1. CNS structures Flashcards
What are the 3 membranes that envelope the brain and spinal cord
Meninges: outer to innermost
- dura mater
- Archnoid mater
- Pia Mater
Dura Mater Reflections
Dural Reflections:
Falx cerebri: crescent shaped piece of dura that splits R and L hemispheres. The superior attachment is attached to the skull and the inferior is free floating
Tentorium Cerebelli: a tent over the cerebellum (horizontal- it splits the occipital lobes and the cerebellum) the anterior portion forms the tentorial incisure/notch and allows the brainstem to connect to the spine
Falx cerebelli: a vertical dural infolding that lies inferior to the cerebellar tentorium in the posterior part of the posterior cranial fossa, partially separates the cerebellum
Diaphragma sella: the smallest dural infolding- a circular sheet of dura suspended between the clinoid process makes a roof over the hypophysial fossa- covers the pituitary
Dural venous sinuses
separation of dura that allows for filling of venous blood
Superior Sagittal- superior portion of falx cerebri (drains the superior portion of the cerebrum)
Inferior Sagittal- inferior portion of falx cerbri (drains the blood from falx and medial cerebrum)
Straight sinus- attaches the conflunce and the inf sagittal
Transverse- lines the tentorium cerebelli
Sigmoid- continuation of the transverse sinus in the medial portion,
Cavernous sinus- edges of the most medial meshwork of veins continuation of superior petrosal
The transverse sinus splits superiorly into a minor superior petrosal (rides along the top of petrosal portion) and a major but short sigmoid which then splits off an inferior petrosal which collects from cavernous and the continuation of the sigmoid is the internal jugular vein
Brain herniation syndromes
- subFALCine: Cingulate gyrus gets pushed under falx cerebri to other side
- Central: brain stem and all brain gets pushed down into foramen magnum
- Transtentorial: medial temporal lobe thru tentorial notch
- Tonsillar: cerebellar tonsils pop thru foramen magnum
Arachnoid Mater
Does not dip into sulci and fissures except in falx and tentorium areas
The CSF in subarachnoid space
Arachnoid villi/granulations return CSF to venous circulation by projecting pieces of arachnoid and subarachnoid space that project into dural venous sinuses to reabsorb CSF
pia mater
final layer of meninges- faithfully follows contours of brain. Forms a perivascular sheath, separates subarachnoid space from the perivascular spaces (Virchow-Robin Spaces)
lateral ventricles
frontal/anterior horn- anterior section (fingers)
body- central part (palm)
temporal/inferior horn- thumb
occipital/posterior horn- arm
atrium- wrist
Interventricular foramen of monroe, 3rd ventricle, cerebral aqueduct of sylvius, fourth ventricle, central canal of spinal cord
Apertures
interventricular foramen of monroe: transports the lateral ventricles CSF to the 3rd ventricle
Third ventricle: floods the Thalamus with CSF
Cerebral aqueduct of sylvius: connects the 3rd ventricle with the 4th ventricle
Fourth ventricle: in the cerebellum, diamond shaped, the top point and bottom points are the superior and inferior medullary velums respectively, The 2 foramen of lushcka (lateral apertures) jut out of the middle of the ventricle and the medial aperture akaka the foramen of magendi is closer to the bottom
central canal of spinal cord accepts the CSF from the 4th ventricles and the choroid plexus secretes CSF in each ventricle
Septum pellucidum and corpus callosum and fornix
septum pellucidum is a thin membrane separating the anterior horns of the left and right lateral ventricles of the bran and connects the corpus callosum and the fornix
Corpus callosum: thick bundle of nerve fibers that connect the left and right cerebral hemispheres largest white mater structure of the brain
The fornix is the bottom part of the corpus callosum
sulcus vs fissure vs gyrus
Brodmanns Areas
sulcus: a small groove of the surface of teh brain
(Sulcus=Small)
Fissure: deep furrow or cleft
Gyrus: a bump on surface of cerebrum
Brodmanns areas: maps the cerebral cortex based on the cellular architecture
major fissures and sulci
Sagittal/longitudinal fissure: deep groove that separates the 2 hemispheres
Lateral Sulcus (sylvian fissure): divides the top of brain from the temporal lobe
Central Sulcus of Rolando: separates frontal and parietal lobe, divides the primary motor cortex (precentral gyrus on the frontal lobe) and the primary somatosensory cortex (postcentral gyrus on the parietal lobe)
Cingulate sulcus: separates the top of brain from the cingulate gyrus (seen in the midsagittal view)
Parietooccipital sulcus: separates pareital and occipital lobes (also seen on the midsagittal vieW)
Calcarine fissure: separates the most bottom portion of the occipital lobe (perpindicular to the parietooccipital sulcus)
Frontal lobe
Function: higher cognitive functions, judgments, controls voluntary movements, MOTOR area for speech
Precentral gyrus: primary motor cortex
superior Frontal gyri: premotor/ suplementary motor cortex
Middle frontal gyri: premotor/ suplementary motor cortex
Inferior frontal gyri: 3 parts
Orbital (by the rostral end - eyes)
Triangular- middle portion, on the left hemisphere serves as Brocas area (speech broduction)
opercular- adjacent to the precentral sulcus also contributes to Brocas in the left side
Orbital gyri: look for the the H on the inferior side of the frontal lobe, splits up the medial, anterior, post, lateral orbital gyri
The olfactory sulcus splits the gyrus rectus (most medial adjacent to longitudinal fissure) and the medial orbital gyrus
anterior paracentral lobule: portion of pre central gyrus on the inside of the midsagittal view
parietal lobe
conscious sensation- temp, pressure, touch, pain
association cortices
Postcentral sulcus and gyrus: primary sensory cortex, Brodmans 3,1,2
Intraparietal sulcus, directly adjacent and perpindicular to postcentral sulcus, splits the superior parietal lobule and inferior parietal lobule
Superior parietal lobule: spatial orientation
Inferior parietal lobule: anterior gyrus: supramarginal gyrus and the posterior portion is the angular gyrus
Precuneus: medial surface of parietal lobe that is adjacent to the parietoocipital sulcus
Posterior paracentral lobule: medial surface of the postcentral gyrus
Temporal lobe
function: comprehension of language
separated from top of brain by the lateral cerebral fissure (sylvian)
Three gyri on cerebral view, Superior (primary auditory cortex, Wernikes Area). middle and inferior
Lateral occipitotemporal/fusiform gyrus: the inferior temporal gyrus wraps around the inferior portion on the inferior side and the middle portion of the temporal lobe is the fusiform gyrus
Around the center of the brain is the parahippocampal gyrus and posterior to that is the lingual gyrus
The very end of the temporal lobe is the temporal pole
occipital lobe
Vision and interpretation of visual images
Preoccipital notch- 5cm in front of occipital pole on the infero lateral border, where the ocipital lobe and the temporal lobe meet
on the medial side is the calcarine sulcus which separatees the cuneus and the lingula gyrus
the striate cortex is the very back of the occipital lobe and is the primary visual cortex, Brodmanns 17
