4-Cranium, Meninges and Ventricles PDF

CRANIUM MENINGES AND VENTRICLES BIO336 Audrey Forbes-Cardinali, D.C. Mercyhurst University  THE SCALP & CRANIUM Serves as the outermost protective layers for the brain Scalp is its own mnemonic device Skin Connective tissue proper Aponeurosis (Galea aponeurotica) Loose ar...

CRANIUM MENINGES AND VENTRICLES BIO336 Audrey Forbes-Cardinali, D.C. Mercyhurst University  THE SCALP & CRANIUM Serves as the outermost protective layers for the brain Scalp is its own mnemonic device Skin Connective tissue proper Aponeurosis (Galea aponeurotica) Loose areolar connective tissue Uncoupling membrane – Clinical relevance Periosteum  THE CRANIUM Major foramina Foramen ovale Foramen spinosum Carotid Canal Jugular foramen Foramen magnum THE CRANIUM  CRANIAL FOSSAE Anterior cranial fossa Frontal lobe Middle cranial fossa Temporal lobe Posterior cranial fossa Cerebellum and brainstem  BRAIN COVERINGS Three layers known as meninges cover the brain and spinal cord Pia mater Arachnoid mater Dura mater Dura mater has two layers: Periosteal layer is bound to inner surface of skull Meningeal layer is fused with periosteal layer in places and folds away from periosteal layer to create dural reflections and dural venous sinuses Falx cerbri Attached to crista galli of ethmoid at anterior end Blends with the tentorium cerebelli at about the straight sinus Tentorium cerebelli Attached to the occiput and temporal bones laterally Create a supratentorial compartment and infratentorial compartment Falx cerebri Tentorium cerebelli  DURAL REFLECTIONS Falx cerebelli Vertical midline reflection of dura beneath the tentorium cerebelli that divides the cerebellar hemispheres. Diaphragm Sellae Is the smallest dural reflection which encases the pituitary gland within the sella turcica. A small aperture in the diphragma sella allows the stalk of the pituitary gland to pass though the diaphragma sellae. Empty saddle syndrome Tentorial incisura AKA tentorial notch U shaped passageway between compartments that houses the brainstem  ARACHNOID AND PIA MATER Both are composed of loose connective tissue Arachnoid remains ‘adhered’ to dura mater due to CSF pressure Pia mater adheres to surface of brain and cord, folding in and around each gyrus. It also surrounds vascular structures creating a perivascular space before fusing with the basement membrane of the vessel. The meninges from three spaces/potential spaces Epidural space Subdural space Subarachnoid space  EPIDURAL SPACE Potential space between cranial bones and periosteal layer of dural Middle meningeal artery and branches travel through this potential space Branch of external carotid artery that ascends through foramen spinosum  SUBDURAL SPACE Potential space between dura mater and arachnoid mater Bridging veins (Ex. Cortical veins) exist with the subdural space and drain into dural venous sinuses.  S U B D U R A L S PAC E AND VENOUS S T RU C T U R E S Potential space between dura mater and arachnoid mater Bridging veins (Ex. Cortical veins) exist with the subdural space and drain into dural venous sinuses. Dural sinuses exist between the layers of dura  SUB ARACHNOID SPACE Space filled with cerebrospinal fluid Cerebral arterial structures pass through this space Arachnoid granulations (AKA Arachnoid vili) are extension of the arachnoid mater that pass from this space through the meningeal layer of dura into dural venous sinuses THE VENTRICLES  THE VENTRICLES Lateral ventricles – within cerebral hemispheres Anterior horn Body Lateral horn Posterior horn Interventricular foramina of Munro – connect each lateral ventricle to third ventricle Third ventricle – between thalami and hypothalamus Cerebral aqueduct (of Sylvius) – within midbrain Fourth ventricle – within pons, medulla and cerebellum Central canal Lateral foramina of Luschka Median foramen of Magendie  CSF vNormal total volume is about 150 cc. vIt is produced by the choroid plexus at a rate of 20 cc/hour, or about 500 cc/day. vThe subarachnoid space widens in a few areas to form larger CSF collections called cisterns.