Part 105

The =levator nasolabialis= is thin and pale, and is undivided.

The =levator labii superioris proprius= may well be termed the =levator rostri=. It has a large penniform belly, which arises in the fossa on the lacrimal bone and maxilla. The tendon ends on the anterior part of the os rostri. A muscular slip connects it with the premaxilla.

The =zygomaticus= arises on the fascia over the masseter and ends at the angle of the mouth.

The =depressor labii inferioris= separates from the buccinator only near the angle of the mouth; it ends by a number of tendinous branches in the lower lip.

The =dilatator naris lateralis= is well developed. It arises under the levator rostri and ends by a tendinous network around the nostril.

The =dilatator naris transversus= is represented only by a few fibers which cross over the os rostri.

The =depressor rostri= arises on the facial crest. It has a long strong tendon which passes below the nostril and turns up and inward to meet the tendon of the opposite side and end in the skin of the snout. It depresses the snout and contracts the nostril.

The malaris is absent, and the other palpebral muscles present no special features.

MUSCLES OF MASTICATION

The =digastricus= has only one belly. It ends on the inner and lower surface of the mandible, in front of the groove for the facial vessels.

The other muscles have no important differential features.

The same is true of the oral hyoid muscles.

MUSCLES OF THE NECK

The =panniculus carnosus= consists of two layers which cross each other obliquely. The fibers of the superficial layer are directed nearly vertically, those of the deep layer toward the face, on which they are continued to form the facial portion.

The =mastoido-humeralis= is described on p. 314.

The =sterno-cephalicus= (Sterno-mastoideus) arises on the sternum and is inserted by a long round tendon on the mastoid process.

The thyroid portion of the =sterno-thyro-hyoideus= has a peculiar arrangement. It arises (separately from the opposite muscle) on the manubrium sterni. About the middle of the neck it has an oblique tendinous intersection, beyond which it divides into two branches; one of these is inserted in the usual fashion, the other ends on the laryngeal prominence. The hyoid portion is well developed.

The =omo-hyoideus= is thin. It arises as in the horse, but has no connection with the mastoido-humeralis nor with the opposite muscle.

The =omo-transversarius= arises on the first or second cervical vertebra (under cover of the mastoido-humeralis), and is inserted into the lower part of the scapular spine.

There are two =scaleni=. The =scalenus ventralis= (s. primæ costæ) resembles that of the ox, is attached to the last four cervical vertebræ, and is perforated by the nerves of the brachial plexus. The =scalenus dorsalis= (s. supracostalis) arises on the transverse processes of the third to the sixth cervical vertebra, and ends on the third rib.

FIG. 226.—SUPERFICIAL MUSCLES OF PIG, AFTER REMOVAL OF PANNICULUS CARNOSUS.

a, Levator nasolabialis; b, levator labii superioris proprius; b′, fleshy slip of b which comes from premaxilla; c, dilatator naris lateralis; d, depressor rostri; e, orbicularis oris; f, depressor labii inferioris; g, zygomaticus; h, masseter; i, i′, i″, brachiocephalicus (cleido-occipitalis, cleido-mastoideus, pars clavicularis); k, sterno-cephalicus; l, sterno-hyoideus; m, omo-transversarius; n, n′, trapezius; o, anterior deep pectoral; p, latissimus dorsi; q, lumbo-dorsal fascia; r, obliquus abdominis externus; r′, aponeurosis of r; s, serratus posticus; t, serratus magnus; u, posterior deep pectoral; v, supraspinatus; w, w′, deltoideus; x, long head of triceps; y, external head of triceps; z, tensor fasciæ antibrachii; 1, brachialis; 2, extensor carpi radialis; 3, extensor digiti quarti; 4, extensor digiti quinti; 5, extensor carpi ulnaris; 6, ulnar head of deep flexor; 7, gluteus medius; 8, tensor fasciæ latæ; 9, 10, 10′, biceps femoris; 11, semitendinosus; 12, semimembranosus; 13, caudal muscles; 14, panniculus adiposus in section. (After Ellenberger, in Leisering’s Atlas.) ]

The =straight muscles= of the head present no special features.

The =longus colli= is separated from the opposite muscle, so that part of the bodies of the cervical vertebræ is exposed as in man.

The =intertransversales= resemble those of the ox.

The =splenius= is thick and extensive. It ends in three parts on the occipital, the temporal, and the wing of the atlas (inconstant).

The =trachelo-mastoideus= is small, and its atlantal portion is blended with the longissimus.

The =complexus= is large, and is clearly divided into two portions: the dorsal portion (Biventer cervicis) is marked by several tendinous intersections; the ventral part is the complexus proper.