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Brain + Behaviour > Brainstem + Cranial nerves 1 + 2 > Flashcards

Brainstem + Cranial nerves 1 + 2 Flashcards

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1
Q

rule of 4, what cranial nerves are found in the following
* midbrain
* pons
* medulla

A
  • Midbrain (lesions here will affect eyes)= CN III-IV
    • Pons (lesions here will affect face mainly)= CN V - VIII
    • Medulla =CN IX - XII
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2
Q

what is the diencephalon made up of + functions

A

diencephalon made up of:
THALAMUS= relay + processing centers for sensory info
HYPOTHALAMUS= centers controlling emotions, autonomic functions, and hormone production

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3
Q

the medulla starts at around what vertebral level

A

medulla starts around C2 vertebrae with spinal cord changing gradually into brainstem

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4
Q

what part of mesecephalon controls ur circadian rhythm (in regards w melatonin)

A

pineal gland (looks like pine cone its above superior collilculi)
pineal gland controls circadian rhythm in regards to melatonin + its involved with appetite control

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5
Q

what links the 3rd and 4th ventricle of the brain

A

the cerebral aqueduct of sylvius links the 3rd and 4th ventricles of the brain

The fourth ventricle is the most inferiorly located ventricle, draining directly into the central canal of the spinal cord. Superiorly, it connects to the third ventricle through a thin canal called the cerebral aqueduct of Sylvius.

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6
Q

what are the functions of the
* superior colliculi
* inferior colliculi

A

superior colliculi=
* involved in eye movements + visual processing
* receives input from retina + other vision related areas
* send output to CN’s involved w eye + neck movements + to lateral geniculate nucleus

inferior colliculi=
* involved w auditory processing
* receives input from ipsilateral + contralateral CN VIII + auditory cortex
* send output to medial geniculate nucleus

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7
Q

where in the brainstem is the substantia nigra located

A

substantia nigra is located in midbrain (mesencephalon)
* rich in dopamine neurons
* part of basal ganglia

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8
Q

what do we mean when we say ‘convergence’ of the eyes+ what muscles does this involve

A

Convergence= When you look at a nearby object, your eyes move inward to focus on it
his action involves** contraction of the medial rectus muscles** of both eyes, with the relaxation of lateral recti resulting in the adduction of both the eyes

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9
Q

what cranial nerves are located in the midbrain (mesencephalon)

A

mesencephalon
* occulomotor (CN III)= controls eyelid, eye movements, pupil + lens
* trochlear (CN IV)= only CN to leave from posterior/dorsal side, involved in eye movement

midbrain= Associated with auditory, visual and pupillary reflexes and with eye movements

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10
Q

what is the largest serotonin nucleus invovled in sleep/wake cycle + depression

A

the largest serotonin nucleus is the dorsal raphe nucleus ventral side of periaqueductal grey
- role in depression + sleep/wake cycle

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11
Q

the pons (metencephalon) has ascending + descending tracts passing through it; it also connects w cerebellum via the cerebellar peduncles.
What cranial nerves stem from the pons?

A

Trigeminal (CN V)
Sensation to face
Motor to muscles of mastication)

Abducens (CN VI)
Eye movements

Facial (CN VII)
Movements of face
Special sense of taste
Parasympathetic to lacrimal and some salivary glands)

Vestibulocochlear (CN VIII)
Hearing and balance

pons= Its main functions are mastication (V), eye movement (VI), facial expression, taste, blinking, salivation, lacrimation (VII), and equilibrium and audition (VIII)

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12
Q

where is the nucleus of the solitary tract found + what is its function

A

the nucleus of the solitary tract is found in the medulla oblongata (continuation of spinal cord)
* it receives info about blood flow + levels of o2 + co2
* when info suggest problem reflexive actions will restore things back to desired range
SO SO SO NECESSARY FOR LIFE

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13
Q

what cranial nerves are found in the medulla (myelencephalon)

A

cranial nerves found in medulla:
***vagus (CN X)= **
- Motor for Gag reflex
- Most of parasympathetic to body

  • glossopharyngeal (CN IX)
    -sensory to back of throat (afferent for gag reflex)
    -motor to soft palate (uvula)
    -parasympathetic to salivary glands (aka parotid glands)
  • spinal accessory (CN XI)
    -motor to muscles on neck

* hypoglossal (CN XII)
-motor to tongue

Associated with equilibrium, audition (VIII), deglutition, salivation, taste (IX), respiration & circulation, GI function (X), neck & shoulder movements (XI) tongue movements (XII), coughing and vomiting (reticular formation)

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14
Q

what cranial nerve leaves from the midline of the midbrain and is the only cranial nerve to leave from posterior/dorsal side of the brainstem

A

trochlear (CN IV) is the only cranial nerve to leave from posterior/dorsal side of the brainstem + it is on the midline

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15
Q

which cranial nerve is responsible for deglutition and where is it found

A

degultition = swallowing

(GLOSSOPHARYNGEAL CN IX) + (VAGUS CN X)

both found in medulla

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16
Q

as a general rule, if a cranial nerve is purely motor it will be more ____, if a cranial nerve is purely sensory it will be more ______

A

if a cranial nerve is purely motor it will be more medial (closer to midline)
if a cranial nerve is purely sensory it will be more lateral

There are pure sensory nerves (I, II, VIII), pure motor nerves (III, IV, VI, XI, XII) and mixed sensory & motor nerves (V, VII, IX, X)

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17
Q

what are the 3 types of motor nuclei

A

There are 3 types of motor nuclei:
* **Somatic motor nuclei **project to skeletal muscle (eye muscles and tongue)

  • Branchial motor nuclei project to muscles derived from branchial arches (craniofacial structures)– movement of jaws (V), facial expression (VII), motor to larynx and pharynx (X) and neck and shoulder muscles (XI)

* Visceral motor nuclei: pre-ganglionic parasympathetic fibres

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18
Q

what is anosmia, and what cranial nerve is damaged if patient presents with this

A

anosmia= ability to perceive smell/odor
likely sign of damage to cranial nerve I = OLFACTORY

19
Q

what cranial nerve causes pupil constriction

A

The oculomotor cranial nerve III plays an important role in the efferent visual system by controlling ipsilateral eye movements, pupil constriction, and upper eyelid elevation

20
Q

what cranial nerves are responsible for the pupillary light reflex?

A

Afferent CN II (optic)
To both pretectal areas
To both Edinger-Westphal nuclei (CN III)

Efferent CN III (oculomotor)
Direct and indirect pupil closure

21
Q

when there’s a lesion to cranial nerve III, and we shine light in patients right eye; what will happen to the left eye?

A

CN III lesion (oculomotor)– loss of motor/efferent supply

so, loss of consensual pupillary light reflex. Eye shone in will respond by constricting but other eye will not constrict

22
Q

when there’s a lesion to cranial nerve II, and we shine light in patients right eye; what will happen to the left eye?

A

CN II lesion (optic)

loss of direct pupillary light reflex. So eye u shine in won’t constrict, the other eye (that’s not shone in) will constrict however

23
Q

what is the accomodation reflex?
What 3 things happen.
Then explain the pathway involving the optic tract mentioning LGN, CN III, medial recti + Edinger-westphal nucleus

A

accomodation reflex= eyes move from focusing on far to near object

3 reactions happen:
-convergence of both eyeballs
-constriction of pupils
-thickening of lens; contraction of ciliary muscles

PATHWAY:
* sight->eye
* optic tract
* through lateral geniculate nucleus (LGN)
* optic radiation-> visual cortex from here splits 2 ways:
1) frontal cortex -> Edinger-westphal nucleus-> pupillary constriction, lens thickeness.
2) CN III motor nucleus-> medial recti-> convergence of ocular axes

24
Q

what is the doll’s eye reflex?

A

Afferent = CN VIII (vestibulocochlear)
Efferent = CN III (oculomotor), CN IV (trochlear) and CN VI (vestibulocochlear)

New-born babies passive turning of head leaves eyes behind (stationary)
Disappears within a week or two

Tested by turning patients head from side to side:
Normal = as head moves in one direction eyes move in opposite to maintain gaze
Positive test (Abnormal) = eyes do not turn with the head
Suppressed in alert patients but surfaces in comatose patients; so in comatose patients we use doll’s eye reflex to see if their brainstem is intact

25
Q

The _____ _____ _______ connects cranial nerve nuclei controlling eye movement and the vestibular nuclei

A

The medial longitudinal fasciculus (MLF) connects cranial nerve nuclei controlling eye movement and the vestibular nuclei

26
Q

what is the role of the medial longitudinal fasciculus (MLF)

A

MLF heavily myelinated composite tract
Extends length of brainstem in paramedian plane
Signals from vestibular nuclei to keep eyes balanced in space despite head movements
MLF becomes the medial vestibulospinal tract (mVST) in the spinal cord
Acts on motoneurons for neck muscles
mVST coordinates reflexive head and neck movements to keep eyes stable in space
Internuclear ophthalmoplegia
Lesion in superior pons between abducent and oculomotor nuclei
Seen in MS
Isolates paralysis of medial rectus on side of lesion on attempted lateral gaze
Mononuclear horizontal nystagmus in adducting eye contralateral to side of lesion

27
Q

what cranial nerves involved with blink reflex

A

Afferent CN V1
Also bright light (CN II), loud noise (CN VIII)
Efferent CN VII

28
Q

internuclear ophthalmoplegia can be seen when u damage which fasciculus?

A

Internuclear ophthalmoplegia(paralysis of eye muscles) occurs with damage to the medial longitudinal fasciculus (MLF).
due to damage to the interneuron between two nuclei of cranial nerves (CN) VI and CN III (internuclear).

PATIENT HAS IMPAIRED ADDUCTION IN EYE IPSILATERAL TO THE AFFECTED MEDIAL LONGITUDINAL FASCICULUS

Normally when looking left, the left abducens nucleus (VI) fires to contract the left lateral rectus and via its connection to contralateral oculomotor nucleus causes contraction of right medial rectus. BOTH EYES LOOK THE SAME DIRECTION. With MLF lesion, this does not occur however convergence is intact (all CN III).

29
Q

what cranial nerve is found between the the posterior cerebral artery and the superior cerebellar artery

A

cranial nerve III (comes out of midbrain) it is often first to be affected by raised intracranial pressure. CN III (oculomotor) is sandwiched between the posterior cerebral artery and the superior cerebellar artery

30
Q

what main artery + its branches supply the medulla

A

verterbral arteries and its branches:

* Anterior spinal artery
* Posterior spinal artery
* Posterior inferior cerebellar artery
* Anterior inferior cerebellar artery * Basal artery
31
Q

what is the blood supply to the pons

A
  • Basilar artery
    • Paramedian branches – pontine arteries
    • Anterior inferior cerebellar artery
  • Superior cerebellar artery
32
Q

what is the blood supply to the medial longitudinal fasciculus, both when its in the midbrain vs pons

A

Arterial vascular supply of the MLF in the dorsal tegmentum of the midbrain is supplied by small perforating branches of the P2 segment of the posterior cerebral artery.

The MLF in the dorsal pons is supplied by small, perforating paramedian arteries that arise from the basilar artery

33
Q

what is the blood supply to the midbrain of brainstem

A
  • Basilar artery
    • Superior cerebellar artery
    • Posterior cerebral artery
  • Choroidal artery
34
Q

what is ataxia

A

Ataxia means without coordination. People with ataxia lose muscle control in their arms and legs. This may lead to a lack of balance, coordination, and trouble walking. Ataxia may affect the fingers, hands, arms, legs, body, speech, and even eye movements.

35
Q

damage to the sympathetic pathway is a clinical sign of what

A

Horner syndrome; a rare condition classically presenting with partial ptosis (drooping or falling of the upper eyelid), miosis (constricted pupil), and facial anhidrosis (absence of sweating) due to a disruption in the sympathetic nerve supply.

the eye can still accomodate but it can’t reflect– like a prostitute/whorener’s can accomodate but not reflect ur needs.

lack of sympathetic supply to the eye. Pupil constricts due to parasympathetic innervation (oculomotor) not being opposed.

36
Q

what are the rule of 4 deficits for the following cranial nerves located in the medulla;
*glossopharyngeal CN IX
* vagus CN X
* spinal accessory CN XI
* hypoglossal CN VII

A

*glossopharyngeal CN IX= ipsilateral pharyngeal sensory loss

  • vagus CN X= ipsilateral palatal weakness
  • spinal accessory CN XI= ipsilateral shoulder weakness
  • hypoglossal CN VII= ipsilateral weakness of tongue
37
Q

what are the rule of 4 deficits for the following cranial nerves located in the pons;
* trigeminal CN V
* abducent CN VI
* facial CN VII
* auditory/ vestibulocochlear CN VIII

A
  • trigeminal CN V= ipsilateral facial sensory loss
  • abducent CN VI= ipsilateral eye abduction weakness
  • facial CN VII= ipsilateral facial weakness
  • auditory/ vestibulocochlear CN VIII= ipsilateral deafness
38
Q

what eye muscles work together to pull your eye down when you’re going downstairs and what cranial nerve(s) innervates them

A

inferior rectus (oculomotor CN III) and superior oblique (trochlear CN IV) working together pull the eye downward without rotating the eye. Three cranial motor nuclei provide efferent control of the extraocular muscles. Activation of the motor neurons produces contraction of the innervated muscle. controls the lateral rectus of the ipsilateral eye.

39
Q

define hemiparesis

A

Hemiparesis is one-sided muscle weakness

40
Q

define dysarthria

if a patient has dysarthria + dysphagia(difficulty swallowing) what cranial nerves most likely injured?

A

Dysarthria is where you have difficulty speaking because the muscles you use for speech are weak.

dysarthria + dysphagia indicates CN IX (glossopharyngeal) = CN X (vagus) injured

41
Q

define analgesia + thermoanalgesia

A

analgesia= the inability to feel pain

thermoanalgesia= inability to sense heat sensation (form of pain heat)

42
Q

what tumour causes Millard Gubler syndrome

A

a Pons tumour will causes millar gubler syndrome:

  • lateral rectus weakness (CN VI abducens damaged) patient cannot abduct eye on side that effected
  • CN VII facial will mean ipsilateral loss of face sensation NO FOREHEAD SPARING

*contralateral ataxia/weakness= as corticospinal tract is damaged

43
Q

what fossa is the brainstem, cerebellum and occipital lobe of cerebrum located in?

A

posterior cranial fossa houses:
*brainstem
*cerebellum
*occipital lobe of cerebrum

44
Q

tentorium cerebelli separates ____ from ____

falx cerebri separates the ____ ______

A

tentorium cerbelli separates cerebrum from cerebellum

falx cerebri separates the cerebral hemispheres

Brain + Behaviour (14 decks)

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