lo THE SURGICAL ANATOMY OF THE HORSE 



have the posterior nares, placing the nasal chamber and the cavity of 

 the pharynx into direct communication with one another. 



The outer wall is formed by the nasal and superior maxillary bones, 

 and the inner wall (which has been removed from the specimen) 

 separates the chamber from that of the left side. This wall is formed 

 by the sfeptum nasi, which for part of its extent is osseous and for 

 the remainder cartilaginous in structure. The posterior part of this 

 partition is formed by the perpendicular plate of the ethmoid and its 

 inferior portion by the vomer, which rests on the line of articulation 

 between the two halves of the hard palate. But much the greater portion 

 of the septum is formed by the septal cartilage, which rests in the cleft 

 of the vomer, and which is attached posteriorly to the anterior extremity 

 of the ethmoidal perpendicular plate. 



To the outer wall are attached the superior and inferior turbinated 

 bones. The former is attached to the nasal bone, and is hence 

 frequently referred to as the nasal turbinated bone. The latter is 

 attached to the superior maxillary bone, being therefore referred to as 

 the maxillary turbinated bone. 



Above the superior turbinated bone is an elongated narrow space 

 which is placed between this bone and the roof of the chamber. This 

 space is the superior or anterior meatus. Two other somewhat similar 

 spaces will be noticed to run longitudinally along the nasal wall. One 

 of these is placed between the two turbinal bones, and the other between 

 the inferior turbinal bone and the floor of the nasal chamber. These 

 spaces are called the middle meatus and the inferior or posterior meatus 

 respectively. 



It should be noted that the communication between the sinuses of 

 the head and the exterior is by way of the middle meatus. The frontal 

 and sphenoidal sinuses communicate with the superior maxillary sinus, 

 and the latter opens into the posterior extremity of the middle meatus by 

 a narrow, curved, slit-like aperture which is not visible in the plate. To 

 bring this opening into the sinus into view, a forcible separation of the 



