AIIS, the sartorius at the ASIS, and the iliopsoas inserts at the lesser trochanter.

Question 202

Topic: Physiology & Rehabilitation

A 32-year-old male powerlifter feels a sudden 'pop' in his chest while performing a heavy bench press. Examination reveals an asymmetric loss of the anterior axillary fold and weakness in internal rotation and adduction of the shoulder. MRI confirms a complete rupture of the pectoralis major. Where is the most common anatomical site of rupture for this injury?

. Muscle belly
. Musculotendinous junction
. Sternal origin
. Clavicular origin
. Distal tendon at the humeral insertion

Correct Answer & Explanation

. Distal tendon at the humeral insertion

Explanation

Pectoralis major ruptures most commonly occur during forceful eccentric contraction, such as the lowering phase of a bench press. The most common location of the tear is an avulsion of the distal tendon from its insertion site on the lateral lip of the bicipital groove of the proximal humerus. Surgical repair is generally recommended for complete ruptures at the insertion in active individuals.

Question 203

Topic: Physiology & Rehabilitation

A 28-year-old male bodybuilder feels a sudden, painful pop in his right anterior chest wall while performing a heavy bench press. Examination reveals an asymmetric chest wall with a palpable defect medial to the axillary fold, and profound weakness with adduction and internal rotation of the arm. Which of the following best describes the typical anatomic site and mechanism of the majority of these injuries?

. Avulsion of the clavicular head from the humerus during eccentric contraction
. Avulsion of the sternocostal head from the humerus during eccentric contraction
. Midsubstance tear of the sternocostal head during concentric contraction
. Rupture at the musculotendinous junction of the clavicular head during concentric contraction
. Avulsion of the sternocostal head from the sternum during eccentric contraction

Correct Answer & Explanation

. Avulsion of the sternocostal head from the humerus during eccentric contraction

Explanation

The pectoralis major is most commonly injured during maximal eccentric contraction, such as the eccentric lowering phase of a bench press. The sternocostal head is typically the most frequently injured portion due to its mechanical disadvantage at the inferior aspect of the tendon footprint. Ruptures most commonly occur as tendon avulsions from the humeral insertion or at the musculotendinous junction. Early surgical repair is indicated for complete tears in active individuals.

Question 204

Topic: Physiology & Rehabilitation
A 3-year-old boy, previously treated with serial casting and Achilles tenotomy for idiopathic clubfoot, presents with a relapsed deformity. On examination, he exhibits dynamic supination of the foot during the swing phase of gait. Passive dorsiflexion is 15 degrees past neutral. What is the most appropriate next step in management?
. Repeated serial casting
. Tibialis anterior tendon transfer to the lateral cuneiform
. Split tibialis posterior tendon transfer
. Cuboid decancellation
. Comprehensive posteromedial release

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Relapse of a clubfoot presenting as dynamic supination during the swing phase in a toddler with preserved passive dorsiflexion is best treated with a tibialis anterior tendon transfer (ATTT) to the lateral cuneiform. This addresses the muscular imbalance. Repeated casting is indicated if there is fixed stiffness or loss of dorsiflexion before tendon transfer.

Question 205

Topic: Physiology & Rehabilitation

During the final 20 degrees of active knee extension, the 'screw-home' mechanism occurs to lock the knee in its most stable position. In an open kinetic chain (e.g., seated leg extension), which of the following best describes this obligatory kinematic coupling?

. The tibia internally rotates on the femur
. The tibia externally rotates on the femur
. The femur internally rotates on the tibia
. The femur externally rotates on the tibia
. The patella translates medially

Correct Answer & Explanation

. The tibia externally rotates on the femur

Explanation

The 'screw-home' mechanism is an obligatory rotation that locks the knee during terminal extension. In an open kinetic chain (where the tibia is free to move), the tibia externally rotates on the fixed femur. Conversely, in a closed kinetic chain (where the foot is planted), the femur internally rotates on the fixed tibia.

Question 206

Topic: Physiology & Rehabilitation

During the late swing phase of the normal gait cycle, the hamstrings undergo an eccentric contraction to decelerate the advancing tibia. Which of the following proprioceptive organs is primarily stimulated by this excessive lengthening, acting to reflexively induce muscle contraction and prevent overstretching?

. Pacinian corpuscles
. Golgi tendon organs
. Ruffini endings
. Muscle spindles
. Free nerve endings

Correct Answer & Explanation

. Muscle spindles

Explanation

Muscle spindles are specialized stretch receptors located within the muscle belly that detect changes in muscle length and the rate of change in length. When a muscle is stretched (lengthened), the muscle spindle is activated and sends afferent signals (via Ia fibers) to the spinal cord, inducing a reflex contraction (myotatic reflex) to prevent overstretching. Golgi tendon organs, in contrast, sense muscle tension (via Ib afferents) and act to inhibit the muscle to prevent avulsion or tearing.

Question 207

Topic: Physiology & Rehabilitation

When comparing different skeletal muscle fiber types, fast-twitch glycolytic fibers (Type IIb) possess which of the following physiological and structural characteristics relative to slow-twitch oxidative fibers (Type I)?

. Higher density of mitochondria
. Heavy reliance on oxidative phosphorylation for energy
. High intracellular myoglobin content
. Rapid fatigue and high glycolytic enzyme capacity
. Smaller alpha motor neuron diameter

Correct Answer & Explanation

. Rapid fatigue and high glycolytic enzyme capacity

Explanation

Type IIb fibers (fast-twitch glycolytic) are specialized for rapid, high-force contractions but fatigue quickly. They have low myoglobin content (appearing 'white'), a low capillary density, and fewer mitochondria. They rely heavily on anaerobic glycolysis for ATP production, hence their high glycolytic enzyme capacity. Type I fibers are 'red', fatigue-resistant, mitochondria-rich, and rely on oxidative phosphorylation.

Question 208

Topic: Physiology & Rehabilitation

A marathon runner sustains a partial gastrocnemius tear. The predominant muscle fibers in this athlete's gastrocnemius are optimized for sustained endurance. Which of the following biochemical and physiological profiles best characterizes Type I muscle fibers compared to Type II fibers?

. High mitochondrial density, aerobic metabolism, and slow twitch properties
. Low mitochondrial density, anaerobic metabolism, and fast twitch properties
. High glycogen content, rapid fatigue, and high peak tension
. Low myoglobin content, high glycolytic enzyme activity, and slow twitch properties
. High capillary density, anaerobic metabolism, and fast twitch properties

Correct Answer & Explanation

. High mitochondrial density, aerobic metabolism, and slow twitch properties

Explanation

Type I muscle fibers are 'slow-twitch' fibers optimized for endurance and postural control. They rely primarily on oxidative (aerobic) metabolism, possess a high density of mitochondria and myoglobin (giving them a red appearance), have an extensive capillary network, and are highly resistant to fatigue. Conversely, Type II fibers ('fast-twitch') rely heavily on glycolytic (anaerobic) metabolism, have lower mitochondrial density, and fatigue much more rapidly but generate higher peak tension.

Question 209

Topic: Physiology & Rehabilitation

During rehabilitation after a prolonged lower extremity immobilization, a physical therapist aims to specifically recruit and rebuild Type I skeletal muscle fibers. Which of the following physiologic characteristics correctly defines Type I muscle fibers?

. They rely primarily on anaerobic glycolysis for ATP production.
. They have a remarkably low density of mitochondria.
. They are rich in myoglobin and highly fatigue-resistant.
. They are the first to atrophy after prolonged immobilization.
. They produce short, powerful bursts of high-tension contraction.

Correct Answer & Explanation

. They are rich in myoglobin and highly fatigue-resistant.

Explanation

Type I muscle fibers (slow-twitch, 'red' muscle) are characterized by their reliance on aerobic oxidative metabolism, extensive capillary supply, high mitochondrial density, and abundant myoglobin. They are highly fatigue-resistant and utilized for endurance and posture. Conversely, Type II fibers (fast-twitch) rely more on anaerobic glycolysis, produce rapid and powerful contractions, and are preferentially affected (atrophy first) during states of prolonged immobilization.

Question 210

Topic: Physiology & Rehabilitation

A 24-year-old female is undergoing physical therapy for patellofemoral pain syndrome. Her therapist prescribes a rehabilitation protocol utilizing both open and closed kinetic chain exercises. To minimize the patellofemoral joint reaction force (PFJRF) and resultant joint stress, in which ranges of motion are open and closed kinetic chain exercises respectively most safely performed?

. Open chain: 0 to 45 degrees of flexion; Closed chain: 0 to 45 degrees of flexion
. Open chain: 90 to 45 degrees of flexion; Closed chain: 0 to 45 degrees of flexion
. Open chain: 0 to 45 degrees of flexion; Closed chain: 90 to 45 degrees of flexion
. Open chain: 90 to 45 degrees of flexion; Closed chain: 90 to 45 degrees of flexion
. Open chain: 45 to 0 degrees of flexion; Closed chain: 45 to 0 degrees of flexion

Correct Answer & Explanation

. Open chain: 90 to 45 degrees of flexion; Closed chain: 0 to 45 degrees of flexion

Explanation

In open kinetic chain (OKC) exercises (e.g., seated leg extension), the PFJRF and stress are highest in early flexion (0-45 degrees) due to decreasing patellofemoral contact area and an increasing lever arm of the lower leg; therefore, OKC is safest performed in deeper flexion (90 to 45 degrees). Conversely, in closed kinetic chain (CKC) exercises (e.g., squats), the PFJRF and stress are highest in deep flexion due to the significantly increased quadriceps force required to resist the body weight lever arm; thus, CKC is safest in early flexion (0-45 degrees).

Question 211

Topic: Physiology & Rehabilitation

A physical therapist designs a rehabilitation protocol for a patient recovering from a hamstring injury, emphasizing exercises that generate the absolute maximum muscle force to stimulate tendon remodeling. According to muscle physiology and the force-velocity relationship, which type of muscle contraction generates the highest maximal tension?

. Fast concentric contraction
. Slow concentric contraction
. Isometric contraction
. Slow eccentric contraction
. Fast eccentric contraction

Correct Answer & Explanation

. Fast eccentric contraction

Explanation

The force-velocity curve of muscle physiology demonstrates that eccentric contractions (lengthening under tension) generate significantly more force than isometric and concentric contractions. Within eccentric contractions, higher velocity (fast eccentric) yields higher tension/force up to a plateau, whereas in concentric contractions, slower velocity generates more force. Therefore, fast eccentric contractions are capable of producing the greatest absolute muscle force.

Question 212

Topic: Physiology & Rehabilitation

A 30-year-old weightlifter feels a sharp 'pop' in his distal arm during a heavy preacher curl exercise. According to the sliding filament theory and the length-tension relationship of skeletal muscle, at what sarcomere length is maximum active isometric force generated?

. When actin and myosin filaments are completely non-overlapping
. When the sarcomere is maximally stretched beyond resting length
. At intermediate lengths with optimal overlap of actin and myosin cross-bridges
. When the Z-lines are abutting the myosin filaments causing maximal shortening
. When the muscle is undergoing rapid concentric isokinetic contraction

Correct Answer & Explanation

. At intermediate lengths with optimal overlap of actin and myosin cross-bridges

Explanation

The length-tension curve of skeletal muscle demonstrates that maximal active tension is generated at an intermediate (resting) sarcomere length (approx. 2.0-2.2 micrometers). At this length, there is optimal overlap between actin and myosin filaments, allowing the maximum number of cross-bridges to form. Extreme stretch eliminates filament overlap, and extreme shortening causes physical interference between filaments and the Z-discs, both of which reduce active tension.

Question 213

Topic: Physiology & Rehabilitation

During normal human gait, the center of mass undergoes specific kinematic displacements. Evaluation of the vertical ground reaction force (vGRF) curve reveals a 'double-hump' pattern. Which phases of the gait cycle correspond to the highest magnitudes of vertical ground reaction force?

. Mid-stance
. Initial contact (Heel strike) and toe-off
. Terminal swing
. Loading response and terminal stance
. Pre-swing

Correct Answer & Explanation

. Loading response and terminal stance

Explanation

During normal walking, the vertical ground reaction force (vGRF) exhibits a characteristic two-peak (double-hump) pattern. The first peak occurs during the loading response (weight acceptance) as the limb absorbs the downward acceleration of the body's mass. The second peak occurs during terminal stance as the plantarflexors forcefully push off, accelerating the body upward and forward. Mid-stance is represented by the trough between these two peaks.

Question 214

Topic: Physiology & Rehabilitation

A thorough understanding of clinical gait analysis is essential for evaluating neuromuscular pathologies. During a normal human gait cycle, the quadriceps muscle group exhibits its peak electromyographic (EMG) activity during which of the following phases?

. Mid-stance
. Terminal stance
. Initial swing
. Terminal swing into early loading response
. Mid-swing

Correct Answer & Explanation

. Terminal swing into early loading response

Explanation

The quadriceps muscle group shows biphasic activity during the normal gait cycle, but it reaches its absolute peak electromyographic (EMG) activity during terminal swing and continues into the early loading response (initial contact to foot flat). During terminal swing, the quadriceps fire concentrically to extend the knee and prepare the limb for heel strike. Immediately following heel strike (loading response), they fire eccentrically to control knee flexion and absorb the shock of impact.

Question 215

Topic: Physiology & Rehabilitation

A marathon runner relies heavily on muscle fibers adapted for prolonged endurance. Which of the following characteristics best describes the predominant muscle fiber type utilized during this activity?

. Fast twitch, anaerobic, high glycogen content
. Slow twitch, oxidative, rich in mitochondria and myoglobin
. Fast twitch, oxidative-glycolytic, intermediate fatigue resistance
. Slow twitch, anaerobic, low capillary density
. Fast twitch, relying on creatine phosphate for energy

Correct Answer & Explanation

. Slow twitch, oxidative, rich in mitochondria and myoglobin

Explanation

Marathon running requires prolonged endurance, which relies on Type I (slow-twitch) muscle fibers. These fibers are characterized by a slow contraction speed, high resistance to fatigue, and a strong reliance on aerobic (oxidative) metabolism. To support this aerobic metabolism, they have a high density of mitochondria, a rich capillary supply, and a high concentration of myoglobin, which gives them a distinct red color.

Question 216

Topic: Physiology & Rehabilitation

The excitation-contraction coupling of skeletal muscle relies heavily on calcium handling. Upon an action potential traveling down the T-tubule, calcium is released from the sarcoplasmic reticulum. What is the immediate direct effect of this intracellular calcium release?

. It binds to tropomyosin, detaching it from the myosin head.
. It binds to troponin C, causing a conformational change that moves tropomyosin to expose the actin binding sites.
. It binds to the myosin head, providing the energy required for the power stroke.
. It alters the helical structure of actin directly, allowing it to accept ATP.
. It binds to troponin I, inhibiting the ATPase activity of myosin.

Correct Answer & Explanation

. It binds to troponin C, causing a conformational change that moves tropomyosin to expose the actin binding sites.

Explanation

According to the sliding filament theory, an action potential triggers calcium release from the sarcoplasmic reticulum. This calcium binds to troponin C, which undergoes a conformational change. This movement pulls tropomyosin away from the myosin-binding sites on the actin filament. Once these sites are exposed, the energized myosin heads can bind to actin to form cross-bridges, leading to the power stroke and muscle contraction.

Question 217

Topic: Physiology & Rehabilitation

During a marathon, an endurance runner predominantly utilizes a specific type of skeletal muscle fiber. Which of the following best characterizes this muscle fiber type?

. High glycogen content, high anaerobic capacity, fast twitch
. High mitochondrial density, high myoglobin content, fatigue-resistant
. Low oxidative capacity, fast twitch, large motor unit size
. High myosin ATPase activity, rapid fatigue, low capillary density
. Low triglyceride content, high glycolytic enzyme activity, fast contraction

Correct Answer & Explanation

. High mitochondrial density, high myoglobin content, fatigue-resistant

Explanation

Type I muscle fibers (slow-twitch) are highly utilized during endurance activities like marathons. They are characterized by high oxidative capacity, high mitochondrial density, high myoglobin content (giving them a red color), and strong resistance to fatigue. Type II fibers (fast-twitch) are utilized for short, explosive movements and have higher glycolytic capacity and fatigue more rapidly.

Question 218

Topic: Physiology & Rehabilitation
A 40-year-old man is transported to the trauma center after a high-speed motorcycle collision. On physical examination, he has dense bilateral loss of motor function, as well as loss of pain and temperature sensation below the T10 dermatomal level. However, his proprioception, vibratory sense, and fine touch sensation remain intact in his lower extremities. Which of the following spinal cord injury syndromes does this presentation most accurately describe?
. Central cord syndrome
. Brown-Séquard syndrome
. Anterior cord syndrome
. Posterior cord syndrome
. Conus medullaris syndrome

Correct Answer & Explanation

. Anterior cord syndrome

Explanation

This classic presentation describes Anterior Cord Syndrome, which results from injury to the anterior two-thirds of the spinal cord (frequently secondary to direct compression or anterior spinal artery territory ischemia). It is characterized by the bilateral loss of motor function (corticospinal tracts) and pain/temperature sensation (spinothalamic tracts) below the level of the injury, with the complete preservation of the dorsal columns (proprioception, vibration, and light touch).

Question 219

Topic: Physiology & Rehabilitation

A 32-year-old bodybuilder feels a pop in his anterior chest while performing a heavy bench press. Examination reveals bruising and a loss of the anterior axillary fold contour. MRI confirms a complete pectoralis major rupture. Which portion of the muscle is most commonly injured in this classic mechanism?

. Clavicular head origin
. Clavicular head insertion
. Sternal head origin
. Sternal head insertion
. Costal attachments

Correct Answer & Explanation

. Sternal head insertion

Explanation

Pectoralis major ruptures typically occur at the insertion of the sternal head onto the humerus during forced eccentric contraction, such as the lowering phase of a bench press.

Question 220

Topic: Physiology & Rehabilitation

A 25-year-old elite track sprinter undergoes a skeletal muscle biopsy. The predominant muscle fibers identified are fast-twitch, easily fatigable, white fibers that contain low concentrations of myoglobin and mitochondria. Which primary biochemical pathway do these specific fibers rely on for ATP production?

. Oxidative phosphorylation
. Beta-oxidation of fatty acids
. Anaerobic glycolysis
. Krebs cycle
. Creatine phosphate shuttle solely

Correct Answer & Explanation

. Anaerobic glycolysis

Explanation

The description perfectly matches Type IIb (or IIx in humans) muscle fibers. These are fast-twitch, highly fatigable, 'white' fibers due to low myoglobin and mitochondrial content. They rely primarily on anaerobic glycolysis for rapid, short-duration energy (ATP) production. In contrast, Type I fibers are slow-twitch, fatigue-resistant 'red' fibers (high myoglobin) that rely heavily on aerobic pathways, including oxidative phosphorylation and beta-oxidation.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page