introduction to skull, parts of skull, bones involved forming skull, different views of skull, norma basalis, anterio cranial middle cranial and posterior cranial fossa, clinical aspects of cranial fossa, foramens present in the cranial fossa

1. CRANIAL FOSSA
Dr SANA YASEEN
ANATOMY DEPARTMENT
KIMS

2. INTRODUCTION
TO SKULL

3. • Skull: skeleton of the head is called skull
• It is divided into two parts:
• Calvaria: brain box
• Facial skeleton including the mandible
BONES OF THE SKULL:
• Skull holds 22 bones of which:
• Calvaria : 8 bones
• Facial skeleton : 14 bones
• These bones are divided in to paired and unpaired bones.

4. CALVARIA / BRAIN
BOX : 8 bones
PAIRED UNPAIRED
Parietal Frontal
Temporal Occipital
Sphenoid
Ethmoid
FACIAL SKELETON: 14
BONES
PAIRED UNPAIRED
Maxilla Mandible
Zygomatic Vomer
Nasal
Palatine
Inferior nasal
concha
Lacrimal

5. METHODS TO STUDY THE SKULL
We can study skull from out side / outer view and from inside /inner view.
External features can be studied from different views:
ANTERIOR VIEW / NORMA FRONTALIS
POSTERIOR VIEW / NORMA OCCIPITALIS
SUPERIOR VIEW / NORMA VERTICALIS
LATERAL VIEW / NORMA LATERALIS
INFERIOR VIEW / NORMA BASALIS

6. NORMA
FRONTALIS
NORMA
OCCIPITALIS
NORMA
LATERALIS
NORMA
VERTICALIS
NORMA
BASALIS

7. NORMA BASALIS

8. SUPERIOR/ INTERNAL INFERIOR/ EXTERNAL

9. An imaginary
transverse line
passing through
the margin of
foramen magnum

10. ANTERIOR CRANIAL FOSSA
MIDDLE CRANIAL FOSSA
POSTERIOR CRANIAL FOSSA

11. ANTERIOR
CRANIAL FOSSA
 BOUNDARIES
 FLOOR
 FEATURES
 CONTENTS
 CLINICALS

12. BOUNDARIES:
• Anteriorly an on each sidde: Frontal Bone
• Posteriorly: border of lesser wing of sphenoid bone, anterior clinoid
process, anterior margin of sulcus chiasmaticus.
FLOOR:
• Median plane: anteriorly cribriform plate of ethmoidal bone
• Posteriorly: superior surface of anterior part of body of sphenoid
• Each side: orbital plate of frontal bone and lesser wing of sphenoid

13. sulcus
chiasmaticus

14. FEATURES
FRONTAL CREST: Act as site of the attachment for the falx cerebri ( a
sheet of dura mater that divides the cerebral hemisphere)
FORAMEN CAECUM: (blind ended) located in median plane at
frontoethmoidal junction.
Content: emissary veins to sperior sagittal sinus
CRIBRIFORM PLATE: (sleeve like) posseses numerous pores. It supports
olfactory bulb.
Content: olfactory nerve (CN I) rootlest

15. FRONTAL
CREST
CRISTA
GILLI
FORAMEN
CEACUM
CRIRIFORM
PLATE
ANTERIOR
CLINOIDAL
PROCESS

16. CRISTA GALLI: is midline projection on the cribriform plate. Another point
for the attachment of falx cerebri. On each sidde of crista galli are
foraminas.
Content: anterior ethmoidal nerve and vessels to nasal cavity
ANTERIOR CLINOIDAL PROCESS:
Rounded endds of lesser wing of sphenoid, serves as attachment for the
tentorium cerebelli (a sheet of dura matter that divides the cerebrum from
cerebellum)

17. BLACK EYE
 A black eye is the appearance of
bruising around the eyes
 Fracture of anterior cranial fossa may
cause bleeding and discharge of CSF
through nose. Blood may also
seepage in to the eyelids causing
condition known as black eye
 A black eye will normally heal without
medical intervention,

18. MIDDLE CRANIAL
FOSSA
 BOUNDARIES
 FLOOR
 FEATURES
 CONTENTS
 CLINICALS

19. Boundaries:
o Anteriorly: lesser wing of sphenoid (posterior border), anterior clenoid
process, sulcus chiasmaticus
o Posteriorly: petrous part of temporal bone , dorsum sellae of sphanoid,
o Laterally: greater wing of sphenoid, anteroinferior angle of parietal bone,
squamous part of temporal bone
Floor:
body of sphenoid (in midddle), greater wing of sphenoid, squamous part of
temporal bone, anterior surface of petrous part of temporal bone

21. Carotid canal

22. FEATURES:
o SULCUS CHIASMATICUS/ OPTIC GROOVE: leads to optic canal.
o OPTIC CANAL: leads to orbit. It allows passage of optic nerve (CN I) and
ophthalmic artery.
o SELLA TURCICA: is the upper surface of the body of sphenoid. It is hollowed
consisting of tuberculum sellae in front, hypophyseal fossa in the middle and
dorsum sellae behind. Superolateral angle of dorsum sellae are expanded to
form posterior clinoid processes.
 tuberculum sellae separates optic groove from hypophyseal fossa.
 hypophyseal fossa lodges hypophysis cerebri. Beneath the fossa lies
sphenoidal air sinuses.

26. o SUPERIOR ORBITAL FISSURE: opens anteriorly into the orbit. Lower
border is marked by small projection, which allows attachment to the
common tendinous ring of zinn. The ring divides fissure into three parts.
It allows passage of
 Lateral part: Lacrimal andd frontal nerve (ophthalmic nerve) - Trochlear
nerve- superior ophthalmic vein- meningeal branch of lacrimal artery-
anastomosis branch of middle meningeal aretry.
 Midddle part: occulomotor nerve CN III- nasociliary nerve (ophthalmic nerve
V1)- abducent nerve
 Medial part: abducent nerve (CN VI) - inferior ophthalmic vein- sympathetic
nerves from plexus around internal carotid artery.

27. Optic canal
Suprior
orbbital
fissure

29. o FORAMEN ROTUNDUM: leads anterior to pterygopalatine fossa
containing pterygopalatine ganglion. Transmits maxillary nerve (CN V2)
o FORAMEN OVALE: leads inferior to infratemporal fossa. Transmits
Mandibular nerve CN V3- accessory meningeal artery- lesser petrosal
nerve
o FORAMEN SPINOSUM : leads inferior to infratemporal fossa.
Transmits middle meningeal vessels – meingeal branch of mandibular
nerve

31. o GROOVE for the midddle meningeal vessels
o FORAMEN LACERUM:
o CAROTID CANAL: just lateral to foramen lacerum, transmits internal
carotid artery and internal carotid nerve plexus
o Hiatus for lesser petrosal and greater petorsal nerve lies lateral to the
canal.
o TEGMEN TYMPANI: is thin plate of bone (petrous part of temporal
bone). Forms roof for tympanic antrum, tympanic cavity an canal for
tensor tympani.
Lateraly is turn downward to form lateral wall of bony auditory tube.

32. FORAMEN
LACERUM
CAROTID
CANAL
HIATUS FOR
GREATER
PETROSAL
AND LESSER
PETROSAL
NERVE

33. Tegmen
tympani

35. CLINICAL NOTES
Middle cranial fossa is commomly fractured; producing following sign/ symptoms
 Bleeding and discharge of csf from ear
 Bleeding from mouth and nose due to sphanoid bone
 CN VII, CN VIII, may also get damage at the point of internal acoustuc meatus.
 Damage to semicircular canal causes vertigo.

36. POSTERIOR
CRANIAL FOSSA
 BOUNDARIES
 FLOOR
 FEATURES
 CONTENTS
 CLINICALS

37. BOUNDARIES:
ANTERIOR : petrous part of temporal bone- ddorsum sellae of sphenoidd
bone-
POSTERIOR: squamous part of the occipital bone
EACH SIDE: mastoid part of temporal bone- parietal bone
FLOOR:
Median area: foramen magnum- occipital bone
Lateral: occipital bone- petrous part of temporal bone- mastoid part of
temporal bone- parietal bone

39. FEATURES:
o FORAMEN MAGNUM: medulla oblongata- meninges- vertebral arteries-
meningeal branch of vertebral arteries- spinal root of accessory nerve.
o INTERNAL OCCIPITAL CREST: runs in the mid line from internal occipital
protuberance to foramen magnum where it forms dpression known as
VERMIAN FOSSA. Internal occipital crest allows attachment of falx
cerebelli.
o INTERNAL OCCIPITAL PROTUBERANCE: corresponds to the external
occipital protuberance. It is related to the confluence of sinuses.

40. FORAMEN MAGNUM
INTERNAL
OCCIPITAL
PROTUBERANCE
VERMIAN FOSSA
INTERNAL
OCCIPITAL CREST
CEREBELLAR FOSSA

41. o TRANSVERSE SULCUS: runs laterally from internal occipital protuberance to the
parietal bone where it becomes continuous with sigmoid sulcus. It lodges transverse
sinus.
o CEREBELLAR FOSSA: on each side of internal occipital crest are cebellar fossa that
holds cerebellar hemisphere.
o INTERNAL ACOUSTIC MEATUS: lies on petrous part of temporal bone above
jugular foramen. Runs in lateral direction about 1cm long.it is laterally close by
lamina cribrosa which seperates it from internal ear.
Transmits: facial nerve (CN VII)- vestibulocochlear nerve (CN VIII)- - labyrinthine artery

43. MASTOID FORAMEN
HYPOGLOSSAL CANAL
INTERNAL
ACOUSTIC MEATUS
JUGULAR FORAMEN

44. o JUGULAR FORAMEN: lies at the posterior end of petro-occipital fissure. It
transmits ; glossopharyngeal nerve (IX)- vagus nerve (CN X)- accessory
nerve (CN XI)- inferior petrosal sinus- sigmoid sinus- posterior meningeal
artery.
o HYPOGLOSSAL CANAL: hypoglossal nerve (CN XII)
o MASTOID FORAMEN: opens in the upper part of mastoid sulcus, locatedd
in mastoid part of temporal bone.
Mastoid sulcus lodges the sigmoid sinus, which becomes the internal jugular
vein as it reaches to jugular foramen.