EXPLANATION OF PLATE II.

Muscles of the Horse.

This illustration shows the superficial muscles of the body after the skin and panniculus carnosis muscle has been carefully removed. This muscle is spread over the greater part of the body, which is related externally with the skin; internally with the superficial layer of muscles. Its action corrugates the skin, and thus enables the animal to expel or shake off insects and irritating bodies, its use being thus protective to some extent; it also supports and binds down the superficial muscles.

SUPERFICIAL LAYER.

The panniculus and tunica abdominalis are removed.

1.

Abducens.

31.

Caput magnum extensor brachii.

2.

Retrahentes muscles.

33.

Extensor metacarpi magnus.

2′.

Attollens maximus.

34.

Humeralis obliquus.

2″.

Attollens anticus.

35.

Extensor pedis.

3.

Temporalis.

36.

Flexor metacarpi externus and medius.

4.

Nasalis longus.

37.

Flexor metacarpi internus.

5.

Orbicularis palpebrarum.

46.

Cervical

6.

Levator labii superioris alæque nasi.

47.

Dorsal serratus magnus.

7.

Dilatator naris lateralis.

48.

Rhomboideus longus.

8.

Orbicularis oris.

49.

Superficialis costarum.

9.

Zygomaticus.

50.

Splenius.

9′.

Buccinator.

52.

Intercostales.

10.

Depressor labii inferioris.

54.

Tensor fasciæ latæ.

11.

Masseter.

55.

Triceps abductor femoris.

12.

Levator humeri.

56.

Gluteus externus.

13.

Trapezius cervicalis.

61.

Biceps rotator tibialis.

14.

Trapezius dorsalis.

62.

Rectus femoris.

15.

Latissimus dorsi.

63.

Vastus externus.

18.

Pectoralis parvus.

65.

Gastrocnemius externus.

19.

Pectoralis magnus.

68.

Flexor pedis perforans.

20.

Sterno-maxillaris.

69.

Peroneus.

23.

Subscapulo-hyoideus.

70.

Extensor pedis.

24.

Antea-spinatus.

71.

Flexor metatarsi.

25.

Teres externus.

72.

Flexor pedis accessorius.

26.

Postea-spinatus.

74.

Obliquus abdominis externus.

30.

Caput medium of the triceps.

Voluntary Muscles.—The voluntary muscles are in groups. The first muscle we will call the student’s attention to, after removing the skin, is the panniculus carnosus (not shown in Plate [I]), which is a thin muscle, and almost entirely covering the body, which is sometimes accidentally removed by a careless person in skinning the animal. The action of this muscle is to shake the skin when flies or other objects bother the horse. This muscle is not shown in Plate [I] it having been removed in order to show the more important ones.

Head Muscles.—At the head there is a group of muscles which assist in chewing, or masticating, the food.