week 5 - brainstem Flashcards
What is the caudal-most grey matter region in the spinal cord?
Conus medullaris at L2
Describe the posterior blood supply to the brainstem
- vertebral artery branches fuse to form basilar artery
- basilar artery branches off to supply many regions of brainstem and other structures
- at the level of pons: anterior inferior and superior cerebellar arteries
- midbrain: posterior cerebral arteries
What do the anterior inferior and superior cerebellar arteries supply?
Surface of the cerebellum
What do the posterior cerebral arteries supply?
Medial and inferior surface of the occipital and temporal lobes
What arises from the vertebral artery?
Posterior inferior cerebellar artery
What do the deep perforating vessels supply?
The brainstem
Describe the brainstem subdivision vasculature
- medial vessels supply medial parts of brain stem eg. Vertebral, spinal branches and basilar arteries
- lateral parts of brainstem and cerebellum supplied by longer vasculature (PICA, ACIA, SCA)
What does the posterior cerebral artery supply?
Occipital and temporal lobes
Which arteries supplies the cerebellum?
- Posterior + anterior inferior cerebellar artery
- Superior cerebellar artery
What are the functions of the brainstem?
- Conduit function
- cranial nerve functions
- integrative centres (reticular formation)
What is the conduit function of the brain stem?
brainstem facilitates ascending and descending pathways
What is the function of the cranial nerves?
- cranial nerves provide sensory input and motor output for the head
- provide parasympathetic motor output
- carry special senses and facilitate reflexes in collaboration with the brainstem
What is the function of the brainstem being a integrative centre? Reticular formation?
- mediation of autonomic control of respiratory and cardiovascular reflexes essential for survival (swallowing)
- modulation of somatic function via descending pathways and sensorimotor integration via cerebellum
Regulation of conscious states, and sensorimotor and cognitive functions via diffuse neuromodulatory system
What is the function of the mesencephalon?
- processing of visual and auditory data
- generation of reflexive somatic motor responses
- maintenance of consciousness
What is the function of the pons?
- relays sensory information to cerebellum and thalamus
- subconscious somatic and visceral motor centres
What is the function of the medulla oblongata?
What is the organisation of the brainstem like?
- brainstem is extension of spinal cord
- transition into brainstem at C2 and above
- sensory nuclei that were dorsal move laterally -> become more lateral and ventral
- motor nuclei that were more lateral, move medially
What does the superior colliculus entail?
Visual information
What does the inferior colliculus entail?
Auditory information
What do the middle and inferior cerebellar peduncle contain?
Most of cerebellar afferents
What can you see form a ventral view onto the spinal cord?
- cerebral peduncle
- basal pons
- pyramid
- olive
- > descending tracts are ventral eg/ corticospinal tract
What is the internal organisation of the midbrain like?
- corticospinal tract descends via cerebral peduncle
- colliculi present on dorsal side of midbrain
Via what structure does the corticospinal tract descend in the pons?
Peduncles
Via what structure does the corticospinal tract descends in the medulla?
Pyramids
What do the middle and inferior peduncles contain?
Ascending cerebellar afferents
What cranial nerves are purely sensory?
1,2,8
What cranial nerves are pure motory?
3,4,6,11,12
What cranial nerve are mixed sensory and motor?
5, 7, 9, 10
Where are the cranial nerves generally located?
Midbrain 2-4
Pons 5-7
Medulla 9-12
Are the sensory nerves and nuclei lateral or medial?
Lateral
Are the motor nerves and nuclei medial or lateral?
Medial
What are cranial nerve nuclei?
- afferent roots arise in cranial ganglia (except mesencephalic nucleus of V)
- sensory afferent roots synapse with second order (relay) neurons in the cranial nerve sensory nuclei within the brainstem
- motor efferent roots arise form cranial nerve motor nuclei
