11 Brainstem and Corticobulbar Pathways - B Flashcards
*What CN is only associated with the medulla
CN 9, 10, 12
*What is the pathway of the accessory n
Located in spinal cord from C1-6 —> foramen magnum —> out jugular foramen
*Lesions of the CN 11 root cause what
-drooping of the shoulder -scapular winging -turning of head to contralateral side
*Axons of MN pass anteriorly in medulla along lateral aspects of medial lemniscus and the pyramid as what CN
CN 12 via the hypoglossal canal
*The hypoglossal n distributes to what mm
Intrinsic tongue mm, hyoglossus, palatoglossus, genioglossus
*The dorsal motor nucleus of vagus is primarily innervation to what
-parasympathetic preganglionic to visceral structures of trachea, bronchi, heart, and GI up to splenic flexure
*The nucleus ambiguus innervate what
Pharyngeal and laryngeal targets Skel M in upper half of esophagus
Somatic afferent (pain & thermal) from a small area of ear, part of the external auditory meatus, dural of the posterior cranial fossa come from what CN
Vagus
Central processes of the vagus (visceral afferent and taste) enter via
Solitary tract and terminate in teh surrounding caudal solitary nucleus
A lesion of the root of the vagus can cause what symptoms
-dysphagia -dysarthria -very few taste defects (laryngeal, epiglottis, posterior most tongue)
*Glossopharyngeal n motor fibers originate from
Inferior salivatory nucleus and nucleus ambiguus
*What does the CN 9 part of nucleus ambiguus o
SE (to stylopharyngeus m) Plays a minor role in the efferent limb of gag reflex
The glossopharyngeal n lesions causes what
-diminished taste on posterior tongue -loss of stylopharngeus which participates in gag refelx
Glossopharyngeal neuralgia is
Intense idiopathic pain along the sensory distribution of the n
*What are the CN at the pon-medulla junction
CN 6, 7, 8
What exits along the caudal edge of the pons
CN 6, 7, 8
The facial motor nucleus follows what path
Arch around the abducens nucleus to exit brainstem
*SE fibers from the facial motor nucleus are joined by axons from
Superior salivatory nucleus (VE pre-gang para)
*The facial n emerges from the brainstem as what
Facial n fibers and intermediate n fibers
What does the facial n provide sensory innervation for
-taste fibers for anterior 2/3 of tongue -cutaneous sensory (SA) fibers from external ear (posterior 1/2 of pinna) and external auditory canal
Taste fibers enter _______ and terminate rostrally in _____________
Solitary tract; gustatory nucleus of solitary nucleus (the central receiving area for all taste sensation)
Facial n sensory fibers to the ear and external auditory canal reach cell bodies in the _________ and their central processes enter _____________ and terminate in ____________
Geniculate ganglion; spinal trigeminal tract; spinal trigeminal nucleus
*The nucleus of the abducens (CN 6) is surrounded by
Internal genu of facial n
SE motor neurons of CN 6 innervate _________________ while interneurons send axons to ___________________
Ipsilateral lateral rectus m; contralateral axons to medial longitudinal fasiculus (target contralateral occluomotor nucleus)
Injury of CN6 in the pons causes
Paralysis of ipsilateral LR muscle *opposite eye adducts b/c interneurons are intact
A lesion of the abducens nucleus causes
Paralysis of of LR ipsilaterally and failure of contralateral medial rectus m to contract toward the side of the lesion
***Damage to the medial longitudinal fasiculus causes
Inability to adduct the contralateral eye on attempted gaze contralaterally ***need to fact check this
CN of the midbrain include
CN 3, 4
*Where are CN 3,4 in relation to the periaqueductal gray
Ventral
CN 3, 4 are exclusively
Motor
What CN do not receive corticonuclear fibers
CN 3, 4
*The trochlear n is the only motor cranial n to do what
Decussate before exiting
*The trochlear nucleus is located where in regards to MLF
Posteriorly but adjacent to
Lesion of the nerve root of CN 4 cause
Paralysis of superior oblique m on that side
*The occulomotor nucleus is located where
Within the ventral portion of the PAG and present in about the rostral half of the midbrain
Innervation of the occluomotor n is ipsilateral except for
Superior rectus m
The Edinger Westphal nucleus sends
Preganglionic gibers to the ciliary ganglion
*The ciliary ganglion gives off short ciliary nn which innervate what
Sphincter pupillae and ciliary mm
*Lesions involving occulomotor nucleus nerve generally have same result
-down and out gaze -diplopia -myadriasis -no accommodation
The corticonuclear system consists of UMN that influence
Motor nuclei of CN 5, 7, 12 Nucleus ambiguus (CN 9, 10) Accessory nucleus (CN 11)
The trigeminal nuclei distributes fibers in what way
Equal numbers b/l
*Muscles in upper 1/2 of face are controlled
Both hemispheres
*Muscles in the lower half of the face are primarily controlled by
Contralateral hemisphere
*A lesion rostral to facial motor nucleus results in
Drooping of mm at corners of mouth and lower face contralaterally (central facial paralysis)
*A lesion of the root of the facial n will result in
Flaccid paralysis of upper and lower portions of face on ipsilateral side (Bell palsy)
*The soft palate/uvula is mainly innervated by
Contralateral MN
*Lesion of the corticonuclear fibers on the right would cause
-weakness of palate arch mm on the left -slight drooping of palatal arch on left -deviation of uvula to right on phonation (left at rest)
Genioglossus is innervated how
Contralaterally from CN 12
Lesions of CN 12 deviate
Towards dysfunction
A left protruding tongue could be caused by
Right corticonuclear fibers (UMN) lesion OR left hypoglossal n (LMN)
