Surgical Anatomy of Skull Base

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Surgical Anatomy of Skull Base

• Dr. Supreet Singh Nayyar, AFMC

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Topography of Skull Base

• Boundaries
• Anterior Incisors upper teeth
• Posterior Superior nuchal line
• Lateral Upper lateral teeth
• Zygomatic arch
• Mastoid process

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Topography of Skull Base
Anterior Skull Base
Central Skull Base
Posterior Skull Base
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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

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• Hypoglossal canal
• Hypoglossal nerve
• Hypoglossal artery

• Jugular Foramen
• Pars nervosa CN IX, inferior petrosal sinus
• Pars vascularis CN X, XI, jugular bulb

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Skull Base Anatomy Review

• Foramen Spinosum
• Middle meningeal artery
• Recurrent branch of mandibular nerve

• Stylomastoid foramen
• Facial nerve
• Stylomastoid artery

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Skull Base Anatomy Review

• Foramen Lacerum
• Ascending pharyngeal artery- meningeal branch
• Nerve of pterygoid canal

• Foramen rotundum
• Maxillary nerve
• Artery of foramen rotundum
• Emissary veins

• Pterygoid canal
• Vidian nerve
• Vidian artery

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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

• Meckels Cave
• Posterior aspect of cavernous sinus
• Gasserian ganglion (sensory root ganglion of CN
  V)

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Skull Base Anatomy Review

• Superior Orbital Fissure
• CN III, IV, V1, VI
• Middle meningeal artery- orbital branch
• Recurrent meningeal artery
• Superior ophthalmic vein

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Central Skull Base
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Central Skull Base
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1
2

• 1

5
3
4
4- Auditory Area5- Articular Area6-
Infratemporal Foss
1- Pharyngeal Area2- Tubal Area3- Neurovascular
Area
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Pharyngeal Area

• Roof of Nasopharynx
• Boundaries of
• Nasopharynx
• Anterior
• Lateral Posterior
• Inferior

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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

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Tubal Area

• Eustachian Tube
• Scaphoid fossa
• Runs b/w petrous
• bone greater wing
• sphenoid
• Opening- nasopharynx
• Paratubal muscles

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Neurovascular Area

• Important structures are
• Carotid sheath its contents
• Styloid apparatus
• Facial Nerve

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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

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Jugular Foramen

• Divided into three compartments

Compartments Contents ( lateral to medial )
Anterior IX Nerve Inferior petrosal Sinus
Middle XI Nerve X Nerve
Posterior IJV
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• Styloid Apparatus
• Bone- Styloid bone
• Ligaments- Stylohyoid
• Stylomandibular
• Muscles- Stylohoid
• Stylopharyngeus
• Styloglossus

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Facial Nerve

• Arise from Stylomastoid Foramen
• Branches
• i) Post auricular nerve
• ii) Digastric branch
• iii) Temporofacial branch
• iv) Cervicofacial branch

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Auditory Area

• Petrotympanic
• fissure of Glaser
• Chorda tympani
• Ant br of
• tympanic artery

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Infratemporal Fossa

• Location below middle
• cranial fossa
• Boundaries
• Contents
• Med Lat Pterygoid M
• Maxillary A
• Maxillary V
• Pterygoid Venous Plexus
• Br of Mandibular N

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Pterygopalatine Fossa

• Small inverted pyramid shaped fossa
• Location
• Boundaries
• Communications

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Anterior Cranial Base
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Anterior Cranial Base from inside
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Floor of Anterior Cranial Fossa

• Depth of Olfactory
• fossa (Keros classification)
• Type I 1-3mm
• Type II- 4-7mm
• Type III- 8-17mm