Largest part of the brain. Divided sagitally into 2 hemispheres, held together/communicate by corpus collosum. Contains cerebral cortex and other subcortical structures. Separated into 4 lobes
Lobes of Cerebrum
Four main lobes: Frontal Parietal Temporal Occipital. Insula as a substructure folded deep within lateral fissure.
Flat, wide bundle of nerve fibers beneath the cortex. Largest white matter structure in the brain. Primary function is allowing communciation between the hemispheres. Interruption has significant loss of neural function
Groove/depression in cerebrum
Super deep sulcus. Main example: lateral fissue
Ridge on the cerebrum
Divided sagitally into two hemispheres, connected by vermis (look like worms!) allowing for communication between the hemispheres. Brain mass posterior to pons and medulla. Control fine motor movement
Allows cerebellum to communicate with rest of brain. Found at intersection of cerebellum with brainstem/pons/cortex
Comprised of midbrain, pons, and medulla oblongata. Midbrain above pons above medulla.
Rostral part of the brainstem. Composed of tectum and cerebellar peduncles (intersection of cerebellum and brainstem)
bulbous part anterior to the medulla
continues with the spinal cord at the foramen magnum
Which two pairs of arteries supply the brain?
Vertebral and internal carotid arteries.
Vertebral arteries unite at lower border of pons to form basilar artery. basilar artery lies in the median groove of the pons and branches to anterior inferior cerebellar arteries (one per side), pontine arteries, superior cerebellar arteries, and posterior arteries.
Anterior inferior arteries
spring from the lower part of the basilar at the junction of the medulla oblongata and the pons. Run laterally along the surface of pons to supply the inferior surface of the cerebellum
4-5 slender twigs which travel laterally from the basilar and supply the pons
Superior cerebellar arteries
Following the basilar artery forward you will see the superior cerebellar arteries springing from the basilar close to its termination. These branches ramify on the upper surface of the cerebellum
Posterior Cerebral artery
Terminal branch of basilar arteries. Note: This is to cerebrum (BIG BRAIN), not cerebellum.
Internal Carotid Arteries
Internal carotid arteries enter the skull through the carotid canal. Once inside the skull, they branch to: Posterior Communicating, Middle Cerebral, Anterior Cerebral.
Posterior Communicating Artery
Occasionally the posterior communicating can be seen arising from the middle cerebral.
Middle Cerebral Artery
Branch of Internal Carotid in brain
Anterior Cerebral Artery
Branch of Internal Carotid in brain. two anterior cerebral arteries disappear in the median longitudinal fissure Before entering the fissure they are joined to each other by the anterior communicating artery
Cerebral Arterial Circle
Circle of Willis, circulatory anastomosis that supplies blood to brain and surrounding structures
Lie internal to cranium, provide covering to brain. Support and protect brain. Enclose a fluid filled cavity: subarachnoid space.
Dura mater, arachnoid mater, pia mater
Cranial dura (unlike the spinal dura) is a two layered structure: External periosteal layer and internal meningeal layer. The internal layer of the dura separates from the external periosteal layer to form different folds and patterns.
External periosteal layer of Dura Mater
Also known as endocranium is formed by the periosteum
Internal meningeal layer of Dura Mater
Strong layer continuous at foramen magnum with the spinal dura
Middle layer, thin filamentous strands.
Innermost layer. Associates with brain
Only fluid filled space (normally). Below arachnoid membrain.
Small protrustions of arachnoid through dura mate. Protrude into venous sinuses of brain and allow CSF to exit the subarachnoid space and enter the blood stream. Consist of arachnoid villi that have one way valves
Structure of dura mater. Largest fold; sickle shaped. Lies in the longitudinal fissure separating the two cerebral hemispheres. Extends from the crista galli of the ethmoid bone anteriorly to the internal occipital protuberance of the occipital bone posteriorly At the posterior end it joins with the upper part of the tentorium cerebelli holding the tentorium up like a tent
Structure of dura mater. Separates occipital lobe from cerebellum. Attaches anteriorly at the clinoid process of sphenoid bone, laterally at the petrous part of the temporal bone, and posteriorly at the occipital bone. Its concave anterior border is free and allows the brain stem to pass through
Dural Venous Sinuses
Endothelial lined spaces between the periosteal and meningeal layers of the dura. Large veins from around the brain empty here. Venous blood coursing in the sinuses leaves the skull at the jugular foramen by draining into the internal jugular vein at the jugular bulb.
Superior Sagittal Sinus
In upper border of falx cerebri, begins at crista galli. Ends at confluence of sinuses
Confluence of sinuses
Located at the internal occipital protuberance of the occipital bone. Dilated junction for superior sagittal, straight, occipital and transverse sinuses
Inferior Sagittal Sinus
Located in the inferior free edge of the falx cerebri. Ends in the free margin of the tentorium cerebelli by emptying into the straight sinus
Located at the junction of falx cerebri and tentorium cerebelli. Drains into confluence of sinuses
Right and left transverse sinuses are a continuation of the superior and straight sinuses respectively. Follows the groove for transverse sinus and end at the petrous bone to become the sigmoid sinus
Form a s-shaped groove in the bone and empty at the JUGULAR FORAMEN, not confluence.
Lies in the attached border of falx cerebelli. Empties into confluence
Located bilaterally on each side of sella turcica. Receives blood from the superior and inferior ophthalmic veins and sphenoparietal sinus. If there was an infection in this area, that sinus could infect all the way back to brain because of reflux (no valves in sinuses)
Small sinuses that course along the lesser wing of the sphenoid bone
Superior Petrosal Sinus
Stretch between the cavernous and transverse sinuses
Inferior Petrosal Sinus
Commence at the cavernous sinus and drain into the jugular foramen
Connect dural venous sinuses with veins outside the skull
Blood supply to menninges
Menningeal arteries. Middle meningeal artery enters skull through the foramen spinosum to supply the dura
Nerve supply of menninges
Largely by the CN V (some from CN X and XII). Dura very sensitive to pain resulting from pressure changes
Centrolateral to brain, separates frontal lobe to parietal lobe
Separates Frontal, Parietal, and Temporal lobes.
Above corpus collosum, separates 2 hemispheres
Structure of dura mater.
Partly separates the cerebellar hemispheres
Small vertical dural folding in the posterior part of the posterior cranial fossa
Attached to the occipital bone