Brain, blood, cranial meninges Flashcards
What are the three parts of the brain stem?
- medulla oblongata
- pons
- midbrain
What are the parts of the diencephalon?
- thalamus
- hypothalamas
What are the general parts of the brain?
- brainstem
- cerebellum
- diencephalon
- telencephalon(cerebral hemispheres)
What are the parts of the medulla?
- anterior median fissure
- pyramids
- olive
- Pre-olivary sulcus
- retro-olivary sulcus
- medullopontine sulcus
Anterior median fissure
- part of medulla
- continuous inferiorly with anterior median fissure of the spinal cord
Pyramids
- part of medulla
- two longitudinal columns
- one on each side of the anterior median fissure
Olive
- part of medulla
- oval elevation lateral to upper part of pyramid
Pre-olivary sulcus
- located between olive and pyramid
- attachment of rootlets of hypoglossal nerve (CN XII)
Retro-Olivary sulcus
- Located posterior to olive
- attachment of rootlets of glossopharyngeal nerve (CNIX), Vagas nerve(CNX)
- the nerves are in line with accessory nerve on spinal cord
Medullopontine sulcus
-divides medualla and pons Nerves attach medial to lateral -Abducens(CN VI) -Facial Nerve(CN VII) -Vestibulocochlear (CN VIII)
Pons
- basilar artery lies in midline groove
- attachment of trigeminal nerve (CN V) on anterior surface
Midbrain
- cerebral crura (white motor tracts): two columns of descending fibers
- attachment of oculomotor nerve (CN III) to medial border of cerebral crura
4th ventricle
-cavity between cerebellum(posterior) and pons/upper medulla(anterior)
how would you view the posterior surface of the brain stem?
-remove cerebellum by cutting 3 pairs of cerebellar peduncles that connect the cerebellum to the brainstem
Rhomboid fossa
- the only hole in an otherwise closed cranial system
- in 4th ventricle
what are the four elevations that mark the posterior surface of the midbrain?
- 2 superior colliculi
- 2 inferior colliculi
superior colliculi
- posterior surface elevations on midbrain
- visual system
Inferior colliculi
- posterior surface elevations on midbrain
- auditory system
what is the only cranial nerve attached to posterior surface of the brain stem?
- trochlear nerve (CN IV)
- emerges immediately below inferior colliculi
what separates the right and left cerebral hemispheres?
- longitudinal fissure
- separation is INCOMPLETE
- at the bottom of the fissure, there are large bundles of fibers that connect the hemispheres
What keeps the right and left hemispheres connected?
- large bundle of fibers located at the bottom of the longitudinal fissure
- called Corpus Callosum
How many lobes does each hemisphere have and name them.
- 5
- frontal
- parietal
- temporal
- occipital
- insular
Central sulcus
-separates frontal and parietal lobes
Lateral sulcus
-separates temporal lobe from frontal and parietal lobes
Where is the insular lobe?
-deep to lateral sulcus
What arteries supply the brain?
- vertebral artery
- internal carotid artery
Vertebral artery
- branch of 1st part of subclavian artery
- enters through foramen magnum
Basilar artery
- right and left vertebral arteries join at medulloponitine sulcus to form this
- runs along anterior midline of pons and then divides into right and left posterior cerebral arteries
Vertebral and basilar arteries supply what?
- spinal cord
- brainstem
- cerebellum
- posterior parts of cerebral hemisphere
Internal carotid artery
- begins at bifurcation of common carotid artery at upper border of thyroid cartillage
- divided into 4 parts(cervical, petrous, cavernous, cerebral)
Cervical part of internal carotid artery
-from origin to base of the skull
Petrous part of internal carotid artery
-within carotid canal in petrous parts of temporal bone
Cavernous part of internal carotid artery
-within cavernous sinus
Cerebral part of internal carotid artery
- after it exits cavernous sinus, to its termination
- divides into anterior and middle cerebral arteries at termination
Internal carotid artery BRANCHES
4
- ophthalmic artery
- posterior communicating artey
- anterior cerebral artery
- middle cerebral artery
Ophthalmic artery
- branch of internal carotid artery
- enters orbit via optic canal with optic nerve
posterior communicating artery
-connects internal carotid artery and posterior cerebral artery
Anterior cerebral artery
-right and left anterior cerebral arteries are connected to each other by anterior communicating artery
Cerebral arterial circle
- circle of willis
- formed by large cerebral arteries and their interconnections on ventral surface of brain
- serves as a potential vascular shunt to help circulation if one of the proximal vessels is blocked
Components of the circle of willis
- anterior communicating arteries
- anterior cerebral arteries
- internal carotid artery
- posterior communicating artery
- posterior cerebral artery
Contents of the cavernous sinus
-posterior communicating artery
-internal carotid artery
-From superior to inferior…
CN III,IV,VI, ophthalmic nerve, maxillary nerve
Borders of the cavernous sinus
- optic chiasm
- sphenoidal sinus
- hypophysis(pituitary gland)
Layers of the dura mater of the brain
Periosteal/endosteal(outer layer)-covers the inner surface of skull bones
Meningeal(inner layer)-dura mater proper, faces brain
-closely united, except where they separate to form dural venous sinus
Dural venous sinus
-venous blood channels lined by epithelium
Dural septa
- formed by meningeal layer
- Flax Cerebri
- sickle-shaped fold that lies in midline between right and left cerebral hemispheres
- basically a pull down of dura
Internal carotid artery BRANCHES
4
- ophthalmic artery
- posterior communicating artey
- anterior cerebral artery
- middle cerebral artery
Ophthalmic artery
- branch of internal carotid artery
- enters orbit via optic canal with optic nerve
posterior communicating artery
-connects internal carotid artery and posterior cerebral artery
Anterior cerebral artery
-right and left anterior cerebral arteries are connected to each other by anterior communicating artery
Cerebral arterial circle
- circle of willis
- formed by large cerebral arteries and their interconnections on ventral surface of brain
- serves as a potential vascular shunt to help circulation if one of the proximal vessels is blocked
Components of the circle of willis
- anterior communicating arteries
- anterior cerebral arteries
- internal carotid artery
- posterior communicating artery
- posterior cerebral artery
Contents of the cavernous sinus
-posterior communicating artery
-internal carotid artery
-From superior to inferior…
CN III,IV,VI, ophthalmic nerve, maxillary nerve
Borders of the cavernous sinus
- optic chiasm
- sphenoidal sinus
- hypophysis(pituitary gland)
Layers of the dura mater of the brain
Periosteal/endosteal(outer layer)-covers the inner surface of skull bones
Meningeal(inner layer)-dura mater proper, faces brain
-closely united, except where they separate to form dural venous sinus
Dural venous sinus
-venous blood channels lined by epithelium
Dural septa
- formed by meningeal layer
- Flax Cerebri
- sickle-shaped fold that lies in midline between right and left cerebral hemispheres
- basically a pull down of dura
Tentorium cerebelli
- crescent-shaped fold that roofs over posterior cranial fossa
- separates cerebellum from occipital lobes of cerebral hemisphere
Flax cerebelli
-small sickle shaped fold in posterior cranial fossa that projects between right and left cerebral hemispheres
Diaphragma sellae
-small circular fold that forms roof of stella turcica(where pituitary stalk sits)
Dural venous sinuses
- located between inner and outer layers of dura mater
- receive blood from brain as well as cerebrospinal fluid from subarachnoid space
- blood collected by dural benous sinuses drains ultimately into internal jugular veins
superior sagittal sinus
- runs along upper border of flax cerebri
- begins at foramen cecum
- terminates in confluence of sinuses
Inferior saggital sinus
- runs along lower, free border of flax cerebri, joins great cerebral vein to form straight sinus
- TAKES BLOOD TO CONFLUENCE OF SINUS
Straight sinus
- runs in midline, along junction of flax cerebri and tentorium cerebelli
- terminates posteriorly in confluence of sinuses
- TAKES BLOOD TO CONFLUENCE OF SINUS
transverse sinus
- takes blood from confluence of sinuses to temporal bone
- becomes continuous with sigmoid sinus
Sigmoid sinus
- direct continuation of transverse sinus
- terminates in jugular foramen and becomes continuous wih internal jugular vein
occipital sinus
- small sinus that runs along posterior border of falx cerebelli
- ends superiorly in confluence of sinuses and inferiorly communicates with internal vertebral venous plexus
cavernous sinus
- in middle cranial fossa, one on each side of the sella turcica
- drains contents of orbit, cerebral hemisphere, pituitary gland, and sphenoparietal sinus
- internal carotid artery and abducens nerve are inside
- drained posterioly by superior and inferior petrosal sinuses
superior petrosal sinus
- runs along superior border of petrous part of temporal bone
- connects cavernous sinus with terminal part of transverse sinus
Inferior petrosal sinus
- runs along inferior border of petrous part of temporal bone
- connects cavernous sinus with internal jugular vein
- DIRECT ROUTE
Sphenoparietal sinus
- small sinus that runs along posterior borner of lesser wing of sphenoid
- drains into cavernous sinus
