Neuro 3: Brainstem and Cranial nerves Flashcards
Define the Brainstem
- The part of the CNS exclusive of the cerebellum that lies between the cerebrum and the spinal cord.
What are the major divisions of the brainstem?
major divisions:
- Medulla oblongata
- Pons
- Midbrain
Area with 4 lumps at top = roof of the ________
Area with 4 lumps at top = roof of the midbrain
The pons = the flood of the __th ventricle
The pons = the flood of the 4th ventricle
What structures are in the midline of the brainstem?
What are their function?
Pineal gland
- releases melatonin
- important in regulating th circadian rhythm
Superior Colliculus
- important in coordination of eye + head movements at the same time
Inferior Colluiculus
- auditory reflexes
what is the ONE cranial nerve that emerges from the BACK of the brainstem?
- Trochlear Nerve (CN IV)
- supplies superior oblique muscle of eye
Dorsal Columns are involved in what 2 main sensory pathways?
- touch
- Proprioception
What are the 4 functional subtypes of the cranial nerves?
(Functional Classification I)
What are they responsible for?
- General Somatic Afferent (GSA)
- -> sensation from skin + mucous memb - General Visceral Afferent (GVA)
- -> sensation from GI tract, heart, vessels + lungs - General Somatic Efferent (GSE)
- -> muscle for eyes + tongue movements - General Visceral Efferent (GVE)
- -> preganglionic parasympathetic
What are the 3 functional Classification II
special…..
- Special somatic afferent
- -> vision, hearing + Equilibrium - Special Visceral Afferent
- -> Smell + taste - Special Visceral efferent
- -> Muscles involved in chewing, facial expression, swallowing, vocal sounds + turning head.
In the embryonic spinal cord,
information goes into the spinal cord via the _____ _____ and leaves the spinal cord via the _____ _____
In the embryonic spinal cord,
information goes into the spinal cord via the DORSAL ROOT and leaves the spinal cord via the VENTRAL ROOT
NOTE: cranial nerve nuclei = arranged in functional columns
-
Describe the appearance of the midbrain
- mickey mouse shaped
- inferior colliculus = low down in the midbrain
What is the substantial nigra ?
substantia nigra = dopaminergic neurones
what do substantia nigra do in normal metabolism?
- they produce neuromelanin
- which is a pigment
- that is black
- as you go through life, it gets darker and darker
What happens in parkinson’s disease in relation to substantia nigra?
in parkinson’s disease
- you lose dopaminergic neurones
- so pale substantia nigra = sign of parkinson’s disease
Pons is in the region of the ___th ventricle
just underneath the ____
Pons is in the region of the 4th ventricle
just underneath the cerebellum
What is the most obvious feature of the Pons?
- transverse fibres
What holds the cerebrum onto the brainstem?
- the cerebral peduncles
and what holds the cerebellum onto the back of the brainstem?
- The cerebellar peduncles
What is the main peduncle of the pons?
- main peduncle = middle cerebellar peduncle.
What is the main feature of the medulla ?
- pyramids start to be seen
- inferior olivary nucleus (bulge on side of medulla)
- -> connected to cerebellum
- -> involved in fine tuning motor movements
dorsal columns can be seen in the lower medulla
- smaller of columns = _____
what does it do? - laterally you have ______
- crossing over of fibres at _______ ______ in the lower medulla
dorsal columns can be seen in the lower medulla
- smaller of columns = GRACILIS
- -> sensory info from lower limb
- laterally you have CUNEATUS
- -> sensory information from upper limb
- crossing over of fibres at PYRAMIDAL DECUSSATION in the lower medulla
What is lateral medullary syndrome caused by:
- caused by thrombosis of vertebral artery or posteriori inferior cerebellar artery
What is lateral medullary syndrome?
- thrombosis of vertebral artery/ posterior inferior cerebellar artery
causes
- vertigo
- ipsilateral cerebellar ataxia
- -> problem with gait on same side of body as lesion
- ipsilateral loss of pain/thermal sense (face)
- horner’s syndrome (loss of sympathetic innervation to head + neck)
- contralateral loss of pain/thermal sense in trunk + limbs
Lateral Medullary Syndrome:
Disturbing the vestibular nucleus causes –>
Disturbing the inferior cerebellar peduncle –>
disrupting sympathetic tract –>
Damage to spinothalamic tract –>
Lateral Medullary Syndrome:
Disturbing the vestibular nucleus causes –> VERTIGO
Disturbing the inferior cerebellar peduncle –> BALANCE PROBLEM
disrupting sympathetic tract –> HORNER’S SYNDROME
Damage to spinothalamic tract –> DAMAGE TO PAIN / SENSORY INFO
What is the function of the cerebral peduncle?
- cerebral peduncle has fibre tracts
- and it also holds cerebral cortex onto the brainstem.
What is the pyramid decussation?
- anatomical basis for contralateral control / crossing over of neurons
