Cns Circuitry Of Cranial Nerve Nuclei 3,4, And 6

Front 1

What is the relationship between motor neurons and place in the brain?

Back 1

In general, cranial nerve nuclei associated with motor stuff are located near the midline

Front 2

What are the nuclei of CN's 346 used for?

Back 2

Ocular motion

Front 3

What are the two nuclei associated with CN III

Back 3

Both are near the midline and in the midbrain
Oculomotor Nucleus
Edinger-Westphal Nucleus

Front 4

Where is the CN 4 located and name, please.

Back 4

Trochlear nucleus
near the midline in the midbrain

Front 5

Where is the CN 6 nucleus located and name?

Back 5

near the midline in caudal pons

Front 6

Name two additional visual pathways that utilize CN III and its nuclei

Back 6

control the size of the pupil
control lens accommodation and convergence

Front 7

What allows both eyes to constrict when light is shown into one eye?

Back 7

via a bilateral neuronal pathway involving the pretectal area and the iris (pupillae muscle)

Front 8

What is the reflex that is stimulated in an eye that light in shown in?

Back 8

direct pupillary light reflex

Front 9

What is the reflex that occurs in the opposite eye that light is shown in?

Back 9

consensual light reflex

Front 10

Describe the mechanicspathway of the pupillary constriction.

Back 10

1st order neuron (bipolar) synapses on 2nd order (ganglion) neuron which forms the optic nerve.
Axons skip the lateral geniculate body and synapse in the pretectal area and project bilaterally to the Edinger-Westphal nucleus, which project to the ciliary ganglion, which projects to the pupillae muscle for constriction.

Front 11

Why, in non-complicated terms, does the pupillary reflex occur in both eyes?

Back 11

Both visual pathways are activated (due to crossing over)

Front 12

Describe the muscles of the Pupil.

Back 12

Sphincter muscle - circular mm
Dilator - longitudinal mm

Front 13

What are the other two visual pathways that utilize CN III?

Back 13

control the size of pupil
lens accommodation and convergence

Front 14

List the pupillary pathway for lens accommodation

Back 14

Information must 1st reach the visual cortex-->neurons from cortex project to pretectal area-->project to oculomotor & Edinger-Westphal nucleus

Front 15

What are the function of the oculomotor & E-W nucleus

Back 15

Oculomotor - causes contraction of the medial recti mm (convergence)
E-W - projects to the ciliary ganglion with causes contraction of the ciliary mm to adjust tension in lens

Front 16

What CN's are needed for the pupillary pathway to work?

Back 16

2 and 3

Front 17

Define accommodation

Back 17

The changing of the shape of the lens

Front 18

Lens at rest?

Back 18

thin

Front 19

What happens to the lens when the cilary mm contracts?

Back 19

Tension is relieved from zonule fibers and lens thickens

Front 20

What happens to the lens as age increases?

Back 20

becomes less pliable

Front 21

In what direction do the axons from the oculomotor nuclei project?

Back 21

Ventral

Front 22

Where can the nuclei of oculomotor nerve be found?

Back 22

midbrain at the level of the superior colliculus

Front 23

Where are the nuclei of CN 4 (Trochlear) found?

Back 23

Midbrain at the level of inferior colliculus

Front 24

Describe the anatomical path for CN 4

Back 24

Projects from the dorsal pons-->axons project to the contralateral side at the decussation of fibers

Front 25

Where is the nuclei of CN VI (Abducens) located?

Back 25

In the Ponds (froggies can also be found here as well)

Front 26

Where does the Abducens nerve end up?

Back 26

In the lateral rectus mm

Front 27

Describe what is involved in moving both eyes horizontally to the left.

Back 27

Left eye - Left PPRN (parapontine reticular nucleus) projects an EBN to the ipsilateral abducens nuclei--> projects an EBN to the ipsilateral LR mm via CN 6 & an EBN to contralateral CN 3 nuclei-->projects and EBN to right MR mm
Right eye - left PPRN sends IBN to contralateral Abducens nuclei-->projects and IBN to R LR mm via CN 6 & and IBN to contralateral CN 3 nucleus, which projects an IBN to left MR mm

Front 28

Define medial longitudinal faciculus

Back 28

connects CN 3,4,6, and 8 (vestibular part)
highway for axons to travel
an interneuron used when above nuclei project contralateral

Front 29

(T or F) CN 7 is a mixed nerve

Back 29

True

Front 30

How many nuclei is CN 7 associated with in the brainstem:
1
4
6
8
144,000

Back 30

144,000, not really. 4

Front 31

Where do the axons of CN 7 exit the brainstem?

Back 31

at the pontomedullary junction, just medial to CN 8

Front 32

How many of each, motor and sensory, components does CN 7 contain

Back 32

2 of each

Front 33

What are the two efferent components of CN 7 and describe?

Back 33

facial motor nucleus - innervates facial muscles of upper and lower face
superior salivary nucleus - parasympathetic innervation for lacrimation and salivation

Front 34

Describe the facial mm nucleus

Back 34

located in the caudal pons-->axons leave nucleus and course awkwardly by traveling dorsally and medially-->wrap around Abducens nucleus-->travel ventral and lateral to exit brainstem

Front 35

What is the facial colliculi?

Back 35

a bump on the pons

Front 36

Describe input to the facial nucleus

Back 36

Recieves cortical motor input from corticobullbar tract

Front 37

Describe cortical input to the cortiobulbar tract

Back 37

Upper face - receives bilateral input from cerebral cortex
Lower face - only receive contralateral input from the cerebral cortex

Front 38

Lesions of the facial motor nucleus cause?

Back 38

ipslateral paresis of the entire face

Front 39

Lesions of the corticobulbar tract cause?

Back 39

affect only the lower face

Front 40

Define upper and lower motor neuron

Back 40

UMN - cerebral cortex-->LMN
LMN - CNS--->muscles

Front 41

Describe the efferent component of CN VII

Back 41

The facial nerve contains parasympathetic preganglionic axons that arise from the superior salivatory nucleus--->axons innervate pterygopalatine and submandibular ganglia--->pterygopalatine = lacrimation and submandibular = salivation (via submandibular and sublingual)

Front 42

Describe the afferent component of CN VII

Back 42

Taste: from the anterior 2/3 of tongue

Front 43

Where are the cell bodies for the afferent portion of CN 7 found?

Back 43

Geniculate ganglion and synapse in the solitary nucleus (tatse)
Genicualte ganglion--->spinal trigeminal tract (outer ear)

Front 44

(T or F) CN 7 conducts somatic sensations from a small area in the pinna

Back 44

True

Front 45

the sensory neurons of CN 7 that conduct sensory info from the pinna have their cell bodies where and synapse where?

Back 45

Geniculate ganglion and spinal trigeminal nucleus