1. Surgical Anatomy of Skull Base
Dr. Supreet Singh Nayyar, AFMC
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2. Topography of Skull Base
Boundaries :
Anterior : Incisors upper teeth
Posterior: Superior nuchal line
Lateral : Upper lateral teeth
Zygomatic arch
Mastoid process

3. Topography of Skull Base
Anterior Skull Base
Central Skull Base
Posterior Skull Base

4. Superior orbital fissure Inferior orbital fissure Optic canal
Skull Base Anatomy Review
Key Openings
Foramen spinosum
Foramen ovale
Foramen lacerum
Foramen rotundum
Foramen magnum
Foramen of vesalius
Jugular foramen
Superior orbital fissure
Inferior orbital fissure
Optic canal
Vidian canal
Hypoglossal canal
Pterygopalatine fossa
7 foramina
2 fissures
3 canals
All with fun stuff inside.

5. Anterior/Posterior spinal arteries Hypoglossal nerve
Skull Base Anatomy Review
Foramen magnum
Medulla oblongata
Vertebral arteries
Anterior/Posterior spinal arteries
Hypoglossal canal
Hypoglossal nerve
Hypoglossal artery
Hypoglossal artery = not always present.
Sometimes, can have a small emissary vein that runs through here that can protrude into the cerebellomedullary cistern and mimic a nerve sheath tumor.
Jugular Foramen
Pars nervosa: CN IX, inferior petrosal sinus
Pars vascularis: CN X, XI, jugular bulb

6. Middle meningeal artery Recurrent branch of mandibular nerve
Skull Base Anatomy Review
Foramen Spinosum
Middle meningeal artery
Recurrent branch of mandibular nerve
Foramen Ovale
Mandibular nerve
Accessory meningeal artery
Lesser petrosal nerve
Emissary veins
Foramen of Vesalius
Sphenoidal Emissary vein
Stylomastoid foramen
Facial nerve
Stylomastoid artery
F.S.:
V3 recurrent = mandibular branch.
Emissary veins in FS and FO connect cavernous sinus with pterygoid plexus of veins = path for nasaopharyngeal tumors.
Foramen of vesalius- inconstant. Anterior and medial to f. ovale. When it does occur, it contains (read slide)

7. Ascending pharyngeal artery- meningeal branch Nerve of pterygoid canal
Skull Base Anatomy Review
Foramen Lacerum
Ascending pharyngeal artery- meningeal branch
Nerve of pterygoid canal
F.L.:read slide
Vidian canal = aka pterygoid canal. Connects pterygopalatine fossa to foramen lacerum. Contains vidian artery (branch of maxillary artery) and nerve.
Vidian nerve = formed by merger of greater superficial petrosal nerve (branch of facial nerve) and deep petrosal nerve.
Foramen rotundum
Maxillary nerve
Artery of foramen rotundum
Emissary veins
Pterygoid canal
Vidian nerve
Vidian artery

8. Drains via: Petrosal sinuses Basilar plexus Pterygoid plexus
Skull Base Anatomy Review
Cavernous Sinus
Receives: Superior opthalmic vein Inferior opthalmic vein Sphenoparietal sinus
Drains via: Petrosal sinuses Basilar plexus Pterygoid plexus
Connection: Circular sinus
Contains: CN III, IV, V1, V2, VI
PPF – foramen rotundum = connection with meckel’s cave, cav sinus, since we’ve mentioned it a few times now and b/c contains a lot of key elements:
Cav sinus- read slide.
V2- lateral wall of CS- then to foramen rotundum
V1- lateral wall of cav sinus- then to superior orbital fissure, along with CN III, IV, VI
Meckel’s Cave
Posterior aspect of cavernous sinus
Gasserian ganglion (sensory root ganglion of CN V)

9. Middle meningeal artery- orbital branch Recurrent meningeal artery
Skull Base Anatomy Review
Superior Orbital Fissure
CN III, IV, V1, VI
Middle meningeal artery- orbital branch
Recurrent meningeal artery
Superior ophthalmic vein
Inferior Orbital Fissure
Infraorbital artery, vein, and nerve (V2 branch)
Optic Canal
Optic nerve
Ophthalmic artery
Speaking of the superior orbital fissure…
Below SOF = IOF.
Optic canal = more superior to SOF.

10. Central Skull Base

11. Central Skull Base 6 1 2 1 5 3 4
4- Auditory Area 5- Articular Area 6- Infratemporal Foss
1- Pharyngeal Area 2- Tubal Area 3- Neurovascular Area

12. Pharyngeal Area Roof of Nasopharynx Boundaries of Nasopharynx :
* Anterior
* Lateral & Posterior
* Inferior

13. Pharyngeal Area Pharyngobasilar fasia Fossa of Rosenmullar
* Location- above &
behind medial end ET
* Depth- 2.5 cm
* Apex- Carotid canal
opening (post) &
f. ovale, f. spinosum
(lat)
* Base- below
Foramen lacerum

14. Tubal Area Eustachian Tube Scaphoid fossa Runs b/w petrous
bone & greater wing
sphenoid
Opening- nasopharynx
Paratubal muscles

15. Neurovascular Area Important structures are:
Carotid sheath & its contents
Styloid apparatus
Facial Nerve

16. Carotid Sheath Compact network of aerolar tissue
Carotid canal to arch of aorta
Encloses : ICA above & CCA below
IJV
Vagus nerve
Carotid Canal : ICA & Carotid plexus
sympathetic nerve
Parts of ICA

17. Divided into three compartments
Jugular Foramen
Divided into three compartments
Compartments
Contents ( lateral
to medial )
Anterior
* IX Nerve
* Inferior petrosal
Sinus
Middle
* XI Nerve
* X Nerve
Posterior
* IJV

18. Styloid Apparatus Bone- Styloid bone Ligaments- * Stylohyoid
* Stylomandibular
Muscles- * Stylohoid
* Stylopharyngeus
* Styloglossus

19. Facial Nerve Arise from Stylomastoid Foramen Branches:
i) Post auricular nerve
ii) Digastric branch
iii) Temporofacial branch
iv) Cervicofacial branch

20. Auditory Area Petrotympanic fissure of Glaser: * Chorda tympani
* Ant br of
tympanic artery

21. Infratemporal Fossa Location : below middle cranial fossa Boundaries
Contents:
* Med & Lat Pterygoid M
* Maxillary A
* Maxillary V
* Pterygoid Venous Plexus
* Br of Mandibular N

22. Pterygopalatine Fossa
Small inverted pyramid shaped fossa
Location
Boundaries
Communications

23. Anterior Cranial Base

24. Anterior Cranial Base from inside

25. Floor of Anterior Cranial Fossa
Depth of Olfactory
fossa (Keros classification)
* Type I – 1-3mm
* Type II- 4-7mm
* Type III- 8-17mm

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