gross brain overview: part i gross brain overview: part i basic neuroscience james h. baños, ph.d

Gross Brain Overview: Part IGross Brain Overview: Part I

Basic NeuroscienceBasic Neuroscience

James H. Baños, Ph.D.James H. Baños, Ph.D.

OverviewOverview

Anatomical DirectionsAnatomical Directions Cranial FossaCranial Fossa MeningesMeninges Pathology of the Cranial Fossa & Pathology of the Cranial Fossa &

MeningesMeninges

Anatomical DirectionsAnatomical Directions

Dorsal fin


Dorsal

Ventral


Dorsal

Ventral

Rostral

Rostrum = Stage or speaking platform

Caudal

Caudus = tail


Dorsal

Ventral

Rostral Caudal

Dorsal-ventral and rostral-caudal are with respect to the neuraxis


But wait……we evolved


But wait……we evolved…

Dorsal

VentralRostral

CaudalDorsal

Ventral

Ventral Dorsal

Rostral Caudal

Caudal


RostralCaudal

Caudal


Dorsal

Ventral

VentralDorsal


Anterior-posterior and superior-inferior are in 3-D spaceAnd do not respect the neuraxis.

Anterior

Anterior

Posterior

Posterior

Superior

Inferior Superior

Inferior


Medial-lateral can also respect either the midline, or some other reference point

Lateral

Medial

A

B


Mesial = Medial

Just to keep it interesting:


Proximal

Distal

Ipsilateral vs. ContralateralIpsilateral vs. Contralateral

Ipsilateral -- On the same side, with respect to Ipsilateral -- On the same side, with respect to a reference pointa reference point

Contralateral -- Opposite side, with respect to Contralateral -- Opposite side, with respect to a reference pointa reference point

Anatomical PlanesAnatomical Planes

Sagittal Plane

Horizontal/axial Plane

Transverse Section

Coronal Plane

Coronal PlaneCoronal Plane

Corona = crown….but think Statue of Liberty

Sagittal PlaneSagittal Plane

Sagittal MRI Mid-sagittal plane

Horizontal PlaneHorizontal Plane

AKA:AKA: Axial planeAxial plane CT planeCT plane

Cranial FossaCranial Fossa


Distinct areas of the skull baseDistinct areas of the skull base Contain and support various parts of the brainContain and support various parts of the brain Contact point for the meningesContact point for the meninges


Anterior cranial fossa -- frontal lobes

Middle cranial fossa -- Temporal lobes

Posterior cranial fossa -- Cerebellum and brain stem

Cranial fossa contain lumen, or holes forCranial fossa contain lumen, or holes forcranial nerves, arterial supply, and venous cranial nerves, arterial supply, and venous

drainagedrainage

MeningesMeninges

MeningesMeninges

Three layers covering the brainThree layers covering the brain Dura materDura mater ArachnoidArachnoid Pia materPia mater

Support, protectionSupport, protection Contain circulating CSF that supports the brainContain circulating CSF that supports the brain

MeningesMeninges

Dura MaterDura Mater

““Tough Mother”Tough Mother” Thick, leathery outer coveringThick, leathery outer covering Adheres to inner surface of skullAdheres to inner surface of skull Support, and forms sinus system (veinous Support, and forms sinus system (veinous

drainage)drainage) Pain sensitivePain sensitive Has own blood supply -- Has own blood supply -- Middle meningeal Middle meningeal

arteryartery

ArachnoidArachnoid

Spongy/fibrous layer between the dura and piaSpongy/fibrous layer between the dura and pia Collagenous connective tissueCollagenous connective tissue Keep brain suspended in meningesKeep brain suspended in meninges

Subarachnoid spaceSubarachnoid space Contains CSFContains CSF

Pia MaterPia Mater

Innermost layerInnermost layer Adheres almost indistinguishably to cortical Adheres almost indistinguishably to cortical

surface, including sulci and gyrisurface, including sulci and gyri Difficult to see grossly or removeDifficult to see grossly or remove

Dura MaterDura Mater

Dura MaterDura MaterMiddle meningeal artery

ArachnoidArachnoid

Pia and arachnoid together are sometimes Pia and arachnoid together are sometimes referred to as the referred to as the leptomeningesleptomeninges

CSF flows between the arachnoid and pia in CSF flows between the arachnoid and pia in the the subarachnoid spacesubarachnoid space

Dural ReflectionsDural Reflections

Dural ReflectionsDural Reflections

Also called Also called dural septadural septa In certain places, the dura doubles on itself and In certain places, the dura doubles on itself and

forms a division or partition between parts of forms a division or partition between parts of the brainthe brain Falx cerebriFalx cerebri Tentorium cerebelliTentorium cerebelli

Falx CerebriFalx Cerebri

Extends down the longitudinal fissure, Extends down the longitudinal fissure, between the cerebral hemispheresbetween the cerebral hemispheres

Forms the triangular-shaped superior sagittal Forms the triangular-shaped superior sagittal sinus superiorlysinus superiorly

Falx CerebriFalx Cerebri

Tentorium CerebelliTentorium Cerebelli

Extends inward between the cerebellum and Extends inward between the cerebellum and occipital lobesoccipital lobes

Forms a “soft top” for the posterior cranial Forms a “soft top” for the posterior cranial fossafossa

Brain stem passes through Brain stem passes through tentorial notchtentorial notch Forms the Forms the transverse sinustransverse sinus posteriorly posteriorly

Tentorium CerebelliTentorium Cerebelli

Pathology of the Pathology of the MeningesMeninges

MeningitisMeningitis

Infection/inflammation of the meningesInfection/inflammation of the meninges BacterialBacterial ViralViral

Can progress toCan progress to More widespread CNS infectionMore widespread CNS infection Hydrocephalus, if flow of CSF is blocked (e.g., Hydrocephalus, if flow of CSF is blocked (e.g.,

purulent accumulation)purulent accumulation)

BleedsBleeds

Epidural HematomaEpidural Hematoma Rupture of middle meningeal arteryRupture of middle meningeal artery Blood accumulates between dura and skullBlood accumulates between dura and skull

Mass effect compresses brainMass effect compresses brain Fed by Fed by arterialarterial perfusion…can grow quickly perfusion…can grow quickly

BleedsBleeds

Epidural HematomaEpidural Hematoma

Masseffect

Midlineshift

BleedsBleeds

Subdural HematomaSubdural Hematoma Rupture of bridging veins from surface of cortex to Rupture of bridging veins from surface of cortex to

veinous sinuses (e.g., superior sagittal sinus)veinous sinuses (e.g., superior sagittal sinus) Accumulates more slowly (veins)Accumulates more slowly (veins) Still results in mass effect and compression of the Still results in mass effect and compression of the

brainbrain Older people particularly susceptible. Why?Older people particularly susceptible. Why?

BleedsBleeds

Subdural Hematoma -- crescent shapedSubdural Hematoma -- crescent shaped

BleedsBleeds

Subdural HematomaSubdural Hematoma

BleedsBleeds

Subarachnoid HemorrhageSubarachnoid Hemorrhage Rupture of cerebral vein or arteryRupture of cerebral vein or artery Bleeding into the subarachnoid spaceBleeding into the subarachnoid space Blood hugs the surface of the brain (i.e., within the Blood hugs the surface of the brain (i.e., within the

subarachnoid space). No mass effectsubarachnoid space). No mass effect Can block flow of CSF and result in Can block flow of CSF and result in

hydrocephalus hydrocephalus

BleedsBleeds

Subarachnoid HemorrhageSubarachnoid Hemorrhage

Herniation SyndromesHerniation Syndromes

subfalcine cingulate herniationsubfalcine cingulate herniation Cingulate gyrus herniates below falx cerebriCingulate gyrus herniates below falx cerebri


Uncal/Transtentorial HerniationUncal/Transtentorial Herniation Uncus (medial temporal lobe) herniates medially over the Uncus (medial temporal lobe) herniates medially over the

edge of the tentorium cerebelli into the brain stemedge of the tentorium cerebelli into the brain stem


Tonsilar HerniationTonsilar Herniation Cerebellar tonsil herniates through the foramen magnumCerebellar tonsil herniates through the foramen magnum

Coming up next…Coming up next…

OrganizationOrganization Developmental/EvolutionaryDevelopmental/Evolutionary MorphologyMorphology

3-D Orientation to Internal 3-D Orientation to Internal StructuresStructures

gross brain overview: part i gross brain overview: part i basic neuroscience james h. baños, ph.d

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