1. Which statement below best describes the spatial relationship between cranial nerve motor and sensory nuclei in the medulla and pons?

A. Motor nuclei are ventral to sensory nuclei.
B. Motor nuclei are dorsal to sensory nuclei.
C. Motor nuclei are medial to sensory nuclei.
D. Motor nuclei are lateral to sensory nuclei.

Comment: Unlike the spinal cord, where the motor nuclei are located ventral to sensory nuclei, it is different in the caudal brain stem. This is because as the fourth ventricle develops, it displaces the sensory nuclei laterally. In the midbrain, the only cranial nerve sensory nucleus, the mesencephalic trigeminal nucleus, is located dorsal to the oculomotor nucleus, a dorsoventral organization like the spinal cord. Here in the midbrain, development of the narrow cerebral aqueduct does not displace the sensory nuclei.

2. Which of the following statements best describes the difference between the innervation of skeletal muscle and smooth muscle by central nervous system neurons?

A. Central nervous system neurons innervate skeletal muscle monosynaptically and innervate smooth muscle disynaptically, via a synapse in peripheral ganglia.
B. Central nervous system neurons innervate skeletal and smooth muscle monosynaptically.
C. Central nervous system neurons innervate skeletal muscle disynaptically, via a synapse in peripheral ganglia, and innervate smooth muscle monosynaptically.
D. Central nervous system neurons innervate skeletal and smooth muscle disynaptically, via a synapse in peripheral ganglia.

3. After an internal capsule stroke, a person can lose some cranial nerve motor functions. When this occurs the lost function typically is expressed only on the contralateral side. Which statement below best explains this contralateral pattern?

A. All corticobulbar projections are contralateral. Thus, a unilateral lesion will produce contralateral deficits affecting all cranial nerve motor nuclei.
B. All corticobulbar projections are bilateral, but the contralateral projections are the strongest. When these strong connections are eliminated after a unilateral lesion, contralateral deficits occur in all cranial nerve motor nuclei.
C. Some cranial nerve motor nuclei receive contralateral corticobulbar projections, whereas others receive a bilateral projection. Nevertheless, the contralateral projections are the strongest, and when they are eliminated after a unilateral lesion, contralateral deficits occur in all cranial nerve motor nuclei.
D. Cranial nerve motor nuclei that receive bilateral corticobulbar projections are protected from gross impairment after unilateral corticobulbar lesions, whereas those receiving a contralateral corticobulbar projection are not and, in consequence, will show gross motor weakness.

4. Which of the following best indicates the location of lost contralateral facial muscle control after a corticobulbar tract stroke?

A. Upper facial muscles
B. Lower facial muscles
C. Upper and lower facial muscles
D. Perioral and buccal muscles for assisting speech

5. A stroke affecting the corticobulbar tract will produce which of the following trigeminal motor impairments?

A. Weakness or paralysis of contralateral muscles of mastication
B. Weakness or paralysis of ipsilateral muscles of mastication
C. Weakness or paralysis of muscles of mastication, bilaterally
D. Minimal weakness because the trigeminal motor nucleus receives a bilateral corticobulbar tract innervation

6. Which of the following statements best describes the corticobulbar projection from the primary motor cortex in the internal capsule?

A. They receive an arterial supply from the posterior cerebral artery.
B. They are located rostral to corticospinal axons.
C. They descend in the anterior limb of the internal capsule.
D. They intermingle with corticospinal axons in the posterior limb of the internal capsule.

Comment: Corticobulbar axons are commonly located in the genu of the internal capsule and corticospinal axons to the cervical spinal cord descend in the adjoining posterior limb. However, corticobulbar axons may be located in the most anterior portion of the posterior limb in some individuals. When this occurs, the corticospinal axons to the cervical spinal cord descend in the adjoining, but more posterior, portion of the posterior limb.

7. A person has a developmental disorder in which some neurons fail to migrate from the ventricular surface during prenatal development. If this condition affects facial motor neurons, where would you expect to find facial motor neurons in this patient compared with a healthy person?

A. Dorsal
B. Ventral
C. Caudal
D. Lateral

Comment: Facial motor neurons migrate from the ventricular surface ventrally, and possibly caudally, during development. This results in the unusual trajectory of facial motor axons as they leave the facial motor nucleus (Figure 11–9). Failure to migrate (in this fictitious condition) would result in retaining a position close to the ventricular floor, thus dorsal to the normal location. Ventral is not expected; this would mean farther migration. Caudal is not expected; this would also mean more migration. Finally, lateral would mean misdirected migration.

8. A person has a stroke that damages the caudal part of the nucleus ambiguus. Which function is most impaired as a result of this lesion?

A. Pharyngeal muscle control
B. Laryngeal muscle control
C. Tongue muscle control
D. Blood pressure regulation

Comment: Nucleus ambiguus has a rostrocaudal organization; motor neurons rostrally innervate pharyngeal muscles and caudally, laryngeal muscles. The tongue is innervated by motor neurons in the hypoglossal nucleus. Blood pressure regulation is more the function of the solitary nucleus and dorsal motor nucleus of the vagus.

9. A person has a posterior inferior cerebellar artery (PICA) stroke. Which of the following indicates a likely motor impairment in this patient?

A. Ipsilateral limb muscle weakness
B. Ipsilateral tongue muscle weakness
C. Ipsilateral laryngeal muscle weakness
D. Ipsilateral facial muscle weakness

10. A person has a posterior inferior cerebellar artery (PICA) stroke. Which statement below best describes the pattern of sensory loss in this patient?

A. Loss of pain and temperature on the contralateral limbs and trunk and the ipsilateral face
B. Loss of pain and temperature on the contralateral limbs, trunk, and face
C. Loss of pain and temperature on the contralateral limbs and trunk and the ipsilateral face, and loss of facial touch ipsilaterally
D. Loss of pain and temperature on the contralateral limbs and trunk and the ipsilateral face, and loss of facial touch contralaterally

Comment: Loss of pain on the contralateral limbs and trunk is because PICA supplies the ascending axons of the anterolateral system. Loss of ipsilateral facial pain is due to the damage to the trigeminal spinal tract, as well as the nucleus. There is no loss of facial touch. This is mediated by the main trigeminal sensory nucleus, which is located in the pons.