Medical Gross Anatomy
Anatomy Tables - Brain Structures
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Medical Gross Anatomy |
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Meningeal Structures & Spaces; Ventricular System |
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| 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 | |
| Structure | Description | Significance |
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| 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. |
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| Copyright© 2000 The University of Michigan. Unauthorized use prohibited. |
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