BIOL 251 MODULE 7 EXAM
REVIEW: QUESTIONS & VERIFIED
ANSWERS SUMMARY
1. Which specific cranial nerve is responsible for monitoring blood pressure via
baroreceptors in the carotid sinus?
A. CN VII (Facial nerve)
B. CN IX (Glossopharyngeal nerve)
C. CN X (Vagus nerve)
D. CN XII (Hypoglossal nerve)
Correct Answer: B. CN IX (Glossopharyngeal nerve)
Explanation: The glossopharyngeal nerve (CN IX) carries visceral sensory
information from the carotid sinus baroreceptors and carotid body
chemoreceptors to the medulla oblongata to regulate blood pressure and blood
gas levels.
,2. During a routine reflex examination, a clinician taps the patellar tendon and observes a
normal extension of the knee. What type of reflex arc is being demonstrated?
A. Polysynaptic ipsilateral stretch reflex
B. Monosynaptic ipsilateral stretch reflex
C. Polysynaptic contralateral withdrawal reflex
D. Monosynaptic contralateral tendon reflex
Correct Answer: B. Monosynaptic ipsilateral stretch reflex
Explanation: The stretch reflex (such as the patellar reflex) is monosynaptic,
meaning the afferent sensory neuron synapses directly onto the efferent alpha
motor neuron on the same side (ipsilateral) of the spinal cord without an
interneuron.
3. A patient presents with structural damage to the ventral root of the C6 spinal nerve.
Which of the following functional deficits would you expect to find?
A. Complete loss of pain sensation in the C6 dermatome
B. Impaired motor control over the muscles innervated by that nerve
C. Inability to detect temperature changes in the upper limb
D. Complete loss of proprioception in the forearm
Correct Answer: B. Impaired motor control over the muscles innervated by that
nerve
Explanation: Ventral roots consist purely of efferent (motor) fibers exiting the
spinal cord. Damage results in motor weakness or paralysis, while sensory
pathways (which travel via the dorsal root) remain intact.
4. Which type of sensory receptor adapts rapidly to sustained stimuli, making it ideally
suited for detecting vibration and deep pressure changes?
A. Ruffini endings
B. Merkel discs
C. Pacinian corpuscles
D. Free nerve endings
Correct Answer: C. Pacinian corpuscles
, Explanation: Pacinian (lamellated) corpuscles are phasic receptors, meaning they
are fast-adapting. They respond rapidly to initial pressure changes and high-
frequency vibrations rather than sustained pressure.
5. In a crossed-extensor reflex, when a person steps on a sharp object, the injured leg
flexes to withdraw. What simultaneously happens in the contralateral leg to maintain
balance?
A. Motor neurons are inhibited, causing the contralateral leg to flex.
B. Motor neurons are stimulated, causing extension of the contralateral leg.
C. Sensory receptors are desensitized to minimize systemic panic.
D. Interneurons block all motor output to prevent muscle fatigue.
Correct Answer: B. Motor neurons are stimulated, causing extension of the
contralateral leg.
Explanation: The crossed-extensor reflex works with the flexor reflex to maintain
balance. The contralateral limb's extensor muscles are stimulated (while flexors
are inhibited) to support the weight of the shifting body.
shifting body.
5. Which cranial nerve is unique because it is the only one that exits the posterior (dorsal)
aspect of the brainstem?
A. CN III (Oculomotor nerve)
B. CN IV (Trochlear nerve)
C. CN V (Trigeminal nerve)
D. CN VI (Abducens nerve)
Correct Answer: B. CN IV (Trochlear nerve)
Explanation: The trochlear nerve (CN IV) is the only cranial nerve that emerges
from the dorsal aspect of the brainstem. It also has the longest intracranial course
before innervating the superior oblique muscle.
, 6. A patient is unable to shrug their shoulders or turn their head against resistance. Which
cranial nerve is likely damaged?
A. CN IX
B. CN X
C. CN XI
D. CN XII
Correct Answer: C. CN XI
Explanation: The accessory nerve (CN XI) supplies somatic motor innervation to
the sternocleidomastoid and trapezius muscles, which control head turning and
shoulder shrugging.
7. Which spinal nerve ramus loops forward to form the complex nerve plexuses supplying
the limbs?
A. Dorsal ramus
B. Ventral ramus
C. Ramus communicans
D. Meningeal ramus
Correct Answer: B. Ventral ramus
Explanation: The ventral rami of spinal nerves form the cervical, brachial, lumbar,
and sacral plexuses. Dorsal rami remain segmented to innervate the deep muscles
and skin of the back.
8. What specific mechanoreceptor is encapsulated, located in the dermal papillae of
hairless skin, and specializes in fine, discriminative touch?
A. Meissner's corpuscle
B. Pacinian corpuscle
C. Ruffini ending
D. Merkel disc
Correct Answer: A. Meissner's corpuscle
Explanation: Meissner's (tactile) corpuscles are rapidly adapting encapsulated
REVIEW: QUESTIONS & VERIFIED
ANSWERS SUMMARY
1. Which specific cranial nerve is responsible for monitoring blood pressure via
baroreceptors in the carotid sinus?
A. CN VII (Facial nerve)
B. CN IX (Glossopharyngeal nerve)
C. CN X (Vagus nerve)
D. CN XII (Hypoglossal nerve)
Correct Answer: B. CN IX (Glossopharyngeal nerve)
Explanation: The glossopharyngeal nerve (CN IX) carries visceral sensory
information from the carotid sinus baroreceptors and carotid body
chemoreceptors to the medulla oblongata to regulate blood pressure and blood
gas levels.
,2. During a routine reflex examination, a clinician taps the patellar tendon and observes a
normal extension of the knee. What type of reflex arc is being demonstrated?
A. Polysynaptic ipsilateral stretch reflex
B. Monosynaptic ipsilateral stretch reflex
C. Polysynaptic contralateral withdrawal reflex
D. Monosynaptic contralateral tendon reflex
Correct Answer: B. Monosynaptic ipsilateral stretch reflex
Explanation: The stretch reflex (such as the patellar reflex) is monosynaptic,
meaning the afferent sensory neuron synapses directly onto the efferent alpha
motor neuron on the same side (ipsilateral) of the spinal cord without an
interneuron.
3. A patient presents with structural damage to the ventral root of the C6 spinal nerve.
Which of the following functional deficits would you expect to find?
A. Complete loss of pain sensation in the C6 dermatome
B. Impaired motor control over the muscles innervated by that nerve
C. Inability to detect temperature changes in the upper limb
D. Complete loss of proprioception in the forearm
Correct Answer: B. Impaired motor control over the muscles innervated by that
nerve
Explanation: Ventral roots consist purely of efferent (motor) fibers exiting the
spinal cord. Damage results in motor weakness or paralysis, while sensory
pathways (which travel via the dorsal root) remain intact.
4. Which type of sensory receptor adapts rapidly to sustained stimuli, making it ideally
suited for detecting vibration and deep pressure changes?
A. Ruffini endings
B. Merkel discs
C. Pacinian corpuscles
D. Free nerve endings
Correct Answer: C. Pacinian corpuscles
, Explanation: Pacinian (lamellated) corpuscles are phasic receptors, meaning they
are fast-adapting. They respond rapidly to initial pressure changes and high-
frequency vibrations rather than sustained pressure.
5. In a crossed-extensor reflex, when a person steps on a sharp object, the injured leg
flexes to withdraw. What simultaneously happens in the contralateral leg to maintain
balance?
A. Motor neurons are inhibited, causing the contralateral leg to flex.
B. Motor neurons are stimulated, causing extension of the contralateral leg.
C. Sensory receptors are desensitized to minimize systemic panic.
D. Interneurons block all motor output to prevent muscle fatigue.
Correct Answer: B. Motor neurons are stimulated, causing extension of the
contralateral leg.
Explanation: The crossed-extensor reflex works with the flexor reflex to maintain
balance. The contralateral limb's extensor muscles are stimulated (while flexors
are inhibited) to support the weight of the shifting body.
shifting body.
5. Which cranial nerve is unique because it is the only one that exits the posterior (dorsal)
aspect of the brainstem?
A. CN III (Oculomotor nerve)
B. CN IV (Trochlear nerve)
C. CN V (Trigeminal nerve)
D. CN VI (Abducens nerve)
Correct Answer: B. CN IV (Trochlear nerve)
Explanation: The trochlear nerve (CN IV) is the only cranial nerve that emerges
from the dorsal aspect of the brainstem. It also has the longest intracranial course
before innervating the superior oblique muscle.
, 6. A patient is unable to shrug their shoulders or turn their head against resistance. Which
cranial nerve is likely damaged?
A. CN IX
B. CN X
C. CN XI
D. CN XII
Correct Answer: C. CN XI
Explanation: The accessory nerve (CN XI) supplies somatic motor innervation to
the sternocleidomastoid and trapezius muscles, which control head turning and
shoulder shrugging.
7. Which spinal nerve ramus loops forward to form the complex nerve plexuses supplying
the limbs?
A. Dorsal ramus
B. Ventral ramus
C. Ramus communicans
D. Meningeal ramus
Correct Answer: B. Ventral ramus
Explanation: The ventral rami of spinal nerves form the cervical, brachial, lumbar,
and sacral plexuses. Dorsal rami remain segmented to innervate the deep muscles
and skin of the back.
8. What specific mechanoreceptor is encapsulated, located in the dermal papillae of
hairless skin, and specializes in fine, discriminative touch?
A. Meissner's corpuscle
B. Pacinian corpuscle
C. Ruffini ending
D. Merkel disc
Correct Answer: A. Meissner's corpuscle
Explanation: Meissner's (tactile) corpuscles are rapidly adapting encapsulated
