Week 1 and 2: The Brain and Environs Flashcards
CNS: Forebrain
cerebral cortex, subcortical structures (basal ganglia, thalamus, hypothalamus)
CNS: Midbrain
midbrain and cerebral peduncles
CNS: Hindbrain
pons, cerebellum and medulla (brainstem)
What does “Lateral” mean?
away from the midline
What does “Medial” mean?
towards the midline
WHat are foramina/foramen?
The holes within the skull are called foramina, and these allow blood vessels, nerves, and the spinal cord to exit the skull compartments within the skull. The vertebral column also has these holes to allow nerves to pass through
Foramen MAgnum
a. The foramen magnum is the largest foramen in the skull and is where the spinal cord exits the skull cavity
b. The foramen magnum is also the point at which the medulla, which is at the base of the brainstem, ends and the spinal cord begins
What are fossa? 3 types + components?
The grooves within the skull create compartments, called fossa, with each forming a base for the lobes of the brain. Both cerebral hemispheres have these grooves in the skull
- ANterior cranial fossa (frontal lobe)
- Middle cranial fossa (temporal lobe)
- Posterior cranial fossa (cerebellum and brainstem)
3 layers of the meninges?
- Dura
- Arachnoid
- Pia
Dura
this tough, fibrous layer is comprised of two distinct layers: an outer periosteal layer that adheres to the skull and an inner meningeal layer
Dura: Exceptions where the outer layer stays attached to the skull and the inner layer folds away are:
the falx cerebri and the falx cerebelli (at the tentorium cerebelli)
where does the Falx cerebri occur?
Falx cerebri – this occurs at the longitudinal fissure that separates the two hemispheres
where does the Tentorium cerebelli occurs and what does it divide?
Tentorium cerebelli – this occurs over the cerebellum
- The tentorium cerebelli divides the posterior fossa, which contains the brainstem and cerebellum, from the rest of the cranial cavity
What is the tentorial incisura?
There is a hole in the tentorium cerebelli, called the tentorial incisura, that allows the brainstem to “pass through” into the foramen magnum
What is the Arachnoid layer?
Arachnoid – is a wispy, “spidery” layer that is attached to the inner layer of the dura. The cerebrospinal fluid (CSF) flows in this layer and blood vessels exit here as well
- subarachnoid space
What is the Pia?
- This innermost meningeal layer is formed from a very thin layer of cells. Unlike the other layers, this layer follows the gyri and sulci of the brain very closely.
- Blood vessels from the arachnoid space need penetrate through the pia to get to the brain
- The pia very closely wraps around these blood vessels at the site of penetrance
Hemorrhage
bursting of a blood vessel that causes blood to leak out
Hematoma
A collection of blood outside of a blood vessel
Aneurysm
enlargement of a blood vessel. This can lead to a leaking of blood, a hemorrhage, if the vessel breaks. If the blood pools outside of the vessel, a hematoma can develop
EPidural space
between the skull and the dura. The middle meningeal artery supplies the dura in this space. This is oxygenated blood.
Middle Menigeal Artery
supplies the dura in the epidural space. This is oxygenated blood.
Subdural space
– between the inner layer of the dura and the arachnoid. Innervation of this space by blood vessels is as follows:
Bridging veins dural venous sinuses sigmoid sinuses jugular vein
Blood vessels in Subdural space
Innervation of this space by blood vessels is as follows:
Bridging veins dural venous sinuses sigmoid sinuses jugular vein
Subarachnoid space + components
– between the arachnoid and the pia (more likely to get hemorrhage)
Contains CSF and major arteries