Interior of the Skull
(Cranial Fossa)
l A- Ant. Cranial fossa
Sup. ___ frontal bone.
Antero. Lat. ___ frontal bone.
Post. ___ lesser wing of sphenoid
Inf. ___ orbital plate of frontal
l Foramina in ant. cranial fossa
1- F.caecum: in front of crista galli , in the median plane at fronto-ethmoidal suture . Transmitting emissary veins from upper nose to the sup.sagittal sinus , but it s usually blind.
2- Olfactory F.: in the cribriform plate of ethmoid , 15-20 in number on each side, for passage of olfactory n. from upper 1/3 of nose to olfactory bulb.
3- Ant. and Post. Ethmoid F.:
- Ant.: in the suture joining lateral margins of cribriform plate of ethmoid , and orbital plate of frontal , behind crista galli
- Post.: in the posterolateral of cribriform plate of ethmoid where it s articnlates with jugum of sphenoid .
*** Both ant. and post. ethmoid f. , transmit n. and vessels of same name.
l Clinical Notes
Fractures of anterior cranial fossa:
* Involve cribriform plate lead to epistaxis accompany by discharge of C.S.F and loss of smell.
** Fracture involve orbital plate of frontal bone lead to subconjunetival which my lead or produce exophthalmus or frontal sinus my involved.
l B- Middle cranial fossa
Ant. ___ lesser wing of sphenoid.
Lat. ___ squamous part of temporal and parietal.
Post. ___ ant. part of petrous of temporal.
Its shape like butterfly :
- Median part is form by body of sphenoid bone.
- Lateral part is form by petrous part of temporal and sequamous part.
l Foramina in Middle cranial fossa
1- Optical canal: in the sphenoid between the body and two roots of lesser wing. Transmit- optic n. and ophthalmic artery inferolateral to the n.
2- Sup. Orbital fissue: in the sphenoid , between body and two wings. Transmit- oculomotor , trochlear , abducent nerves
lacrimal ,frontal,nasociliary nreves,superior of ophthalmic vein.
3- F. Rotundum: in the greater wing of sphenoid infero lateral to medial end of sup. Orbital fissure .transmits max. division of V nerve.
4- F. Ovale: in the greater wing of sphenoid ,postero- lateral to f. rotundum , opens in the base of skull at the root of L. pterygoid plate.
Transmits- mand. n. , lesser petrosal n. , accessory meningeal art. and emissary veins from cavernous sinus to pterygoid plexus.
5- F. Spinosum: in the greater wing of sphenoid , also it s posterolateral to foramen ovale.
** Transmits middle meningeal art. and branch of mand. nerve. ( nervous spinosus) and middle meningeal vein.
6- F. lacercum:
between the sphenoid , apex of petrous temporal and basilar part of occipital b., usually filled by cartilage during life , but may transmit meningeal branch of ascending pharyngeal art. and emissary veins from cavernous sinus to pterygoid plexus , it also transmit (I.C.A) entering from behind and emerging above, also transmit greater petrosal n. (inter from above and behind leaving ant. as n. pterygoid canal. Opens in base of skull at root of median ptergoid plate .
7- Carotid canal: nternal carotid artery enter and reach the side of body of sphenoid, then enter cavernous sinus to reach the region of anterior clinoid process.
l Clinical Notes
Fractures in middle cranial fossa is common site of fractures of skull.
Because of its position and weakened by numerous foramen and canals, so frequently tegman tympani if fracture and tympanic membrane is torn,so blood and C.S.F are discharged from ear.
l C- Post. cranial fossa:
Ant. ___ post part of petrous of temporal
Lat. ___ parietal and mastoid process of temporal
Post. ___ occipital
Inf. ___ foramen magnum
** largest and deepest cranial fossa and lodges the hindbrain (cerebellum,pons,medalla oblangata).
l Foramina in Post. cranial Fossa
1- Int. acoustic meatus: in post sur. of petrous temporal
Transmit- Facial , vestibulocohlear nerves , labyrinthine artery.
2- Jugualr F.: between jugular f. and occipital b.
Tansmits- 9,10,11th , inf petrosal sinus , IJV , menigeal branch of occipital artery.
3- Hypoglossal canal: in occipital b. above ant. part of condyle . transmit- hypoglossal n. and it s meningeal branch and also emissary veins from basilar plexus of veins to IJV.
4- Condylar canal: from the lower part of sigmoid groove in lateral of occipital b. to condylar fossa on ext. sur. of occipital b. behind the condyle . transmits emissary veins (from sigmoid sinus to occipital veins and meningeal branch of occipital artery.
5- Mastoid F.: in petrous temporal near post. margin of lower part of sigmoid groove , passing backwards to open behind mastoid process.
Transmits – emissary veins ( from sigmoid sinus to occipital veins) , also meningeal branch of occipital artery.
l Cranial Nerves:
1- Olfactory n. ___ smell sense
2- Optic n. ___ sight
3- Oculomotor ___ muscles of eye ball
4- Trochlear n.
5- Trigeminal n.
6- Abducent n.
7- Facial n.
8- Anditory n.
9- Glossopharyngeal n.
10- Vagus n.
11- Accessory n.
12- Hypoglossal n.