The brainstem Flashcards
What are the embryological names for forebrain, midbrain and hindbrain?
Forebrain: prosencephalon
Midbrain: mesencephalon
Hindbrain: rhombencephalon
Main role of the midbrain?
Maintaining conciousness, processing visual and auditory data
Main role of the pons?
Relays sensory information to cerebellum and thalamus
Main role of the medulla?
Relays information to the thalamus
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
3 things that brainstem mediates
Autonomic control of respiratory and cardiovascular reflexes
Somatic/ autonomic modulation via descending pathways
Diffuse neuromodulatory systems regulate conscious states
What is found in dorsal part of brainstem?
Cranial nerve nuclei and sensory reflex centres
What is found in middle part of brainstem?
Ascending motor pathways and reticular formation
What is found in ventral part of brainstem?
Descending motor pathways
Describe organisation of cranial nerve nuclei in the dorsal brainstem?
Motor nuclei- medial
Mixed nuclei- more lateral
Sensory nuclei- sensory
What does tectum and tegmentum (of midbrain) mean?
Tectum= roof Tegmentum= body
Where do the corticospinal and corticobulbar tracts pass?
Through cerebral peduncle of the midbrain
What are the white parts of the internal pons?
Remnants of corticospinal tract
What can be found in open medulla?
Cranial nerves, inferior cerebral peduncle, nuclear groups that project to cerebellum
Where do cranial nerve afferents arise from?
Ganglia
Where are second order sensory neurons located?
Cranial nerve nuclei
Which cranial nerves are only sensory?
I, II, VIII
Which cranial nerves are only motor?
III, IV, VI, XI and XII
Which cranial nerves are mixed?
V, VII, IX and X
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
At what level does spinal cord begin to become brainstem?
C2
Describe position of nuclei, midline to laterally, in the brainstem
Somatic motor (LMN)
Visceral motor (pre ganglionic parasympathetic)
Visceral sensory
Somatic sensory
Define cranial nerve nuclei
Columns of neurons associated with cranial nerves
What type of nerve is hypoglossal? What does it innervate?
Somatic motor
Internal and external tongue muscles
What type of nerve is spinal accesory? Where does it arise from?
Branchial motor
Arises from branchial motor neurons in spinal cord