EXAM I Flashcards
How many pairs of spinal nerves are there?
31
Two main subdivisions of the nervous system
Somatic and visceral (autonomic)
Where do the cell bodies of somatic sensory neurons lie?
In the PNS in the dorsal root ganglion
Which neuron’s axon is longer in the sympathetic division, preganglionic or postganglionic?
Postganglionic
Which neuron is longer in the PSNS, pregang. Or postgang?
Preganglionic
What neurotransmitter is released from SNS postganglionic neuron
Norepinephrine
What splanchnic nerves are parasympathetic?
Pelvic
Where are visceral afferent cell bodies located?
DRG or cranial nerve ganglion
What CNs are special sensory?
I, II, VII, VIII, IX, X
What CNs are motor?
III, IV, V, VI, VII, IX, X, XI, XII
What is the largest CN?
Trigeminal
Smallest CN?
Trochlear
What CNs exit the superior orbital fissure?
III, IV, V1, VI
What CNs exit the internal acoustic meatus?
VII and VIII
What CNs exit the jugular foramen?
IX, X, XI
Two types of upper motor neurons and where they can be found?
Pyramidal: in the cortex
Extrapyramidal: found in the brainstem
Where do pyramidal fibers synapse?
Rexed lamina 7 and 9
Where do extrapyramidal UMNs synapse?
Rexed lamina 7, brainstem and CN nuclei
Where are cell bodies of LMNs located?
Rexed lamina IX and CN nuclei of origin
How many neurons in the somatic sensory pathway?
3
Where are first order neurons in the somatic sensory pathway located?
DRG and synapse in the spinal cord
Where do second order sensory neurons terminate?
Thalamus, after decussating
Where do third order sensory neurons relay information to?
From thalamus to cerebral cortex (post central gyrus mostly)
Where are olfactory neurons found?
In the superior nasal cavity in the superior nasal concha only
What are the receptors of olfactory neurons called?
Olfactory hairs
Are olfactory neurons axons myelinated?
No, but are covered by schwann cells
What is the path of olfactory neurons?
They enter through the cribiform plate, go through the olfactory bulb and synapse on mitral cells
What are found at the synapses between olfactory neurons and mitral cells?
Synaptic glomeruli
Where do fibers from the medial olfactory stria go?
Cross the midline via the anterior commissure and travel to the opposite olfactory bulb
Where do lateral olfactory stria fibers go?
Carry info to the primary olfactory cortex (periamygdaloid and prepiriform area, including the uncus) broadman area 34
How many neurons in the olfactory pathway?
2
Is smell segregated into right and left?
No
Why is the sensory olfactory pathway only a 2 neuron pathway?
Mitral axons do not go through the thalamus, go straight to the cortex
What sign is associated with CSF leakage?
Halo sign (CSF)
What nerve is poorly developed in humans and was important for tracking prey?
Vomeronasal nerve
Three tunics of the eye and what they consist of….
Fibrous tunic (outer): sclera and cornea Vascular tunic (middle): ciliary body, iris and choroid Retina (inner): 10 layers (know diagram page 174)
Three types of cones
Red, green and blue
What is required for cones to function and where are they most concentrated?
Require light, and concentrated on the center of the retina (fovea)
What layer are bipolar cells found in?
The inner nuclear layer
What layer is the synapse between bipolar and ganglion cells?
Inner plexiform layer
Where do ganglion cells lead?
Information is conveyed in the nerve fiber layer toward the optic disc, axons are carried in the optic nerve after leaving the eye
Are optic nerve axons myelinated?
Yes, not myelinated in the retina until they leave the eye
What cells form the myelin on CN II?
Intrafascicular oligodendrocytes
What fibers from the eye from CN II will decussate?
Fibers from the medial side of each retina
Where does the CN II fibers terminate?
One of three nuclei: lateral geniculate body (MC) and relayed to cortex in the occipital lobe (Bdmn 17), superior colliculus and relayed to tectospinal tract, or pretectal nucleus of the midbrain
What muscles are innervated through tectospinal tract?
SCM and trapezius
How many neurons in the vision pathway?
4
Lesion of the optic nerve would cause:
Smaller field of vision, loss of depth perception
Loss of the optic chiasma would cause?
Tunnel vision
Loss of an optic tract would cause?
Loss of right or left visual field
How to test direct and consensual light reflex
Flashlight
How does the eye change for an accommodation reflex?
Changing the shape of the lens
How to test corneal reflex
Touch the cornea and the eye will shut
What is the convergence reflex?
The eyes move together
What extraoccular muscles does CN III supply?
All except superior oblique and lateral rectus
Where do oculomotor nuclei originate?
Periaqueductal grey, anterior to cerebral aqueduct
What part of the cortex sends axons to the oculomotor nuclei?
BDMN 8
Where else does the CN III nuclei receive fibers from?
Superior colliculus and medial longitudinal fasciculus
Where does CN III exit the CNS?
Interpeduncular fossa
Where does CN III go after it penetrates the dura?
Travels along the cavernous sinus and exits the skull through the superior orbital fissure. Then splits into superior and inferior rami in the eye socket.
Muscles supplied by the superior ramus of CN III
Superior rectus
Levator palpebrae superioris
Muscles supplied by inferior ramus
Medial rectus: medial branch
Inferior rectus: central branch
Inferior oblique: lateral branch
What is contained in the accessory oculomotor nucleus? Where do these fibers go?
Preganglionic Parasympathetic neurons. These fibers follow the oculomotor nerve and synapse in the ciliary ganglion
Where is the ciliary ganglion located?
Posterior to the eyeball 1 cm anterior the SOF
Where do postgang parasymp fibers go after they leave the ciliary ganglion? What do they supply?
Follow ciliary arteries and pierce the sclera (know schematic page 179)
Supply:
Ciliaris
Sphinter pupillae
Are fibers exiting the oculomotor nuclei UMN or LMN?
LMN because axons extend into the PNS
Muscle supplied by trochlear nerve
Superior oblique muscle
Where is the trochlear nucleus located?
Periaqueductal gray caudal to oculomotor nuclei
What part of cerebral cortex sends axons to the trochlear nucleus?
BDMN 8
Where else does does the trochlear nucleus receive axons from?
Superior colliculi and medial longitudinal fasciculus
What is the course of CN IV when is exits the CNS?
Curves around the brainstem and continues in the lateral wall of the cavernous sinus. Enters the orbit throught the SOF and supplies superior oblique.
How to test trochlear nerve destruction
Have patient look down. NOT down and out because other muscles will be involved
What muscle does the abducens nerve supply?
Lateral rectus
Where is the abducens nucleus located?
Caudal part of the pons, at floor of the rhomboid fossa.
How do axons from the abducens nucleus exit the CNS?
Axons project anteriorward and exit CNS at the border of the pons
What type of fibers do the trochlear and abducens nerves use to communicate with the cavernous plexus?
Sympathetic
Where does the abducens nerve travel after it penetrates the dura?
Travels along the cavernous sinus and exits skull through the SOF, innervates lateral rectus
What is strabismus?
Eyes are not pointing at the same thing (think Steve Buscemi’s character from Mr. Deeds)
Internal strabismus vs external strabismus?
Internal: eyes cross (converge)
External: eyes diverge
Diplopia definition
Double vision from an alignment problem or processing error. Difficult to demonstrate objectively
Ptosis definition
One eyelid drops due to weakness of levator palpebrae superioris. Oculomotor nerve lesions may be the cause
Two types of Oculomotor paralysis
External ophthalmoplegia
Internal ophthalmoplegia
What does external ophthalmoplegia involve?
External strabismus; affected eye deviates down & out
Diplopia
Ptosis
Internal ophthalmoplegia involves…
Inability to constrict pupil as well as loss of light and accommodation reflexes
Characteristics of trochlear paralysis
Rare
Internal strabismus, inability to look down causing difficulty descending stairs
Etiologies of ophthalmoplegia
Uncal herniation, PCA aneurysms, or diabetes
Abducens paralysis characteristics
Most common
Internal strabismus and diplopia
Internuclear ophthalmoplegia involves what structures? Will present how?
Involves damage to the MLF
Will cause nystagmus when abducting the eye
Does trigeminal carry more motor fibers or more sensory fibers?
Sensory
Three trigeminal nuclei or TERMINATION
Main sensory nucleus
Spinal nucleus
Trigeminal mesencephalic nucleus
Trigmenial nucleus of ORIGIN
Trigeminal motor nucleus
Peripheral ganglion associated with the trigeminal nerve
Trigeminal (semilunar) ganglion—> peripheral sensory neurons
Sensory pathway to the main trigemnial spinal nuclei
1) Cell bodies are located in the trigeminal ganglion
2) Peripheral processes go from face to the ganglion
3) Central processes go from trigeminal ganglion, enter CNS to go to main trigeminal nucleus or spinal nucleus
What types of sensations go to the main Trigeminal nucleus? Spinal nucleus?
Main trigeminal: Touch, vibration and joint proprioception
Spinal: pain and temperature
Pathway to the mesencephalic nucleus
1) Dendrites from periphery pass THROUGH the trigeminal gang, enter CNS and ascend to mesencephalic nucleus
2) these are the only primary sensory neurons that have cell bodies in the CNS
What types of sensation are carried to the (trigeminal) mesencephalic nucleus?
Proprioceptive info from the TMJ
Where do axons from the motor nucleus go when they leave the CNS?
Travel through the trigeminal ganglion and are carried in the mandibular division
What muscles do axons from the motor nucleus supply?
Muscles of mastication
What parts of the brain does the motor nucleus receive info from?
Cerebral cortex, reticular formation, red nucleus, tectum, MLF and the mesencephalic nucleus
Apparent origin of the trigeminal nerve
Lateral aspect of pons
What is significant about the trigeminal (Meckel’s) cave?
Trigeminal ganglion is found here, it is pouch of dura in the petrous part of the temporal bone
Three branches that arise from the trigeminal ganglion
Ophthalmic
Maxillary
Mandibular
Function of V1
Sensory only
Sensory from skin over the nose, forehead and scalp
Sensation from mucous membranes in the frontal and sphenoid sinus and membranes covering the nasal septum
When does the meningeal nerve arise and what does it supply?
Arises before ophthalmic leaves the SOF and supplies dura in the middle cranial fossa
Course of the lacrimal nerve
Travels along the superior part of lateral rectus muscle, passes through the lacrimal gland and goes to skin of the upper eyelid
What does the lacrimal nerve supply
Lacrimal gland
Parasympathetic fibers to lacrimal gland as well (from V2)
How do parasympathetic fibers get to the lacrimal nerve?
They originate in pterygopalatine ganglion (CN VII) and reach the nerve by way of zygomatic and zygomaticotemporal nerves (CN V2)
What is the largest of the four branches of ophthalmic?
Frontal nerve
Two branches of frontal nerve and their functions
Supratrochlear: sensation from the medial corner of the eye
Supraorbital: sensation from conjunctiva, upper eyelid and forehead, and mucous membrane lining the frontal sinus
What are the four branches of of ophthalmic?
Meningeal
Lacrimal
Frontal
Nasociliary
What are the three branches of and two terminal branches of nasociliary?
A communicating branch to ciliary ganglion Long ciliary nerve Posterior ethmoid nerve Anterior ethmoid nerve Infratrochlear nerve
Function of long ciliary n.
Supplies the eyeball
Function of posterior ethmoid n.
Sensory info from sphenoidal and ethmoidal sinuses
Fxn anterior ethmoid n.
Supplies skin over the nose by way of external nasal nerve, mucous membrane on anterior part of nasal septum by internal nasal nerve
Fxn infratrochlear nerve
Supplies medial corner of eye and lacrimal sac
When the Maxillary division goes through the foramen rotundum, where does it enter?
Pterygopalatine fossa
What is the sensory function of the maxillary division as a whole?
Sensation from skin between eyes and mouth, over cheeks and temples. Also, info from mucosa in maxillary sinuses, conchae, palate and gingiva
What are the four branches of V2
Middle meningeal n.
Zygomatic nerve
Ganglionic branches
Infraorbital nerve
When is middle meningeal nerve given off? What does it supply?
Before the division exits the round foramen
Supplies meninges of middle cranial fossa
How does zygomatic nerve enter the orbit?
Inferior orbital fissure
Three branches of zygomatic nerve
Communicating branch
Zygomaticotemporal
Zygomaticofacial
What is the fxn of communicating branch of the zygomatic nerve?
Carries postgang. Parasymp. Fibers from pterygopalatine ganglion to the lacrimal gland
What does zygomaticotemporal supply?
Skin over the temple
What does zygomaticofacial supply?
Skin over the cheek
What do the ganglionic branches of maxillary supply?
Sensory info from the upper pharynx, nasal cavity, and palate through the pterygopalatine ganglion to the maxillary division
What branches does the infraorbital nerve give rise to
Posterior, middle and anterior superior alveolar nerves
How does infraorbital nerve enter the orbit?
It goes through the inferior orbital fissure and infraorbital canal
Infraorbital nerve supplies…
Skin of lower eyelid, skin over the upper jaw and the maxillary sinus
What do posterior middle and anterior superior alveolar nerves supply?
Sensory info from the teeth
Which of the three branches of trigeminal distribute postgang parasymp fibers from the pterygopalatine ganglion?
Maxillary
How do pregang parasymp fibers reach the pterygopalatine ganglion?
From the facial nerve by way of the greater petrosal nerve
Are there sympathetic fibers in the pterygopalatine ganglion?
Yes, they run THROUGH it by way of fibers from the superior cervical ganglion
Do sensory fibers pass through the pterygopalatine ganglion?
Yes
Does the mandibular division exit the foramen ovale as one root?
No, it exits as a large sensory root and a small motor root which combine in the infratemporal fossa
Mandibular carries sensation from where?
Skin over the mandible, posterior cheek, and posterior temple, also from mucosa of lower oral cavity and cheeks
What does the motor aspect of V3 innervate?
8 muscles, including muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid)
What two branches are given off V3 in the infratemporal fossa?
Recurrent meningeal branch (nervus spinosum) and medial pterygoid nerve
What does recurrent meningeal supply?
Sensory info from dura of middle cranial fossa, anterior cranial fossa and calvarium
What does medial pterygoid nerve supply?
Motor supply for medial pterygoid muscle. Some fibers pass through otic ganglion to innervate tensor veli palatine and tensor tympani
For V3, the anterior division is predominantly _________ and the posterior division is primarily ____________
(Motor or sensory)
Motor, sensory
Four branches from the anterior division of V3
Masseter
Deep temporal
Lateral pterygoid
Buccal
Three branches from the posterior division
Auriculotemporal
Lingual nerve
Inferior alveolar nerve
What does the masseter nerve innervate?
Motor innervation from the masseter, sensory info from the TMJ
Deep temporal nerve supplies…
Temporalis muscle
Lateral pterygoid nerve supplies…
Lateral pterygoid muscle
Buccal nerve supplies…
Sensation from the cheek (skin and mucosa) and the buccal gingivae of the molars
What does the auriculotemporal nerve pass through?
Through the parotid gland, posterior to the TMJ and into the infratemporal fossa
What does the auriculotemporal nerve innervate?
Carries sensory info from skin of temple and ear, also carries postgang parasymp fibers from the otic ganglion to parotid gland.
Lingual nerve supplies…
Sensory info from mucosa of oral cavity.
What branch of CN VII does the lingual nerve combine with in the infratemporal fossa?
chorda tympani
Inferior alveolar nerve supplies…
Sensory info from the lower teeth and chin
Three branches of inferior alveolar nerve
Incisive branch
Mental nerve
Motor fibers
Incisive branch of inferior alveolar supplies…
Incisors, canines, 1st premolars and the adjacent gingivae
Mental nerve supplies…
Labial gingivae sensation adjacent to the incisors and the skin of lower lip and chin
Motor fibers from inferior alveolar nerve innervate…
Mylohyoid and the anterior belly of digastric
What two autonomic ganglia communicate with the mandibular division?
Submandibular ganglion and the otic ganglion
The submandibular ganglion receives preganglionic fibers from where?
CN VII by way of the lingual nerve, after it combines with chorda tympani
How does the otic ganglion send postganglionic fibers?
By way of auriculotemporal nerve, to the parotid gland
The higher up the lesion on the MO, will it affect a greater or lesser area of the face?
Greater
Will the lingual nerve ever convey taste info?
Yes, to the chorda tympani
CN VII (facial nerve) is also known as
The nerve of facial expression (supplies motor innervation to many facial muscles)
What is the primary nucleus of origin of CN VII?
The motor nucleus of the facial nerve
What nucleus contributes pregang parasymp fibers to the facial nerve?
Superior salivary nucleus
Where do sensory fibers from the facial nerve terminate where?
Upper part of the solitary nucleus
Where are the cell bodies of the sensory neurons of CN VII found?
Geniculate ganglion
What sensation is carried to the geniculate ganglion?
General sensation from the external ear and lateral tympanic membrane
What part of the tongue for taste is innervated by the facial nerve?
Anterior 2/3 of the tongue
Where are the cell bodies of “taste” neurons found? Where do they terminate?
The cell bodies are found in the geniculate ganglion and the axons terminate in the solitary nucleus
Are there any motor fibers in the geniculate ganglion?
Yes, LMN from the motor nucleus of CN VII travel THROUGH the geniculate ganglion before innervating the muscles of facial expression
Which cerebral hemisphere does each motor nucleus of CN VII receive information from?
Both cerebral hemispheres
The part of the motor nucleus of CN VII innervating the lower part of the face will receive fibers from what hemisphere?
ONLY from the contralateral cortex
What other structure, besides the cortex does the motor nucleus of CN VII receive info from?
Reticular formation
Where do pregang parasymp fibers from the superior salivary nucleus synapse?
In the pterygopalatine ganglion or the submandibular ganglion
What do postgang fibers of CN VII innervate?
Lacrimal gland, submandibular and sublingual glands as well as other small glands
Apparent origin of the facial nerve?
Lateral pontomedullary sulcus
Two roots of facial nerve present at the apparent origin
Motor root (facial nerve proper) Intermediate nerve (carries sensory and parasymp fibers)
Where do the roots of facial nerve combine?
Internal acoustic meatus
Where is the geniculate ganglion located?
Where the facial nerve bends posteriorly after entering the face
Course of the greater petrosal nerve
Comes off the geniculate ganglion, travels anterior through the hiatus of the greater petrosal nerve, re-enters the temporal bone through foramen lacerum, travels in the pterygoid canal and joins the pterygopalatine ganglion
The greater petrosal nerve is also called
Superficial petrosal nerve
Where is the nerve to the stapedius given off?
In the internal acoustic meatus (facial canal)
What does nerve to the stapedius supply?
Stapedius muscle of the middle ear
Where does chorda tympani arise?
In the facial canal
Fxn of chorda tympani
Carries preganglionic parasympathetic fibers and taste fibers from anter 2/3 of tongue
What three nerves arise off of facial nerve in the facial canal?
Greater petrosal, nerve to the stapedius and chorda tympani
Course of chorda tympani
Arises off facial in the facial canal, traverses the tympanic cavity and leaves the temporal bone through the pterygotympanic fissure where it combines with the lingual nerve
What three branches of facial nerve are located between the stylomastoid foramen and the parotid gland?
Digastric branch
Stylohyoid branch
Posterior auricular nerve
What is innervated by the digastric branch of CN VII?
Posterior belly of the digastric muscle
What is innervated by the stylohyoid branch of facial nerve?
Stylohyoid muscle
What two branches does the posterior auricular nerve divide into?
Occipital branch and auricular branch after traveling posteriorly to the ear
What is formed when the facial nerve enters the parotid gland?
The parotid plexus
What two trunks arise at the parotid plexus?
Temporofacial and cervicofacial
What 5 main branches arise from the temporofacial and cervicofacial trunks of CN VII?
Temporal branches Zygomatic branches Buccal branches Marginal mandibular branch Cervical branch
What do the temporal branches of CN VII alone supply?
Intrinsic auricular muscles as well as superior and anterior auricular muscles
In conjunction with zygomaticofacial nerve (V2) and auriculotemporal nerve (V3), what muscles are supplied by the temporal branches of CN VII?
Orbicularis oculi, currugator supercilii and frontal belly of the occipitofrontalis
What is supplied by zygomatic branches of CN VII?
Orbicularis oculi
What is supplied by buccal branches of CN VII?
The buccinator, orbicularis oris and levator anguli oris
What is supplied by the marginal mandibular branch of CN VII?
Risorius, and chin and lower lip muscles
What is supplied by the cervical branch of CN VII?
The platysma
What is facial nerve paralysis called?
Bell’s palsy
Why would a superficial parotidectomy be necessary? What nerves would be implicated?
If the parotid gland is cancerous
All nerves arising from the parotid plexus may be implicated
