Cranium and brain Flashcards
Identify the different tissue components of the scalp
Skin - highly vascular, sweat glands, sebaceous glands, hair follicles
Connective tissue - supplied by cutaneous nerves, highly vascularised
Aponeurosis - membranous sheet
Loose connective tissue - not continuous with the pericranium, allows movement of the scalp
Pericranium - dense connective tissue continuous with the endocranium
Which parts of the brain sit in:
- Anterior cranial fossa
- Middle cranial fossa
- Posterior cranial fossa
Anterior - frontal
Middle - Temporal
Posterior - Cerebellum and brainstem
Layers of the meninges
Dura mater (periosteal outside and meningeal inside)
Arachnoid mater
Pia mater
What divides the 2 cerebral hemispheres
Falx cerebri
Falx cerebra is attached
Anteriorly to the ethmoid and frontal bones
Posteriorly it blends with the tentorium cerebelli
Tentorium cerebelli divides
cerebrum from cerebellum
Tentorium cerebelli is attached
Posteriorly to the occipital bone, laterally to the superior border of the temporal bone
The anterior and medial borders of the tentorium cerebelli are free and form an oval opening in the midline called the
Tentorial notch
What passed through the tectorial notch
midbrain
The subarachnoid space enlarges in certain areas called
subarachnoid cisterns
CSF is produced by
choroid plexus (where the vessels of the pia mater come into contact with the ependymal lining of the central canal)
Flow of CSF
Flows through ventricles - lateral –> 3rd –> aqueduct –> 4th –> central canal (v little actually flows through the central canal, most enters the subarachnoid space)
CSF returns to the venous system via the
arachnoid villi (project as arachnoid granulations into the superior sagittal sinus)
What is hydrocephalus and mechanisms
Dilatation of the cerebral ventricular system
Overproduction of CSF. Obstruction of flow of CSF. Failure to reabsorb CSF.
explain herniation
When a space occupying lesion (blood, tumour, oedema, cyst) causes a rise in intracranial pressure and causes the brain to shift cross structures within the skull
Types of herniation
Subfalcine (most common)
Uncal
Tonsillar
Subfalcine herniation
When innermost parts of the frontal lobe shifts under part of the falx cerebri
May interfere with blood vessels to the frontal lobe
Brain receives blood supply from:
Vertebral arteries and internal carotid arteries
The 2 vertebral arteries enter the cranial cavity through the….
they fuse just inferior to the …. to form the…
foramen magnum
fuse inferior to the pons to form the basilar artery
The internal carotid arteries enter the cranial cavity through the…
Carotid canals
Describe the venous drainage of the brain
Blood drains into the small venous channels, then into the larger cerebral, cerebellar and brainstem veins, then into the dural venous sinuses
what are the dural venous sinuses
endothelial lined spaces between the meningeal and periosteal layers of the dura mater
the dural venous sinuses lead to the
internal jugular veins
Superior sagittal sinus receives blood from
cerebral veins from the superior surface of the cerebral hemispheres, diploid and emissary veins and veins from the fall cerebri
Blood from the superior sagittal sinus drains
posteriorly
at the internal occipital protuberance it turns right to form the right transverse sinus
as the right transervse sinus passes the … it turns into the …
petrous temporal bone
sigmoid sinus
which 2 sinuses/veins join to form the straight sinus
inferior sagittal sinus and great cerebral vein
the straight sinus drains….and turns left at the …. to form the
posteriorly
internal occipital protuberance to form the left transverse sinus
The straight sinus receives blood from the
inferior sagittal sinus
cerebral veins
superior cerebellar veins
veins from the fall cerebri
which sinuses empty into the confluence of sinuses
superior sagittal
straight sinus
occipital sinus in the fall cerebra
what is the confluence of sinuses and where is it
a dilated space
at the internal occipital protuberance
the confluence of sinuses drains into
the left and right transverse sinuses
as the transervse sinuses leave the … bone they becomes the
occipital bone
sigmoid
the sigmoid sinuses end at the beginning of the
internal jugular veins
where are the paired cavernous sinuses
on the lateral aspect of the body of the sphenoid bone
the right and left sinuses lie either side of the pituitary fossa
cavernous sinuses receive blood from…
cerebral veins
emissary veins
ophthalmic veins
the cavernous sinuses communicate with the transverse sinuses and internal jugulars via
petrosal sinuses
Where do the diploid veins run?
Drain into
between the internal and external tables of compact bone in the roof of the cranial cavity
drain into dural venous sinuses
Emissary veins pass from to
from outside the cranial cavity into the dural venous sinuses
Why are the emissary veins important clinically?
they are a conduit for which infections can enter the cranial cavity because they have no valves
which vein acts as a conduit for infection from the face to the brain? What does it connect with?
Facial vein
with the cavernous sinus
What is the pterion? and its clinical significance?
The point where the frontal, temporal, parietal and sphenoid bones all meet on the lateral aspect of the skull
thinnest and weakest part of the skull
anterior division of the middle meningeal artery lies deep to the pterion - injury can cause extradural haemorrhage
severe damage can affect deeper branches of the MCA - subarachnoid haemorrhage
What goes through the cribriform plate?
Olfactory
What goes through the optic canal
Optic nerve
ophthalmic artery
What goes through the superior orbital fissure
Oculomotor Trochlear Trigeminal a - ophthalmic division Abducens superior ophthalmic vein
What goes through the foramen rotundum
Trigeminal b - maxillary division
What goes through the foramen ovale
Trigeminal c - mandibular division
What goes through the foramen spinosum
middle meningeal artery and vein
What goes through the carotid canal
internal carotid artery
What goes through the internal acoustic meatus
Facial
Vestibulocochlear
labyrinthine artery
What goes through the jugular foramen
Glossopharyngeal
Vagus
Accessory
What goes through the hypoglossal canal
Hypoglossal
What goes through the foramen magnum
Vertebral arteries
medulla of brain
spinal roots of accessory nerve
