SKULL

Skull divded to

Cranium

Face

Cranium (8)

Frontal

Parietal (Paired)

Temporal (Paired)

Sphenoid

Ethmoid

Occipital

Facial (14)

Zygomatic (2)

Maxillae (2)

Nasal bone (2)

Lacrimal (2)

Vomer

Palatine (2)

Inferior Conchae (2)

Mandible

Cranial Cavity

Vault of Skull – Sutures and in the midline shallow sagittal groove that lodges superior sagittal sinus.

Base of skull

- Anterior Cranial Fossa

- Middle Cranial Fossa

- Posterior Cranial Fossa

Pterion

-Weakest point of skull- Sphenoid, Parietal, Frontal and Temporal bone meets- Anterior Division of Middle Meningeal Artery runs underneath

Base of Skull: Ant Cranial Fossa Houses frontal lobe

Anteriorly: Post Wall of Frontal bone

Posteriorly: Lesser wing of Sphenoid

Medial: Anterior Clinoid Process

Lateral : Frontal bone & Pterion

Floor: Cribriform plate, orbital plate of frontal bone, ethmoid, & crista galli.

Ant Cranial Fossa

Main Anatomic Features in ACF Frontal crest :- It’s a midline bony ridge

that projects upwards and provide attachment to the falx cerebri.

Crista galli :- (latin for cock’s comb) Provides the site for anterior most attachment of the falx cerebri.

Cribriform plate :- It is a sheet of bone which contains numerous small foramina – these transmit olfactory nerve fibres(CN I) into the nasal cavity

Middle Cranial Fossa

Anteriorly: Lesser wing of Sphenoid

Posteriorly: Petrous part of Temporal Bone

Laterally: Squamous parts of Temporal bone

Greater Wing of Sphenoid

Parietal bone

Floor: Greater wing of Sphenoid

Squamous and Petrous parts of Temporal Bone

Middle Cranial Fossa

Foramina of MCF

Features Location Relevance

Superior Orbital Fissure Between Greater and Lesser Wing of Sphenoid

Lacrimal N (V1)Frontal N (V1)Trochlear N(IV th Nerve)Superior Ophthalmic VeinOculomotor N (III)Nasociliary N (V1)Abducent Nerve (VI)

Foramen Rotundum Greater wing of Sphenoid Maxillary Nerve

Foramen Ovale Greater wing of Sphenoid MALEMandibular NAccessory Meningeal NLesser Petrosal NEmissary Vein

Foramina of MCF

Features Location Relevance

Foramen Spinosum Greater Wing of Sphenoid MENMiddle Meningeal Artery & VeinEmmisary VeinSpinosus Nerve

Foramen Lacerum Apex of Petrous part of Temporal Bone

Transmits Internal Carotid Artery from Carotid Canal to enter Cavernous SinusGreater Petrosal N.

Superior Orbital Fissure

Superior Orbital Fissure

Ant Clinoid Process

Posterior Cranial Fossa

Houses Cerebellum, pons and Medulla Oblangata

Anterior : Superior border of Petrous part of Temporal Bone

Post: Internal Surface of Squamous part of Occipital Bone

Floor: Basilar, condylar, mastoid part of temporal bone,

Squamous part of occipital bone

Foramina in PCF

Features Location Relevance

Internal Acoustic Meatus Posterior Surface of petrous part of Temporalbone

Vestibulocochlear N (VIII)Facial N (VII)

Jugular Foramen Between Petrous part of Temporal bone and occipital bone

Inferior Petrosal SinusGlossopharngeal N (IX)Vagus N (X)Acessory N (XI)Sigmoid Sinus

Hypoglossal Canal Above Anterolateralboundary of Foramen Magnum

Hypoglossal Nerve (XII)

Foramen Magnum Central part of OccipitalBone

Medulla OblangataMeningesSpinal parts of Accessory Nerves (XI)2 Vertebral Arteries