Flashcards in The Brain Deck (23):
What are the major structures of the diencephalon?
- (diencephalon is one part of the prosencephalon; the other part, telencephalon, becomes the cerebral hemispheres)
- thalamus and hypothalamus (also the epithalamus and pineal body/gland)
Where is the insula?
- the insula is the part of the cortex that is hidden deep within the lateral sulcus
What are the major gyri and sulci of the brain surface?
- central sulcus (between frontal and parietal); pre- and post-central gyri
- lateral sulcus (between frontal/parietal and temporal); superior, middle, and inferior temporal gyri
What are the major gyri and sulci of the medial half of the hemisphere?
- parieto-occipital sulcus
- calcarine sulcus of occipital lobe
- cingulate gyrus (just above the corpus callosum)
What is located on the underside of the frontal lobes?
- the olfactory tracts (containing the olfactory nerves) and their terminal olfactory bulbs
- anterior half of the optic nerves
What is located on the underside of the hemispheres, between the two temporal lobes?
- the posterior half of the optic nerves, the optic chiasm, and the optic tracts (note that the optic tracts form the chiasm, from which the nerves extend)
- the pituitary gland (on the inferior surface of the optic chiasm)
- mamillary bodies (of the hypothalamus)
Explain the layout of the basal ganglia in relation to the thalamus.
- anterior to the thalamus and just lateral to the anterior horn of the lateral ventricle lies the large caudate nucleus (the head is anterior to the thalamus and the tail extends posteriorly, wrapping underneath the thalamus to lie just above the lentiform nucleus)
- just lateral to the caudate nucleus is the internal capsule, just lateral to this is the lentiform nucleus (putamen and globus pallidus)
- lateral to the lentiform nucleus is the external capsule, the claustrum, the extreme capsule, and then the insula (so we've hit the lateral edge of the cortex)
- (the amygdala is found on the tail of the caudate nucleus, which rests above the lentiform nucleus)
Describe the structure of the lateral ventricles.
- each lateral ventricle has an anterior horn (extending into frontal lobe), posterior horn (extending into occipital lobe), and inferior horn (extending down and forward into temporal lobe) forming a C shape that surrounds the 3rd ventricle
What separates the anterior horn of one lateral ventricle from the other?
- the septum pellucidum
What foramina are involved in the ventricular system?
- interventricular foramina of Monro (lateral ventricles flow into 3rd ventricle)
- foramina of Luschka (lateral aperture of 4th ventricle into SAS)
- foramen of Magendie (medial aperture of 4th ventricle into SAS)
Where is the 4th ventricle?
- 4th ventricle is located in the posterior portions of the pons and medulla (essentially between the brainstem and cerebellum, but being a part of the brainstem)
- the floor is made up of the dorsal aspects of the pons and medulla
- the walls are made up of the superior and inferior cerebellar peduncles
- the roof is essentially made up of the cerebellum and is where the apertures are found
What are choroid plexuses?
- these form CSF
- they are highly vascular fringes of tufts of pia mater covered in modified ependyma that project into the lateral, 3rd, and 4th ventricles
Which major arteries supply the brain?
- 2 internal carotid arteries (will form the middle and anterior cerebral arteries)
- 2 vertebral arteries (will form the posterior cerebral arteries)
What are the major branches of the posterior arterial system (the verterbrobasilar system)?
- posterior inferior cerebellar arteries
- posterior spinal arteries
- anterior spinal artery
- anterior inferior cerebellar arteries
- labrynthine arteries
- basilar artery
- pontine arteries
- superior cerebellar arteries
- posterior cerebral arteries
What are the major branches of the anterior arterial system (the carotid system)?
- middle cerebral arteries
- ophthalmic arteries
- posterior communicating arteries
- anterior choroidal arteries
- anterior cerebral arteries
- anterior communicating artery
What type of artery is the ophthalmic artery? What does this mean in terms of vision?
- this is an end-artery, meaning it doesn't have any collateral pathways
- this means that if the ophthalmic artery is occluded, blindness will definitely occur
Where do vertebral arteries arise from? What vertebral level do they enter the spinal column at?
- they are branches from the subclavian arteries
- they pass between C6 and C7, ascending in the transverse foramina of C6 to C2 before wrapping around and entering via the foramen magnum
What is the falx cerebri? The falx cerebelli?
- these are dural folds projecting into the brain, allowing for venous drainage
- (recall that there are two layers of dura mater: the outer periosteal layer and the inner meningeal layer)
- the falx cerebri is the much larger fold extending down into the longitudinal fissure
- the falx cerebelli projects between the cerebellar hemispheres
What is a 3rd major dural fold?
- the tentorium
- this is a horizontal dural fold that extends between the cerebral hemispheres and the cerebellar hemispheres
What are the major dural venous sinuses?
- the superior sagittal sinus (this is the main one involved with CSF drainage)
- the sigmoid sinus (continuation of the transverse sinus) and the inferior petrosal sinuses are responsible for most of the drainage; these form the internal jugular vein in the jugular foramen
Where are the thalamus and hypothalamus located?
- thalamus is below the corpus callosum; the two thalami are found on either side of the 3rd ventricle
- below and anterior to the thalamus is the hypothalamus (the pituitary gland extends from just below the hypothalamus)
Are the mammillary bodies part of the midbrain or the thalamus?
- anatomically, they are part of the midbrain
- functionally, they are part of the thalamus