Cranial Cavity

Question 1

Anterior Cranial Fossa

Answer 1

(anterior vs middle) Posterior edge oflesser wing of sphenoid and anterior border of chiasmatic groove

Frontal lobes of cerebrum

there are three bones in the anterior cranial fossa :
FRONTAL, ETHMOID, SPHERNOID

crista gali (ethmoid) will be a feature that the dura
attaches to

–>olfactory nerve (CN-I) fibers pass through the
cribiform plate as they go to the nasal cavity.

–>Aneterior clinoid processes are part of the
anterior cranial fossa but the rest of the sella
turcica is part of the middle cranial fossa.

Anterior ethmoidal foramen transmits the anterior ethmoidal artery, nerve and vein.

Posterior ethmoidal foramen transmits the posterior ethmoidal artery, nerve and vein

Question 2

Middle Cranial Fossa

Answer 2

(anterior vs. middle) lesser wing of sphenoid and anterior border of chiasmatic groove
(middle vs. posterior) Ridge of petrous part of
temporal bone (petrous ridge) and posterior edge of dorsum sellae

*NOTE: two openings from the external aspect of the skull that lead into the cranial cavity. The SUPERIOR ORBITAL FISSURE - opens into the space between the greater and lesser wing of the sphenoid in the cranial cavity. The OPTIC CANAL opens into the SELLA TURCICA in the sphenoid bone.

The middle cranial fossa includes the SPHENOID, TEMPORAL, and PARIETAL BONES.

Temporal lobes of cerebrum, diencephalon
and midbrain

• optic canal: optic nerves (CN II) and ophthalmic arteries into the orbital cavities.
• superior orbital fissure opens anteriorly into the orbit. It transmits the oculomotor nerve (CN III), trochlear nerve (CN IV), ophthalmic branch of the trigeminal nerve (CN V1), abducens nerve (CN VI), opthalmic veins and sympathetic fibres.
• Foramen rotundum opens into the pterygopalatine fossa and transmits the maxillary branch of the trigeminal nerve (CN V2).

Foramen ovale opens into the infratemporal fossa, transmitting the mandibular branch of the trigeminal nerve (CN V3) and accessory meningeal artery.

• Foramen spinosum also opens into the infratemporal fossa. It transmits the middle meningeal artery, middle meningeal vein and a meningeal branch of CN V3 (nervous spinosus)
• Foramen of vesalius (sphenoidal emissary foramen); IF PRESENT is next to ovale
• Hiatus of the greater petrosal nerve – transmits the greater petrosal nerve (a branch of the facial nerve)
• Hiatus of the lesser petrosal nerve – transmits the lesser petrosal nerve (a branch of the glossopharyngeal nerve)
• Carotid canal – located posteriorly and medially to the foramen ovale. This is traversed by the internal carotid artery, which ascends into the cranium to supply the brain with blood. **deep petrosal nerve also passes through this canal.

At the junction of the sphenoid, temporal and occipital bones is the foramen lacerum. In life, this foramen is filled with cartilage, which is pierced only by small blood vessels.

Question 3

Posterior Cranial Fossa

Answer 3

Division between middle
and posterior cranial fossae: ridge of petrous part of
temporal bone (petrous ridge) and posterior edge of dorsum sellae

Pons, medulla and cerebellum

includes TEMPORAL BONE, OCCIPITAL, PARIATAL, SPHENOID (Clivus - portion posterior to sella turcica)

• The internal acoustic meatus: the petrous part of the temporal bone; the facial nerve (CN VII), vestibulocochlear nerve (CN VIII) and labyrinthine artery.
• foramen magnum: transmits the medulla of the brain, meninges, vertebral arteries, spinal accessory nerve (ascending), dural veins and anterior and posterior spinal arteries, vertebral plexus of veins,
• The jugular foramina are situated either side of the foramen magnum. Each transmits the glossopharyngeal nerve (CN-IX), vagus nerve (CN-X), spinal accessory nerve (descending) (CN-XI),
• internal jugular vein
• inferior petrosal sinus
• sigmoid sinus
• meningeal branches of the ascending pharyngeal and occipital arteries.
• confluence of sinusesA

Immediately superior to the anterolateral margin of the foramen magnum is the hypoglossal canal. It transmits the hypoglossal nerve (CN-XII) through the occipital bone.

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Question 4

Extracerebral Hemorrhaging

Answer 4

Extradural Hemorrhage: Meningeal Artery
- blood collecting between the endosteal layer
of the dura and the bone itself. –> it is
usually the middle meningeal artery that is
rupturing

Subdural Hemorrhage: Bridging Vein
- between dura and arachnoid – bridging veins traveling from dura to sinuses are rupturing

Subarachnoid Hemorrhaging: Artery supplying
the brain
-Between arachnoid and pia
– blood pooling in the subarachnoid space – artery
supplying the brain are rupturing.