42 



SUPERIOR MAXILLARY BONES. 



Fig- 23.* The body is triangular in form, 



and hollowed in its interior into 

 a large cavity, the antrum max- 

 illare (antrum of Highmore). It 

 presents for examination four sur- 

 faces, external or facial, internal or 

 nasal, posterior or zygomatic, and 

 superior or orbital. 



The external, or facial surface, 

 forms the anterior part of the bone ; 

 it is irregularly concave, and pre- 

 sents a deep depression towards its 

 centre, the canine fossa, which gives 

 attachment to two muscles, the com- 

 pressor nasi and levator anguli oris. 

 Immediately above this fossa is the 

 infra-orbital foramen, the termina- 

 tion of the infra- orbital canal, trans- 

 mitting the superior maxillary nerve, 



and infra-orbital artery; and above the infra-orbital foramen, the 

 lower margin of the orbit, continuous externally with the rough arti- 

 cular surface of the malar process, and internally with a thick ascend- 

 ing plate, the nasal process. Towards the middle line of the face this 

 surface is bounded by the concave border of the opening of the nose, 

 which is projected forwards at its inferior termination into a sharp 

 process, forming, with a similar process of the opposite bone, the na- 

 sal spine. Beneath the nasal spine, and above the two superior 

 incisor teeth, is a slight depression, the incisive, or my rtiform fossa, 

 which gives origin to the depressor labii superioris alaeque nasi muscle. 

 The myrtiform fossa is divided from the canine fossa by a perpen- 

 dicular ridge, corresponding with the direction of the root of the canine 

 tooth. The inferior boundary of the facial surface is the alveolar 

 process which contains the teeth of the upper jaw ; and it is separated 

 from the zygomatic surface by a strong projecting eminence, the malar 

 process. 



The internal, or nasal surface, presents a large irregular opening, 

 leading into the antrum maxillare ; this opening is nearly closed in the 



* The superior maxillary bone of the right side, as seen from the lateral 

 aspect. 1. The external, or facial surface ; the depression in which the figure 

 is placed is the canine fossa. 2. The posterior, or zygomatic surface. 3. The 

 superior, or orbital surface. 4. The infra- orbital foramen ; it is situated imme- 

 diately below the number. 5. The infra-orbital canal, leading to the infra- 

 orbital foramen. 6. The inferior border of the orbit. 7- The malar process. 

 8. The nasal process. 9. The concavity forming the lateral boundary of the 

 anterior nares. 10. The nasal spine. 11. The incisive, or myrtiform fossa. 

 12. The alveolar process. 13. The internal border of the orbital surface, which 

 articulates with the ethmoid and palate bone. 14. The concavity which arti- 

 culates with the lachrymal bone, and forms the commencement of the nasal 

 duct. 15 The crista nasalis of the palate process, i. The two incisor teeth. 

 c. The canine, b. The two bicuspidati. m. The three molares. 



