INTERIOR OF CRANIUM - 29

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What are the 5 bones of the skull?: 1. Norma frontalis
2. Norma lateralis
3. Norma occipitalis
4. Norma ventralis
5. Interior of Base of
Cranium
What are the 2 main divisions of the skull?: 1. Neurocranium (braincase)
2. Viscerocranium (facial
bones)
What are the bones of the neurocranium?: 1. Frontal bone (2)
2. Parietal bone (2)
3. Occipital bone (1)
4. Ethmoid bone (1)
5. Sphenoid bone (1)
6. Temporal bone (2)
What are the bones of the Viscerocranium?: 1. Maxilla (2)
2. Palantine (2)
3. Zygomatic (2)
4. Lacrimal (2)
5. Nasal (2)
6. Vomer (1)
7. Inferior nasal concha (2)
8. Mandible (1)
What three of bones are normally single units in the adult, but are seen in the fetus to be of compound origin?: 1. Frontal bone (sometimes divided in the adult by a metopic suture)

2. The right and left maxilla (each of which is in two parts during early development

3. The mandible (whose right and left sides fuse at the mandibular symphysis during early childhood
What is the big bone that moves the skull?: Parietal bone
What 3 bones form the calvaria, or skull cap that covers the top of the brain?: 1. Frontal bone (2)
2. Parietal bone (2)
3. Occiptal bone (1)
What are the portions of the temporal bone?: 1. squamous portion
2. petrous portion
3. tympanic portion
What are the processes of the temporal bone?: 1. Zygomatic
2. Mastoid
3. Styloid
What is the importance of the tympanic cavity of the temporal bone?: It has auditory ossicles that form the "TMJ" joint with the mandible
What 3 bones make up the nasal septum?: 1. Sphenoid
2. Ethmoid
3. Vomer
What are conchae?: They are parts of the nasal cavity that increase the surface area for air conditioning purposes
What are the 2 modes of bone development?: 1. Intramembraneous ossification: bone formed in membrane (dermal bone)

2. Endochondral ossification: bone formed in cartilage
What are the 3 categories for the development of the skull?: 1. Primitive cranial skeleton
2. Mammalian neurocranium
3. Mammalian viscerocranium
What 2 things did the primitive neurocranium consist of?: 1. Chondrocranium, which is the base that enclosed the brain and supported the olfactory, optic, and otic capsules.

2. Dermatocranium was the external dermal bones that became the calvaria of the skull and it was also most facial bones that gave rise to teeth.
What was the viscerocranium of the mammalian neurocranium derived from?: Former gill arches (facial and ventral neck skeleton) and they include both endochondrally and membrane ossified parts.
What are the 2 parts of the neurocranium?: 1. Membranous VAULT
2. Endochondral BASE
The developing bones of the VAULT are separated by what 4 things?: Spaces including:
1. anterior fontanelles
2. posterior fontanelles
3. anterolateral fontanelles
4. posterolateral fontanelles
Why is the braincase flexible at birth?: Because most of the brain growth happens after birth due to the need for a larger brain and the narrow pelvises of females.
The mammalian viscerocranium consists of what?: Branchial arch derivatives and makes up the facial skeleton
What is a cranial fossae and what are the 3 types?: Fossa means an anatomical groove or pit and the three types are:
1. Anterior cranial fossa
2. Middle cranial fossa
3. Posterior cranial fossa
What does the anterior cranial fossa consist of?: 1. lesser wing of the sphenoid bone

2. foramina of cribiform plate

3. foramen caecum
4. anterior and posterior ethmoidal foramina
Why are frontal bones important?: They are the eyeballs and they sepatrae the eye socket from the brain above
What is the crista galli?: It is an upright ridge or process on the anterior portion of the cribiform plate where the anterior part of the falx cerebri is attached.
What does the middle cranial fossa consist of?: 1. Optic canal
2. Superior orbital fissure
3. Foramen lacerum
4. Foramen spinosum
5. Hypophyseal fossa
What does the posterior cranial fossa consist of?: 1. Internal acoustic meatus
2. Jugular foramen
3. Hypoglossal canal
4. Foramen magnum
What is the role for the S shaped groove for the transverse sinus called the sigmoid sinus?: They are for the venus sinus that drains blood from the brain and towards the heart
What is unique about the occipital bone?: It has 4 centers of ossification
What is in the olfactory foramina/cribiform plate?: CNI
What are 2 things in the optic canal?: 1. CNII
2. Opthalmic artery
5 things in the superior orbital fissure?: 1. CNIII
2. CNIV
3. CNVI
4. Opthalmic vein
5. Opthalmic nerve (CN V1)
2 things in the inferior orbital fissure?: 1. CNV2
2. Opthamic vein
1 thing on the foramen rotundum?: CNV2
1 thing in foramen ovale?: CNV3
1 thing in foramen spinosum?: Middle meningeal artery
1 thing in carotid canal?: Internal carotid artery
Anything in foramen lacerum?: nothing! It was closed by cartilage in life
2 things in the internal acoustic (auditory) meatus?: 1. CNVII
2. CNVIII
4 things in the Jugular foramen?: 1. CNIX
2. CNX
3. CNXI
4. Internal jugular vein
4 things in the foramen magnum?: 1. CNXI
2. Spinal cord
3. Vertebral artery
4. Spinal artery
1 thing in the hypoglossal foramen?: CNXII
What are meninges?: They are membranes covering the brain between the bone of the skull and the brain itself.
What are the 3 subdivisions of the meninges?: 1. Pia mater
2. Arachnoid mater
3. Dura mater
Distinguish between the 3 subdivisions of the meninges?: 1. Pia mater is the innermost layer attached to the surface of the brain.

2. Arachnoid mater has weblike extensions that extend to the pia and it creates the subarachnoid space.

3. Dura mater is the tough outermost layer with 2 layers of its own that are stuck together.
What is the significance of the subarachnoid space?: It is where the CSF circulates.
What are the two layers of the dura mater?: 1. An internal meningeal sheet.
2. An external periosteal sheet that is tightly attached to the skull bone or inner calvaria
What is the blood supply of the dura mater?: 1. Middle meningeal artery
2. Opthalmic artery
3. Vertebral artery
4. Occipital arterty
What is the nerve supply of the dura mater?: The dura is between the cerebellum and cerebrum and most of the sensory nerve supply is from CNV1, V2, V3 and some CNX but there is also cervical nerves
Where there is a gap in the brain what happens?: The blood from the brain flows in to form a vein and it is continous with the internal jugular vein and some of the venous sinuses can come from the scalp (emissary) and the brain
What can happen if there is an infection on the scalp?: The infection can pass through the vein and infect the meninges to give you meningitis.
What are venous sinuses?: They are spaces between the 2 layers of the dura mater
Describe dural folds?: They are formed by the meningeal sheet of the dura mater pulling away from the periosteal sheet and they support the brain within the cranial vault and create spaces for venous sinuses.
What are the 4 dural folds?: 1. Falx cerebri
2. Falx cerebelli
3. Tentorium cerebelli
4. Diaphragma sellae
What are the 2 venous sinuses?: 1. Superior saggital sinus
2. Inferior saggital sinus
What happens when the sinuses come together?: The blood goes through transverse sinus, sigmoid
Where do cavernous sinuses get their blood supply from?: They get their blood supply from the opthalmic vein of the orbit.
Why are cavernous sinuses important?: They are very important
because infection of the side of the nose can move inward into the cavernous sinus and cause serious thrombosis because the sinuses are related to a lot of structures such as the cranial nerves.
What are the stalks of the pituitary gland and what is the main blood supply to the brain?: Its stalk are CNII, CNIII, CNIV and the main blood supply to the brain is the internal carotid artery.
What are Arachnoid Granulations?: They are cauliflower shaped processes that are enlarged villi of the arachnoid membrane and they protude into the superior saggital sinus and they absorb CSF into the venous system, therefore letting the arachnoid be in contact with the blood.
Differentiate btw epidural and hematoma?: Epidural means on top of the dura and hematoma means blood clot
What can happen when there is a blow upside the head and there is a fracture?: There is a rupture vesels and the middle meningeal artery inside, between the calvaria and periosteal layer of the dura so this pushes the dura aweay from the bone and towards the brain and displaces the brain and the falx cerebri = extradural hematoma
What is extradural hematoma?: Blood collects between the the calvaria and periosteal layer of the dura.
Whst is subdural hematoma?: This happens when venous blood collects between the dura matter and subarachnoid space.
When can subdural hematoma occur?: In elderly people with atrophy of the brain and their brain shrinks away from the meningeal coverings and there is blood below the dura and outside the arachnoid.
What is subarachnoid hemorrhage?: This occurs when blood flows into the subarachnoid space and mixes with cerebospinal fluid.
Why does a subarachnoid hemorrhage occur?: It occurs due to ruptured arteries of the circle of willis so there is arterial blood in the subarachnoid space mixing with the CSF.
What is an Aneurism?: It occurs when there is a weak spot in the wall of an artery and the wall starts to balloon out and this can lead to rupture and bleeding

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