Mechanism To Protect Spinal Cord

These flashcards cover key vocabulary and concepts related to the Nervous System as discussed in the A&P II lecture.

CNS

Central Nervous System, the part of the nervous system consisting of the brain and spinal cord.

Meninges

A system of membranes that surrounds the brain and spinal cord.

Ventricular System

The internal skeleton within the brain that includes fluid-filled spaces.

Circle of Willis

A specialized blood supply system for the brain that provides multiple pathways for blood to reach every part.

Blood-Brain Barrier

The structure of capillaries that protects the brain by limiting the substances that can enter its tissues.

CSF

Cerebrospinal Fluid, a fluid that cushions the brain and spinal cord.

Dura Mater

The outermost layer of the meninges that is tough and protective.

Arachnoid Mater

The middle layer of the meninges, which has a spider-web-like structure. ( arachnoid (meaning spider), which has connective tissue projections (“spider-web” like called trabeculae) that bind with pia)

Pia Mater

The innermost layer of the meninges that is tightly attached to the surface of the brain.

Mechanical force absorption

The mechanism by which most parts of the CNS are surrounded by bone to absorb impact.

Protective bone shape

The bone surrounding the brain is curved to help distribute and transfer force.

Bone trabeculae

Structures within the bone that assist in transferring mechanical force away from the brain.

Gap requirement

The necessary space between the bone and the brain that ensures force radiates rather than causing direct damage.

Fluid sac analogy

The meninges act like an airbag, occupying the gap between bone and brain to prevent contact and absorb force.

Pathogen

A type of bacteria or agent that can cause disease.

Meningitis

A potentially fatal condition caused by a bacterial pathogen entering the subarachnoid space.

PATD acronym

An acronym representing the three layers of the meninges in order: Pia, Arachnoid, Trabeculae,and Dura.

Connective tissue projections

The "spider-web" like structures in the arachnoid mater called trabeculae that bind with the pia mater.

What makes up the dura?

A combination of the periosteal membrane and the meningeal layer.

cohesion

The force holding the periosteal membrane and the dura together so they act as one unit against the skull.

Epidural space

The layer or space located between the dura mater and the skull.

Subdural space

The layer or space located between the dura mater and the arachnoid mater.

Subarachnoid space contents

The space between the pia and arachnoid mater which contains CSF (cerebrospinal fluid).

Arachnoid villi

Protrusions of the arachnoid membrane that act as valves for CSF to enter venous blood.

Dura Sinus

A sac filled with venous blood that acting as a gap between the bone and meninges.

CSF drainage condition

CSF pushes through into the blood only when the pressure of CSF is greater than the pressure of the blood.

High blood pressure effect

Excessive pressure in the dura sinus (e.g., during migraines) prevents CSF from draining, causing headaches.

Low CSF pressure effect

A state where the meninges shrink, often causing pain.

Lateral ventricles

The two largest ventricles (1 and 2) located deep within the cerebral hemispheres.

Third ventricle location

The fluid-filled space located between the thalamus and the hypothalamus.

Fourth ventricle location

The space situated underneath the cerebellum and above the brain stem.

Cerebral aqueduct

The structure that connects the 3rd and 4th ventricles.

Cerebral aqueduct blockage

An obstruction here causes CSF to get stuck in the lateral and 3rd ventricles, leading to pressurized fluid.

Choroid plexus

The structure inside each ventricle that constantly produces CSF, regardless of pressure.

Apertures

Openings in the ventricular system where CSF exits into the subarachnoid space.

Arachnoid granulations

Structures that drain CSF into the venous sinuses from the subarachnoid space.

Number of Dural Sinuses

There are 7 dural mater sinuses located on each side of the head.

Nature's artery count

To protect the brain and ensure survival, nature provides 4 main arteries to the brain rather than just one.

Circle of Willis purpose

To provide redundancy and ensure multiple blood sources can supply the entire brain if one or two vessels fail.

Anastomosis

The connection between blood vessels that enables the flow of blood from different sources.

Internal Carotid Arteries

Arteries that run up through the neck to the bottom of the brain to provide blood supply.

Vertebral Arteries

Arteries that run up through the transverse foramen of C1 to C7 to reach the brain.

Basilar Artery

The vessel formed by the joining of the two vertebral arteries.

Posterior Communicating Artery

The vessel that connects the basilar artery to the internal carotid arteries.

Anterior Cerebral Arteries

Branches of the internal carotid arteries that supply the medial and parietal lobes.

Anterior Communicating Artery

The vessel that connects the two anterior cerebral arteries.

Middle Cerebral Artery

The artery that supplies most of the lateral surface of the cerebral hemispheres.

Posterior Cerebral Arteries

Branches of the basilar artery that supply the medial and inferior surfaces of the occipital and temporal lobes.

Simple Squamous Cells

The type of cells that form the walls of the capillaries in the brain.

Tight Junctions

The specialized connections between capillary cells in the brain that eliminate gaps and protect against pathogens.

Closed System

The nature of capillary beds where materials can only enter or exit through regulated transport, not through gaps.

Glia role in BBB

Cells that cover the surfaces of capillaries to "cement" the blood-brain barrier closed.

Membrane permeability exception

Small lipids (like alcohol) can pass through the BBB because the plasma membrane is a phospholipid bilayer.

Facilitated diffusion in BBB

One of the primary ways non-lipid contents of blood leave the capillaries to enter brain tissue.

Definition of Redundancy

The presence of multiple ways or structures to achieve the same function, such as the Circle of Willis or excess neurons.

Vascular system goal

To deliver oxygen and nutrients to cells while removing waste products.

Capillary transport

The only site in the vascular system where the actual transport of materials can occur.

Spinal cord meninges attachment

Unlike the brain, the meninges of the spinal cord do not attach to the periosteum of the bone.

Meninges spinal extent

The protective membranes extend down to the level of S2.

Spinal cord extent

The actual neural tissue of the spinal cord typically ends at the level of L1.

What does high pressure in the subarachnoid space do to the meniges?

strechtes them

What does low pressure in the subarachnoid space do to the meniges?

shrinks them

What are the 4 internal chambers in the ventricular system connected by?

vascular shunts