HEAD AND NECK 



those fibres which tend to displace the margins of wounds of the 

 face, and necessitate the application of numerous and firmly 

 tied sutures in order to secure quick and accurate union. Whilst 

 reflecting the skin the dissector must be careful to keep his knife 

 playing against its deep surface ; otherwise he is certain to 

 injure the sphincter muscle of the eyelids, and the superficial 

 extrinsic muscles of the ear which lie in the temporal region. 



After the skin is reflected, clean the superficial muscles. 

 That which will first attract attention is the orbicularis oculi, 

 around the orbit. Above the orbicularis oculi is the frontal 

 belly of the epicranial muscle. To the medial side of the orbi- 

 cularis oculi lie the muscles of the nose. Below the eye the 

 muscles of the upper lip pass downwards to the orbicularis oris 

 and the mouth. Passing forwards and upwards, over the posterior 

 part of the lower border of the mandible, are the upper and 

 posterior fibres of the platysma, and more medially are the 

 muscles of the lower lip (Fig. 2). 



Commence with the orbicularis oculi (O.T. orbicularis palpe- 

 brarum), which lies in and around the region of the eyelids. 

 Pull the eyelids laterally and note a prominent cord-like band 

 which extends from the frontal process of the maxilla to the 

 medial commissure, where it becomes continuous with both 

 eyelids ; it is the medial palpebral ligament (O.T. internal tarsal 

 ligament). A somewhat similar band, the lateral palpebral 

 raphe (O.T. external tarsal ligament), extends from the lateral 

 commissure to the zygomatic bone. After the medial palpebral 

 ligament has been recognised, clean first the thicker orbital part 

 of the orbicularis oculi, which covers the superficial bony 

 boundaries of the orbit, and then the thinner palpebral portion, 

 which lies in the eyelids. The palpebral part is not only thin 

 but also pale, and its fibres, in each eyelid, sweep in gentle curves 

 from the medial palpebral ligament to the lateral palpebral 

 raphe, gaining attachment to both. 



Next clean the orbicularis oris, which surrounds the mouth, 

 and take care not to injure the other muscles of the lips which 

 blend with the margins of the orbicularis oris. Attempt to 

 define the depressor septi nasi which springs from the middle of 

 the upper border of the orbicularis oris and is inserted into the 

 lower part of the septum of the nose (Fig. 2) . 



After the two orbicular muscles have been cleaned, turn to 

 the frontal belly of the epicranius, which lies above the orbicu- 

 laris oculi. Its fibres run upwards and backwards from the 

 orbicularis oculi, with which it blends, to the tendinous sheet 

 called the galea aponeurotica, which covers the vertex of the 

 skull and connects the frontal belly with the occipital belly 

 of the muscle. The edge of the knife must be kept parallel 

 with the fibres of the muscle, and as the cleaning proceeds avoid 

 injuring the branches of the supra-orbital nerve and artery 

 which pierce the muscle. From the medial margin of the frontal 

 belly of the epicranius trace a small bundle of muscle fibres, 

 called the procerus, downwards to the dorsum of the nose, and 

 at the same time secure the supra -trochlear nerve and the 

 frontal branch of the ophthalmic artery which pierce the muscle 

 at the medial part of the upper margin of the orbit. Below the 

 procerus secure the angular head of the quadratus labii superioris, 

 a muscular slip which springs from the frontal process of the 



