Lecture6 Flashcards
These nuclei tend to be located in the lateral brainstem.
sensory nerve
Which cranial nerves do not originate in the brainstem?
Olfactory I, Optic II, and Spinal Accessory XI
These nuclei tend to be located in the medial brainstem.
motor nerve
Nerves with mixed sensory and motor fibers must have more than one nucleus of origin, one ______ and one ______.
sensory (afferent), motor (efferent)
Where are the sensory receptor cell bodies located?
never in the nucleus itself, just outside the CNS in the ganglion
Which cranial nerves innervate extrinsic eye muscles?
Oculomotor III - levator palpebri, superior, inferior, and medial recti, inferior oblique; Trochlear IV - superior oblique; Abducens VI - lateral rectus
Which cranial nerves are considered to be “pure” motor?
Oculomotor III, Trochlear IV, Abducens VI, Hypoglossal XII
Which cranial nerves are considered to be “pure” sensory?
Olfactory I, Optic II, Vestibulocochlear VIII
Which cranial nerves are considered to be “mixed” nerves?
Trigeminal V, Facial VII, Glossopharyngeal IX, Vagus X, Spinal Accessory XI
This cranial nerve innervates the bulk of the eye muscles.
Oculomotor III
How would a lesion affecting the Oculomotor Nerve III affect the eye?
It would go “down and out” also dilation with damage to E-W nucleus fibers
What is responsible for the parasympathetics to the eye (constrict the pupil and accommodate the lens)?
Edinger-Westphal Nucleus of the Oculomotor Nerve III
What is unique about the Trochlear Nerve IV?
It exits the brainstem dorsally and crosses on the way out before passing through the superior orbital fissure.
How many types of neurons are in the Oculomotor Nerve III?
2; one in oculomotor nucleus (GSE) and one in post-ganglionic fibers of Edinger-Westphal nucleus (GVE)
Superior Colliculus
posterior in the midbrain, associated with visual tracking (reflexive), interconnected with oculomotor nucleus
Describe the path of the Oculomotor Nerve III fibers (GSE and GVE).
GSE oculomotor nucleus fibers - exit the midbrain between the two crus in the interpeduncular fossa and goes through the superior orbital fissure to innervate the eye muscles; GVE E-W nucleus fibers - same as GSE except go into eye
Where is the Trochlear nucleus located?
in the posterior inferior midbrain, just below the oculomotor nucleus
Which extraocular muscle does the Trochlear nerve IV innervate?
superior oblique
Damage to the Trochlear Nerve IV can result in what?
strabismus, patient sees double and eye will look up and out
What is the functional component of the Trochlear Nerve IV?
GSE
What is the functional component of the Abducens Nerve VI?
GSE
What is the general location and pathway of the Abducens Nerve VI?
upper motor neuron in the motor cortex will have axons that cross midline, synapse in the abducens nucleus (create a bulge in the fourth ventricle) in the posterior inferior pons
Which extraocular muscle does the Abducens Nerve VI innervate?
lateral rectus
Which cranial nerve’s fibers go around the abducens nucleus before they exit (creates the facial colliculus)?
Facial Nerve VII
Lesions affecting the Abducens Nerve VI would result in?
medial strabismus, patient sees double, one eye is crossed
What is the functional component of the Hypoglossal Nerve XII?
GSE
Describe the basic anatomy and pathway of the Hypoglossal Nerve XII?
upper motor neuron in the motor cortex will have axons that cross midline, synapse in the hypoglossal nucleus in the posterior inferior medulla then innervate intrinsic tongue muscles
What are the intrinsic tongue muscles innervated by the Hypoglossal Nerve XII?
hyoglossus - depresses and retracts tongue, genioglossus - protrudes tongue for speech, styloglossus - retracts tongue for speech
How would a patient with a lesion affecting the Hypoglossal Nerve XII present?
impaired speech, slurred, trouble swallowing and breathing
Which components are found in the “mixed” nerves?
GSE, GVE, SVA, SVE
All general sensation of the head goes through which cranial nerve?
Trigeminal Nerve V
What are the functional components of the Trigeminal Nerve V?
GSA, SVE
What is the basic anatomy and general pathway of the motor component of the Trigeminal Nerve V?
SVE, from the motor cortex fibers synapse with the trigeminal motor nucleus in the posterior superior pons and then innervate the muscles of mastication
Which muscles are innervated by the trigeminal motor nucleus?
muscles of mastication (masseter, temporalis, pterygoid muscles…first branchial arch), tensor tympanii, tensor veli palatini
Trigeminal Ganglia
aka semi-lunar ganglia, consists of psuedo-unipolar cells, GSA, sits on the lateral walls of sella turcica, three divisions for V 1-3
Cavernus Sinus
prone to infection and will cause decreased sensation to the face (Trigeminal Nerve V)
Describe the sensory (GSA) pathway of the Trigeminal Nerve V.
sensory receptor out in periphery that will transduce sensory, synapse in one of the three trigeminal nuclei (mesencephalic, chief sensory, descending spinal)
- first order mesencephalic and chief sensory
- second order cross the midline (damage on one side will affect the opposite side) and go to area of the thalamus known as VPM
- third order fibers go to sensory cortex
Where is the location of each of the sensory nuclei of the Trigeminal Nerve V?
mesencephalic - midbrain (III, IV, and VI), chief sensory - pons (VII, IX, and X as well as V1, V2, and V3), descending spinal - medulla and down into spinal cord (dorsal horn is continuous with this)
What are the three peripheral divisions of the Trigeminal Nerve V?
V-1 - opthalmic branch - innervation to forehead, V-2 - maxillary branch - innervation to cheek, V-3 - mandibular branch - innervation to jaw
Which nucleus of the Trigeminal Nerve V would be associated with sensory input from the eyes (which is needed for motor control)?
mesencephalic nucleus in the midbrain
List some possible symptoms of a patient with damage to the Trigeminal Nerve V.
the jaw would move one way or the other, tensor veli palatini - can’t tense soft palate so problems with phonetics, tensor tympanii - can’t hear as well, if sensory nuclei affected can’t feel on the head as well
List the functional components of the Facial Nerve VII.
GSA, GVA, SVE, SVA, GVE
SVE Component of the Facial Nerve VII
second branchial arch, muscles of facial expression, stapedius, posterior belly of digastric
GVE Component of the Facial Nerve VII
parasympathetic system, lacrimal gland - tears, submandibular gland - salivary, sublingual gland - salivary
SVA and GVA Components of the Facial Nerve VII
taste in anterior 2/3 of tongue
A lesion affecting the Facial Nerve VII could result in?
if lesion on right, muscles on the right will be not functioning (muscles on the left will be unopposed and contracted) so face will shift to the left, sensitive to sounds, eyes and mouth can dry out, digestive problems from lack of saliva
Describe the basic pathway of the motor components of the Facial Nerve VII.
motor areas of cerebrum then corticobulbar fibers synapse with facial motor nucleus to muscles of facial expression (SVE) OR motor areas of cerebrum then hypothalamic autonomic fibers synapse with superior salivatory nucleus to either sphenopalatine ganglion to lacrimal gland or submandibular ganglion to sublingual and submandibular glands (GVE)
-four types of neurons in this system
Involuntary parasympathetic or sympathetic systems must have at least ___ neurons.
three (motor cortex/preganglionic neuron/postganglionic in the ganglia)
Volitional systems must have at least ___ types of neurons.
2
What are the three general functions of the Facial Nerve VII?
innervate muscles of mastication, sensory for taste, and parasympathetic for salivary glands
Which cranial nerve(s) is primarily responsible for taste, touch and pain sensation of the tongue, and motor to the tongue?
Facial Nerve VII for taste (anterior 2/3), Trigeminal Nerve V for touch and pain, Hypoglossal Nerve XII for motor control
Which cranial nerve is responsible for taste from the posterior of the tongue and palate?
Glossopharyngeal Nerve IX (also gag reflex)
Regardless of origin, all taste fibers synapse with the _______ nucleus.
solitary
Describe the basic pathway of the sensory component (GSA) of the Facial Nerve VII.
external stimuli to sensory receptors then fibers synapse with the spinal nucleus of the trigeminal nerve V, cross midline to VPM and finally sensory cortex (first, second, and third order neurons)
Describe the basic pathway of the visceral sensory components of the Facial Nerve VII.
same as GSA plus visceral and special visceral afferents (GVA, SVA) synapse with solitary nucleus then cross midline to PBN–>VPM in thalamus to sensory cortex (four types of neurons in this system)
What are the functional components of the Glossopharyngeal Nerve IX?
GVE, SVE, GVA, SVA
Describe the basic pathway of the visceral sensory components (GSA, GVA, SVA) of the Glossopharyngeal Nerve IX.
same as Facial Nerve VII! (external stimuli to sensory receptors then fibers synapse with the spinal nucleus of the trigeminal nerve V, cross midline to VPM and finally sensory cortex plus visceral and special visceral afferents (GVA, SVA) synapse with solitary nucleus then cross midline to PBN–>VPM in thalamus to sensory cortex (four types of neurons in this system)
What functions are associated with the solitary nucleus complex?
taste to tongue and control BP and pH of blood in the brain (SVA and GVA, Facial Nerve VII, Glossopharyngeal Nerve IX, and Vagus Nerve X)
The corticobulbar fibers from the motor area of the cerebrum synapse with the ______ _______ and then the lower motor neuron of the ____________ Nerve innervates the stylopharyngeous muscle (SVE).
nucleus ambiguus, Glossopharyngeal IX
Explain the parasympathetic (GVE) portion pathway of the motor component for the Glossopharyngeal Nerve IX.
motor areas of the cerebrum to hypothalmic autonomic fibers synapse with the inferior salivatory nucleus then to otic ganglia (associated with trigeminal nerve) and finally parotid gland
How many types of neurons are involved with the motor component pathway of the Glossopharyngeal Nerve IX?
4
What are the functional components of the Vagus Nerve X?
GSA, SVE, GVE, SVA, GVA
Which cranial nerves are associated with the spinal nucleus of the Trigeminal Nerve V?
Facial Nerve VII, Glossopharyngeal Nerve IX, and Vagus Nerve X (GSA)
The SVA and GVA components of the Vagus Nerve X synapse with the _______ nucleus then cross the midline to the PBN then VPM (thalamus) and to the sensory cortex.
solitary (taste from root of tongue to roof of mouth)
Describe the basic pathway of the SVE component of the Vagus Nerve X.
motor areas of the cerebrum to corticobulbar fibers synapse with nucleus ambiguus to innervate pharyngeal constrictor muscles, esophagus, larynx (vocal cords)
Describe the basic pathway of the GVE component of the Vagus Nerve X.
parasympathetic, from motor areas of the cerebrum the hypothalamic autonomic fibers synapse with dorsal motor nucleus then enteric ganglia to innervate trachea, heart, stomach & intestines up to left colic flexure (most of the gut)
Which cranial nerves carry sensation for taste?
Facial Nerve VII, Glossopharyngeal Nerve IX, and Vagus Nerve X
Damage to the GVE component of the Vagus Nerve X would result in what abnormalities?
sympathetics will be unopposed so HR will go up, digestion down, respiration increases, problems swallowing and speaking
Damage to the SVE component of the Vagus Nerve X would result in what abnormalities?
damaged pharyngeal constrictor so problems swallowing, low volume voice if larynx affected
What are the functional components of the Spinal Accessory Nerve XI?
GSE, SVE
What is the GSE motor component pathway of the Spinal Accessory Nerve XI?
motor areas of the cerebrum to corticospinal fibers synapse with spinal nucleus in the cervical spinal cord (C3 and C4) then fibers go through the jugular foramen to innervate the trapezius and SCM
The nucleus ambiguus is associated with which cranial nerves?
motor nucleus associated with Glossopharyngeal Nerve IX, Vagus Nerve X, and Spinal Accessory XI
What is the basic pathway of the SVE motor component of the Spinal Accessory Nerve IX?
motor areas of cerebrum then corticobulbar fibers synapse with nucleus ambiguus which innervates muscles of the pharynx and larynx (cranial portion from the ambiguus and the nerve is distributed by vagus nerve to larynx and pharynx)
The superior and inferior salivatory nuclei supply the parasympathetic innervation of the various salivary glands and send their axons through the ________ and ___________ nerves.
Facial VII, and Glossopharyngeal IX
What are the three nuclei and associated basic functions for the Vagus Nerve X?
nucleus ambiguus - motor to the neck and thorax, dorsal nucleus of the vagus - parasympathetic to mucus and gastric glands, solitary nucleus - sensation for taste and pressure
The Spinal Accessory Nerve XI runs alongside the medulla and exits the skull with the ______ and _______ nerves.
Glossopharyngeal IX, Vagus X
When evidence of nerve damage is present, where are the two possible locations of a lesion?
peripheral lesion in the nerve, or a central lesion in the brainstem