Medical Gross Anatomy
Anatomy Tables - Brain Structures

Meningeal Structures & Spaces; Ventricular System

Structure Description Significance
arachnoid mater thin layer, pressed against inner surface of the dura mater by cerebrospinal fluid pressure arachnids are spiders, the space deep to this layer has a spider web-like appearance
meninges three layers of tissue covering brain & spinal cord - dura mater, arachnoid mater, & pia mater
dura mater two types described which differ in structure "tough mother"; it is the most durable of the meninges and provides support and protection for the brain and spinal cord
dura mater, cranial outermost covering of the brain, described as 2 layers: periosteal outer layer and meningeal inner layer dural venous sinuses lie between layers of the cranial dura; meningeal layer forms folds that help to support brain: falx cerebri & cerebelli, tentorium cerebelli
dura mater, spinal outermost covering of the spinal cord, it forms the dural sac containing the spinal cord within vertebral canal dural sac ends at S2, coccygeal ligament (filum terminale externum) continues inferiorly to attach to coccyx
epidural space surrounds dural sac within vertebral canal contains epidural fat & internal vertebral plexus of veins
subarachnoid space between archnoid mater & pia mater it contains cerebrospinal fluid and cobweb like filaments
pia mater lies on surface of the brain & spinal cord "delicate mother", it is the most delicate of the meninges, it has 2 specializations: denticulate ligament & filum terminale internum
denticulate ligament a lateral extension of pia mater from the spinal cord it attaches to the dura mater to anchor spinal cord; forms a scalloped free border; there are 2 (one on each side)
filum terminale internum inferior extension of pia mater from the conus medullaris of the spinal cord it becomes enclosed within the filum terminale externum
filum terminale externum inferior extension of the dura mater below the end of the dural sac at S2 it attaches to the coccyx; also known as the coccygeal ligament
ventricle, lateral paired spaces within cerebral hemispheres drain cerebrospinal fluid to third ventricle via interventricular foramina
ventricle, third midline space within diencephalon between paired dorsal thalami, above hypothalamus communicates rostrolaterally with paired lateral ventricles via interventricular foramina, communicates posteroinferiorly with fourth ventricle via cerebral aqueduct
ventricle, fourth midline space between cerebellum posteriorly and pons and upper medulla anteriorly communicates anterosuperiorly with third ventricle via cerebral aqueduct, drains CSF via median aperature and lateral aperatures
choroid plexus vascular membranes within the ventricles that produce cerebrospinal fluid
tela choroidea double layer of pia mater from which project the choroid plexi of the third and fourth ventricle
interventricular foramina paired communications between paired lateral ventricles and the third ventricle a.k.a. foramina of Monro
cerebral aqueduct canal connecting third and fourth ventricles, passing through midbrain a.k.a. aqueduct of Sylvius
median aperature midline, irregular foramen draining fourth ventricle posteroinferiorly into cerebellomedullary cistern a.k.a. foramen of Magendie
lateral aperature paired foramina draining fourth ventricle laterally into cerebellomedullary cistern a.k.a. foramina of Luschka
central canal of medulla canal through lower medulla, continuous above with fourth ventricle, continuous below with central canal of spinal cord
pontine cistern subarachnoid cistern anterior to lower pons and upper medulla
interpeduncular cistern subarachnoid cistern anterior to cerebral peduncles
cerebellomedullary cistern subarachnoid cistern inferior to cerebellum and posterior to medulla receives CSF from fourth ventricle via lateral & median aperatures
lumbar cistern subarachnoid cistern inferior to conus meullaris, superior to end of dural sac at S2 contains cauda equina; site of lumbar puncture for CSF sample
falx cerebri cresent-shaped sagittally-oriented fold of dura mater lying between cerebral hemispheres
falx cerebelli small, cresent-shaped sagittally-oriented fold of dura mater lying between cerebellar hemispheres
tentorium cerebelli tent-like sheet of dura mater covering of cerebellum, oriented somewhat transversely midbrain passes through tentorial notch
diaphragma sellae dura mater forming roof of hypophyseal fossa pierced by stalk of hypophysis
arachnoid granulations projections of arachnoid mater through dura into superior sagittal sinus, to drain CSF

Gross Features of the Brain & Spinal Cord

Structure Description Significance
forebrain a.k.a. prosencephalon comprises telencephalon or cerebral hemispheres and diencephalon; site of origin of cranial nerves I & II; contains lateral & third ventricles
midbrain a.k.a. mesencephalon connects forebrain & hindbrain; site of origin of cranial nerves III & IV; contains cerebral aqueduct
hindbrain a.k.a. rhombencephalon comprises metencephalon or pons & cerebellum and myelencephalon or medulla oblongata; site of origin for cranial nerves V-XII (except spinal part of accessory nerve); contains fourth ventricle
diencephalon caudal portion of prosencephalon/forebrain comprises thalamus, metathalamus, subthalamus, epithalmus; contains third ventricle
telencephalon rostral part of prosencephalon/forebrain comprises cerebral hemispheres & basal ganglia; contains lateral ventricles
mesencephalon a.k.a. midbrain
metencephalon rostral part of rhombencephalon comprises pons & cerebellum
myelencephalon caudal part of rhombencephalon comprises medulla oblongata
rhombencephalon a.k.a. hindbrain
cerebral hemispheres a.k.a. telencephalon comprises: cortex featuring gyri, sulci, fissures & lobes; commisures connecting parts; basal ganglia; contains lateral ventricles; origin of cranial nerve I - olfactory
longitudinal fissure midline, sagittal cleft separating the paired cerebral hemispheres
sulcus, lateral separates frontal lobe and temporal lobe insula lies in floor
sulcus, central separates frontal and parietal lobes, and also precentral gyrus (motor) from postcentral gyrus (sensory)
lobe, frontal rostral to central sulcus comprises prefrontal (emotions, personality) & precentral (1st somatomotor) areas
lobe, parietal separated from frontal lobe by central sulcus, separated from occipital lobe by line through parieto-occipital sulcus comprises 1st & 2nd somatosensory areas
lobe, occipital posterior to line through parieto-occipital sulcus comprises primarily visual cortex
lobe, temporal separated from frontal lobe by lateral sulcus primarily concerned with hearing
gyrus, precentral most posterior gyrus of frontal lobe; lies rostral to central sulcus part of somatomotor cortex
gyrus, postcentral most rostral gyrus of parietal lobe; lies posterior to central sulcus comprises the primary somatosensory cortex
medulla oblongata a.k.a. myelencephalon; most caudal portion of brainstem continuous with spinal cord at foramen magnum; upper portion forms floor of fourth ventricle; site of origin for cranial nerves IX, X, XI (cranial root), & XII
brain stem comrpises midbrain, pons & medulla oblongata
pons anterior portion of metencephalon site of origin of cranial nerves V, VI, VII & VIII; forms part of anterior wall of fourth ventricle
pyramids paired paramedian elevations on anterior surface of medulla; separated by anterior median fissure contain pyramidal tracts
olives paired elevations lateral to pyramids of medulla contain olivary nuclei
cerebellum posterior part of metencephalon largest part of hindbrain; important for coordination of movement
horizontal fissure dorsolateral fissure of cerebellum separates cerebellum into superior & inferior surfaces
cerebellar peduncle, inferior connects cerebellum to medulla
cerebellar peduncle, middle connects cerebullum to pons
cerebellar peduncle, superior connects cerebellum to pons
cerebral peduncle largest part of midbrain; divided into crus cerebri & tegmentum by substantia nigra connects forebrain with hindbrain
crus cerebri part of cerebral peduncle connects forebrain with hindbrain
superior colliculi paired elevations of midbrain tectum part of corpora quadrigemina; important for reflex movements of eye, head & neck
inferior colliculi paired elevations of midbrain tectum part of corpora quadrigemina; important for auditory reflexes
pineal gland a.k.a. pineal body represents an endocrine gland attached to diencephalon
mamillary bodies paired elevations caudal to tuber cinereum & infundibulum of hypophysis
corpus callosum midline part of great cerebral commissure connects paired cerebral hemispheres
anterior median fissure midline fissure on anterior surface of spinal cord & medulla anterior spinal artery lies superficially in fissure
posterior median sulcus midline furrow on posterior surface of spinal cord
posterolateral sulcus furrow posterolaterally on spinal cord at entrance of dorsal rootlets posterior spinal arteries lie superficially
conus medullaris tapered end of spinal cord at vertebral level L2
cauda equina "horse's tail", collection of dorsal & ventral rootlets in lumbar cistern between vertebral levels L2 & S2
spinal nerve point at which dorsal & ventral rootlets meet, and dorsal & ventral primary rami diverge; located at intervertebral foramen 31 pairs of spinal nerves - 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal


Note: This table presents brain and spinal cord anatomy used in the typical gross anatomy course.


The material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest & Jaye Schlesinger
Published by ILOC, Inc., New York
Copyright © 1995, unauthorized use prohibited.
 The excellent editorial assistance of
Dr. Pat Tank, UAMS
is gratefully acknowledged.
Copyright© 2000 Thomas R. Gest, PhD Unauthorized use prohibited.