Neuroanatomy Lab 4

Front 1

Cranial nerves associated with nucleus and tractus solitarius

Back 1

VII, IX, X

Front 2

Cranial nerves associated with nucleus ambigus

Back 2

IX, X, XI

Front 3

Cranial nerves associated with dorsal motor nucleus vagus (parasympathetic)

Back 3

X only

Front 4

Cranial nerves associated with anterior horn

Back 4

XI only
Motor cell bodies in anterior horn [C1-C5]

Front 5

Location of nucleus and tract solitarus

Back 5

Posterolateral medulla (extend from caudal to rostral medulla)

Front 6

Modalities carried by nucleus and tract solitarus

Back 6

– Special sensory [taste] : VII and IX
– Visceral sensory: IX, X

Front 7

Where do the fibers for CN VI, IX, X terminate within the nucleus solitaire

Back 7

- Tastes fibers [7 and 9] terminate in the rostral part
– General visceral afferents [9 and 10] terminate in middle and caudal parts respectively

Front 8

Pathway from nucleus solitarius --> cortex

Back 8

nucleus ambigus --> dorsal motor nucleus of X --> Thalamus (VPM) and hypothalamus --> somatosensory cortex (post central gyrus)

Front 9

What types of information is being carried by cranial nerves IX and X to the nucleus solitarus

Back 9

– Gag reflex [9]
– Stretch of gut, blood pressure receptors, blood oxygen [10]

Front 10

Modalities carried by nucleus ambiguus

Back 10

– Somatic motor : IX and X
– Parasympathetic : vagal neurons to heart

Front 11

Location of nucleus ambiguus

Back 11

Central part of tegmentum of medulla, medial to spinal tract and nucleus of V.
- extends from caudal to rostral medulla

Front 12

Targets for nerves arising from nucleus ambiuus

Back 12

IX and X: voluntary skeletal muscle of
- soft palate
- pharynx
- larynx
- upper part of esophagus

X: Parasympathetic to heart (cardioinhibitory)
- most rostral cells are parasympathetic

Front 13

Where do fibers leaving nucleus ambiuus emerge on brainstem?

Back 13

posterior to olive

Front 14

Modalities carried by dorsal motor nucleus of vagus (DMN X)

Back 14

Parasympathetic (visceral motor)

Front 15

Location of DMN X

Back 15

Dorsal medulla, lateral to hypoglossal nucleus
(extends from caudal to rostral medulla)

Front 16

Input to DMN X

Back 16

from hypothalamus

Front 17

Fibers from DMN X emerge where on brainstem?

Back 17

Groove posterior to olive (as part of X)

Front 18

Targets for fibers leaving DMN X

Back 18

- thoracic viscera and abdominal viscera (smooth muscles and glands of resp and GI tracts)
- cardiac muscle

Front 19

Locations of spinal trigerminal nucleus

Back 19

nucleus extend from cervical spine level to rostral pons

Front 20

Modalities carried by spinal trigeminal nucleus

Back 20

pain and temp (and some touch)

* NB main input to spinal trigeminal nucleus is from CN V

Front 21

Where do neurons leaving trigeminal nucleus travel to?

Back 21

- cross midline
- ascend to VPM of thalamus

Front 22

Location of accessory nucleus

Back 22

cell bodies in anterior horns of C1-C5

Front 23

Accessory nerve path after leaving spinal cord

Back 23

from C1-C5 --> foramen magnum --> join with fibers of X --> exit through jugular foramen --> to target

** corticobulbar fibers to the accesory nucleus project IPSILATERALLY for SCM and CONTRALATERALLY for trapezius

Front 24

Targets for accessory nerve

Back 24

- trapezius
- SCM

Front 25

modalities carried in chief sensory nucleus of V by CN IX

Back 25

general somatic afferent

Front 26

function of spinal trigeminal nucleus & cheif sensory ncl. of V for CN IX

Back 26

general sensation from the posterior 1/3 of tongue, tonsil, skin of external ear, internal surface of tympanic membrane, pharynx

Front 27

Functions of nucleus of tractus solitarius for CN IX

Back 27

- chemoreceptors and baroreceptors from carotid body
- gag sensation from pharynx (afferent limb of gag reflex)
- taste from posterior 1/3 of tongue

Front 28

Function of nucleus ambiguus for CN IX

Back 28

innervation of stylophayngeus m.

Front 29

Function of inferior salivatory nucleus for CN IX

Back 29

stimulation of parotid gland

Front 30

Modality carried by inferior salivatory nucleus for IX

Back 30

General visceral efferent (parasympathetics) to parotid

Front 31

Summary pf 6 main functions of glossophayngeal nerve

Back 31

- general sensation to post 1/3 tongue etc (GSA)
- chemoreceptors and baroreceptors (GVA)
- gag sensation (GVA)
- taste from post 1/3 tongue (SVA)
- stylopharygeus muscle (SVE)
- parotid gland (GVE)

Front 32

GSA functions of vagus

Back 32

Sensation from
- posterior meniniges
- concha
- skin of back of ear and ext. aut meatus
- pharynx
- larynx

Front 33

GVA functions of vagus

Back 33

- larynx
- trachea
- esophagus
- thoracix and abd viscera
- stretch receptors in walls of aortic arch
- chemoreceptors in aortic bodies adj. to arch

Front 34

SVE functions of vagus

Back 34

innervate:
- constrictor muscles of pharynx
- levator palatini
- salpingophayngeus
- palatophayngeus
- palatoglossus
- cricothyroid
- intrinsic muscles of larynx

Front 35

GVE functions of vagus

Back 35

Parasympathetics to:
- smooth muscles and glands of pharynx, larynx and thoracic and abd viscera
- cardiac muscle

Front 36

Clinical signs of damage to nucleus of tractus solitarius

Back 36

- difficulty in regulating BP

Front 37

Clinical signs of damage to nucleus ambiguus

Back 37

- hoarse voice (when unilateral)
- difficulty with phonation
- efferent limb of gag reflex

Front 38

Clinical signs of damage to dorsal vagus of nucleus

Back 38

- trouble with swallowing
- history of tachycardia

Front 39

All taste fibers project to

Back 39

The solitary nucleus --> VPM --> insula --> postcental gyrus

Front 40

Location of hypoglossal nucleus

Back 40

Adjacent to midline and Medela, extends caudal to rostral

Front 41

Where to hypoglossal axons exit the spinal cord

Back 41

In the groove between the pyramid and olive

Front 42

What are the targets for the hypoglossal nerve

Back 42

All the tongue muscles except palatoglossus

Front 43

Corticobulbar fibers: bilateral, ipsilateral for contralateral?

Back 43

- Corticobulbar fibers are bilateral except for genioglossus. [UMN input to genioglossus neuron is contralateral].

Front 44

Actions of genioglossus muscle

Back 44

– When both genioglossus muscles are innervated –-> protrusion of the tongue

– When genioglossus is innervated only on one side –-> tongue deviates to the side of lesion

Front 45

Describe the innervation of the pupil

Back 45

– Innervated by parasympathetic [GVE] fibers originating in that Edinger-Westphal nucleus
– Fibers travel with CN 3
– Innervation causes people constriction

Front 46

Describe the pupillary light reflex

Back 46

Can be tested on an unconscious patient, reflex is direct and concentual.

– Structures and eye detect high levels of light
– Sensory information is carried optic tract then via the superior brachium to the pre-tectal nucleus
– Synapse
– Information carried to Edinger Westphal nucleus
– Synapse and EW nucleus and innervation of CN 3 (PSNS fibers)
– Innervation of ciliary ganglion
– Synapse
– Shorts ciliary nerve
– Innervation of constrictor muscle of the iris

Front 47

What causes pupil dilation

Back 47

– Due to loss of constrictor tone
Or
– Due to high sympathetic tone [simulating pupillodilator muscle]

Front 48

Describe pupilodilator reflex

Back 48

Tested by pinching of skin near they eye to increase symptathetic tone

– if a information travels from posterior hypothalamus to bring some meticulous formation
– Fibers terminate in lateral horns of C6-T1
*Synapse
–preganglionic fibers travel from lateral corn to superior cervical ganglion
*synapse
– Postganglionic sympathetic fibers travel through the carotid plexus
– Travel along with the nasociliary nerve then with ciliary nerves to the dilator muscle of the iris

Front 49

Where do sympathetic fibers innervating the pupil originate

Back 49

Superior cervical ganglion

Front 50

Describe the corneal reflex [blink]

Back 50

– Sensory information is carried by the CNV to the chief sensory nucleus
*synapse
– Information is carried through the spinal tract of V and the spinal nucleus of V
– continues to facial motor nucleus
*synape
– CN VII fibers innervate orbicularis oris muscle
– Blink

Front 51

What is accommodation

Back 51

– Convergence [near] reflex

Near Triad:
Eyes converge
Rounding of the lens
Pupillary constriction

Front 52

Accomodation: Pathway from visual cortex to ocular motor nuclear complex

Back 52

visual cortex --> visual association cortex --> superior brachium --> superior colliculus/pretectal area --> oculomotor nucleus & EW nucleus --> *synapse*
--> medial rectus muscle and
--> cilliary gangilion --> iris and cilliary muscles innervated

==> Pupils constrict, lens rounds and eyes converge

Front 53

What's the difference between feeling something at the back of your throat or gagging

Back 53

Feel = Trigeminal GSA fibers
Gag = Glossophayngeal GVA fibers

Front 54

Describe the gag reflex

Back 54

– Sensory input carried by CN9 to tractus and nucleus solitarius
* Synapse
– Fibers continue to nucleus ambiguus
*Synapse
– CN X fibers project to striated muscles of the pharynx

Front 55

Describe the decerebrate position

Back 55

Upper and lower limbs extended

Front 56

What is the anatomical basis for decerebrate [extensor] postureing

Back 56

– Lesion to midbrain or rostral pons, involving the red nucleus
– All the descending cortical systems are interrupted
– Excitatory and inhibitory components of reticular formation intact
– Excessive excitatory input to gamma motor neurons via reticulospinal fibers + loss of coritcal inhibition --> extensor rigidity

Front 57

Described decorticate position

Back 57

Upper limbs flex, lower limbs extend

Front 58

What is the anatomical basis for decorticate [flexor] posturing

Back 58

– Lesion rostral to read anything
– All the sending cortical systems are interrupted
– Rubrospinal and reticulospinal trucks still intact
– spinal tract influences primary flexor muscles of upper extremities
– Activation of rubrospinal system by cerebellar nuclei allowing for increased flexor tone in upper limbs
– Lower extremities exhibit hypertonicity for the same reason as the cerebration

Front 59

What are the four anatomical landmarks involved in uncal herniations

Back 59

– The Uncus [of the temporal lobe]
– The tentorial notch
– The third cranial nerve
– The midbrain cerebral peduncle

Front 60

Anatomically what happens in a transtertorial herniation

Back 60

Movement of brain from it supratentorial space down through the tentorial notch --> part of the temporal lobe is pushed under the tentorium cerebelli

Front 61

What structures are contained within the tentorial notch

Back 61

- CN III
- midbrain (cerebral peduncle)
- posterior cerebral artery

Front 62

Symptoms of transtertorial herniations

Back 62

– Pupil dilation due to compression of parasympathetic fibers of the constrictor papillae muscle (EW nucleus)
– Contralateral motor sign due to compression of cerebral peduncle (before cross over at pyramids)

Front 63

What is a false localizing sign

Back 63

When the opposite cerebral peduncle is pushed up against the tentorial notch, while the uncus compresses the ipsilateral third nerve and PCA

Front 64

What causes it tonsillar herniation

Back 64

– Intercranial pressure* within the posterior fossa compresses the brainstem and cerebellum
– Cerebellar tonsils are forced into the foramen magnum compressing the medulla

* elevator pressure may originate in the posterior fossa or be transmitted from the supratentorial space

Front 65

What are the symptoms of a tonsillar herniation

Back 65

– Death due to compression of the breathing centers and the medulla

Front 66

What causes a subfalcine herniation

Back 66

– Unilateral pressure of cerebral hemispheres presses cingulate gyrus under the falx cerebri
– Possible compression of the anterior cerebral artery can lead to further complications

Front 67

Symptoms of subfalcine herniation

Back 67

– Contralateral UMN signs in the lower limb to the compression of the anterior cerebral artery

Front 68

Functions of reticular formation

Back 68

– Controls movement
– Modulation of pain transmission
– Autonomic reflex circuitry
– Control arousal and consciousness
– Central pattern generators

Front 69

Functions of the medial zone of the reticular formation

Back 69

Participates in the control of movement through connections with both the spinal cord and the cerebellum

Front 70

Functions of the lateral zone of the reticular formation

Back 70

Is involved and sensory pathways
Modulates the transmission of information in pain pathways

Front 71

Function of central pattern generators of reticular formation

Back 71

Control complex motor pattern such as gate, swelling, breathing etc.