1 70 HEAD AND NECK 



and turn it upwards with the attached temporal muscle. A 

 very oblique cut is required ; it should extend from the centre 

 of the incisura mandibulae above, downwards and forwards, 

 to the point where the anterior margin of the ramus meets the 

 body of the mandible. First use the saw, and then complete 

 the division with the bone forceps. The buccinator nerve 

 (O.T. long buccal) and its companion artery are in a position of 

 danger during this dissection, and must be carefully guarded. 

 They proceed downwards and forwards, under cover of the lower 

 part of the temporal muscle, and not infrequently the nerve 

 traverses the substance of the muscle. The coronoid process 

 and the temporal muscle must be thrown well upwards, and the 

 muscular fibres must be separated, by the handle of the knife, 

 from the bone forming the lower part of the temporal fossa, in 

 order that deep temporal nerves and arteries may be exposed, 

 as they ascend between the cranial wall and the muscle. At 

 this stage the middle temporal artery will also be exposed as it 

 extends upwards upon the squamous part of the temporal bone. 

 If it is injected branches will be found passing from it to the 

 temporal muscle. The zygomatico -temporal nerve should now 

 be traced to the point where it emerges from the minute aperture 

 on the temporal surface of the zygomatic bone. At that point 

 it lies under cover of the temporal muscle. 



The infratemporal region (O.T. pterygo-maxillary) may now 

 be fully opened up by removing a portion of the ramus of the 

 mandible. Two horizontal cuts must be made one through 

 the neck of the mandible, and the other immediately above the 

 level of the mandibular (O.T. inferior dental) foramen. To 

 find the level of the foramen, thrust the handle of the knife 

 between the ramus and the subjacent soft parts, and carry it 

 downwards. Its progress will soon be arrested by the entrance 

 of the inferior alveolar vessels and nerve into the foramen, and 

 the lower border of the instrument will correspond with the line 

 along which the bone should be cut. Both incisions should 

 be made with the saw, until the lateral table of the bone is 

 cut through, and then the bone forceps may be employed to 

 complete the division. Lastly, remove the fat and areolar 

 tissue. 



When the fat and areolar tissue are removed, the pterygoid 

 muscles will come into view. The external pterygoid extends 

 backwards to the neck of the mandible. The internal pterygoid, 

 embracing the anterior part of the external pterygoid muscle 

 between its two heads of origin, proceeds downwards and 

 backwards upon the deep surface of the ramus of the mandible. 

 The great blood vessel of the space the internal maxillary artery 

 passes forwards upon (frequently under cover of) the lower 

 head of the external pterygoid muscle. The nerves of the region 

 also will be found in close relationship to the same muscle. 

 Emerging from between its upper border and the cranial wall, 

 at the level of the infratemporal crest, are the masseteric and 

 the posterior deep temporal nerves posteriorly, and the anterior 

 deep temporal nerve anteriorly ; appearing from under cover of 

 its lower border are the inferior alveolar nerve, which descends 

 to the alveolar foramen of the mandible, and more anteriorly 

 the lingual nerve ; whilst emerging between the two heads of 

 the external pterygoid is the buccinator nerve. The spheno- 



