CRANIAL CAVITY: DURA MATER, DURAL VENOUS SINUSES

CRANIAL CAVITY

Contents of Cranial Cavity

Brain
Meninges → dura mater, arachnoid mater, pia mater
Cranial nerves I–XII
Arteries → internal carotid artery, vertebral arteries and branches
Veins → cerebral veins
Dural venous sinuses
Pituitary gland
CSF-filled subarachnoid space
Venous plexuses and emissary veins
Portions of cranial bones forming vault and base

DURA MATER

Folds of Dura Mater

Falx cerebri
• Crescent-shaped fold
• Lies between right and left cerebral hemispheres
• Attached to crista galli (anterior) and internal occipital protuberance (posterior)
• Contains superior and inferior sagittal sinuses

Tentorium cerebelli
• Horizontal dural fold
• Separates cerebrum from cerebellum
• Contains transverse and superior petrosal sinuses
• Forms tentorial notch for brainstem passage

Falx cerebelli
• Small midline fold
• Between cerebellar hemispheres
• Contains occipital sinus

Diaphragma sellae
• Small circular fold
• Covers pituitary gland in sella turcica
• Pierced by infundibulum

DURAL VENOUS SINUSES (Classification)

Paired Sinuses
Transverse sinus
Sigmoid sinus
Cavernous sinus
Superior petrosal sinus
Inferior petrosal sinus
Sphenoparietal sinus
Petroclival sinus

Unpaired Sinuses
Superior sagittal sinus
Inferior sagittal sinus
Straight sinus
Occipital sinus
Basilar venous plexus
Intercavernous sinus

PITUITARY GLAND

Morphology

Small pea-sized endocrine gland
Situated in hypophyseal fossa of sphenoid bone
Covered superiorly by diaphragma sellae
Connected to hypothalamus by infundibulum
Two functional parts
• Anterior pituitary (adenohypophysis)
• Posterior pituitary (neurohypophysis)

Anterior Pituitary
• Glandular epithelium
• Produces GH, TSH, ACTH, FSH, LH, Prolactin

Posterior Pituitary
• Neural origin
• Stores and releases ADH and oxytocin from hypothalamus

Clinical Importance of Pituitary Gland

Pituitary adenoma
• Common tumor
• Compresses optic chiasma → bitemporal hemianopia

Hormonal disorders
• Excess GH → gigantism in children, acromegaly in adults
• Deficiency GH → pituitary dwarfism
• Excess ACTH → Cushing disease
• ADH deficiency → diabetes insipidus

Pituitary apoplexy
• Sudden hemorrhage into gland
• Headache, vomiting, vision loss, CN palsies

Surgical importance
• Access through sphenoid sinus (transsphenoidal approach)

CAVERNOUS SINUS

Anatomy

Located on either side of body of sphenoid bone
Extends from superior orbital fissure to apex of petrous temporal bone

Structures inside the sinus
Internal carotid artery
Abducent nerve (CN VI)

Structures in lateral wall of sinus
Oculomotor nerve (CN III)
Trochlear nerve (CN IV)
Ophthalmic nerve (V1)
Maxillary nerve (V2)

Tributaries
Superior ophthalmic vein
Inferior ophthalmic vein
Sphenoparietal sinus
Superficial middle cerebral vein

Drainage
Superior petrosal sinus
Inferior petrosal sinus
Pterygoid venous plexus

Clinical Importance of Cavernous Sinus

Cavernous sinus thrombosis
• Infection spreads from face, nose, orbit via ophthalmic veins
• Symptoms: fever, severe headache, proptosis, chemosis

Cranial nerve palsies
• CN III, IV, V1, V2, VI affected
• Loss of eye movements, facial pain, diplopia

Carotid-cavernous fistula
• Abnormal communication between ICA and sinus
• Pulsating exophthalmos

Danger triangle of face
• Infection spreads directly to cavernous sinus
• High-risk condition