09 15 2014 Brainstem Flashcards Preview

Neurology 1- M2 > 09 15 2014 Brainstem > Flashcards

Flashcards in 09 15 2014 Brainstem Deck (72):

function of brainstem

1. conduit function
2. cranial nerve function
3. integrative function


Sensory CNs



Motor CNs



Mixed CNs




1. Some
2. Say
3. Money
4. Matters
5. But
6. My
7. Brother
8. Says
9. Big
10. Brains
11. Matter
12. most


Motor Somatic Efferent nuclei

relates to the framework of the body (skeletal muscles that originates from embryonic somites-- extra ocular and tongue muscles)


Motor Visceral General nuclei (efferent)

Relates to efferent fibers that activate the viscera or organs

-preganglionic parasympathetic for cranial, thoracic, and abdominal smooth muscle (viscera)


Motor visceral special nuclei (efferent)

activates striated muscle
-muscle from embryonic branchial arches
-facial expression, jaw muscles, laryngeal and pharyngeal muscles, sternocleidomastoid.


Sensory Somatic afferent nuclei

caries information about the changes in environment from the framework of the body


Sensory General Somatic Afferent nuclei

refers to the impulse that begin at or near the body surface

-pain, temperature, touch, pressure


Sensory Special Somatic Afferent

highly specialized sensory system--
-vision (light)
-hearing (sound)


Sensory General Visceral Afferent

receptors from in/around mucus membrane or in organ walls impulses about physical distention or chemical composition of substances or organic wall.


Sensory Special Visceral Afferent

refers to specialized chemical stimuli

-smell and tase


Hypoglossal nerve

(what in intervates is on another card)

motor-- General somatic efferent GSE (ONLY)

-LMN exits between olive and pyramid (medulla) LMN is ipsilateral
- hypoglossal triangle -- floor of fourth ventricle
-Controls movement of tongue and maintains muscle tone

-UMN (corticobulbar tract) is mostly contralateral


What muscles does the hypoglossal nerve innervate?

innervates all intrinsic muscles and all but one of the extrinsic tongue muscles

-does not innervate palatoglossus muscle (CN X)


CN XII (Cn # 12) nucleus is innervated by:

1. -Corticobulbar pathway (is mainly crossed for XII)
-voluntary movement

2. Reticular neurons for automatic movements
-control of stereotyped movements while eating and swallowing.


Upper motor lesion in Hypoglossal cranial nerve?

- Tongue deviates to the side opposite of the damage

-if lesion on the left, the right side of the tongue is weak. Tongue is pushed to right side because of weakened muscles


lower motor lesion in Hypoglossal cranial nerve?

-tongue deviates to the same side of damage

-Damage is on the left (right corticobulbar tract has already crossed and is now on the left). The tongue deviates to the left because left muscles are weak.)

* Muscle atrophy in tongue


What happens when you have a bilateral lesion of CN 12?

-disability in speaking
-severe swallowing difficulty of food


Common causes of CN 12 lesions

-motor neuron disease
-tumors of medulla and base of skull

(LMN disease)


Spinal Accessory nerve - composition

MOTOR ONLY! composed of fibers from medial motor nuclei in ventral horn of caudal medulla and the accessory nucleus (close to pyramidal decussation).

LMN in medulla and cervical cord (C1-C5)


Spinal Accessory nerve : branchial motor part

Ipsilateral innervation of sternomastoid and trapezius muscle.
(spinal part)


Spinal Accessory nerve: Visceral motor part

Joins CN X to control larynx
(accessory part)


Lesion of Spinal Accessory nerve

Head turns to side opposite of lesion.

Sternomastoid m. turns head to opposite side. So a lesion would cause the more powerful side to take over, so therefore, the head will face the side that has been lesioned

-ipsilateral shoulder drop
-weakened voice or hoarseness


Vagus Nerve General

BOTH Motor and Sensory

Forms Vagal triangle (floor of 4th ventricle)


Vagus Nerve (efferents vs. afferents)

2 Efferents: (MOTOR)

1. General Viseral Efferent (GVE)
Preganglionic parasympathetic
heart, lungs, GI (to splenic flexure)
- neurotransmitter ACh
2. Special Visceral Efferent (SVE)
-Pharyngeal and laryngeal muscles (swallowing and vocalization)

3 Afferents: (SENSORY)

1. General Somatic Afferent
-pharynx, meninges, small region of external ear.
2. Special Visceral Afferent
-taste from epiglottis and pharynx
3. Genreal Visceral Afferent
-chemoreceptors, baroreceptors of aortic arch


Where are the Vagus Cranial nerve GVE fibers located?

GVE- general visceral efferent
-preganglionic parasympathetic
heart lungs and GI

- Dorsal motor nucleus of X


Where are the SVE fibers of CN # 10 located?

Special Visceral Efferents:
-pharyngeal and upper esophageal muscles
(Swallowing and gag reflex)
-Larynx muscles (vocalization)

Nucleus Ambiguus


Where are the GSA fibers located (for CN 10)?

GSA= general somatic sensory
Pharynx, larynx, meninges, small region of outer ear
- afferents join nucleus of CN 5


Where are the Special Visceral afferent fibers of the CN 10 located?

SVA - taste of epiglottis and posterior pharynx

Nucleus Solitarius


Where are the GVA fibers of CN 10 located?

General visceral afferents- chemo receptors, baroreceptors of aortic arch, cardiorespiratory system, digestive system

Nucleus Solitarius


Complete lesion of CN 10 can cause what?

Unilateral lesion of vagus nerve can cause what?

- Fatal

-widespread dysfunction of the palate, pharynx and larynx

(if lesion of right CN 10)
-right palatal arch sagging, deviation of uvula to the left, right vocal muscles paralysis


Glossopharyngeal Nerve (general)

BOTH sensory and motor


Glossopharyngeal Nerve
-efferents vs. afferents

2 Efferents (Motor)
1. GVE - general visceral efferent
-preganglionic parasympathetic to parotid gland
2. SVE special visceral efferent -- stylopharyngeal muscles

3 Afferents (Sensory)
1. GSA- general somatic afferent
-pharnyx, posterior 1/3 of tongue, middle ear, small region of external ear
2. SVA-- special visceral afferent
- taste from posterior 1/3 of tongue
3. GVA- general visceral afferent
-chemorecepors and baroreceptors from carotid body.


Where are the GVE fibers of CN 9 located?

General visceral efferent:
-preganglionic parasympathetics to parotid gland

-inferior salivary nucleus (in PONS)
---> work their way to otic ganglion = parasympathetic to parotid gland


Where are the SVE fibers of CN 9 located?

Special visceral efferent-- branchial motor
-stylopharyngeal muscles
- elevates pharynx during talking and swallowing

Nucleus Ambiguus


Lesions at N. ambiguous causes what?

Affects CN 10: SVE fibers
-pharynx, larynx, meninges, small region of outer ear

Affects CN 9 : SVE fibers
-pharynx, posterior 1/3 of tongue, middle ear, small region of external ear.

LMN are going to be affected -- muscle atrophy!!

-Ischaemic lesions
-Intramedullary tumors
-Motor Neurons disease
-Myastenia gravis

Glossopharyngeal neuralgia-- episodes of severe throat and ear pain.


Vascular supply to the medulla?

Medial : Anterior Spinal Artery
Lateral : PICA
Rostral: Vertebral artery- paramedian branches


Anterial spinal artery-- regions it hits in medulla

Pyramids, medial leminiscus, hypoglossyl nucleus


Vertebral artery helps supply what structure in the medulla?

Inferior olivary nucleus


What structures in the medulla does the PICA play a big role in?

Solitary nucleus, Nucleus Ambiguus


Meduallry syndrome. What if it happens on the left side?

Blockage of Anterior spinal artery

1. right corticospinal tract
2. left 1/2 of tongue
3. right touch/vibration lost


Lateral Medullary Syndrome?

Blockage of PICA
-hits N. Soletarious and other sensory parts (pain and temperature)


CN 5 (general)

Both motor and sensory

Muscles of mastications, proprioception, touch and temperature, pain and temperature


Types of fibers in CN 5?

SVE: special visceral efferent (branchial motor)
-muscles of mastication and tensor tympani muscle

GSA: general somatic afferent: proprioception (pons--> midbrain); Touch and temperature (pons); Pain and temperature (pons --> spinal cord)


There are 4 main things that the CN 5 does? aka What pathways (sensory/ motor) does it contribute too?

1. motor (pons)
2. propriception (pons--> midbrain)
3. Touch and temperature (pons)
4. pain and temperature (mid pons--C2-C3 spinal cord)


Pain and temperature pathway of CN5:

GSA - general somatic afferent fibers
-ipsilateral impulses of pain temerpature some touch from head, face and neck
- spinal trigeminal tract

1st order neuron is in trigeminal ganglion
2nd order = Spinal nucleus of medulla
3rd = VPM (thalamus) (crossed projection to VPM)


Touch pathway of CN 5:

GSA- touch and pressure from face, mouth anterior 2/3 of tongue, nasal sinuses

1st order neuron : trigeminal ganglion
2nd order neuron in main/principle/chief nucleus --- crosses immediately to VPM.
3rd neuron continues to homonculus


Proprioception of CN 5:

GSA -- primary sensory neurons innervate muscles of mastication, project to motor nucleus of 5.

1st neuron is in CNS -- mesencephalic nucleus


Motor fivers for CN 5 pathway:

innervates muscles of mastication and tensor tympani

Nucleus: Trigeminal motor nucleus
-ocated mid pons medial to the chief sensory nucleus


What happens if there is a lesion in the CN5 ?

when chin opens, it deviates away from lesion


What is trigeminal neuralgia (Tic doloureux)

-recurrent episode of brief severe pain lasting from seconds to a few minutes (V2-V3)

-facial sensation is normal


What are some things that may cause sensory loss via CN 5?

-Herpes Zoster
-Metabolic disease


Facial nerve (general) and fibers

Both sensory and motor

2 efferent
1. SVE
-special visceral efferent: mucles of expression and stapedius muscle

2. GVE
-general visceral efferent: pre ganglion sympathetic for lacrimal, and all salivary glands EXCEPT parotid (CN9)

3 afferent
1. GSA- general somatic afferent: small region of outer ear

2. SVA- special visceral afferent: taste to anterior 2/3 of tongue

3. GVA- general visceral afferent: mucosal membrane of nasopharynx


Facial motor nucleus (CN 7)

SVE: muscles of facial expression and stapedius

Turns around abducens nucleus and forms the Facial colliculi -- fibers exit in corder of ponto-medllary junction.

Present in pons close to mandibular nucleus of 5.


CN7 - role in corneal reflex?
-1st synapse?
-second synapse?

1. cornea
2. opthalmic nerve of V
3. Spinal nucleus of trigeminal
4. Facial nucleus
5. orbicularis oculi


CN7 role in sucking reflex
-1st synapse?
-second synapse?

1. lips
2. Mandibular nerve CN V
3. Pontine nucleus of V
4. Facial nucleus
5. orbicularis oculi


CN7 role in blinking to light reflex
-1st synapse?
-second synapse?

1. retina
2. Opthalmic nerve
3. Superior colliculus
4. Facial nerve
5. orbicularis oculi


CN7 role in blinking to noise
-1st synapse?
-second synapse?

1. Cochlea
2. Cochlea nucleus
3. Inferior colliculus
4. Facial nucleus
5. orbicularis oculi


CN7 role in sound attenuation
-1st synapse?
-second synapse?

cochlea nucleus
superior olivary nucleus
Facial nucleus
Stapedius muscle


Superior Salivatory nucleus (SSNU)

GVE- general visceral efferents -- preganglion parasympathetic innervation for lacrimation and salivation (except parotid gland).


Facial nerve- rostral solitary nucleus

SVA- special visceral afferent : taste from anterior two thirds of tongue


Facial nerve-- pain, temperature, touch, pressure

GSA- general somatic afferent: back of the outer ear (also Cn 9, 10)

Information travels into the spinal trigeminal nucleus and then information crosses as part of trigemino-thalamic projections to thalamus (VPM)


Vascular supply to pons?

Basilar artery

1. Superior cerebellar artery = rostral pons
2. Basilar paramedian arteris = medial region in pons cross section
3. AICA = lateral and caudal pons


Tracts in the pons that could be affected if anything happened to paramedial branches of the basilar artery

-pontine nucleus, Medial lemniscus, CST and coticobulbar tracts, abducens nucleus


Tracts in the pons that could be affected if anything happened to AICA

Lateral pons
-descending sympathetics
- Spinal trigeminal nucleus and tract (V)
-Facial nucleus and nerve fascicles (CN 7)
-Middle cerebellar peduncle


Horner's syndrome

Strong pupillary constriction (only parasympathetic fibers are working)and drooping of eye lid, decreased sweating (anhidrosis), increased skin temperature, flushing of skin.

-Descending from hypothalamus
-goes through midbrain and pons (AICA)
-intermediolateral column = pre ganglion sympathetics fibers that go out to ganglion chain (ACh)
- Post-sympatic neuron follows arteries and innervates the dilator muscle (ciliary muscle)


Occularmotor nerve

MOTOR only -- GSE: eye muscles except lateral rectus and superior oblique.

Also Innervates levator palpebrae superioris muscle

Comes out in the interpeduncular fossa -- this is also where the prepontine cistern is.

Edinger-Westphal nucleus (part of oculotomotor nucleus -GSE) -- sphincter pupillage, ciliary muscle (final destination after synapse in parasym. ganglion)


Trochlear Nerve

motor only--GSE: innervates the superior oblique muscle of the eye (down and out)

Trochear nucleus


Lateral motor systems

Lateral corticospinal tract: movement of contralateral limbs

Rubiospinal tract - movement of contralateral limbs (humans unknown)


Medial motor systems

Anterior corticospinal tract: control of bilateral axial and girdle muscles

Vestibulospinal tract: medial VST: Positioning of head and neck; lateral VST =balance

Reticulospinal tracts: automatic posture and gait-related movements

Tectospinal tract: coordination of head and eye movement (uncertain in humans)


midbrain-- Blood supply and areas they can affect

SCA and proximal PCA -- superior colliculus

Proximal PCA: lateral to cerebral aqueduct
-Reticular formation, STT, Descending sympathetics, medical lemniscus, red nucleus, substance nigra, pyramidal tract (CST, corticobulbar tracts)

Paremedian branches: affect medial oculomotor nucleus and nerve fascicles. Can affect medical 1/2 of red nucleus.