The brainstem Flashcards by Alice Scholfield

What are the embryological names for forebrain, midbrain and hindbrain?

Forebrain: prosencephalon
Midbrain: mesencephalon
Hindbrain: rhombencephalon

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Main role of the midbrain?

Maintaining conciousness, processing visual and auditory data

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Main role of the pons?

Relays sensory information to cerebellum and thalamus

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Main role of the medulla?

Relays information to the thalamus

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3 general functions of the brainstem?

Conduit: long tracts to/from spinal cord pass through brainstem
Cranial nerves: sensory input and motor output, as well as parasympathetic motor output
Sensorimotor integration: connects to cerebellum

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3 things that brainstem mediates

Autonomic control of respiratory and cardiovascular reflexes
Somatic/ autonomic modulation via descending pathways
Diffuse neuromodulatory systems regulate conscious states

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What is found in dorsal part of brainstem?

Cranial nerve nuclei and sensory reflex centres

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What is found in middle part of brainstem?

Ascending motor pathways and reticular formation

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What is found in ventral part of brainstem?

Descending motor pathways

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Describe organisation of cranial nerve nuclei in the dorsal brainstem?

Motor nuclei- medial
Mixed nuclei- more lateral
Sensory nuclei- sensory

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What does tectum and tegmentum (of midbrain) mean?

Tectum= roof
Tegmentum= body

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Where do the corticospinal and corticobulbar tracts pass?

Through cerebral peduncle of the midbrain

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What are the white parts of the internal pons?

Remnants of corticospinal tract

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What can be found in open medulla?

Cranial nerves, inferior cerebral peduncle, nuclear groups that project to cerebellum

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Where do cranial nerve afferents arise from?

Ganglia

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Where are second order sensory neurons located?

Cranial nerve nuclei

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Which cranial nerves are only sensory?

I, II, VIII

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Which cranial nerves are only motor?

III, IV, VI, XI and XII

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Which cranial nerves are mixed?

V, VII, IX and X

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Describe 3 types of cranial nerve motor nuclei

Somatic motor nuclei project to skeletal muscle
Branchial motor nuclei project to muscles derived from branchial arches (craniofacial structures such as movement of jaw, expression etc)
Visceral motor nuclei: preganglionic parasympathetic fibres

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At what level does spinal cord begin to become brainstem?

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Describe position of nuclei, midline to laterally, in the brainstem

Somatic motor (LMN)
Visceral motor (pre ganglionic parasympathetic)
Visceral sensory
Somatic sensory

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Define cranial nerve nuclei

Columns of neurons associated with cranial nerves

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What type of nerve is hypoglossal? What does it innervate?

Somatic motor

Internal and external tongue muscles

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What type of nerve is spinal accesory? Where does it arise from?

Branchial motor | Arises from branchial motor neurons in spinal cord

What does spinal accesory nerve innervate?

Trapezius and sternocleidomastoid

Where does spinal accesory nerve enter/ exit the skull?

Enters through foramen magnum | Exits through jugular foramen

What type of nerve is vagus? Where does it arise from?

Mixed nerve | Arises from nucleus ambiguus

What type of nerve is glossopharyngeal?

Mixed (although mainly has sensory functions)

Functions of glossopharyngeal nerve

Parasympathetic secretomotor to parotid special sensory- detects taste at back of mouth touch fibres from back of mouth

What happens if there is damage to vagus?

Loss of voice on affected side

What happens if there is damage to glossopharyngeal?

Loss of gag reflex on affected side

What type of nerve is vestibulocochlear? What information does it convey?

Sensory | Special sense of hearing, perception of self motion, head position and spatial orientation

What type of nerve is facial?

Mixed

5 somatic branches of facial nerve

Temporal, zygomatic, buccal, mandibular, cervical

What does facial nerve parasympathetic output control?

Nasal secretion and lacrimation

Sensory input from facial nerve? Describe course of sensory fibres?

Taste afferents from anterior 2/3 of the tongue | Travel from chorda tympani via geniculate ganglion to rostral nucleus of solitary tract

What type of nerve is trigeminal?

Mixed nerve

Motor output of trigeminal nerve?

V3: motor to muscles of mastication

What does the medial longitudinal fasciculus connect?

The cranial nerve nuclei controlled eye movement and vestibular nuclei

Which cranial nerves innervate extraocular eye muscles?

III, IV and VI

What does damage to the medial longitunal fasciculus cause? Why?

Internuclear pohthalmoplegia Normally when looking left VI nucleus fres to contract left lateral recus. The righ lateral rectus also contracts due to connection to contralateral oculomotor nucleus. Both eyes should look in same direction, but if there is damage to MLF this doesn t work

What usually causes unilateral internuclear ophthalmoplegia?

A stroke

What usually causes bilateral internuclear ophthalmoplegia?

What is the role of signals from vestibular nuclei?

Keep the eyes balanced in space, despite head movements

What does the MLF become in the spinal cord?

Medial vestibulospinal tract

Role of medial vestibulospinal tract?

Acts on motor neurons in neck to coordinate reflexes

What cranial nerves coordinate pupillary light relfex?

CNII in and III out

What is the reticular formation?

Forms a core of interconnecting neurons Key centre for regulating conciousness Integrates and modulates inputs

What does reticular formation have output to?

hypothalamus, cortex, limbic system and descending projections

What part of brainstem produces noradrenaline?

Locus coeruleus

What part of brainstem produces serotonin

Raphe nuclei

What part of brainstem produces dopamine?

Substantia nigra and ventral tegmental area

What part of the brainstem produces acetyl choline?

Pedunculopontine nucleus

What is the function of dopamine made in substantia nigra?

Control of movement

Low levels of dopamine from SN=

parkinsons

What is function of dopamine made in ventral tegmental area?

organising behaviour, focusing and attention, reward and motivation

Disturbance of dopamine levels from VTA=

Schizophrenia and addiction

Functions of noradrenaline?

activates motor system so reflees are faster, inhibits pain,

Functions of serotonin?

Rostrally: inhibit basal forebrain GABA cells to produce arousal Caudally: modulates pain perception

Results of deficits in serotonin?

OCD, depression, anxiety, aggresion

How would you define a monoamine and cholinergic brainstem centre

Nuclei containing specific neurotransmitters which modulate variety

What controls noradrenaline release?

Sympathetic nervous system control centre activated by the hypothalamus Descending fibres carried in reticulospinal tract activate preganglioninc sympathetics