The Skull & Cranial Cavity• Brain• Meninges• Cranial nerves• Arterial supply• Venous sinuses
30 March 2009Dr Frank CT Voon
Temporal
Occipital
Parietal
Ethmoid
Sphenoid
Frontal
• Tip: PETS OF or FPOETS.
The Neurocranium
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
• Cerebral hemispheres• Diencephalon• Midbrain• Pons and cerebellum• Medulla oblongata• Spinal cord
Parietal lobeFrontal lobe
Occipital lobe
Temporal lobe
Motor cortex Sensory cortex
The Cranial nerves
• Olfactory• Optic• Oculomotor• Trochlear• Trigeminal• Abducens
• Facial• Vestibulocochlear• Glossopharyngeal• Vagus• Accessory• Hypoglossal
The 12 cranial nerves
Foramina
• 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
Anterior cerebral artery
Anterior communicating artery
Internal carotid artery
Middle cerebral artery
Posterior cerebral artery
Vertebral artery
Pontine arteries
Posterior communicating artery
Superior cerebellar artery
Anterior inferior cerebellar artery
Basilar artery
Anterior choroidal artery
Ophthalmic artery
Perforating arteries
Circle of Willis
The flow of CSF
Superior sagittal sinus
White matter
Gray matter
Falx cerebri
SkinClose tissue
AponeurosisLoose tissue
Endosteum
Periosteum
Diploe
Pia mater
Arachnoid mater
Dura mater
Outer table
Inner table
Subdural space
Subarachnoidspace
Cerebrospinal fluid
Arachnoid granulationsEmissary veins
Venous sinusesSuperior Sagittal Sinus
Inferior Sagittal Sinus
Straight Sinus
Tran
sver
se S
inus
Sigmoid
Cavernous Sinus
Superior Petrosal Sinus
InferiorPetrosalSinus
Occ
ipita
l Sin
us
Jugular foramen
Confluence
Internal occipital protruberance
Internal Jugular Vein
Sinus
The Scalp and Cranial Cavity• Skin• Close subcutaneous tissue• Aponeurosis• Loose areolar tissue• Periosteum
• Outer table• Diploe• Inner table• Endosteum • 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