F THE MUSCLES OF THE HEAD. 377 
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The levator labii inferioris aleeque nasi is a narrow band arising from the root 
of the nasal process of the maxilla. It descends alongside the nose, and is inserted 
partly into the ala of the nose and partly into the orbicularis oris muscle. 
3. The muscles of the mouth comprise eleven muscles, of which one, the 
orbicularis, is a single muscle, the others being bilaterally placed: levator labu 
superioris aleeque nasi, levator labii superioris, levator anguli oris, zygomatici (major 
and minor), risorius, depressor anguli oris, depressor labii inferioris, levator ment, 
and buccinator. 
The orbicularis’ oris is the sphincter muscle surrounding the lips. It is con- 
tinuous with the other muscles converging to the mouth. It les between the skin 
and mucous membrane of the mouth, and is limited above by the nose, below by 
the junction of lower lip and chin. Its mesial fibres are attached above to the 
septum of the nose (naso-labial band) and to the incisor fossa (superior incisive 
bundle); below to the lower jaw on each side of the symphysis (inferior incisive 
bundle). These bundles radiate outwards to join the rest of the muscle, which is 
joined at its margin by the levators and depressors of the lower lip and angle of the 
mouth, and by the buccinator muscle. The /ower fibres of the muscle are continued 
laterally into buccinator and levator anguli oris ; its wpper fibres are continued into 
the buccinator and depressor anguli oris. 
The levator labii superioris aleeque nasi has been already described. 
The levator labii superioris arises from the superior maxilla just above the 
infraorbital foramen. It passes almost vertically downwards to join the orbi- 
cularis oris and the skin of the upper lip between the attachments of the levator 
labii superioris aleeque nasi and the levator anguli oris. It conceals the infra- 
orbital vessels and nerve. 
The levator anguli oris arises from the canine fossa of the upper jaw below the 
infraorbital foramen and under cover of the foregoing muscle. It is directed 
outwards and downwards, to be inserted into the orbicularis oris and the skin at the 
angle of the mouth. 
The zygomatici (major and minor) are more superficial than the preceding 
muscle. 
The zygomaticus minor is the anterior muscle. It arises from the malar bone, 
and is often continuous with the most peripheral fibres of the orbicularis palpe- 
brarum. It is directed obliquely downwards and forwards over the levator anguli 
oris, to be inserted, along with the levator labii superioris, into the orbicularis oris. 
The zygomaticus major is a narrow muscular band which arises from the malar 
portion of the zygomatic arch. It passes to the angle of the mouth, to be inserted 
partly into the skin, partly into the orbicularis oris. 
The risorius is a thin flat muscle which forms partly a continuation of the 
platysma myoides on the face, partly a separate muscle, with an origin from the 
masseteric fascia. It passes transversely forwards, to be inserted at the angle of the 
mouth into the orbicularis oris and skin. 
The depressor anguli oris arises from the external oblique line of the lower jaw 
and from the platysma myoides. It is triangular in form, its fibres converging to 
the angle of the mouth, where they are inserted into the orbicularis oris and the 
skin. Some of the fibres reach the upper lip through the orbicularis muscle. 
The depressor labii inferioris arises from the outer surface of the lower jaw 
beneath and internal to the depressor anguli oris. It is quadrilateral in form, and 
is directed upwards, to be inserted into the orbicularis oris and the skin of the lower 
lip. Its external fibres conceal the mental foramen, and are overlapped by the 
depressor anguli oris. Its internal fibres join with those of the opposite muscle. 
The levator menti is a small muscle which arises from the incisor fossa of the 
lower jaw, and passing forwards, is inserted into the skin of the chin. 
The buccinator muscle forms the lateral wall of the mouth, and is in series 
posteriorly with the constrictor muscles of the pharynx. It arises (1) from the 
alveolar arches of the upper and lower jaws, and between these attachments, from 
the pterygo-mandibular ligament. Its fibres are directed forwards to the angle of 
the mouth, where they blend with the corresponding (upper and lower) portions of 
