Comparative Anatomical Studies On The Ethmoid Bone In Human And Canis(dogs):

Akram Mohamed El-gindy

The ethmoid bone is one of the most complicated structures in thehuman body, and its anatomy is very complex.A brief review of the available literatures on this structure in manand dog is given.”’:<’t- o~mprehensrive descrniption 0 f’ cnsta gaIII’,perpen icular plate and ethmoidal labyrinth is given.cribriform plate,The present work gives a precise study on the morphologicalfeatures of the ethmoid bone in comparative study with that of the dog.The morphological study of both man’s and dog’s ethmoid bone wasdone using ten fresh dried skulls of human being, and other ten fresh driedSkullS;:t~The sense of smell in carnivora especially dogs affords an adequateea for the purposes of olfaction in comparison to man. This was provedby ~ study in the following points which also show the aspects ofdifference of the ethmoid bone in man and dog :_Projection of the nose of the dog anteriorly._Great length of the nasal cavity in the dog._ The ethmoid bone of man lies between the two orbits while in the dog iY ~situated between the maxillary bones._ The ethmoid bone in man is cuboidal III shape, while in the dog it iselongated.- The crista gallilow crest. is well developed in man while in dog it ifdimemary_ The perpendicular plate is triangular in shape and lies more anteriorly indog, while in man it is rectangular in shape and lies posteriorly._ The cribriform plate in man extends from the frontal bone anteriorly tothe sphenoid bone posteriorly, while in the dog it extends from the i:merplate of the medial chamber of the frontal sinus dorsally, to the innerplate of the presphenoid bone ventrally._ The forward protrusion of the nose of the dog pulling with it the midlineof the cribriform plate causing it to be concave in shape, pulling also thefrontal bone antro-ventrally and the sphenoid bone antro-dorsally.Hence the frontal sinus is expanded and formed from medial and lateralchambers and the sphenoid bone consists of pre and basisphenoid._ The cribriform plate in man is elongated while in the dog it is deep andconcave. ~_ The lamina cribrosa in man is narrow with few foramina iicontrary withthat of the dog where it is broad, wide, with great surface are a andcontains numerous perforations ._ The ethmoidal labyrinth in man consists of ethmoidal air cells while inthe dog it consists of endo and ectoturbinates. Each turbinate ISconvoluted to provide a wide surface area for the olfactory mucosa,_ The turbinate bones extend into the cavity of the frontal sinus and thepresphenoid bone in the dOg~ in turn increas~~the available surfacewith olfactory extensions.