The Skull & Cranial Cavity
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Dr Frank CT Voon
Brain
Meninges
Cranial nerves
Arterial supply
Venous sinuses
30 March 2009
The Neurocranium
Frontal
Parietal
Occipital
Ethmoid
Temporal
Sphenoid
•Tip: PETS OF or FPOETS.
The Cranium
• The cranium (skull) is the skeleton of the
head.
• It consists of a neurocranium and a
viscerocranium.
• The neurocranium is also known as the
cranial vault.
• The viscerocranium is also known as the
facial skeleton.
The Neurocranium
• The neurocranium (cranial vault) has a
roof and a floor.
• The roof (calvaria or skull cap) is shaped
like a dome.
• The basicranium (cranial base) forms the
floor.
• It encloses the cranial cavity.
The Neurocranium
• It is formed by 8 bones, the frontal, parietal,
occipital, temporal, ethmoidal and sphenoidal
bones.
• The frontal, occipital, ethmoidal and sphenoidal
bones are single and thus are in the midline.
• The parietal and temporal bones are bilateral
and hence are paired.
• The fibrous joints between the bones are known
as sutures.
Intramembranous ossification
• The frontal, parietal and temporal bones
are formed by intramembranous
ossification and are known as flat bones.
• Do note that these flat bones forming the
calvaria are actually curved, with a convex
external surface and a concave internal
surface.
Endochondral ossification
• The sphenoid, ethmoid and temporal
bones are mainly formed by endochondral
ossification and are known as irregular
bones.
• These bones form the cranial base.
• The ethmoid is a part of both the
neurocranium and viscerocranium.
The Brain and spinal cord
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Cerebral hemispheres
Diencephalon
Midbrain
Pons and cerebellum
Medulla oblongata
Spinal cord
Motor cortex
Sensory cortex
Parietal lobe
Frontal lobe
Occipital lobe
Temporal lobe
The Cranial nerves
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Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
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Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Accessory
Hypoglossal
The 12 cranial nerves
Foramina
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Structures that pass through the foramina
Cranial nerves
Arteries - Internal carotid and vertebral
Veins – sigmoid sinus and beginning of
internal jugular vein
• Spinal cord – Foramen magnum
Circle of Willis
Anterior cerebral artery
Internal carotid artery
Middle cerebral artery
Posterior cerebral artery
Anterior communicating artery
Perforating arteries
Ophthalmic artery
Anterior choroidal artery
Posterior communicating artery
Superior cerebellar artery
Basilar artery
Pontine arteries
Anterior inferior cerebellar artery
Vertebral artery
The flow of CSF
Superior sagittal sinus
Arachnoid granulations
Emissary veins
Skin
Close tissue
Aponeurosis
Loose tissue
Periosteum
Outer table
Diploe
Inner table
Dura mater
Endosteum
Arachnoid mater
Subdural space
Subarachnoid
space
Pia mater
Gray matter
White matter
Falx cerebri
Cerebrospinal fluid
Venous sinuses
Superior Sagittal Sinus
Confluence
Internal
occipital
protruberance
Jugular foramen
Internal Jugular Vein
The Scalp and Cranial Cavity
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Skin
Close subcutaneous tissue
Aponeurosis
Loose areolar tissue
Periosteum
• Outer table
• Diploe
• Inner table
• Endosteum
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Endosteal layer of dura mater
Menigeal layer of dura mater
Arachnoid mater
Pia mater
• Brain
• Grey matter
• White matter
• Ventricles
Meninges and spaces
– Extradural space
• Dura mater
– Subdural space
• Arachnoid mater
– Subarachnoid space
• Pia mater
– Gray matter
– White matter
– Ventricles