Brainstem Flashcards
What are the components of the brainstem?
- Midbrain
- Pons
- Medulla
What is in the dorsal surface of the midbrain?
Tectum
- Superior colliculus – visual map of the world
- Inferior colliculus – auditory map of the world
What is in the ventral surface of the midbrain?
- Cerebral peduncles – contains corticospinals, corticobulbar, corticopontie fibers
- Interpeduncular fossa – depression between peduncles – CNIII comes out of here
What is the anterior segment of the brainstem? middle? posterior?
- Anterior = basilar
- Middle = Tegmentum
- posterior = Tectum (only in midbrain, roof over cerebral aqueduct)
What is contained in the basilar region?
- Descending tracts
- Motor nuclei: pons, substantia nigra
- Pontocerebellar axons
What is contained in the tegmentum?
- Cranial nerve nuclei
- Reticular formation
- Ascending sensory tracts and sensory nuclei
- Medial longitudinal fasciculus – fiber tract that coordinates head and eye movements
What is contained in the caudal medulla?
- Pyramids
- Medial lemniscus
- Dorsal column nuclei and tracts
- Spinal trigeminal nucleus and tract
- Inferior olivary nucleus
What is another name for the middle cerebellar peduncle?
Brachium pontis
What is contained in the midbrain?
- Cerebral peduncles (crus cerebri) -Cortico- bulbar, spinal and pontine tracts
- Red nucleus
- Substancia nigra
- Medial lemniscus and spinothalamic tracts
- Periaqueductal gray
- Oculomotor nucleus
- Tectum
In the brainstem, where are the motor tracts located? sensory? visceral?
Motor = medial (General Somatic Efferrent; GSE)
Sensory = lateral (S[pecial]SA and GSA)
Visceral = In between, lateral horn (motor medial, sensory lateral)
- General = touch vibration, movement
- special = vision, taste, hearing
What are the main functions of cranial nerves that exit the brainstem?
- Motor innervation to muscles of face, eyes, tongue, jaw and two neck muscles
- Somatosensory information from skin and muscles of face and TMJ, and special sensory information
- Parasympathetic regulation of heart rate, blood pressure, digestion, breathing, and some eye muscles
What part of the brainstem regulates consciousness? (small damage to this area can produce coal, loss of awareness)
Reticular formation
- small injuries cause problems with consciousness, where as you need significant CC damage to see problems with consciousness
Ascending reticular activating system (ARAS); Project to cerebral parts of consciousness systems (basal forebrain, thalamus, cerebral cortex); Basal forebrain – in telencephalon
Reticular formation
Projects to widespread areas of cortex; May contribute to: Modulation of level of awareness, Sleep/wake cycle; damaged in Alzheimer’s disease
Basal forebrain
What is the neurotransmitter in the basal forebrain?
ACh
