CONTENTS
OF CRANIAL FOSSAE
DR.TARAKESWARRAO.
SKULL
• Highly modified region of
Axial Skeleton
• NEURO CRANIUM
– Enclose and protect brain
– Attachment for head +
neck muscles
• SPLACHOCRANIUM
– Form cavities for sense
organs
– Opening for air + food
passage
– Hold teeth
– Anchor face muscles
CRANIUM
CRANIAL BONES :8
 Frontal
 Occipital
 Sphenoid
 Ethmoid
 Parietal (2)
 Temporal (2)
FACIAL SKELETON
• Facial – 14
 Mandible
 Maxilla (2)
 Zygomatic (2)
 Nasal (2)
 Lacrimal (2)
 Palatine (2)
 Vomer
 Inf. Nasal Conchae(2)
SKULL
FRONTAL BONE
 Forms anterior portion of cranium
 Superior part of the face
 Anterior floor of cranial cavity
PARIETAL BONE
 Forms roof and sides of cranium
OCCIPITAL BONE
 Forms the posterior part of the cranium and the base
 Internally forms the posterior cranial fossa( contains the
cerebellum)

Foramen magnum
SKULL
•
•



Bones of the skull are
flat.
The joints between the
bones are called
sutures( interlocking
and immovable)
coronal suture
sagittal suture
lamdoid suture
SKULL
•
Internal aspect shows 3
steps
 Posterior cranial fossa
basement
 Middle cranial fossa
1st floor
 Anterior cranial fossa
2nd floor
* Each fossa has a specific
lobe of the brain sitting
inside it
ANTERIOR CRANIAL FOSSA
•
•
•
•
Contains FRONTAL LOBES of cerebral hemispheres
Anterior: frontal bone
Posterior: lesser wing of sphenoid
Floor : orbital plate of frontal bone,cribriform plate of
ethmoid,lesser wings and body of sphenoid
• Orbital plates of frontal bone separates orbit from frontal
lobes
MIDDLE CRANIAL FOSSA
• It contains HYPOPHYSIS CEREBRI in the middle and
TEMPORAL LOBE on each side
• The floor is shaped like butterfly
• Small median part & pair of expanded lateral parts
• Median part : formed by upper surface of body of
sphenoid
• Presents Sulcus chaismaticus ,Sella turcica
• Lateral part :formed by greater wing of sphenoid,
squamous and petrous part of temporal bone
POSTERIOR CRANIAL FOSSA
• Deepest of 3 fossae
• Lodges hind brain
CEREBELLUM, PONS, MEDULLA OBLONGATA
• Roof: Tentorium cerebelli
• Bound anteriorly : superior border of petrous
temporal bone,dorsum sellae
• Surrounds foramen magnum
ENCEPHALON
• PROCENCEPHALON (fore brain)
* DIENCEPHALON
hypothalamus
thalamus
* TELENCEPHALON
right $ left cerebral hemispheres
• MESENCEPHALON
mid brain
• RHOMBENCEPHALON (hind brain)
* metencephalon (pons)
* myelencephalon (medulla oblongata)
* cerebellum
Lobes of the cerebrum
•
•
•
•
Frontal
Parietal
Occipital
Temporal
* Note: Occasionally, the Insula is considered the fifth lobe. It is located deep
to the Temporal Lobe.
GYRI AND SULCI
Frontal
• The Frontal Lobe of the brain is located anterior to the central sulcus
&above the posterior ramus of the lateral sulcus.
-Motor (area) function
- Memory Formation
- Emotions
- Decision Making/Reasoning
-Personality
-FRONTAL EYE FIELD
FRONTAL EYE FIELD
• In the middle frontal gyrus
• Parts of areas 6, 8, 9
• Stimulation of this area –
conjugate movements
• Also head movements &
dilatation of the pupil
• Connected to the cortex of
occipital lobe
Frontal eye field
Parietal Lobe
• The Parietal Lobe of the brain lies behind the
central sulcus.
-Senses and integrates sensation(s)
-Sensory areas 1, 2, 3
- Spatial awareness and perception
(Proprioception )
Parietal Lobe - Cortical Regions
• Primary Somatosensory Cortex (Postcentral
Gyrus) – Site involved with processing of tactile
and proprioceptive information.
• Somatosensory Association Cortex - Assists
with the integration and interpretation of
sensations relative to body position and orientation
in space. May assist with visuo-motor coordination.
• Primary Gustatory Cortex – Primary site
involved with the interpretation of the sensation of
Taste.
Occipital Lobe
• The Occipital Lobe of the Brain is
the area behind the first
imaginary line from parietooccipital sulcus.
• Its primary function is the
processing, integration,
interpretation, etc. of VISION and
visual stimuli.
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Visual cortex
• Located in the occipital lobe both above and
below the calcarine sulcus
• Area 17 is limited ant by the lunate sulcus
• Receive fibres of optic radiation
• It is continuous above and below with area
18 & beyond with area 19
• Areas 18, 19 are responsible fpr
interpretation of visual impulses reaching
area17 – called psychovisual areas (visual
assosciation areas)
VISUAL CORTEX
Primary Visual
Cortex (area 17)
Visual
Association Area
(areas 18, 19)
Temporal lobe
• The Temporal Lobe lies below the posterior
ramus of the lateral sulcus.
• They
play an integral role
in the following functions:
- Hearing(aoustic area41)
- Organization/Comprehension
of language
- Information Retrieval
(Memory and Memory Formation)
• makes up a fourth of the
brains major part
• makes up 11% of the mass
of the brain
• also called the lesser brain
• consists of 2 hemispheres
connected by the vermis
• has outer gray matter, inner
white matter, deeper area of
gray matter the cerebellar
nuclei
• Fibres enter or leave the
cerebellum via cerebellar
puduncles, the superior,
middle and inferior.
• functionally it smooths and
coordinates body
movements that are directed
by other brain regions, and
hepls maintain posture and
equilibrium.
CEREBELLUM
• the 3 regions of the
brainstem are the midbrain,
pons and medulla oblongata
• MIDBRAIN
- it has a central cavity called
the cerebral aqueduct whch
divides it into 2 parts
- cerebral puduncles lie
ventrally
- tectum lies dorsally, which
are made up of nuclei called
the corpora quadrigemina (
superior colliculi- associated
with visual reflexes, inferior
colliculi- associated with
auditory reflexes)
- the superior cerebellar
puduncles connect the
midbrain to the cerebellum
BRAINSTEM
• PONS•
•
•
•
it is the bridge between the rt
and left halves of the
cerebellum .
it is attached to the cerebellum
via the middle cerebellar
puduncle
Trigeminal N emerges at
junction bet pons & middle
cerebellar peduncle
6, 7, 8 cranial N ‘s emerge
anteriorly (junction of pons and
medulla)
MEDULLA OBLONGATA
-it is continous with the spinal cord at the level of the foramen
magnum
-the cranial nerves which emerge are the 9th, 10th ,11th and 12th
-it is attached to the cerebellum via the inferior cerebellar
puduncle
RETICULAR FORMATION
• this runs through the central core
of the pons, midbrain and medulla
• consists of loose cluster of neurons
• forms the reticular activating
system-maintaining conciousness
and alertness
VENTRICLES OF THE BRAIN
• expansions of the brains central cavity
• contain csf formed by the choroid plexus of the
ventricles
• Lined by ependyma
• continous with each other and the central canal of
the spinal cord
• 1. lateral ventricle---- cerebral hemispheres
• 2. third ventricle---diencephalon (bet rt & lt thalami)
• 3. midbrain---cerbral aqueduct
• 4. hindbrain---- fourth ventricle (situated dorsal to
pons & upper part of medulla and ventral to
cerebellum)
CSF
• csf present around the
brain and spinal cord
(the sub arachnoid
space)
• reduces the wt of the
brain by 97%
• 100-160 ml
• 25 ml in ventricles
• formed in the choroid
plexus
Blood supply
BLOOD SUPPLY
OF BRAIN
The brain is one of the most
metabolically active organs
receiving
17% of the total cardiac output
20% of the oxygen available
in the body.
The brain : blood from 2
sources
carotid &vertebral.
80% : carotid,
20% : vertebral.
INTERNAL
CAROTID
ARTERY
• Gives off two major
branches to the brain
* anterior cerebral
* middle cerebral
VERTEBRAL
ARTERIES
• At the lower border of pons
the 2 vertebral a’s unite to
form BASILAR artery
• At the upper border of pons,
bifurcates into 2 posterior
cerebral a’s
• Int carotid & vertebrobasilar
systems are connected by
posterior communicating a’s
• The 2 ant cerebral a’s are
connected by anterior
communicating a’s
• Results in an arterial ring
“CIRCULUS ARTERIOSUS”
or CIRCLE OF WILLIS
•
•
•
•
Medulla
Branches of vertebral a’s
Ant & posst spinal a’s
Post inferior cerebellar a.
•
•
•
•
•
•
Pons
Basilar a.
Paramedin br’s
Cicumferential br’s
Ant inf cerebellar
Superior cerebellar a’s
•
•
•
•
•
•
Mid brain
Basilar a.
Post cerebral
Superior cerebellar a’s
Post comm
Anterior choroidal a’s
CEREBELLUM
• Superir surface: superior cerebellar
br’s of basilar a.
• Inferior surface:
- anteriorinferior cerebellar of
basilar a.
- post inferior cerebellar of
vertebrala.
ARTERIAL SUPPLY OF THE
CEREBRAL CORTEX
• Cortical branches of
anterior, middle &
posterior cerebral a’s
• SUPEROLATERAL
SURFACE
• Mainly middle cerebral
artery
• 1 inch border- ant
erebral a.
• Occipital lobe- post
cerebral a.
• Inferior temp gyruspost cerebral a.
• MEDIAL SURFACE
• Mainly anterior
cerebral a.
• Occipital part by
posterior cerebral a.
• INFERIOR SURFACE
• Orbital surface
-lateral: middle
cerebral
-medial: anterior
cerebral
• tentorial surface
-posterior cerebral
• Temporal pole:
middle cerebral
VISUAL AREA
• Supplied mainly by the posterior
cerebral artery
• Part of the visual area responsible for
macular vision lies in the region where
the territories of middle & posterior
cerebral a’s meet
• “ supplied by middle cerebral a.”
• Sparing of macular vision in cases of
thrombosis of possterior cerebral a.
VENOUS DRAINAGE
• Veins superficial & deep
open into dural venous
sinuses
• Superior saggital
• Inferior saggital
• Straight
• Transeverse
• Sigmoid
• Cavernous
• Sphenoparietal
• Petrosal
• Occipital
• Ultimately reach sigmoid
• Become continuous with
internal jugular vein
CAVERNOUS SINUS
• A large venous space in the
middle cranial fossa
• On either side of body of
sphenoid bone
• Caverns – trabeculae
• Floor: endosteal duramater
• Roof, lateral wall, medial
wall: meningeal duramater
• Ant: upto medial end of SOF
• Post: upto apex of petrous
temporal bone
• 2 cm long
• 1 cm wide
RELATIONS
• Outside:
* sup: optic tract, ICA, ant
perforated substance
* inf: foramen lacerum, jn
of body & gr wing of
sphenoid
* Med: hypophysis, sph air
sinus
* Lat: temporal bone
* Ant: SOF, apex of orbit
* Post: apex of pet temp &
crus cerebri of
midbrain
•
•
•
•
•
•
In lateral wall
Occulomotor N.
Trochlear N.
Ophthalmic N.
Maxillary N.
Trigeminal ganglion
• Through centre
• ICA
• Abducent N.
VISUAL
PATHWAY
•
•
•
•
INTRACRANIAL PART OF
OPTIC n.
1 CM LENGTH
ABOVE CAV SINUS
CONVERGES WITH ITS
FELLOW TO FORM
CHIASMA
• OPTIC CHIASMA
•
•
•
•
•
•
•
Flattened structure
12 mm horz, 8mm ap
Ensheathed by pia, surr by
CSF
Lies over diaphragma sella
Cont with tracts
Nasal half deccusate
Central 80%
• Optic tracts
• Cylindrical bundles of
N. fibres
• From postlat aspect of
chiasma bet tuber
cinerium & ant perf
subs
• Fibres frtom temp half
of retina on same side
& nasal half of opp side
• Ends in LGB
• Pupillary reflex fibres
pass to sup colliculi
• LGB
• Oval
• 6 layers of neurons
• Optic radiations
• Geniculocalcarine
pathway
• Fan out to form
medullary optic lamina.
• Inferior fibres subserve
upper visual fields- into
the temporal
• Superior fibres
subserves inferior
visual fields- through
parietal to visuals
cortex.
visual cortex
• On the medial aspect of
occipital in and near the
calcarine fissure extending
on to the lateral aspect
• Visuosensory area- striate17
• Visuopsychic areasperistriate (18) and
parastriate(19)
• Stria of gennari- layer of
medullated fibres
Arrangement of nerve
fibres and different
parts
• Distal region of optic nerve
• Optic tract
• Lateral geniculate body
• Optic radiations
• Visual cortex
• Optic chiasma : mainly
branches of anterior cerebral
and ICA.
• Optic tract: posterior
communicating artery, anterior
choroidal and middle cerebral
artery.
• LGB: posterior cerebral artery
,anterior choroidal artery
• Optic radiations: anterior
choroidal artery, deep optic
artery (MCA), calcarian
branches of posterior cerebral
artery.
• Visual cortex: mainly posterior
cerebral artery through
calcarian arteries, terminal
branches of MCA.
THANK YOU