Referred from different sources , here i present a very concise presentation on CRANIAL CAVITY . This presentation will give you complete knowledge of the topic cranial cavity with well elaborated and intellectual diagrams hand picked from F. Netter. ......... Do like and share , Leave your comments so as to get more stuff like this in future.
2. Introduction to Cranial Cavity
Cavity 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 .
3. 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
4. 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
5. 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.
6. 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.
7. DURAMATER
The duramater is the toughtest and thickest
membrane in our body
Develops from the mesoderm surrounding the
neural tube
This 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.
8. 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.
9. 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 ,
nd rd
10. 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.
12. 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
13. CAVERNOUS SINUS
INTRODUCTION
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.
14. Relations of Cavernous sinus
Superiorly : 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.
15.
16. 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.
17. Structures passing through the medial
aspect of the sinus
Internal 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.
18. Tributaries or incoming
channels
FROM THE ORBIT
1. The superior opthalmic vein
2. A branch of the inferior opthalmic vein or sometimes the vein itself
3. The central vein of the retina may drain either into the superior
opthalmic vein or into the cavernous sinus.
From the brain
1. Superficial middle cerebral vein .
2. Inferior cerebral veins from the temporal lobe
FROM THE MENINGES
1. 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.
19. 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.
20. FACTORS HELPING EXPULSION OF
THE BLOOD FROM THE SINUS
EXPANSILE PULSATIONS OF THE
INTERNAL CAROTID ARTERY
WITHIN THE SINUS
GRAVITY
POSITION OF THE HEAD
21. 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.
22. Interior of the sinus shows
Openings 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
From
Superior cerebral veins which never open into the
venous lacunae
Parietal emissary veins
Venous lacunae, usually three on each side which
first, receive the diploic and
23. 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.
25. 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.
26. Tributaries of sigmoid sinuses
The mastoid and condylar emissary veins.
Cerebellar veins.
Internal auditory veins.
27. 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.
28. Relations
Superiorly:
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 sinuses
On each side:
covernous sinus and its contents
29.
30. 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.
31. 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.
32.
33. Arterial supply of pituitary gland
One superior hypophyseal artery on each side which
supplies:
1. Ventral part of the hypothallamus
2. Upper part of the infundibulum
3. 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.
34.
35. VENOUS DRAINAGE
Short 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.
