Unit 5: Lecture 2 (Cranial Meninges, Ventricles, Cerebrospinal Fluid, & Brain Basics)

Dura mater

What is the outermost, toughest, and most fibrous of the meninges?

Periosteal and meningeal layers

What are the two layers of the dura mater?

Periosteal layer

What layer of the dura mater is adherent to the inner surface of the skull and functions as the

cranial periosteum?

Meningeal layer

What layer of the dura mater is in contact with the underlying arachnoid mater and continues

inferiorly with the spinal dura mater?

Arachnoid mater

What is the delicate, avascular membrane that lines the inner surface of the dura mater? It does not closely follow the contours of the brain but bridges over its sulci.

Arachnoid mater

What is separated from the pia mater by the subarachnoid space, which contains CSF, arteries, and veins?

Arachnoid trabeculae

What is composed of collagenous fibers and extend through the subarachnoid space to the pia, effectively suspending the brain in CSF?

Pia mater

What is the thin, vascular connective tissue layer that adheres tightly to the surface of the brain, following its contours into sulci and around gyri?

Epidural space

What is the potential space between the periosteal dura and the inner table

of the skull? It does not exist under normal circumstances but may become a real space in

trauma, often due to arterial bleeding (e.g., middle meningeal artery rupture).

Subdural space

What is the potential space located at the dura-arachnoid junction? This space can become actualized in pathologies such as subdural hematoma due to tearing of bridging veins.

Subarachnoid space

What is the true space located between the arachnoid and pia mater? It contains CSF and many arteries and veins. Clinically, it is accessed during procedures like lumbar puncture (in the spinal region) and can be a site of hemorrhage in conditions such as subarachnoid hemorrhage.

Epidural (extradural) homatoma

What type of hematomas occur between the skull and periosteal dura mater? They are usually the result of trauma that causes rupture of the middle meningeal artery, often due to a temporal bone fracture.

Brief loss of consciousness, a lucid interval, then rapid neurological deterioration.

What does epidural (extradural) hematoma typically present with?

Subdural (Dural Border) Hematoma

What type of hematomas occur between the dura and arachnoid mater at the dural border cell layer? They are typically caused by tearing of bridging veins that traverse this space en route to the dural venous sinuses.

Subdural (Dural Border) Hematoma

What type of hematoma is more common in older adults due to brain atrophy, which stretches the bridging veins, increasing susceptibility to rupture from minor head trauma? Symptoms may develop insidiously over hours, days, or even weeks

CT

What type of imaging is used for hematomas?

Falx cerebri

What is the largest dural reflection? It is a sickle-shaped vertical partition that descends in the longitudinal fissure between the cerebral hemispheres. It attaches anteriorly to the crista galli of the ethmoid bone and posteriorly blends with the tentorium cerebelli.

Falx cerebelli

What is the small vertical dural fold located inferior to the tentorium cerebelli? It partially separates the two cerebellar hemispheres and attaches to the internal occipital crest. The occipital sinus runs in its posterior margin.

Tentorium cerebelli

What is the broad, crescent-shaped dural fold that separates the occipital lobes of the cerebrum above from the cerebellum below? It attaches to the clinoid processes anteriorly, the petrous ridges laterally, and the internal occipital crest and transverse sinuses posteriorly.

Transtentorial (uncal) herniation

What type of herniation can compress the oculomotor nerve (CN III), resulting in a fixed, dilated pupil on the affected side?

Sellar diaphragm

What is the small circular dural fold that forms the roof of the sella turcica? It covers the superior aspect of the pituitary gland and contains an aperture for the infundibulum (pituitary stalk) to connect the gland to the hypothalamus.

Dural venous sinuses

What are endothelial-lined spaces between the periosteal and meningeal layers of the dura mater?

Superior sagittal sinus→ Confluence of sinuses→ Transverse sinus→ Sigmoid sinus→ Internal jugular vein

What is the primary drainage pathway (superior sagittal route)?

Inferior sagittal sinus→ Straight sinus → Confluence of sinuses → Transverse sinus → Sigmoid sinus → Internal jugular vein

What is the alternate midline drainage pathway (inferior sagittal route)?

Cavernous sinus→ Superior petrosal sinus → Transverse sinus → Sigmoid sinus → Internal jugular vein OR → Inferior petrosal sinus → Internal jugular vein

What are the cavernous sinus drainage pathways?

Superior and inferior ophthalmic veins and sphenoparietal sinus

What are the major inputs to the cavernosus sinus?

Middle meningeal; maxillary

The primary arterial supply to the cranial dura mater is via branches of the _____ _____ artery, which is a branch of the _____ artery (a terminal branch of the external carotid artery).

Middle meningeal artery

What artery is vulnerable at the pterion, a thin area where multiple skull bones meet? Trauma here may rupture the artery, causing an epidural hematoma that can rapidly increase intracranial pressure.

Tentorial nerve, a branch of Ophthalmic divison of trigeminal nerve CN V1

What is the cranial dura primarily innervated by?

Lateral ventricles

What are the paired C-shaped ventricles located in each cerebral hemisphere; consist of anterior, posterior, inferior horns and a central body? They communicate with the third ventricle via the interventricular foramina (of Monro).

Third ventricle

What is the narrow midline cavity in the diencephalon bordered by the thalami?

It receives CSF from both lateral ventricles.

Cerebral aqueduct

What is the narrow channel in the midbrain connecting the third and fourth ventricles? It is the most common site for congenital obstruction.

Fourth ventricle

What is located between the pons and cerebellum, it receives CSF from the cerebral aqueduct? CSF exits the ventricular system through median and lateral apertures into the subarachnoid space.

Choroid plexuses in the lateral ventricle - interventricular foramina - third ventricle - cerebral aqueduct - fourth ventricle - median aperture and paired lateral apertures - subarachnoid space - dural venous sinuses - superior sagittal sinus

What is the CSF flow pathway?

Hydrocephalus

What refers to the abnormal accumulation of cerebrospinal fluid (CSF) in the ventricular system of the brain?

Overproduction of CSF, obstruction of CSF flow, and impaired absorption of CSF

What are the three man mechanisms of hydrocephalus?

Headache, nausea, vomiting, and papilledema.

What may increased intracranial pressure due to hydrocephalus cause?

Macrocephaly, bulging fontanelles, and developmental delays.

What may be caused in infants due to increased intracranial pressure from hydrocephalus?

Communicating

What type of hydrocephalus is more common in adults and may present with headache, ataxia, or urinary incontinence?

Longitudinal fissure

What divides the brain into two hemispheres?

Central sulcus

What divides the frontal and parietal lobes?

Lateral sulcus

What divides the temporal lobe from the frontal and parietal lobes?

Rostral

What term is used to mean toward the frontal pole in the brain?

Caudal

What term is used to mean toward the occipital pole in the brain?

Gray matter

What type of matter consists of neuronal cell bodies, unmyelinated axons, dendrites, and glial cells?

Cerebral cortex and cerebal nuclei

What are the two regions in which gray matter is found?

White matter

What type of matter is is composed mostly myelinated axons organized into fiber tracts?

Projection, commissural, and association fibers

What are the 3 types of white matter fibers?

Projection fibers

What type of white matter fibers connect cortex with subcortical structures, brainstem, and spinal cord?

Commissural fibers

What type of white matter fibers connect corresponding cortical areas between hemispheres (e.g., corpus callosum)?

Association fibers

What type of white matter fibers connect regions within the same hemisphere?

Pia mater

What meninge adhered directly to the brain?