Lecture 10 - Intracranial Anatomy Flashcards
What two parts make up the neurocranium?
Cranial vault/calavaria (top) & Cranial base (bottom)
How does the cranial vault form?
intramembranous ossification
How does the cranial base form?
endochondral ossification
What makes up the viscerocranium?
face & mandible
What two types of bone comprise the cranial vault?
Compact bone: hard, inner & outer layers
Diploe: middle, spongy bone
Cranial sutures
Fibrous joint held together by Sharpey’s fibers (collagen type III)
Sutural (wormian) bones
small, irregular bones that develop within sutures
Emissary veins
external veins that drain through diploic veins to internal dural sinuses
Dural sinuses
A potential route of infection from the scalp into the cranial cavity
What are the 4 paranasal sinuses & the cells that act as another “sinus”
Frontal, ethmoidal, sphenoidal, maxillary (antrum)
mastoid air cells
Semilunar hiatus
Drains frontal, maxillary, and anterior ethmoidal sinuses into the nasal cavity
Where do the posterior ethmoidal and sphenoidal sinuses drain into?
The nasopharynx
What nerve runs through the maxillary sinus?
maxillary nerve (2nd branch of trigeminal CN V)
What are the 3 meningeal layers?
Dura mater, arachnoid mater, pia mater
What is the order of the tissue layers on the cranium?
Skin, periosteum, bone, dura mater, arachnoid mater, pia mater
What artery supplies the meninges?
middle meningeal artery branch from the maxillary artery
What is the modality & innervation of the meninges in the anterior & middle cranial fossae?
GSA, Trigeminal (CN V)
What is the modality & innervation of the meninges in the posterior cranial fossa?
GSA, Glossopharyngeal (CN IX), Vagus (CN X), & C1-C3
What structures does the dura mater form?
The folds around the parts of the brain including: tentorium cerebelli & falx cerebri
What sinuses do the dural folds contain?
Dural sinuses
Falx cerebri
Separates the left and right cerebral hemispheres
Tentorium cerebelli
Separates the cerebrum and cerebellum
What meningeal layer allows for CSF to enter the dural sinuses and return to systemic circulation?
Bonus: What are these structures called?
Arachnoid mater
Bonus: arachnoid granulations
Pia mater
Impermeable to CSF fluid and forms perivacular spaces which act as the brains’ lymphatic system
Where is the superior & inferior sagittal sinuses?
In the falx cerebri
Where is the straight sinus?
At the junction of falx cerebri & tentorium cerebelli
Where is the transverse sinus?
In tentorium cerebelli
Where does the sigmoid sinus drain into?
It drains into the internal jugular vein
What does the cavernous sinus surround?
The internal carotid artery
Where does the internal jugular vein exit the skull?
The sigmoid sinus
Where do the vertebral veins exit the skull?
Through the vertebral venous plexuses through the foramen magnum
Where does the maxillary vein exit the skull?
It exits through the cavernous sinus and pterygoid venous plexuses
What is located in the anterior cranial fossa?
Frontal lobes & olfactory bulbs
What is located in the middle cranial fossa?
Temporal lobe, pituitary gland, and the cavernous sinus
What is located in the posterior cranial fossa?
Cerebellum, medulla, & pons
What vessels are located in the middle cranial fossa?
The internal carotid artery, ophthalmic arteries, and middle meningeal vessels
What nerves are located in the middle cranial fossa?
Meningeal nerves, CN II, II, IV, V, VI, Trigeminal ganglion, greater facial nerve, and lesser petrosal nerves
Anastomosis
An alternative route for vascular flow commonly found in joints or organs with high vascular requirements
What does the external carotid artery supply?
face, scalp, skull, & meninges
What does the internal carotid artery supply?
brain & eyes
What does the carotid sinus measure?
Blood pressure
What does the carotid body measure?
Blood oxygen content
What connects the cavernous sinus to the facial vein?
Ophthalmic veins
