The Brain Stem

Components of the brainstem

Midbrain
Pons
Medulla

Receptor types of the vertical tracts of the brainstem

Sensory
Motor
Autonomic

Which vertical tracts of the brainstem pass through relatively unaltered

Spinothalamic
Medial leminiscus
Sympathetic
Parasympathetic
Corticospinal

Which vertical tracts of the brainstem have various synapses within the brainstem

Spinocerebellar
Corticobulbar
Corticopontine
Corticoreticular

Which vertical tracts of the brainstem originate in the brainstem

Tecto, rubro, reticulo, vestibulo, ceruleo, and raphe spinal

Basilar section

Motor
Cortico - bulbar, spinal, pontine, reticular tracts

Tegementum

Sensory tracts
Cranial nerve nuclei
MLF
Reticular formation

Tectum

Midbrain only

What is the reticular formation

Neural network in tegmentum

What are the three longitudinal zones in the reticular formation

Lateral
Medial
Midline

Lateral zone

Sensory and cortical input
Info conveyed to medial and midline
Adjusts general level of neuronal activity and arousal

Medial zone

Vital functions
Project to cranial nerve nuclei and spinal cord
Posture via reticulospinal tracts

Midline zone

Pain control via raphe nuclei
Adjusts levels of consciousness

What does the tegmental area release

Dopamine

What does the ventral tegmental area deal with

Motivation and decision making

What stimulates the ventral tegmental area

Amphetamines/cocaine

What does morphine do in the ventral tegmental area

Inhibits inhibitory input to the area

What does anti-psychotic meds do in the ventral tegmental area

Block D2 dopamine receptors

What does the pedunculopontine nucleus release

Acetylcholine

Connections in the pedunculopontine nucleus

GP and STN of BG

What does stimulation of the pedunculopontine nucleus cause

Induced walking

What does the raphe nuclei release

Serotonin

What does the raphe nuclei play a role in

Onset of sleep and quality of sleep
Has a profound effect on mood
Controlling descending pain

What does the locus ceruleus/medial reticular zone release

Norepinepherine

Where does the locus ceruleus/medial reticular zone project through

Brain and spinal cord

What does the locus ceruleus/medial reticular zone do

Inhibit pain

What does the medial reticular zone do

Help regulate the ANS

What are the functions of the medulla

Control of eye and head movements
Coordinate swallowing
Regulate cardiovascular, respiratory and visceral activity

What are the functions of the pons

Process motor info from cortex to the cerebellum
Process sensory info from face CN V
Control muscles of facial expression
Lateral movement of eye
Control chewing
Contributes to respiration

What are the functions of the midbrain

Eye movement
Reflexive eye and head movements
Consensual and accommodation reflexes of eye
Dopamine to BG circuit via substantia nigra
Locomotion on postural influence
Pain suppression via PAG

What are the 4 D’s of brainstem dysfunction

Dysphagia
Diplopia
Dysmetria
Dysarthria

What are other common manifestations of brainstem dysfunction

Problem with vital functions
Disorders of consciousness
Contralateral and ipsilateral signs

Deficits of the medial medullary syndrome

Contralateral hemiplegia
Contralateral loss of position sense
Ipsilateral deviation of tongue

Deficits of lateral medullary syndrome

Contralateral loss of pain/temp of the body
Ipsilateral loss pain/temp of the face
Dysphagia, gag reflex
Nausea, vertigo
Ipsilateral ataxia
Ipsilateral Horner’s

Symptoms of Horner’s

Drooping eyelid (ptosis)
Smaller pupil (miosis)
Decreased sweating (anhidrosis)
Flush or redness of face

Deficits of medial pontine syndrome

Contralateral hemiplegia
Contralateral loss of position sense
Ipsilateral rectus paralysis
Paralysis of conjugated gaze toward lesion

Deficits of lateral pontine syndrome

Ataxia, fall toward lesion
Vertigo, nausea, deafness
Ipsilateral paralysis of facial muscles
Ipsilateral paralysis of mastication muscles
Ipsilateral Horner’s
Ipsilateral decrease in pain/temp in face
Contralateral decrease in pain/temp in body
Loss of conjugate gaze

Deficits of midbrain anterior lesions

Contralateral hemiparesis
Loss of eye movement

Structure damaged in midbrain anterior lesions

Corticospinal tract
Oculomotor nerve

Deficits of midbrain tegmental lesions

Ipsilateral loss of eye movement
Contralateral loss of all sensation in face and body
Ipsilateral decreased coordination, ataxia