Brain stem

brainstem divisions

• tectum (green): DORSAL, consist of superior and inferior colliculi

• basis (purple): MOST VENTRAL, contains corticospinal and corticobulbar tracts

• tegmentum (blue): contains main bulk of brainstem nuclei and reticular formation

corticobulbar tract

• travel w the corticospinal tract → terminates on cranial nuclei in brainstem → cranial nuclei sends axons (cranial nerves) → control muscles of head, neck, face

control movements from neck and above

superior border of brainstem

mammillary bodies - posterior commissure

inferior border of brainstem

pyramidal decussation

which cranial nerve is derived from brainstem?

CN 3 to CN 12

which main part of the brain does the brainstem belong to?

the mesencephalon

corticospinal tract

motor fibers carry movement related info from primary motor cortex to spinal cord

control movement of whole body

sphenoid bone

• contain sella turnica, optic groove, optic canal, superior orbital fissure, foramen rotundum, foramen ovale

optic canal

transmits optic nerve and ophthalmic artery

optic groove

houses optic chiasm

sella turcica

houses pitutitary gland

superior orbital fissure

transmist CN 3, 4, V1 (ophthalmic division), 6, ophthalmic veins

petrous portion of temporal bone

pg 14

occipital bone (inferior 2/3)

add picture

sphenoid bone (superior 1/3)

internal acoustic meatus

• in the posterior fossa

• CN 7 and 8 exit from the auditory canal

middle cranial fossa foraminas

• optic canal

• superior orbital fissure

• foramen rotundum

• foramen ovale

• foramen spinosum

• foramen lacerum

optic canal

• CN 2

• ophthalmic artery

superior orbital fissure

• CN 3-4-5(1)-6

• ophthalmic veins

V(1) - ophthalmic nerve

foramen rotundum

CN V2 - maxillary nerve

foramen ovale

CN V3- mandibualr nerve

foramen spinosum

middle meningeal artery

meningeal nerve V3

mid-sagittal section

add picture from lecture pg 18

identify structures on a mid sagittal MRI

sphenoid sinus, pituitary gland, clivus, optic chiasm, mammillary body, midbrain, pons, medulla, 4th ventricle, cerebellum

reticular formation

• the portion of brainstem tegmentum where nuclei are not visible w staining

• rostral reticular formation: alertness

• caudal reticular formation: respiration and circulation

neurotransmitters

2 types:

• neurotransmission: mediate communication between neurons - Glutamate (excitatory) and GABA (inhibitory)

• neuromodulation: facilitate or inhibit the communication between neurons - NE, serotonin, histamine, dopamine, Ach

Norepinephrine (NE)

Effects: 

• excite/inhibit the cortex, mostly excite the thalamus

• modulate attention, sleep-wake states and mood

serotonin

in 2 regions of raphe nucleus

1. rostral : sleep-wake cycle, mood, contribute to depression, anxiety, OCD

2. caudal : pain modulation, reathing, temperature regulation

dopamine

in 3 different regions:

1. mesostriatal: dysfunction causes Parkinson’s disease (treat w dopaminergic agonists)

2. mesolimbic: plays a role in reward and addiction, overactivity relates to hallucination in schizophrenia (treat w dopaminergic agonists)

3. mesocortical: plays a role in working memory, damage may cause cognitive deficits in Parkinson’s

histamine

• most is in mast cells outside the nervous system for immune and allergic responses

• may be important for alert state

• antihistamine meds cause drowsiness by blocking CNS histamine receptors