Functional Components Of The Cranical Nerves Flashcards
What type of sensations do the Cranial Nerves have? (Sensory, motor or both)
- S Some
- S Say
- M Marry
- M Money
- B But
- M My
- B brother
- S Says
- B Bad
- B Business
- M Marry
- M Money
( Some Say Marry Money But My Brother Says Bad Business Marry Money)
What does each division of trigeminal function as? (S/M/B)
V1 and V2 are only sensory
V3 is both Sensory and Motor
What are the most complex CN’s having motor, sensory, parasympathetic and taste functions?
Facial (CN VII)
Glossopharyngeal (IX)
Vagus (X)
Where are the cranial motor nuclei found?
In the brainstem in a rosarla-caudal order
The nucleus ambiguous contains LMNs or what CN?
CN IX and X
What is the cranial motor nuclei for CN IX and X?
Nucleus ambiguous
What CN’s do not receive input from the motor homunculus due to requirement of highly coordinated bilateral movements?
Nucleus of CN III, IV, and VI
In what nucleus’s do the cortico-bulbar zones not synapse?
In the nucleus of CN III, IV and VI
What do the Trochlear and the abducens nerves innervate?
Lateral Rectus (6)
Superior Oblique (4)
What does the spinal accessory nerve (CNXI) innervate?
Only the trapezius and sternocleidomastoid muscles
Where are the cell bodies of the LMNs located for CN XI?
In the upper 4-5 cervical levels of the spinal cord and are therefore activated via the cortico-spinal pathway
What is the response in an UMN Lesion?
- Damage to the axons of UMNs prior to the decussation results in paralysis of the associated muscles on the contralateral side.
- If the injury is to the spinal cord, the paralysis will be on the ipsilateral side. There is an increasing spasticity (rigidity) and no regeneration.
What does damage to LMN cause?
Results in ipsilateral flaccidity (loss of tone), weakness, but regeneration is possible
Why is the brainstem considered the housekeeping center?
It’s neuronal circuits regulate many autonomic functions
What cranial nuclei are in the midbrain?
CN III and IV
What cranial nuclei are in the pons?
Nuclei for V and VI
What CN nuclei are in the medulla oblongata?
CNS VII, IX, X and XII
Where are the nuclei for CN XI?
In lamina IX in the upper cervical spinal cord
Where do pain second order neurons synapse? (Periphery)
In lamina I/II about the level of entry into the spinal cord.
They decussate and ascend in the lateral spino-thalamic tract to synapse in the VPL of the thalamus
Where do 2nd order neurons for touch go when they enter the spinal cord?
Ascend in the dorsal columns to synapse on 2nd order neurons in either the nucleus gracilis or cuneatus in the brainstem. They decussate forming the medial lemniscus and ascend to synapse on 3rd order neurons in the VPL. 3rd order go to cortex.
What are the characteristics of 1st order neurons for pain and touch? (PNS)
- Their cell bodies reside in afferent ganglia outside the CNS
- There are no synapses in afferent ganglia
- The neurons are modality specific
What predominates the sensory information from the orofacial region?
The three branches of the trigeminal nerve
Where is the cell body for 1st order neurons of the trigeminal system?
The trigeminal ganglion
Where do the axons that exit the skulls from the trigeminal terminate?
In the skin of the face in front of the tragal line
2nd order neurons for orofacial pain travel in what tract?
The spinal tract
Where is the cell body of 2nd order neurons for touch from the orofacial region?
The pontine nucleus
Where is the cell body of 2nd order neurons for pain from the orofacial region?
Spinal nucleus
2nd order axons for pain and touch from the orofacial region decussate and synapse on what part of the thalamus with the 3rd order neurons?
The VPM of the thalamus
Note: CN’s go to VPM and spinal nerves to VPL
Parasympathetics and sympathetic are ____ only.
Motor
Input from what location drives the para/sympathetic?
Hypothalamus
What do the postganglionics of the para ANS release?
Acetylcholine
What do the sympathetic of the ANS release in post ganglionic neurons?
Nor-adrenaline (norepinephrine)
What facial structures receive only sympathetic innervation?
Dilator muscle of iris
Superior tarsal muscle
Blood vessels
What facial structures receive only parasympathetic innervation?
Sphincter and ciliary muscles of the iris
Where is the cell body for the sympathetic of the face?
The cell bodies of pre-ganglionic neurons reside in lamina VII (aka the intermediolateral horn) at T1-T2
Where do pre-ganglionic neurons for the sympathetic spirit synapse when they are headed to the head?
Superior cervical ganglion
Why is it important not to damage blood vessels during surgery of the head region?
Post-ganglionic axons of the ANS (sympathetic) follow blood vessels to their targets
How can disruption of the sympathetic supply occur?
Compression of cervical or thoracic sympathetic chain on affected side.
A (pancoast) tumor on the apex of the lung
What are the symptoms of Horner’s syndrome?
(EF’ing PAM)
Enopthalmos
Flushing of the face due to dilation of blood vessels
Pseudoptosis
Anhidrosis
Miosis
What muscle causes pseudoptosis in Horner’s?
Paralysis of the superior tarsal muscle
What muscle causes Miosis in Horner’s?
Inactivation of the dilator muscle
What muscle causes enopthalmos in Horner’s?
Inactivation of the Mueller muscle
What nerves are associated with parasympathetics?
III, VII, IX, X
Where do the parasympathetics that travel with cranial nerve 3 originate and synapse?
What muscle does this regulate?
O: Nucleus of Edinger-Westphal
S: ciliary ganglion
M: sphincter muscle
Where do the parasympathetics that travel with cranial nerve VII originate and synapse?
What does it innervate?
O: Superior salivary nucleus
S: 2 different ganglia (to learn later)
I: lacrimal, submandibular and sublingual salivary glands
Where do the parasympathetics that travel with cranial nerve IX originate and synapse?
What does it innervate?
O: inferior salivary nucleus
S: otic ganglion
I: parotid gland
What accounts for activation of all 3 salivary glands in the face?
The inferior and superior salivatory nuclei
Where do the parasympathetics that travel with cranial nerve X originate and Innervate?
O: dorsal motor nucleus
I: viscera in the thorax and part of the abdomen
What are exits of the cranial nerves?
Cribiform plate- I Optic Canal - II Superior orbital fissure - 3,4,V1,6 Foramen rotunda - V2 Foramen ovale - V3 Internal acoustic meatus - 7,8 Jugular foramen - 9,10,11 Hypoglossal canal - 12
What houses the lower motor nucleus for vagus and glossopharyngeal nerves?
The nucleus ambiguous
What tract do UMN’s of the CN’s travel in beside CN XI?
Cortico-bulbar tract
What muscles does the occulomotor nerve innervate?
Levator palpebrae sup.
Inferior oblique
Sup., inf. And medial rectus
What muscles does V3 innervate?
Masseter Medial and lateral pterygoid Ant. Belly of digastric Temporalis Tensor tympani Tensor palatini Mylohyoid
What does the Abducens nerve innervate?
Lateral rectus
What does the facial nerves Innervate (muscle)
Stylohoid
Post. Belly of digastric
Muscle of facial expression
Stapedius
What muscles does the vagus and glossopharyngeal nerves innervate?
Larynx and pharynx muscles
Levator palati
Stylopharyngeus
What muscles does spinal accessory nerve innervate?
Trapezius
Sternocleidomastoid
What muscles does the hypoglossal nerve innervate?
Intrinsic muscles of the tongue
Hypoglossal
Genioglossus
Styloglossus
What is plasticity?
The ability of the brain to reorganize neurons in order to learn new functions (or relearn)
Where are the cell bodies for pain got second order neuron in the face?
Nucleus of Spinal tract
What constricts blood vessels?
Sympathetic
What is the pathway of the sympathetic supply to oro-facial region?
- The cell bodies of pre-ganglionic neurons reside in lámina VII at T1-T2
- Their axons exit via the ventral root and enter the sympathetic chain via white rami communicantes
- The axons course up the sympathetic chain to the superior cervical ganglion where they synapse on the post-ganglionic neurons
- Postganglionic axons follow blood vessels to their targets
What is a sunken eye called?
Enophthalmos
What are the neurons with parasympathetic function?
III oculomotor
VII facial
IX Glossopharyngeal
X vagus