Neuro Cranial Nerves & Myotactic Rflx MCQ's

1. As a 4th year medical student, you are examining a patient with ptosis (drooping of the eyelid), dilation of the pupil and a downwardly abducted eye. You conclude that the patient has sustained damage to which of the following?

Abducens nerve

Oculomotor nerve

Trochlear nerve

Principal sensory nucleus of V

Facial nerve - Dell's palsy

The patient's symptoms of ptosis (drooping of the eyelid), dilation of the pupil, and a downwardly abducted eye are indicative of damage to the oculomotor nerve. The oculomotor nerve is responsible for controlling the movement of the eyelid and pupil, as well as the movement of the eye in an upward and inward direction. Damage to this nerve can result in the characteristic symptoms observed in the patient. The other options listed do not match the patient's symptoms and are therefore not the correct answer.

Explanation

The patient's symptoms of ptosis (drooping of the eyelid), dilation of the pupil, and a downwardly abducted eye are indicative of damage to the oculomotor nerve. The oculomotor nerve is responsible for controlling the movement of the eyelid and pupil, as well as the movement of the eye in an upward and inward direction. Damage to this nerve can result in the characteristic symptoms observed in the patient. The other options listed do not match the patient's symptoms and are therefore not the correct answer.

2. The cell bodies of parasympathetic (GVE) axons are found in which of the following cranial nerves?

CN I, CN II, CN VIII

CN II, CN III, CN IV, CN VI

CN III, CN VII, CN IX, CN X

CN V, CN VII, CN X

CN II, CN IX, CN X

The cell bodies of parasympathetic (GVE) axons are found in cranial nerves CN III, CN VII, CN IX, and CN X. These cranial nerves are responsible for controlling various parasympathetic functions in the body, such as pupillary constriction (CN III), salivation and lacrimation (CN VII), swallowing and secretion (CN IX), and digestion and cardiac function (CN X).

Explanation

The cell bodies of parasympathetic (GVE) axons are found in cranial nerves CN III, CN VII, CN IX, and CN X. These cranial nerves are responsible for controlling various parasympathetic functions in the body, such as pupillary constriction (CN III), salivation and lacrimation (CN VII), swallowing and secretion (CN IX), and digestion and cardiac function (CN X).

3. Which 2^ndorder neurons are involved with relaying touch & proprioceptive information to the somatosensory cortex from the face?

Principal (main) sensory nucleus of V

Nucleus gracilis

Motor nucleus of V

Nucleus cuneatus

Ventral horn neurons

The principal (main) sensory nucleus of V is involved in relaying touch and proprioceptive information to the somatosensory cortex from the face. This nucleus is located in the trigeminal nerve, which is responsible for transmitting sensory information from the face to the brain. Therefore, it plays a crucial role in processing touch and proprioceptive sensations from the face and relaying them to the somatosensory cortex for further interpretation and perception.

Explanation

The principal (main) sensory nucleus of V is involved in relaying touch and proprioceptive information to the somatosensory cortex from the face. This nucleus is located in the trigeminal nerve, which is responsible for transmitting sensory information from the face to the brain. Therefore, it plays a crucial role in processing touch and proprioceptive sensations from the face and relaying them to the somatosensory cortex for further interpretation and perception.

4. You are examining a 20-year old male who has suffered a severe concussion after playing in the neighborhood hockey game. You notice that his left eye is depressed and exhibits exotropia and the pupil is dilated. What two nuclei are most likely affected in this young man?

Trochlear and salivatory nuclei

Trochlear and Edinger-Westphal nuclei

Oculomotor and Edinger-Westphal nuclei

Abducens and Edinger-Westphal nuclei

Oculomotor and salivatory nuclei

The correct answer is Oculomotor and Edinger-Westphal nuclei. The symptoms described, including exotropia (outward deviation of the eye) and dilated pupil, suggest dysfunction of the oculomotor nerve (cranial nerve III). The oculomotor nucleus controls the movement of the eye muscles, including the medial rectus muscle responsible for inward movement of the eye. The Edinger-Westphal nucleus, which is located within the oculomotor nucleus, controls the constriction of the pupil. Damage to both nuclei can result in the observed symptoms.

Explanation

The correct answer is Oculomotor and Edinger-Westphal nuclei. The symptoms described, including exotropia (outward deviation of the eye) and dilated pupil, suggest dysfunction of the oculomotor nerve (cranial nerve III). The oculomotor nucleus controls the movement of the eye muscles, including the medial rectus muscle responsible for inward movement of the eye. The Edinger-Westphal nucleus, which is located within the oculomotor nucleus, controls the constriction of the pupil. Damage to both nuclei can result in the observed symptoms.

5. A 79-year old man is experiencing peripheral nerve damage of his lower right limb. Which of the following is characteristic of lower motor neuron damage?

Hyperreflexia

Increased tone

Hyporeflexia

Spastic paralysis

Increased muscle mass

Hyporeflexia is characteristic of lower motor neuron damage. Lower motor neurons are responsible for transmitting signals from the spinal cord to the muscles, and damage to these neurons can result in decreased reflexes or hyporeflexia. This is because the communication between the spinal cord and the muscles is disrupted, leading to a decrease in the normal reflex responses. The other options, such as hyperreflexia, increased tone, spastic paralysis, and increased muscle mass, are more commonly associated with upper motor neuron damage.

Explanation

Hyporeflexia is characteristic of lower motor neuron damage. Lower motor neurons are responsible for transmitting signals from the spinal cord to the muscles, and damage to these neurons can result in decreased reflexes or hyporeflexia. This is because the communication between the spinal cord and the muscles is disrupted, leading to a decrease in the normal reflex responses. The other options, such as hyperreflexia, increased tone, spastic paralysis, and increased muscle mass, are more commonly associated with upper motor neuron damage.

6. When testing the sensory innervation of the face, it is important to remember that the skin on the tip of the nose is supplied by which nerve?

Zygomatic branch of the facial nerve

Maxillary division of the trigeminal nerve

Ophthalmic division of the trigeminal nerve

Buccal branch of the mandibular nerve

Buccal branch of the facial nerve

The skin on the tip of the nose is supplied by the ophthalmic division of the trigeminal nerve. The trigeminal nerve is responsible for sensory innervation of the face, and it has three main divisions: ophthalmic, maxillary, and mandibular. The ophthalmic division supplies sensation to the forehead, upper eyelid, and tip of the nose. Therefore, when testing the sensory innervation of the face, it is important to remember that the skin on the tip of the nose is supplied by the ophthalmic division of the trigeminal nerve.

Explanation

The skin on the tip of the nose is supplied by the ophthalmic division of the trigeminal nerve. The trigeminal nerve is responsible for sensory innervation of the face, and it has three main divisions: ophthalmic, maxillary, and mandibular. The ophthalmic division supplies sensation to the forehead, upper eyelid, and tip of the nose. Therefore, when testing the sensory innervation of the face, it is important to remember that the skin on the tip of the nose is supplied by the ophthalmic division of the trigeminal nerve.

7. SVA axons are contained in which of the following cranial nerves?

CN III, CN VII, CN IX

CN V, CN VIII, CN IX

CN VII, CN IX, CN X

CN II, CN X, CN XI

CN V, CN X, CN VII

SVA axons are contained in cranial nerves CN VII, CN IX, and CN X.

Explanation

SVA axons are contained in cranial nerves CN VII, CN IX, and CN X.

8. A lesion at the level of the cerebral peduncle would affect descending fibers of the corticospinal tract. Disruption of these axons would result in which of the following?

Flaccid paralysis

Areflexia

Hypotonicity

Positive Babinski sign

Absent Babinski sign

A lesion at the level of the cerebral peduncle would affect descending fibers of the corticospinal tract. The corticospinal tract is responsible for voluntary motor control. When this tract is disrupted, it can lead to an abnormal response known as the Babinski sign. The Babinski sign is characterized by the extension of the big toe and fanning of the other toes when the sole of the foot is stroked. In a normal response, the toes would flex instead. Therefore, a lesion at the level of the cerebral peduncle would result in a positive Babinski sign.

Explanation

A lesion at the level of the cerebral peduncle would affect descending fibers of the corticospinal tract. The corticospinal tract is responsible for voluntary motor control. When this tract is disrupted, it can lead to an abnormal response known as the Babinski sign. The Babinski sign is characterized by the extension of the big toe and fanning of the other toes when the sole of the foot is stroked. In a normal response, the toes would flex instead. Therefore, a lesion at the level of the cerebral peduncle would result in a positive Babinski sign.

9. A developmental disorder resulting in the failure of the mesencephalon to develop would result in the loss of which of the following structures?

Facial nuclei

Spinal trigeminal nuclei

Oculomotor nuclei

Hypoglossal nuclei

Dorsal motor nuclei of X

If the mesencephalon fails to develop, it would result in the loss of the oculomotor nuclei. The oculomotor nuclei are responsible for controlling the movement of the eye muscles, including the muscles that control eye movement in different directions and the muscles that control the size of the pupil. Without the development of the mesencephalon, which is a part of the midbrain, the oculomotor nuclei would not form properly, leading to a loss of their function in controlling eye movements.

Explanation

If the mesencephalon fails to develop, it would result in the loss of the oculomotor nuclei. The oculomotor nuclei are responsible for controlling the movement of the eye muscles, including the muscles that control eye movement in different directions and the muscles that control the size of the pupil. Without the development of the mesencephalon, which is a part of the midbrain, the oculomotor nuclei would not form properly, leading to a loss of their function in controlling eye movements.

10. You are on your emergency medicine rotation and are assisting in the examination of a patient who has been in a vehicular accident. You noticed when testing the cranial nerves, the patient's tongue deviates towards the left upon protrusion. Which cranial nerve is damaged in this case?

The facial nerve on the left

The facial nerve on the right

The mandibular division of trigeminal (V3) on the right

The hypoglossal nerve on the right

The hypoglossal nerve on the left

The patient's tongue deviating towards the left upon protrusion suggests damage to the left hypoglossal nerve. The hypoglossal nerve is responsible for controlling the movement of the tongue. Damage to this nerve can result in weakness or paralysis of the muscles of the tongue on the affected side, causing the tongue to deviate towards the damaged side.

Explanation

The patient's tongue deviating towards the left upon protrusion suggests damage to the left hypoglossal nerve. The hypoglossal nerve is responsible for controlling the movement of the tongue. Damage to this nerve can result in weakness or paralysis of the muscles of the tongue on the affected side, causing the tongue to deviate towards the damaged side.

11. Which of the following nuclei is associated with both CN IX and CN X and is important in providing innervation to the voluntary muscles of the larynx, pharynx and palate?

Rostral nucleus solitaries

Edinger-Westphal nucleus

Dorsal motor nucleus of X

Nucleus ambiguous

Facial nuclei

The correct answer is Nucleus ambiguous. The nucleus ambiguous is associated with both CN IX (glossopharyngeal nerve) and CN X (vagus nerve) and is responsible for providing innervation to the voluntary muscles of the larynx, pharynx, and palate. It plays a crucial role in controlling functions such as swallowing, speech, and vocalization.

Explanation

The correct answer is Nucleus ambiguous. The nucleus ambiguous is associated with both CN IX (glossopharyngeal nerve) and CN X (vagus nerve) and is responsible for providing innervation to the voluntary muscles of the larynx, pharynx, and palate. It plays a crucial role in controlling functions such as swallowing, speech, and vocalization.

12. Which of the following cranial nerves does not have a parasympathetic central connection with the brain?

CN III

CN V

CN VII

CN IX

CN X

CN V, also known as the trigeminal nerve, does not have a parasympathetic central connection with the brain. The trigeminal nerve is primarily responsible for sensory information from the face and motor control of the muscles involved in chewing. It does not have a direct role in parasympathetic functions such as regulating heart rate, digestion, or glandular secretion.

Explanation

CN V, also known as the trigeminal nerve, does not have a parasympathetic central connection with the brain. The trigeminal nerve is primarily responsible for sensory information from the face and motor control of the muscles involved in chewing. It does not have a direct role in parasympathetic functions such as regulating heart rate, digestion, or glandular secretion.

13. A 32-year-old man developed hoarseness of voice, inability to swallow and restricted movement of the tongue after open heart surgery. Peripheral injury of cranial nerves was suspected, and it was thought that the duration of the surgery together with the endotracheal tube cuff and trans-esophageal echocardiography probe pressure, as well as the head and neck position might have been the causes of this complication. Which cranial nerves were involved?

IX and X

IX, X and XII

VII and XII

V/3 and IX, X

V/3 and XII

The patient's symptoms of hoarseness of voice, inability to swallow, and restricted movement of the tongue suggest involvement of multiple cranial nerves. The glossopharyngeal nerve (IX) innervates the throat muscles and is responsible for swallowing. The vagus nerve (X) innervates the vocal cords and is responsible for voice production. The hypoglossal nerve (XII) innervates the tongue muscles and is responsible for tongue movement. Therefore, the involvement of cranial nerves IX, X, and XII can explain the patient's symptoms.

Explanation

The patient's symptoms of hoarseness of voice, inability to swallow, and restricted movement of the tongue suggest involvement of multiple cranial nerves. The glossopharyngeal nerve (IX) innervates the throat muscles and is responsible for swallowing. The vagus nerve (X) innervates the vocal cords and is responsible for voice production. The hypoglossal nerve (XII) innervates the tongue muscles and is responsible for tongue movement. Therefore, the involvement of cranial nerves IX, X, and XII can explain the patient's symptoms.

14. An 18-year-old male presented to the Emergency Room bleeding profusely from a deep cut in the left occipital triangle of his neck and undergoes emergency surgery to repair his internal jugular vein. He survives his injury but he is found on neurological examination to have left-sided weakness in shrugging his shoulder, cannot turn his head to the left against resistance, has a flat left soft palatal arch, and lacks a gag reflex on the left side. What additional clinical sign would be expected in this patient?

Ptosis on the left side that disappears on upward gaze

Profound ptosis on the left side

Dry eye on the left side

Gustatory sweating over the left parotid gland

Dry mouth

Dry mouth, also known as xerostomia, is a common clinical manifestation of damage to the glossopharyngeal nerve (CN IX) and/or the vagus nerve (CN X). In this case, the patient's injury likely resulted in damage to these nerves, leading to the loss of the gag reflex on the left side and the flat left soft palatal arch. Dry mouth can occur due to decreased salivary gland function, which is controlled by these cranial nerves. Therefore, it would be expected as an additional clinical sign in this patient.

Explanation

Dry mouth, also known as xerostomia, is a common clinical manifestation of damage to the glossopharyngeal nerve (CN IX) and/or the vagus nerve (CN X). In this case, the patient's injury likely resulted in damage to these nerves, leading to the loss of the gag reflex on the left side and the flat left soft palatal arch. Dry mouth can occur due to decreased salivary gland function, which is controlled by these cranial nerves. Therefore, it would be expected as an additional clinical sign in this patient.

15. A 42-year-old man comes to the emergency department with an abscess of the parotid gland that is subsequently excised and drained. The physician who performs this procedure knows that innervation to the parotid gland is provided by what type of axons and which cranial nerve?

SVA; CN X

SVA; CN IX

GVE; CN X

GVE: CN IX

GVE; CN VII

The correct answer is GVE: CN IX. The parotid gland is innervated by the glossopharyngeal nerve (CN IX), which carries general visceral efferent (GVE) fibers. These fibers are responsible for providing parasympathetic innervation to the gland, controlling its secretory function.

Explanation

The correct answer is GVE: CN IX. The parotid gland is innervated by the glossopharyngeal nerve (CN IX), which carries general visceral efferent (GVE) fibers. These fibers are responsible for providing parasympathetic innervation to the gland, controlling its secretory function.

16. A patient exhibits a loss of pain sensation on the right side of his face. What cranial nerve is affected and a lesion to which of the following tracts would result in the deficit exhibited in this case?

CN V; Left Trigemino-Thalamic tract

CN VII; Left spinal tract of V

CN V; Right Trigemino-Thalamic tract

CN V, Left spiral tract of V

CN VII; Right tractus solitarius

The correct answer is CN V; Left Trigemino-Thalamic tract. The patient's loss of pain sensation on the right side of his face suggests a lesion in the trigemino-thalamic tract, which is responsible for transmitting sensory information, including pain, from the face to the brain. The involvement of CN V (trigeminal nerve) indicates that the deficit is related to the sensory innervation of the face. The mention of "left" suggests that the lesion is on the left side of the brain, affecting the left trigemino-thalamic tract.

Explanation

The correct answer is CN V; Left Trigemino-Thalamic tract. The patient's loss of pain sensation on the right side of his face suggests a lesion in the trigemino-thalamic tract, which is responsible for transmitting sensory information, including pain, from the face to the brain. The involvement of CN V (trigeminal nerve) indicates that the deficit is related to the sensory innervation of the face. The mention of "left" suggests that the lesion is on the left side of the brain, affecting the left trigemino-thalamic tract.

17. A 22 year old truck driver suffers a crush injury to the 'left arm after a road accident. The mixed spinal nerves leaving the spinal cord at levels C5 and C6 are affected, with impingement and major inflammation. The damage is limited to the peripheral nervous portions of these nerves only. Which below is the most likely finding in this patient with regard to his Deep Tendon (Myotatic) Reflexes?

Areflexia (no reflex) - Left Biceps Brachii muscle

Hypo-reflexia (diminished reflex) - Right Biceps Brachii muscle

Hyper-reflexia (overactive reflex) - Left Biceps Brachii muscle

Hyper-reflexia - Right Biceps Brachii muscle

Hypo-reflexia - Left Biceps Brachii muscle

The injury to the mixed spinal nerves at levels C5 and C6, along with the impingement and inflammation, would affect the transmission of nerve signals to the left Biceps Brachii muscle. This would result in a diminished reflex response in the left arm, leading to hypo-reflexia.

Explanation

The injury to the mixed spinal nerves at levels C5 and C6, along with the impingement and inflammation, would affect the transmission of nerve signals to the left Biceps Brachii muscle. This would result in a diminished reflex response in the left arm, leading to hypo-reflexia.