Coverings of the CNS, the Ventricular System and Blood Supply

ANHB2217

Neurocranium

Viscerocranium

Neurocranium = cranial bones enclosing the brain

Viscerocranium = facial bones enclosing/supporting viscera

What are cranial fossa

Name the cranial fossa and their location

AMPF

Depression at the bottom of the skull

Anterior cranial fossa- frontal lobes

Middle cranial fossa- temporal lobes

Posterior cranial fossa- brainstem and cerebellum

Foramen magnum- medulla becomes spinal cord

Other foramen present for cranial nerves (Cribriform plate-olfactory)

Label the bones

What do cranial meninges do

Hold and protect CNS

What are the 3 meningeal layers

DASP and their roles

Dura mater- tough fibrous membranes

• Falx cerebri, tentorium cerebelli- adhere to the skull, contains folds that separate the lobes of the brain, surrounds CNS and SC, ensures tight fit to prevent movement of brain

Arachnoid mater- soft translucent, avascular

Subarachnoid space- contains CSF produced from choroid plexus

Pia mater- microscopically small and highly vascular

Dura mater

FFT

Identify the two folds of the three in the diagram

Falx cerebri-separates the two cerebral hemispheres

Falx cerebelli- separates the two cerebellum hemispheres

Tentorium cerebelli- separates the cerebellum from the cerebrum

Superficial veins vs deep veins

In subarachnoid space eg cerebral veins

Drain the internal structures of the forebrain eg great cerebral vein

Name the 6 dural venous sinuses

Superior sagittal

Inferior sagittal

Straight

Confluence of sinuses

Transverse

Sigmoid

Identify roughly where the superior sagittal sinus, inferior sagittal sinus, straight sinus, transverse sinus, and confluence of sinuses are located

Identify where the transverse sinus, confluence of sinuses and straight sinus would be

How does deoxygenated blood drain from the brain

Inferior sagittal sinus drains to straight sinus which with superior sagittal sinus and occipital sinus drains to the confluence of sinuses

These drain into the 2 transverse sinuses which drain to the two sigmoid sinuses which drain to the 2 internal jugular vein (2 for left and right)

Identify the superior sagittal, inferior sagittal and straight sinuses

Which veins do the neck and face drain from?

Neck- internal, external and anterior jugular veins

Face- mainly internal jugular veins

Where is CSF created and by what cells?

What cells regulated entry of blood to the brain?

Epithelial cells of the choroid plexuses create CSF

Endothelial cells of blood-brain barrier regulate the entry of blood to the brain

Where are choroid plexuses found?

lateral, 3rd and 4th ventricle space

Description of ventricular system

A set of interconnected “spaces/cavities” that circulate cerebrospinal fluid (CSF)

CSF flow pathway

Most CSF exits through what

Choroid plexus, lateral ventricle, interventricular foramen (foramen of Monro), 3rd ventrile, cerebral aqueduct (aqueduct of Sylvius), 4th ventricle, CSF leaves via the 2 lateral (foramina of Luschka) and 1 median aperture (foramen of Magendie) of 4th ventricle and enter subarachnoid space

Most CSF exits through median aperture → cistern magna (between the cerebellum and medulla)

Identify the lateral, 3rd and 4th ventricles

Draw roughly where the lateral, 3rd and choroid plexus would sit

CSF circulates around what and how is it reabsorbed

What happens with age

CSF circulates around the CNS and is reabsorbed mostly at the superior sagittal sinus via arachnoid villi

With age the arachnoid villi become hypertrophic and are called granulations

Hydrocephalus and how it’s caused

Communicating and non-communicating: how they’re caused, examples and side effect of non-communicating

Caused by abnormal buildup of CSF within the ventricular system

Communicating (nonobstructive) -impaired CSF reabsorption w/o obstruction

• Ex. Impairment of arachnoid villi

Non-communicating (obstructive) -obstruction of CSF

• Notable side effect: Chiari malformation- downward displacement of cerebellum through foramen magnum

• Ex. Tumour in the cerebral aqueduct

Brian is supplied by which two vessels?

Carotids terminate into what 2 arteries?

Internal carotid arteries and vertebral arteries

Carotids terminate into the anterior and middle cerebral arteries

Vertebral arteries converge where to create what artery and what 2 arteries does this artery terminate into

Medulla/pons to create basilar artery

Basilar artery gives rise to many arteries before terminating into the superior cerebellar arteries and posterior cerebral arteries

Anterior cerebral artery, middle cerebral artery and posterior cerebral artery stroke symptoms

Anterior cerebral artery stroke symptoms

• Loss of smell (anosmia): olfactory bulb and tract

• Weakness or paralysis of lower limb: motor cortex

Middle cerebral artery stroke symptoms

• Speech impairments/aphasia: Broca’s & Wernicke’s

• Weakness or paralysis of the face and upper limb: motor cortex

Posterior cerebral artery stroke symptoms

• Cortical blindness: occipital lobe

• Face blindness (prosopagnosia): temporal lobe

Identify what arteries supply these regions

Identify what arteries supply these regions

Identify what arteries supply these regions