2^74 TEE MUSCLES. 



be considered as the semispinalis of the coccygeal region ; indeed, it is confounded 

 with that muscle of the back and loins by its anterior extremity, and appears to 

 continue it to the inferior extremity of tl;e tail. 



The fasciculi composing it arise from the spinous processes of the last lumbar 

 vertebrte, through the medium of the semispinalis, and from the coccygeal bones. 

 The tendons terminating these fasciculi are deep and not very distinct. 



It responds : outwardly, at the posterior extremity of the longissiraus dorsi, 

 to the inferior ilio-sacral ligament and the coccygeal aponeurosis ; inwardly, to 

 the semispinalis and the coccygeal vertebrae ; above, to the superior muscle ; 

 below, to the inferior muscle, from which it is nevertheless separated by several 

 small independent muscular fasciculi, which are carried from one coccygeal 

 vertebra to another. (Leyh designates these the intertransversales of the tail.) 



It incUnes the tail to one side. 



2. ISCHIO-COCCYGEUS (COMPRESSOB COCCYGIS) (Fig. 167, 4). 



A small, thin, Avide, and triangular muscle, situated against the lateral wall of 

 the pelvis, at the internal face of the sacro-sciatic hgament. 



It is attached, by an aponeurosis, to that Ugament and to the ischiatic ridge ; 

 it is then directed upwards to be fixed, by its muscular fibres, to the side of the 

 last sacral vertebra and the first two coccygeal bones. 



It is related, outwardly, with the sacro-sciatic ligament, and inwardly to the 

 lateral sacro-coccygeus and the rectum. 



It depresses the eniiie caudal appendage. 



Region of the Head. 



The head has a large number of muscles disposed around the mouth, nostrils, 

 eyelids, the external ear, inferior maxilla, and os hyoides. They will be divided 

 into five secondaiy regions. 



A. Facial Eegion. 



This region includes those muscles of the head which form a part of the 

 framework of the lips, cheeks, and nostrils. Authoi-s are far from being 

 unanimous with regard to the nomenclature and description of these muscles. 

 We recognise eleven, which are enumerated below, chiefly according to the 

 nomenclature of Girard. They are : the labial {orbicularis oris) ; zygomatiais ; 

 supermaxillo-labialis {nasalis longus, or levator labii superioris proprius) ; maxillo- 

 labialis {depressor labii inferioris) ; mento-labialis, suspensor of the chin (levator 

 menti), which act on the lips ; alveolo-Jabialis {buccinator), which moves the 

 jaw ; supernaso-labialis {levator labii superioris alcequi nasi), which moves lips 

 and nostrils ; great supermaxillo-nasalis {dilatator naris lateralis), small super- 

 maxillo-nasalis {dilatator naris superior), naso-transversalis {dilatator naris 

 transversalis), which dilate the nostrils and false nostrils only. 



1. Labialis, or Orbicularis of the Lips (Orbicularis Oris) (Fig. 167, 27). 



Preparation. — Remove with scissors the skin covering the two portions of this muscle ; 

 afterwards the buccal mucous membrane and subjacent glands within the lips, to expose its 

 internal face. 



The orbicularis, disposed as a sphincter around the anterior opening of the 

 mouth, is regarded as the intrinsic muscle of the lips, and is composed of two 

 portions or fasciculi — one for the upper, the other for the lower lip. United to 



