Fliss Dan M. - Atlas of Surgical Approaches to Paranasal Sinuses and the Skull Base

Anterior and middle cranial base. ( a ) On the left side, the floor of the anterior fossa and the upper portion of the maxilla have been removed to expose the structures deep to the anterior and middle cranial fossa. The frontal, ethmoidal, and sphenoid sinuses and the nasal cavity lie below the medial part of the anterior cranial base. The orbit and maxilla are located below the lateral part of the anterior cranial base. The sphenoid sinus and sella are located in the medial part of the middle cranial base, and the infratemporal and pterygopalatine fossae are located below the lateral part of the middle cranial base. The carotid arteries pass upward on the medial part of the middle cranial base and are intimately related to the sphenoid and cavernous sinuses. The infratemporal fossa, which contains branches of the mandibular nerve, pterygoid muscles, pterygoid venous plexus, and maxillary artery, is located below the middle cranial base and greater sphenoid wing. The alveolar process of the maxilla, which encloses the roots of the upper teeth, has been preserved on the left side. The maxillary nerve enters the pterygopalatine fossa, which is located medial to the infratemporal fossa between the posterior wall of the maxilla and the pterygoid process of the sphenoid bone. ( b ) Superior view of the anterior and middle cranial base. The infratemporal fossa is located posterolateral to the maxilla. The right ethmoid air cells are exposed on the medial side of the right orbit. The nasal cavity extends upward between the ethmoid sinuses. ( c ) Oblique anterior view. The facial structures on the right side have been removed to expose the orbital apex located above the maxillary sinus. The wall of the right maxillary sinus forms the floor of the orbit, much of the lateral wall of the nasal cavity, and the anterior wall of the pterygopalatine and infratemporal fossa. On the left side, the mandibular nerve enters the infratemporal fossa. The maxillary nerve enters the pterygopalatine fossa, which is located in the lateral wall of the nasal cavity and contains the maxillary nerve, pterygopalatine ganglion, and terminal branches of the maxillary artery. ( d ) Anterior view. The orbital apex is located above the pterygopalatine fossa. The frontal branch of the ophthalmic nerve passes along the roof of the orbit, and the infraorbital branch of the maxillary nerve courses in the floor of the orbit. The posterior ethmoid air cells are located medial to the orbital apex. The vomer forms the posterior part of the nasal septum and attaches to the maxilla and palatine bones below and to the body of the sphenoid bone above. The sphenoid sinus is located in the middle cranial base below the sella turcica. The upper brainstem is seen in the posterior part of the exposure. A artery, Alv alveolar, Car carotid, Cart cartilage, CN cranial nerve, Eth ethmoid, Eust eustachian, Front frontal, Gang ganglion, Infraorb infraorbital, Infratemp infratemporal, M muscle, Max maxillary, N nerve, Nasolac nasolacrimal, Orb orbital, Pit pituitary, Pteryg pterygoid, Pterygopal pterygopalatine, Sphen Sphenoid, Sphenopal sphenopalatine (From Rhoton Jr AL. The anterior and middle cranial base. Neurosurgery. 2002;51(1 Suppl):S273302; with permission )

Specimen divided in the midsagittal plane to show the endoscopic endonasal approaches to the cranial base in midline through the frontal sinus, ethmoid sinus, sphenoid sinus, and nasopharynx. ( a ) Anterior cranial base approaches in midline through the frontal and ethmoid sinuses. ( b ) Approaches through the sphenoid sinus to the sellar region. ( c ) The endoscope is oriented downward to the nasopharynx for C1C2 approaches. Eth ethmoid, Eust eustachian, Front frontal, Gl gland, Pit pituitary, Sphen sphenoid

Lateral view of the anterior, middle, and posterior cranial base. ( a ) The bone and structures lateral to the orbit, infratemporal, and pterygopalatine fossa and the parapharyngeal space and petrous part of the temporal bone have been removed to expose the structures below the anterior, middle, and posterior cranial base. The orbit and maxillary sinus are located below the anterior cranial base. The infratemporal and pterygopalatine fossae and the parapharyngeal space are located below the middle cranial base, and the suboccipital area is located below the temporal and occipital bones. The first trigeminal division is related to the upper part of the orbit. The second trigeminal branch is related to the lower part of the orbit and maxilla. The mandibular nerve exits the cranium through the foramen ovale and enters the infratemporal fossa. The pterygoid and levator and tensor veli palatini muscles have been removed to expose the eustachian tube and its opening into the nasal pharynx. The lateral part of the temporal bone has been removed to expose the cochlea, vestibule, and semicircular canals. The petrous carotid passes upward and turns medially below the cochlea. The sigmoid sinus turns downward under the semicircular canals and vestibule where the jugular bulb is located. The segment of the vertebral artery passing behind the atlanto-occipital joint is located below the posterior cranial base. ( b ) The dura has been opened to show the relationships of the frontal and temporal lobes and the cerebellum to the cranial base. The orbit is exposed below the frontal lobe. The pterygopalatine and infratemporal fossae and the temporal bone are located below the temporal lobe. The jugular bulb and internal jugular vein have been removed to show cranial nerves 9 through 12 exiting the jugular foramen. A artery, Car carotid, CN cranial nerve, Eust eustachian, Front frontal, Gr greater, Inf inferior, Infraorb infraorbital, Infratemp infratemporal, Int internal, Jug jugular, Lat lateral, M muscle, Max maxillary, N nerve, Ped peduncle, Pet petrosal, Pterygopal pterygopalatine, Rec rectus, Semicirc semicircular, Sphen sphenoid, Temp temporal, V vein, Vert vertebral (From Rhoton Jr AL. The anterior and middle cranial base. Neurosurgery. 2002;51(1 Suppl):S273302.; with permission )