Transcript Brainstem (Medulla), Brain vasculature & Ventricular system

Brainstem
Medulla
David A. Morton, Ph.D.
Jan 17th, 2013
Objectives
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Describe the trajectory of the cranial nerves, their components, and their
functions
Identify and locate the CN’s associated with the medulla, the pons and the
midbrain.
Explain how cranial nerves differ from spinal nerves
List the cranial nerves that contain parasympathetic fibers, the location of their
nuclei, and their function
Recognize the major internal and external landmarks on the dorsal and ventral
surface of the brain stem, so that you can determine if a gross or stained cross
section is medulla, pons or midbrain.
Identify on a typical cross section all the brain stem nuclei containing motor
neurons that end on striated muscle.
Explain why cranial nerves are so important in localizing lesions.
Name reflexes that test these nerves and brain stem levels.
Relate branches of the vertebrobasilar blood supply to the medulla and pons
explaining the deficits that would occur with vascular occlusion.
Internal anatomy of brainstem
The fate of the alar and basal laminae
• Why are brain stem sensory nuclei lateral
Alar
Sulcus
limitans
Som S
VS
VM
SM
to motor nuclei in brainstem?
BM
Basal
Medulla
Som S
Alar
Sulcus
limitans
VS
VM
SM
Basal
Spinal cord
Medulla oblongata
External anatomy:
• Pyramid
• Olive
• CNN VIII, IX, X, XI and XII
• Fourth ventricle
• Vertebral arteries
VIII
O
Medulla
P
Horizontal section
IX & X
XII
XI
O
P
Medulla oblongata
Solitary nuclei
and tract
Som S
Alar
VS
VM
SM
BM
Basal
Medulla
Nucleus
ambiguus
Medulla Oblongata
Hypoglossal nucleus (CN XII)
• Somatic motor
• Comparable to ventral horn
• Tongue muscles
Medulla Oblongata
Dorsal motor nucleus (CN X)
• Visceral motor
• Comparable to lateral horn
• Origin of preganglionic
parasympathetic neurons
Medulla Oblongata
Inferior salivatory nucleus (CN IX)
• Visceral motor
• Comparable to lateral horn (can
not see it on brains)
• Origin of preganglionic
parasympathetic neurons to otic
ganglion
Medulla Oblongata
Nucleus ambiguus (CN IX and X)
• Branchial (spec visc) motor
• Origin of BM neurons for IX and X
Medulla Oblongata
Reticular formation
• Forms the central core of brain stem
• Nuclear groups not obvious
Medulla Oblongata
Vascular supply:
• Vertebra artery
•Anterior spinal artery
PICA
• PICA
Vert
Ant sp
Objectives
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Explain what the meninges cover and what spaces they surround.
For each meningeal space describe a classic source for blood in the space.
Describe where CSF is produced and how it circulates and is removed.
Name the most likely sites of obstruction of CSF circulation and the
consequences.
• Explain how the Blood Brain Barrier is different from the CSF Brain interface.
Cranial Meninges
Dura mater
Arachnoid mater
Pia mater
Cranial Meninges
Dura mater (2 layers in the skull)
• Periosteal layer and Meningeal layer
• Dural venous sinus
Dural
Venous
sinuses
Meningeal hemorrhages
Blood in meningeal spaces or potential spaces
1.
Epidural hemorrhage
2.
Subdural hemorrhage
3.
Subarachnoid hemorrhage
Epidural space
Dura mater
• Middle meningeal artery
Epidural hemorrhage
Torn middle meningeal a.
Epidural hemorrhage
Subdural space
Dura mater
• Bridging cerebral vein
• Courses between cerebrum
and dural venous sinus
Subdural hemorrhage
Torn bridging cerebral v.
What space is the artery
located?
Dural
Venous
sinuses
Brain arteries – Subarachnoid space
Internal carotid artery (ICA)
• Ophthalmic
• Anterior cerebral
• Middle cerebral
Vertebral artery
• PICA
• Basilar
• AICA
• SCA
• Posterior cerebral
Cerebral arterial circle of Willis
• Anterior communicating
• Anterior cerebral
• ICA
• Posterior communicating
• Posterior cerebral
Subarachnoid hemorrhage
Stroke
Organize the following terms:
Cerebral aqueduct
Lateral ventricle
4th ventricle
Arachnoid granulations
Superior sagittal sinus
Lateral apertures
3rd ventricle
Subarachnoid space
Aqueduct of Sylvius
Foramen of Magendie
Median aperture
Foramen of Monro
Interventricular foramen
Foramen of Luschka
Choroid plexus
Lateral ventricle
Mesencephalic aqueduct
The following terms are in order:
Choroid plexus
Lateral ventricle
Interventricular foramen
Lateral ventricle
Foramen of Monro
3rd ventricle
Cerebral aqueduct
Aqueduct of Sylvius
4th ventricle
Lateral apertures
Foramen of Luschka
Median aperture
Foramen of Magendie
Subarachnoid space
Arachnoid granulations
Superior sagittal sinus
Mesencephalic aqueduct
The ventricular system
The ventricles, lined by ependymal cells, are obvious internal landmarks, and are
important as internal structures to relate other structures to. Try to visualize them and
rotate them with the brain. They will form the “wire frame” for our orientation to the
brain.
The ventricular system
The ventricular system
Hydrocephalus is dilation of all or part of the ventricular system due to
obstruction of CSF flow. There are two types:
1. Obstructive (non-communicating) hydrocephalus. Block in the ventricular
system or the outlet foramina.
2. Communicating (non-obstructive) hydrocephalus. Block in the subarachnoid
space or the arachnoid granulations.
a. Meningitis followed by scarring.
b. Subarachnoid hemorrhage, meningeal fibrosis and scarring
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Hydrocephaly
1. Obstructive (noncommunicating) hydrocephalus.
Block in the ventricular system or
the outlet foramina.
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Hydrocephaly
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2. Communicating (nonobstructive) hydrocephalus.
Block in the subarachnoid space
or the arachnoid granulations.
Figure 12.26a Formation, location, and circulation of CSF.
Superior
sagittal sinus
4
Choroid
plexus
Arachnoid villus
Interventricular
foramen
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater
1
Right lateral ventricle
(deep to cut)
Choroid plexus
of fourth ventricle
3
Third ventricle
Cerebral aqueduct
Lateral aperture
Fourth ventricle
Median aperture
Central canal
of spinal cord
(a) CSF circulation
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1 CSF is produced by the
choroid plexus of each
ventricle.
2 CSF flows through the
ventricles and into the
subarachnoid space via the
median and lateral apertures.
Some CSF flows through the
central canal of the spinal cord.
3 CSF flows through the
subarachnoid space.
4 CSF is absorbed into the dural venous
sinuses via the arachnoid villi.