CC-BY-NC 3.0 MEDIAL MAXILLECTOMY Johan Fagan Medial maxillectomy refers to surgical re- turbinate (concha) is resected with a medial section of the medial and superomedial maxillectomy, but the middle turbinate is walls of the maxillary antrum. It is increas- generally preserved, unless involved by pa- ingly being done by transnasal endoscopic thology. technique for suitable cases and when the required expertise and technology are avail- Frontal sinus able. This chapter will only deal with the Posterior ethmoidal foramen Orbital process palatine bone open surgical medial maxillectomy tech- Anterior ethmoidal Sphenopalatine foramen nique. foramen Foramen rotundum Maxillectomy is potentially complicated by Lacrimal fossa injuries to the orbital contents, lacrimal ap- Uncinate Max sinus ostium paratus, optic nerve, ethmoidal arteries, in- Pterygoid canal Inferior turbinate Pterygopalatine canal tracranial contents, and may be accompa- Palatine bone nied by brisk bleeding. A sound under- Lateral pterygoid plate standing of the 3-dimensional anatomy of Pyramidal process palatine bone the maxilla and the surrounding structures Figure 1: Lateral view of maxilla with windows cut in is therefore essential. Hence the detailed de- lateral and medial walls of maxillary sinus scription of the surgical anatomy that fol- lows. Frontal sinus Surgical Anatomy Crista galli Sella turcica Bony anatomy Figures 1 & 2 illustrate the detailed bony anatomy relevant to medial maxillectomy. Uncinate Critical surgical landmarks to note include: • The level of the floor of the anterior cra- Maxillary sinus ostium nial fossa (fovea ethmoidalis and cribri- Medial pterygoid plate Pterygoid hamulus form plate) corresponds with anterior and posterior ethmoidal foramina lo- Figure 2: Bony anatomy of the lateral wall of the nose cated along the frontoethmoidal suture line Figure 3 demonstrates the anatomy of the • The proximity (5-11mm) of posterior medial wall of the nose in a cadaveric skull. ethmoidal foramen and artery to the op- Note in particular the thin lamina papyra- tic nerve within the optic foramen cea, the lacrimal fossa, the frontoethmoidal suture line and the anterior and posterior Figure 2 illustrates the bony anatomy of the ethmoidal foramina and the infraorbital fo- lateral wall of the nose. The inferior ramen. http://openbooks.uct.ac.za/ENTatlas 29-1 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery Ant ethmoidal for Frontoethmoidal suture Floor anterior cranial fossa Post ethmoidal for Optic foramen Lamina papyracea Sup orbital fissure Lamina papyracea Middle turbinate Inf orbital fissure Lacrimal fossa Uncinate process Infraorbital foramen Inferior turbinate Infraorbital nerve Maxillary sinus Inferior turbinate Figure 3: Bony anatomy in cadaver Figure 5: Anatomy in the coronal plane through the Figure 4 demonstrates the coronal anatomy anterior ethmoids midway along a medial maxillec- at the level of the anterior extent of a medial tomy maxillectomy. Specifically note the lacrimal sac, which is normally transected at surgery Figures 6 & 7 demonstrate the value of using in the lacrimal fossa, and the relative heights the anterior and posterior ethmoidal arter- of the floors of the antrum and the nasal ies and frontoethmoidal suture line to de- cavity. termine the level of the floor of the anterior cranial fossa when opening the lamina pap- yracea from the orbital side during medial Anterior cranial fossa floor maxillectomy. Frontonasal duct Fovea ethmoidalis Lacrimal sac in lacrimal fossa Anterior ethmoidal foramen Anterior end of maxillary sinus Lamina papyracea Uncinate process Inferior turbinate Infraorbital nerve Figure 4: Coronal CT slice through lacrimal fossa Figure 5 demonstrates the coronal anatomy Figure 6: Note the position of the anterior ethmoidal artery where it passes through its foramen which is lo- midway back along a medial maxillectomy. cated in the frontoethmoidal suture line Specifically note the infraorbital nerve in the orbital floor, the thin lamina papyracea and the relative heights of the floors of the antrum and the nasal cavity. http://openbooks.uct.ac.za/ENTatlas 29-2 Johan Fagan Posterior ethmoidal foramen Optic nerve Infraorbital nerve Lamina papyracea Nasolacrimal duct Ground lamella Zygoma Inferior orbital fissure Pterygomaxillary fis- sure Pterygopalatine fossa Figure 7: Coronal slice through posterior ethmoids demonstrating posterior ethmoidal foramen and optic Figure 9: Axial cut at level of infraorbital nerve and nerve orbital floor Figure 8 demonstrates the coronal anatomy immediately posterior to the maxillary si- nus, which is in the plane through which a Infraorbital foramen total maxillectomy is done, and in which the Inferior turbinate internal maxillary artery and its branches as Zygoma well as the sphenopalatine ganglion and its branches are encountered within the ptery- Pterygomaxillary fissure gopalatine fossa. The pterygopalatine fossa Pterygoid plates communicates laterally with the infratem- Figure 10: Axial cut at level of infraorbital foramen poral fossa via the pterygomaxillary fissure, and pterygoid plates and medially with the nasal cavity via the sphenopalatine foramen. The bony anatomy of the hard palate is il- lustrated in Figure 11. Orbital apex Sphenopalatine foramen Pterygopalatine fossa Incisive foramen Pterygomaxillary fissure Horizontal plate of palatine Pterygoid plates bone Figure 8: Coronal cut immediately behind the maxil- Greater palatine foramen lary sinus through the orbital apex, pterygoid plates Lesser palatine foramina and pterygopalatine fossa. Pterygoid plates Figures 9 & 10 show axial views of the anat- omy of the maxillary sinus. The posterior Figure 11: Anatomy of hard palate resection lines of total and inferior maxil- Vasculature lectomies pass through the pterygopalatine fossa and pterygomaxillary fissure and the An understanding of the blood supply of anterior aspect of the pterygoid plates. the maxilla permits the surgeon to antici- pate when and where to encounter bleed- Medial maxillectomy is done medial to the ing, and to plan the sequence of the surgery infraorbital nerve. to reserve the bloodier parts of the surgery http://openbooks.uct.ac.za/ENTatlas 29-3 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery until last so as to minimise blood loss and to avoid blood obscuring the surgical field. Transverse facial artery Internal maxillary artery The only significant vein encountered dur- External carotid artery ing maxillectomy is the angular vein (Fig- ure 12) at the medial canthus. Facial artery Figure 13: Facial artery and origin of internal maxil- lary artery, both branches of the external carotid ar- tery Angular vein Angular artery Infraorbital ar- tery Figure 12: Vasculature around the orbit The blood supply to the maxilla and para- nasal sinuses originates both from the exter- nal and internal carotid artery systems. The Figure 14: Branches of internal maxillary artery; blue shaded area is the 2nd part of artery before it enters arterial supply relevant to maxillectomy is the pterygopalatine fossa as follows: • Facial/external maxillary artery, a branch of the external carotid artery courses in the soft tissues of the face and past the medial canthus as the angular artery (Figures 12, 13) • Internal maxillary artery, a branch of the external carotid artery (Figures 13, 14), passes through the pterygo-maxil- lary fissure to enter the pterygopal- atine fossa Branches of the internal maxillary artery of surgical significance include: • Greater palatine artery (descending palatine) (Figure 14): It passes inferiorly from the pterygopalatine fossa through the pterygopalatine canal (Figure 1) and http://openbooks.uct.ac.za/ENTatlas 29-4 Johan Fagan emerges from the greater palatine fora- • Ophthalmic artery: It emerges with the men of the hard palate (Figure 11). It optic nerve from the optic canal, 44mm then runs anteriorly medial to the supe- from the anterior lacrimal crest and ap- rior alveolus and enters the incisive fo- proximately 6 mm (5-11 mm) from the ramen (Figure 11) posterior ethmoidal foramen • Infraorbital artery: It courses in the in- fraorbital groove and canal with the in- Nerves fraorbital nerve in the floor of the or- bit/roof of antrum and exits anteriorly The maxillary division of V (V2) enters the via the infraorbital foramen to supply pterygopalatine fossa via foramen rotun- the overlying soft tissues of the face (Fig- dum. The only branch of surgical signifi- ures 12, 14) cance is the infraorbital nerve. It runs in the • Sphenopalatine artery (Figure 14): It floor of the orbit/roof of the antrum to exit enters the nasal cavity through spheno- from the infraorbital foramen (Figure 15). palatine foramen at the back of the su- The only other major nerve that has to be perior meatus where it gives origin to considered at maxillectomy is the optic posterior lateral nasal branches nerve. • Posterior septal artery: This is a branch of the sphenopalatine artery and crosses the posterior nasal cavity just above the posterior choana to end on the nasal septum; one branch descends in a groove in the vomer to enter the incisive canal and anastomose with the greater palatine artery Branches of the internal carotid artery of surgical significance include: Figure15: V2, pterygopalatine ganglion and infraor- • Anterior ethmoidal artery: It originates bital nerve from the ophthalmic artery and enters the orbit through the anterior eth- Orbital structures moidal foramen (Figure 3) which is lo- cated 25 mm from