Presented by :

Tarun K. Ubhu

CRANIAL CAVITY DEPARTMENT OF ANATOMY

Introduction to Cranial CavityCavity present in cranium of skull is

known as Cranial Cavity. It contains brain , meninges , venous

sinuses, all cranial nerves , four petrosal nerve , part of internal carotid artery and a part of vertebral artery besides the special senses.

The anterior branch of middle menengial artery lies at the Pterion and is prone rupture in extra dural haemorrhage .

CRANIAL FOSSAE 1. Anterior cranial fossa

accommodates the anterior lobe of brain.

2. Middle cranial fossa is much wider than the anterior cranial fossa and contains the 2 temporal lobes of brain.

3. Posterior cranial fossa is much shallower and wider than the middle cranial fossa and it accommodates the occipital lobes of the brain.

Anterior Fossa Boundaries Anteriorly and laterally Frontal bone Floor: Orbital plate of frontal bone, ethmiod cribriform plate ,

anterior border of sphenoid’s lesser wings and crista galli Posteriorly: Posterior border of lesser wing of sphenoid, anterior

clinoid process and sulcus chiasmaticus. Crista galli It is a sharp upward projection of ethmoid bone in the

midline, for the attachment of falx cerebri. Foramen cecum Small aperture between the crista galli and the crest of

the frontal bone

Middle Fossa Boundaries Anteriorly Post border of the lesser wings of sphenoid, anterior

clinoid processes and sulcus chiasmaticus. Posteriorly Superior borders of petrous part of temporal and

sphenoids dorsum sella. Laterally Squamous part of temporal and some part if parietal and

greater wings of sphenoid. Floor Greater wing of sphenoid and petrous and squamous parts

of the temporal bone. In the centre, floor is formed by the sella tursica of body of

sphenoid.

Posterior Fossa Boundaries Anteriorly Superior border of the petrous part of

temporal bone and dorsum sallae. Posteriorly Internal surface of squamous part of the

occipital bone. Floor Basilar, squamous & condylor parts of the

occipital bone & mastoid part foramen magnum forms the central part of the

floor.

DURAMATER The duramater is the toughtest and thickest

membrane in our body Develops from the mesoderm surrounding the

neural tubeThis is conventionally described as two layers: the

endosteal layer and the meningeal layer. These are closely united except along certain lines, where they separate to form venous sinuses.

The outer layer is highly vascular whereas the inner layer is more fibrous and has little blood supply .

Vault is supplied by middle meningeal artery. Anterior cranial fossa by anterior ethmoidal , posterior ethmoidal and

opthalmic meningeal branches of arteries. Middle cranial fossa by middle meningeal , accessory meningeal and

internal carotid arteries. Posterior cranial fossa by meningeal branches of vertebral ,

opthalmic and acending pharyngeal arteries.

BLOOD SUPPLY OF DURAMATER

NERVE SUPPLY OF DURAMATER

The dura of the vault has only a few sensory nerves which are the opthalmic branches of trigeminal nerve

The dura of floor has rich nerve supply and quite sensitive to pain.1. The ACF is supplied mostly by the anterior ethmoidal nerve and

partially by maxillary nerve.2. The MCF is supplied by maxillary nerve in the ant. Half , and

branches of mandibular nerve and from the trigeminal ganglion.3. The PCF is supplied chiefly by recurrent branch from 1st , 2nd and

3rd cervical spinal nerves by meningeal branches of 9th and 10th cranial nerves.

Layers of Dura Mater

The endosteal layer periosteum covering the inner surface of the skull bones.

Does not continuous with the dura mater of the spinal cord.

The meningeal layer is the dura mater proper, covering the brain

Continuous with the dura mater of the spinal cord.

It provides tubular sheaths for the cranial nerves.

Outside the skull, fuse with the epineurium of the nerves.

Folds of Dura Mater

VENOUS SINUSES OF DURAMATER . (Venous spaces whose walls are formed of duramater)

These are Have inner lining of endothelium Have no muscles in their walls Have no valves Receive blood from brain,meninges and bones of skull.

Some are also poured by CSF. They communicate with veins outside the skull throug

emissionary veins. These communications help to keep the pressure of blood of venous sinuses constant.

There are 23 venous sinuses: Paired venous sinuses : 8

Unpaired venous sinuses : 7

CAVERNOUS SINUSINTRODUCTION It is one of the paired sinuses It is a large venous space

situated in the middle cranial fossa on either side of the body of the sphenoidal bone.

Floor and medial walls of it are formed by the endosteal duramater and lateral walls are formed by meningeal duramater

Anteriorly : extend upto medial end of the ant. orbital fissure.

Posteriorly : extend upto apex of petrosal temporal bone.

2 cm long and 1cm wide on each side

Relations of Cavernous sinusSuperiorly : optic tract, optic chiasma, olfactory

tract, internal carotid artery and anterior perforated substance.

Inferiorly : Foramen Lacerum and the junction of the body and greater wing of the sphenoid bone.

Medially : Hypophysis Cerebri and Sphenoidal air sinus.

Laterally : Temporal bone of uncus.Below laterally : Mandibular nerve.Anteriorly : superior orbital fissure and the apex

of the orbit.Posteriorly : Apex of the Petrous temporal and

the Crus Cerebri of the midbrain.

RELATION OF CAVERNOUS SINUS

Structures within the lateral wall ( from above downwards)Occulomotor nerve: in the anterior part of the sinus.

It divide into sup. and inf. divisions which leaves the sinus by passing though the sup. Orbital Fissure

Trochlear: nerve in the anterior part of sinus it crosses superficially to the occulomotor nerve and enters the orbit through sup. Orbital fissure.

Opthalmic nerve : In the ant. part of the sinus. It divide into lacrimal, frontal and nasocilliary nerves.

Maxillary nerve : It leaves the sinus by passing through foramen rotundum on its way to pterigopalatine fossa.

Trigeminal ganglion : The ganglion and its dural cave projects into the post. Part of the lateral wall of the sinus.

Structures passing through the medial aspect of the sinusInternal carotid artery with the

venous and sympathetic plexus around it.

Abducent nerve, inferolaterally to the internal carotid artery.

The structures in the lateral wall and on the medial wall are separated from blood by endothelium lining.

Tributaries or incoming channels FROM THE ORBIT1. The superior opthalmic vein2. A branch of the inferior opthalmic vein or sometimes the vein

itself3. The central vein of the retina may drain either into the superior

opthalmic vein or into the cavernous sinus. From the brain1. Superficial middle cerebral vein .2. Inferior cerebral veins from the temporal lobe FROM THE MENINGES1. Sphenoparietal sinus .2. The frontal trunk the middle meningeal vein may

drain either into the pterygoid plexus through the foramen ovale or into the sphenoparietal or cavernous sinus.

DRAINING CHANNELS OR COMMUNICATIONS Into Transverse sinus through Superior Petrosal sinus. Into Internal Jugular Vein through inferior petrosal sinus

and through a plexus around the internal carotid artery. Into Pterygoid plexus of veins through the emissionary

veins passing through the foramen ovale, thge foramen lacerum and the emissary sphenoidal foramen.

Into the facial veinn through the superior opthalmic vein. The right and left cavernous sinus communicate with

each other through the anterior and posterior intercavernous sinus and through the basilar plexus of veins.

ALL THESE COMMUNICATIONS ARE VALVELESS AND BLOOD CAN FLOW THROIUGH THEM IN ANY DIRACTION.

FACTORS HELPING EXPULSION OF THE BLOOD FROM THE SINUSEXPANSILE PULSATIONS OF THE

INTERNAL CAROTID ARTERY WITHIN THE SINUS

GRAVITYPOSITION OF THE HEAD

SUPERIOR SAGGITAL SINUS It occupies the upper convex, attached margin of

the falx cerebri. It begins anteriorly at the crista galli by the union

of tiny meningeal veins. Here it communicates with the veins of the frontal sinus, and occasionaly with the veins of the nose ,through the foramen caecum.

As the sinus runs upwards and backwards, it becomes progressively larger in size.

Its triangular in crossection. It ends near the internal occipital protuberance by

turning to one side, usually the right and becomes continuous with the right transverse sinus.

Interior of the sinus showsOpenings of the superior cerebral veins.Openings of the venous lacunae, usually 3 on each

side.Arachnoid villi and granulations projecting into the

lacunae as well as into the sinus.Numerous fibrous bands crossing the inferior angle of

the sinus.Tributaries

FromSuperior cerebral veins which never open into the

venous lacunaeParietal emissary veinsVenous lacunae, usually three on each side which first,

receive the diploic and

TRANSVERSE SINUS These are large sinuses in

which right one is larger than the left.

It is situiated in the post. Part of the attached margin of tentorium cerebelli

Right sinus : continuation of the superior saggital sinus

Left sinus : continuation of straight sinus.

Each extends from external occipital protuberance to the posteroinferior angle of the parietal bone at the base of the mastoid process where it bends downwards and becomes the sigmoid sinus.

Tributaries of transverse sinus1. Superior petrosal sinus2. Inferior cerebral veins3. Inferior cerebellar veins4. Diploic (posterior temporal) vein5. Inferior anastomotic vein.

SIGMOID SINUS◦ Each sinus( left and

roight) is direct continuation of the transverse sinus.

◦ It is S-shaped and hence the name.

◦ Extends from posteroinferior angle of the parietal bone to the posterior part of the jugular foramen where it becomes the superior bulb of the internal jugular vein.

◦ It grooves the mastoid part of the temporal bone , where it is separated anteriorly from the mastoid antrum and mastoid air cells by only a thin plate of bone.

Tributaries of sigmoid sinusesThe mastoid and condylar emissary

veins.Cerebellar veins.Internal auditory veins.

HYPOSPHYSIS CEREBRI(Pituitary Gland)Small endocrine gland situated in relation to

the base of the brain.It lies in the hypophyseal fossa or sella

turcica.The fossa is roofed by the diaphragm sellae,

the stalk of hypophyseal sellae peirces diaphragm sellae and is attached above to the floor of 3rd ventricle.

Often called master of endocrine orchestra because it produces number of hormones which control the secretion of many other endocrine glands of the body.

RelationsSuperiorly: Diaphragma sellae optic chiasma tubercinerium infundibular recess of 3rd ventricle Inferiorly: itrregular venoud channels b/w the two layers of

duramater lining the floor of hypophyseal fossa hypophyseal fossa sphenoidal air sinusesOn each side: covernous sinus and its contents

RELATIONS OF PITUITARY

Subdivisions of hypophysis cerebri Adenohypophysis develops from the as an

upward growth called the rathke’s pouch from the ectodermal roof of stomodeum .

It includes pars anterior which is the largest part of

the gland. pars intermedia : formed of the thin strip which

is separated from the ant. Lobe by an interglandular cleft( a remenant of rathke’s pouch).

pars tuberalis : an upward extension of the ant. Lobe that surrounds and form part of the infundibulum.

Neurohypophysis develops as an downward growth from the floor of diencephalon and is connected to the hypothallamus by a neural pathway.

It includes: pars posterior : it is smaller than

the ant. Lobe, lies in post. Concavity of larger ant. Lobe.

infundibular stem : which contains neural connects of post. lobe with the hypothallamus.

BLOOD SUPPLY OF PITUITARY GLAND

Arterial supply of pituitary gland One superior hypophyseal artery on each side which

supplies: 1. Ventral part of the hypothallamus2. Upper part of the infundibulum3. Lower part of infundibulum through a separate long

branch called as trabeculum artery. One inferior hypophyseal artery on each side which

divide into medial and lateral branches which join one another to form arterial ring around the posterior lobe and also anatlomose with branches from superior hypophyseal artery.

The portal vessels are of great functional importance because they carry the hormones releasing factors from the hypothallamus to the ant. Lobe where they control the secretion of the different glandular cells.

BLOOD SUPPLY OF PITUITARY

VENOUS DRAINAGEShort veins emerge on the surface

of the gland and draion into the neighbouring venous sinuses.

The hormones passes out the gland from the venous blood and is carried to their target cells.

NEURAL SUPPLY FROM HYPOTHALAMUS TO PITUITRY

THANKS .......... STAY TUNED