Vascular System

What are the 3 protective layers of protective covering for the brain?

1. dura mater

2. arachnoid mater

3. pia mater

What is the dura mater?

• most superficial and consists of 2 layers

1. outer (periosteal/endosteal layer) is more inelastic than inner meningeal layer

2. outer layer (meningeal layer) only in cranium (not in the spinal cord) and contains meningeal arteries

   1. epidural space between the layers and intended to create sinuses (sinus = layers of dura are separated)

What is the dura mater split into?

• falx cerebri which is the portion down the longitudinal fissure wrapping between hemispheres of cerebrum

• falx cerebelli separates the 2 sides and wrapping of the cerebellum

• tentorium cerebelli which is a tent like shape that separates the cerebellum from the cerebrum

• diaphragma sella that comes under the brain just over the pineal gland

What is the arachnoid mater?

• middle layer that contains spider-like webbings and blood vessels pass through that space in the subarachnoid space

What is the pia mater?

• highly vascular that follows the contours of the brain and forms the choroid plexus in ventricles to help create CSF

Identify the layers

Identify the 2 structures of the dura mater here

4 = falx cerebri and 1 = falx cerebelli

Identify the 2 structures of the dura mater

Why is the vascular system important for the brain?

• brain has very little storage capacity for nutrients but needs glucose and oxygen, has a high metabolic rate, and brain doesn’t store energy (need specific amounts and proportions or else if affects function)

  • vascular system is central to keep the brain alive

What is the difference between arteries and veins?

• arteries = takes oxygenated blood from the heart and around the body

• veins = returns deoxygenated blood to the lungs and heart

• Note: every place there is an artery there is a vein

• capillaries = allows the communication between the arteries and veins (interface)

Posterior Supply vs. Anterior Supply

• posterior = providing blood to the back part of brain to the following structures: cerebellum, brainstem, occipital lobe, cochlea

• anterior = providing blood to the front part of the brain to the following structures: lateral and medial surfaces of frontal, parietal, temporal lobes, and retina

How does the posterior supply deliver blood?

• blood starts from the heart and goes up the aorta and you will either go to the right or left subclavian artery to cross over, goes up the vertebral arteries then it goes up to the basilar artery to merge at the base of the brain and then you have lots of options

  • you can split off into the pontine arteries to go to the pons

  • you can go to the posterior part of the cerebrum through the posterior cerebral artery to to the occipital lobe

  • you can also go to the cerebellum through cerebellar arteries like the posterior inferior cerebellar artery or you can go to the anterior inferior cerebellar artery

  • you can also go the superior cerebellar artery to go to the top of the cerebellum