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Brainstem Medulla. David A. Morton, Ph.D. Jan 17 th , 2013. Objectives. 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. - PowerPoint PPT Presentation
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BrainstemMedulla
David A. Morton, Ph.D.Jan 17th, 2013
Objectives• 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
Alar
Basal
Sulcus limitans
Spinal cord
Som S
VS
VM
SM
Alar
Basal
Sulcus limitans
Medulla
Som S
VSVM
SMBM
The fate of the alar and basal laminae
• Why are brain stem sensory nuclei lateral
to motor nuclei in brainstem?
External anatomy:
• Pyramid
• Olive
• CNN VIII, IX, X, XI and XII
• Fourth ventricle
• Vertebral arteries
Medulla oblongata
IX & XXII
XI
VIII
Medulla
4 th vent.
O P
Horizontal section
O
P
Alar
Basal
Medulla
Som SVS
VMSM
BM
Sulcus limitans
Solitary nuclei and tract Spinal
trigeminal
nucleus
Hypoglossal
nucleus
Inf sal and dorsal vagal nuclei
Nucleus ambiguus
Medulla oblongata
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
• PICAPICA
Ant sp
Vert
Objectives
• 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 materArachnoid materPia mater
Cranial Meninges
Cere
bral
vv.
Dural Venous sinuses
Dura mater (2 layers in the skull)• Periosteal layer and Meningeal layer
• Dural venous sinus
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 hemorrhageTorn 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.
Dural Venous sinuses
What space is the artery located?
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
Subarachnoid space
Lateral ventricle
Lateral ventricle
Interventricular foramen
Foramen of Monro
3rd ventricle
Cerebral aqueduct
Aqueduct of Sylvius
Mesencephalic aqueduct
4th ventricle
Lateral apertures
Foramen of Luschka
Median apertureForamen of Magendie
Arachnoid granulationsSuperior sagittal sinus
Choroid plexus
Organize the following terms:
Subarachnoid space
Lateral ventricleLateral ventricle
Interventricular foramen Foramen of Monro
3rd ventricle
Cerebral aqueduct Aqueduct of Sylvius Mesencephalic aqueduct
4th ventricle
Lateral apertures
Foramen of Luschka
Median aperture
Foramen of Magendie
Arachnoid granulations
Superior sagittal sinus
Choroid plexus
The following terms are in order:
The ventricular systemThe 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
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Hydrocephaly
1. Obstructive (non-communicating) hydrocephalus. Block in the ventricular system or the outlet foramina.
Copyright © 2010 Pearson Education, Inc.
Hydrocephaly2. Communicating (non-
obstructive) hydrocephalus. Block in the subarachnoid space
or the arachnoid granulations.
Copyright © 2010 Pearson Education, Inc.
Figure 12.26a Formation, location, and circulation of CSF.
Superiorsagittal sinus
Arachnoid villus
Subarachnoid spaceArachnoid materMeningeal dura materPeriosteal dura mater
Right lateral ventricle(deep to cut)
Choroid plexusof fourth ventricle
Central canalof spinal cord
Choroidplexus Interventricularforamen
Third ventricle
Cerebral aqueductLateral apertureFourth ventricleMedian aperture
(a) CSF circulation
CSF is produced by thechoroid plexus of eachventricle.
1
CSF flows through theventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord.
2
CSF flows through thesubarachnoid space.
3
CSF is absorbed into the dural venoussinuses via the arachnoid villi.
4
1
2
3
4