222 THE MUSCLES. 



10. Tlie Middle (Intermediate) Anterior Muscle. 

 Synonyim. —Meiius anterioi-Bourgelat. Myrtiformis of Man. (Depressor labii 

 superiori—Percivall. Incisive muscle of the upper lip—Leyh. A portion of the 

 orbicularis, according to Eigot.) 



Bourgelat thus names a deeply-situated muscle whicli is fixed to the 

 inner face of the premaxillary bone, above the incisor teeth, and whose 

 fibres ascend to meet those of the posterior portion of the small super- 

 maxillo-nasalis muscle, to terminate with them on the anterior appendix of 

 the inferior turbinated bone ; some fibres become lost in the lip. It is 

 regarded as a dilator of the entrance to the nasal fossa. 



To study thia muscle, it is necessary to raise the upper lip and remove tlie mucous 

 membrane covering it. It may be dissected at the same time as the bony attachments of 

 the superficial plane of the alveolo-labialis muscle. 



11. Maxillo-lahialis. (Fig. 110, 28.) 



Synonyms.— Depressor labii inferioris— Bijoi. A dependency of the buccinator of 

 Man. {Depressor lahii inferioris — Percivall. Inferior maxiUo-labialis — Leyli. Depressor 

 anguli oris of Man.) 



Situation — Direction — Form — Structure.— Sitnatei along the inferior 

 border of the alveolo-labialis, whose direction it follows, this muscle forms a 

 long narrow fasciculus, terminating inferiorly by an expanded tendon. 



Attachments. — 1, By its superior extremity, to the anterior border of 

 the lower jaw, in common with the deep plane of the alveole labialis — fixed 

 origin ; 2, By its terminal tendon, to the skin of the lower lip — movable 

 insertion. 



Relations. — Outwardly, with the masseter and the facial portion of 

 cuticularis of the neck ; inwardly, with the maxillary bone ; in front, with 

 the alveolo-labialis muscle, with which it is directly united in its upper two- 

 thirds. 



Actions. — It separates the lower from the upper lip, and pulls it to the 

 side if one alone acts. 



12. Mento-lahialis or Muscle of the Chin. (Pig. 110, 29.) 



(iSj/nonj/ms.— Percivall appears to describe this and the next muscle as one. It is the 

 gnadratua menti of Man.) 



This name is given to a musculo-fibrous nucleus, forming the base of the 

 rounded protuberance beneath the lower lip in front of the beard. This 

 single nucleus is confounded,- in front, with the orbicularis of the lips, and 

 receives into its upper face the insertion of the two posterior middle muscles 

 (levatores menti). 



13. Middle (Intermediate) Posterior Muscle. 



Si/nonT/TOs.— Medius posterior — Bourgelat. {Levator menti — FercivaU. Incisive musde 

 of the lower Up — Leyh.) 



Bourgelat describes, by this name, a small muscular fasciculus, analogous 

 in every respect to the medius anterior. This little muscle takes its origin 

 from the external surface of the body of the lower jaw, beneath the inter- 

 mediate and comer incisors ; from thence it descends into the texture of the 

 lip, to unite with that of the opposite side on the upper face of the^jnento- 

 kbialis. Several authors have described it as a dependent of the last rafecle. 



