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Flashcards in Cranial Nerves_ Medulla Deck (49)
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Closed medulla (nuclei) -->

• caudal end of IVth ventricle
• Inferior olivary nucleus or complex
• Nucleus cuneatus, n. gracilis
• Hypoglossal nucleus
• Spinal Trigeminal Nucleus (Spinal nucleus of V)


Close medulla (tracts) :

•pyramids •medial lemniscus
• spinothalamic tracts (spinal lemniscus)
• internal arcuate fibers
• ventral trigeminothalamic tract • spinal trigeminal tract
• fasciculus cuneatus, f. gracilis • dorsal spinocerebellar tract
• medial longitudinal fasciculus (MLF)
• cuneocerebellar tract [medial vestibulospinal tract]
• lat. vestibulospinal tract • hypoglossal nerve fibers


Open medulla (nuclei) : caudal end of IVth ventricle -->

• pontomedullary junction
• inferior olivary nucleus
• spinal nucleus of V • hypoglossal nucleus
• dorsal motor nucleus of the • • • Vagus (parasympathetic)
• nucleus ambiguus (lower motor neurons for CN IX and X)
• vestibular nuclei (medial and inferior)
• dorsal, ventral cochlear nucleus


Open medulla tracts:

• Pyramids lat. vestibulospinal tract
• medial lemniscus
• inferior cerebellar peduncle
• hypoglossal nerve fibers • olivocerebellar fibers
• ventral trigeminothalamic tract • lateral spinothalamic tract
• med. vestibulospinal tract (MLF) • spinal tract of V • medial longitudinal fasciculus


Hypoglossal nerve (CN XII) =

is a motor nerve that supplies both the intrinsic and extrinsic muscles of the tongue.


The cell bodies of the lower motor neurons are in the hypoglossal nucleus, located near the __________ of the medulla (ventral to the central canal or ______________).

4th ventricle


The axons pass inferolateral next to the _______________________________ to exit the medulla as rootlets in the ventrolateral (____________) sulcus.

medial lemniscus and pyramid



Corticobulbar fibers (cortical control; upper motor neurons) arise from the _________ region of the precentral gyrus (Primary motor cortex) and descend with the corticospinal tract to the medulla where most of the fibers cross the midline and synapse in the _______________________ hypoglossal nucleus




The _______________ nucleus receives indirect sensory information from solitary nucleus (taste) and sensory trigeminal nuclei (bolus of food in the oral cavity) by way of multisynaptic connections in the ____________________. This reflex pathway controlling the tongue is involved in swallowing, suckling and chewing.


reticular formation


Clinically, a lower motor neuron lesion of the hypoglossal nerve or nucleus results in paralysis and muscle wasting of both the intrinsic and extrinsic muscles on the __________________ side.



Upon protrusion of the tongue, it deviates toward the side of the lesion due to the unopposed action of the intact _________________________ muscle.

contralateral genioglossus


What is dysarthria.

Patients have difficulty with eating and speaking


An upper motor neuron lesion that occurs at a level prior to the crossing, results in:

weakness of only the extrinsic muscles (primarily genioglossus) on the side contralateral to the site of the lesion.


Which way will the tongue deviate upon voluntary protrusion in this case?



The _________________ nerve is important in identifying the level of lesions (strokes) in the medulla.



A stroke of a paramedian branch of the anterior spinal artery may result in combinations of damage to the:

hypoglossal nerve fibers
adjacent pyramid
medial lemniscus and ventral trigeminothalamic tract


The result (of a stroke of a paramedian branch of the anterior spinal artery) is a lower motor neuron symptom involving the tongue (deficit is noted ipsilateral or contralateral?) and upper motor neuron symptoms involving the ____________ (deficit is noted ipsilateral or contralateral?).




What sensory deficits may also accompany the motor signs in this example?



This type of combination of lower and upper motor neuron signs that are demonstrated on opposite sides of the neuraxis occur where a motor cranial nerve exits along the:

This combination of symptoms is called an:

midline adjacent to the descending corticospinal fibers

alternating hemiplegia.


What cranial nerve(s) supply the somatosensory and taste components for the tongue?

trigeminal, facial, glossopharyngeal


Accessory nerve (CN XI) =

contains a few lower motor neurons in nucleus ambiguus that innervate a few of the laryngeal muscles (cranial component).


The cell bodies innervating the sternocleidomastoid and trapezius muscles (spinal component) are located in the cervical levels of the spinal cord (dorsal to the ventral horn). Axons of the spinal component leave the spinal cord and ascend into the cranial cavity to re exit the skull as the ______________ nerve. For the cranial component, a small number of fibers exit the medulla along with the _____________ nerve.




Upper motor neurons (corticobulbar fibers) descend with the corticospinal fibers, decussate at the _________________________ and terminate in the cervical region (___________).

pyramidal decussation



Clinically, to test for involvement of the spinal part of CN XI the patient is asked to:

The cranial component is indistinguishable from the ___________ nerve.

turn the head (sternocleidomastoid) or shrug the shoulders (trapezius).



Vagus nerve (CN X)

has several functional components.


Vagus nerve (CN X)
Lower motor neurons located in _______________________innervate skeletal muscles of the soft palate, larynx and pharynx, including vocalis muscle (True vocal folds).

nucleus ambiguus


Vagus nerve (CN X)
Nucleus ambiguus is located in the _____________________ and is not easily identified (a clue to its name). It contains lower motor neurons for CN ___ and ___ as well as for the cranial part of CN ___.

reticular formation
X, IX , XI


Vagus nerve (CN X)
Preganglionic parasympathetic cell bodies are located primarily in the dorsal motor of _____________. The axons exit the _____________ as rootlets of X and synapse on postganglionic neurons in visceral walls of glands, cardiac muscle and smooth muscle of the thorax and abdomen.

nucleus of X



Vagus nerve (CN X)
Sensory fibers travel along the solitary tract to end in the ________________. This component is carrying ________________________ from pharynx, larynx and thorax and abdomen. Some of these fibers may enter the spinal trigeminal nucleus (Remember, pain of the face).

solitary nucleus

pain and pressure


Vagus nerve (CN X)
Upper motor neurons (corticobulbar) innervate the nucleus ambiguus _____________ .


(Therefore, a unilateral lesion of the upper motor neurons would not be easily noticed.)