Endonasal identification of the orbital apex.
OBJECTIVE
To describe anatomical landmarks for endoscopic endonasal approaches to the orbital apex and to measure the distances between those landmarks.


METHODS
In this anatomic study, the nasal fossae of 30 adult fresh cadavers were dissected (n = 60 half-skulls). One double-injected orbit was carefully dissected, mainly focusing on the neurovascular structures. The orbital apex was dissected under endoscopic endonasal visualization in all cases. The distances between the ethmoidal crest and choanal arch to the optic canal (OC) and superior orbital fissure (SOF) were measured and recorded.


RESULTS
The sample was predominantly male (63.3%, 19/30 cadavers). The following correlations between measurements according to side were observed: ethmoidal crest to OC, r = 0.748 (P = 0.0001); ethmoidal crest to SOF, r = 0.785 (P = 0.0001); choanal arch to OC, r = 0.835 (P = 0.0001); choanal arch to SOF, r = 0.820 (P = 0.0001).


CONCLUSIONS
In the cadavers studied in this sample, the ethmoidal crest and choanal arch were relevant structures and exhibited consistent measurements. Spearman correlation coefficients were greater than 0.7, which is indicative of good correlation between measurements obtained in the skull halves of each cadaver. Comparison of the measurements obtained in different sides showed similar values, with no statistically significant differences in the distances between any of the proposed anatomic landmarks.
Department of Otolaryngology, University of Sao Paulo, Sao Paulo, Brazil.
Miguel S
MS
Tepedino
Division of Otolaryngology and Head-Neck Surgery, Albany Medical College, Albany, New York.
Carlos D
CD
Pinheiro-Neto
Department of Otolaryngology, University of Sao Paulo, Sao Paulo, Brazil.
Thiago F P
TF
Bezerra
Department of Neurological Surgery.
Paul A
PA
Gardner
Department of Neurological Surgery.|Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, U.S.A.
Carl H
CH
Snyderman
Department of Otolaryngology, University of Sao Paulo, Sao Paulo, Brazil.
Richard L
RL
Voegels
D000328:Adult; D059925:Anatomic Landmarks; D002102:Cadaver; D004724:Endoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009666:Nose; D009915:Orbit / Q000033:anatomy & histology*; D009916:Orbital Diseases / Q000175:diagnosis*
Orbit; anatomy; cadaver; cavernous sinus; ophthalmic artery; optic nerve; paranasal sinuses; pterygopalatine fossa; skull base; surgical endoscopy