Ethmoid bone

Recent advances inclnde the nse of a fornical incision, which is considered a technical advance in decompression surgery because it allows good views of the medial and lateral walls of the orbit. Additionally, a transcaruncu-lar approach to the medial wall allows easy removal of the ethmoid bones. 

The olfactory perception can be reinforced by sniffing i.e. by swirling the air intermittently over the ethmoid bone below the olfactory epithelium. The swirling effect causes the active components producing the smell to flow past the olfactory epithelium several times (instead of just once), thereby reinforcing the effect (particularly important in quality testing in the case of weak samples or samples with only very minor differences between them). 

This effect can also be reinforced by smacking one s lips or slurping. This causes additional air to be sucked into the mouth, so that the active parts of the substances producing the smell are carried and swirled past and round the back of (= retro) the ethmoid bone. 

The solution should be inserted laterally toward the midline of the superior concha of the ethmoid bone, not the base of the nasal cavity where it will run down the throat and into the eustachian tube. 

The upper respiratory tract, particularly the nose, has a unique anatomy that performs normal physiologic functions as well as innate defense against inhaled toxicants. The nose extends from the nostrils to the pharynx. Inspired air enters the nose through the nostrils. The nasal cavity is divided longitudinally by a septum into two nasal compartments. In most mammalian species, each nasal cavity is divided into a dorsal, ventral, and middle (lateral) meatus by two turbinate bones, the nasoturbinate and maxilloturbinate. These turbinates project from the dorsolateral and ventrolateral wall of the cavity, respectively. In the posterior portion of the nose, the ethmoid recess contains the ethmoturbinate. The nasal cavity is lined by a vascular mucosa that consists of four distinct types of epithelia. In rodents, these epithelia are (1) the stratified squamous epithelium that lines the nasal vestibule and the floor of the ventral meatus in the anterior portion of the nose (2) the non-ciliated, pseudostratified, transitional epithelium that lies between the squamous epithelium and the respiratory epithelium and lines the lateral meatus (3) the ciliated respiratory epithelium that lines the remainder of the nasal cavity anterior and ventral to the olfactory epithelium and (4) the olfactory epithelium (neuroepithelium) that lines the dorsal meatus and ethmoturbinates in the caudal portion of the nose. The relative abundance and exact locations of these upper respiratory epithelium differ among mammalian species. 

The preorbltal sac of Muntjac lies rostral to the anterior comer of the eye, in the preorbital fossa (which is formed by the maxillary, ethmoid and lacrimal bones). The opening of the sac is a long, sigmoidal slit, measuring 20 25 mm in fixed material. A pigmented furrow, extending posteriorly from this slit, crosses over the orbital rim and... 

Medially, the bony orbit is confined by the ethmoid, lacrimal, sphenoid, and maxillary bones. The most anterior part of the medial wall of the orbit includes the nasolacrimal fossa, with the aperture of the nasolacrimal duct. 

The nasal sinuses include four pairs of aerated cells in the bones of the skull, named after the four bones in which they are located frontal, sphenoid, ethmoid, and maxillary. These sinuses are lined with epithelium similar to that of the nasal passages. This epithelium contains goblet cells that secrete mucus, which is normally moderately thin and clear, and ciliated cells whose purpose is to move the secretions out of the sinuses into the nasal passages, assisted by gravity. 

The placoderm endoeranium is composed of two units (Figure 13.1). The posterior unit represents the main endocranial body which extends from the ethmoid to the occipital margins. As mentioned above, this bone does not show any trace of ventral or otico-occipital fissure like those present in osteichthyans and in some chondrichthyans Pucapampella, Maisey, this volume). The anterior unit is composed of the paired nasal capsules which are always enclosed in an ossification including the endoskeleton and its dermal cover. 

Course of ethmoid commissure middle portion through median rostral (0) sutural course (1) through bone centre (2). 

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