Book VII. PHYSIOLOGY OF THE HORSE. 909 



point of view they may be considered as supplying tlie part of the points of the* fingers in man. 

 The cheeks are equally muscular and movable, but are more furnished with hair ; and the beard, in ad- 

 dition to its thin hairy expansion, has a set of long hairs. 



5709. The internal parts of the motiih are the teeth, already described (5591.), the gums," the 

 alveolary edges, the palate, the tongue, and the parts of the great posterior cavity. ThegMwsare a 

 spongy substance which embraces and holds fast the teeth in their alveolary sockets. The membrane 

 which covers the gums at the lower part of the channel forms a kind of fold to connect and confine the 

 tongue on each side. These folds are called the barbs, and are apt to be mistaken and cut off as excres- 

 cences. The bars are the spaces in the jaw left between the grinders and nipper teeth ; and which man, 

 ever ready to take advantage for his own purijoses, has applied to ensure obedience by placing on its 

 sensitive surface the pressure of the bridle bit. The palate forms a bony arch, covered by membranous 

 folds, which are apt, when the stomach is affected, to become swollen, in which case the horse is said 

 to have the lampas or lampers. (5756.) By means of these rugose folds, the food is retained within 

 the mouth. The airtain of the palate or velum palati, which is situated at the extreme end of the pala- 

 tine arch, is stretched directly across the hinder mouth, and is not intercepted as in man by the 

 pendulous body, termed uvula. This palate curtain is intended to shut out the communication between 

 the mouth and the great cavity of the fauces, which it docs at all times, except when the horse is 

 swallowing, at which period the curtain is forced back and the food passes. From this cause likewise 

 the horse is prevented breathing but by his nostrils ; and when any air does pass by the mouth, as in 

 coughing, crib. biting, &c., it is only effected by a forcible displacement of the curtain. 



5710. The tongue is a long fleshy mass {fig. 616 e), which adapts itself below to the form of the channel, 

 and above to the arch of the palate: its external surface is rough by means of papilte, which are inclined 

 backwards, and thus resist the loss of the food received within the mouth. In some animals, as the ox, 

 bear, &c., they are very large, and in the cat pointed. The tongue is a very principal organ in mastica- 

 tion, carrying, by its great mobility, the food into evefy direction until fully acted upon, and finally 

 passing it into the pharynx. 



5711. Sense qf tasting. It is not observed that this sense is so diversified in brutes as in man ; but it is 

 instinctively so correct, that it seldom errs in the herbivorous tribes ; and when it does, there is reason 

 to suspect some present defect in the organ, arising from morbid sympathy, which (as in the instance of 

 salt-water, of which at some times horses will drink immoderately,) prompts them to take in matters they 

 are accustomed to refuse. Taste was given to brutes to regulate their other senses, and thus there are 

 few plants or substances, whose application to the tongue, under ordinary circumstances, produces an 

 agreeable efTect, but such as are proper for food. Nature, therefore, stimulates her creatures to search 

 for edibles by a double motive, the calls of hunger and the pleasures of taste j and these are usually in 

 unison, for the nausea of repletion destroys the appetite of taste. 



5712. The pharynx. Both the cavities of the mouth and nose terminate in the great cavity of the 

 fauces called by this name, to which also is appended another lesser opening called the larynx, immedi- 

 ately appropriate to the entrance of the trachea or windpipe. Within this great chamber, at the after, 

 part of the mouth, shut from it by a membrane only, is the eustachian cavity, into which the eustachian 

 tube oj)ens, and which great membranous hollow is unknown to man and most quadrupeds {fig. 616 rf). 

 Its use is not understood, but it is probably connected with the voice. 



5713. The larynx is situated at the posterior part of the former cavity, and appears as a cartilaginous box 

 between the os hyoides, to which it is attached for support. This cartilaginous box, or entrance to the wind- 

 pipe, is formed of several jHcces, and is furnished with a kind of movable door, which, in ordinary cases, 

 exactly fills up the cavity left by the arch of the palate curtain, thereby shutting the cavity of the mouth, 

 and forcing the animal to breathe through his nasal openings. In extraordinary cases, as when the ani- 

 mal swallows food, this cartilage is forced down, and then it becomes a door to the glottis or funnel part 

 of the trachea, and thus prevents the entrance of extraneous matter into the lungs. All these parts are 

 operated on by numerous muscles. 



5714. The voice. The larynx forms the larger part of a funnel-shaped tube, intended to introduce air 

 within the lungs ; but it has also another important office in being the organ of the voice. The cartilages 

 of the larynx are very movable on one another, and are furnished with muscular cords, which tighten 

 or relax them ; besides which, they are also furnished with peculiar and appropriate sacs or cavities, in. 

 dependent of the tracheal opening ; and which are of different magnitudes and directions in different 

 animals. The cartilages of the larynx being acted on by the cordse vocales, produce different degrees of 

 density, and consequently different degrees of expansion in the laryngeal sacs ; by which, either in ex- 

 piration or inspiration, are produced different degrees of vibration, and consequent intonation. Neighing 

 appears produced wholly by expirations through the nose, as are most of the tones of the horse's voice. 

 This is proved by slitting the nasal cartilage, which wholly stops it. Knuchering, as it is termed, is only a 

 lesser neigh, with shorter, deeper, and less forcible tones. The former sound is used as a call, the latter as 

 either call or recognition. It is likewise, when used mildly, significant of joy and affection, and is then 

 beautifully .sonorous. The horse has an acute sound produced by inspiration, usually descriptive of lust : 

 in most other cases his intonations are accompanied by expirations; nor does it appear that the tongue 

 or teeth of the horse are much concerned in the modulations of his voice. 



5715. The parotid glands, or, in the language of farriers, thevives, are two considerable bodies on each 

 side of the head, extended from the base of the car around the angle of the jaw. Each parotid is a con- 

 glomerate gland, furnished with numerous little ducts, which unite into one, and enter the mouth about 

 the second molar tooth. These glands furnish saliva for the use of the mouth, and it is an induration 

 and gathering, either in them or the maxillary glands, which forms the strangles of young horses. As- 

 sistant to these in the furnishing of saliva are the maxillary glands, situated within the branches of the 

 lower jaw> and the sublingual also. 



SuBSECT. 11. The Neck. 



5716. The external parts qfihc neck are the common coveruigs which have been described ; the cervical 

 ligament, the muscles, and the jugular or neck veins, &c. The cervical ligament {fig. 616 i), is a very 

 strong substance, in some i)arts semimuscular, and in all extremely elastic, stretched from the occipitil 

 bone along the back of all the cervical vertebra; exce{)t the first. Continued on the spinous processes of 

 the dorsal vertebra;, it fills up the dip or depression of the spinal column of the neck, so completely as to 

 form the neck either into a plane, or an elegantly convex line upwards. By its extreme tenacity, the 

 ponderous mass of the head is preserved in its situation, without the necessity of an immense mass of 

 muscle, which would, without this contrivance, have been necessary. It is to an injury received at the 

 upper and anterior part of this ligament, that the pole evil is owing. The muscles of the neck are too 

 numerous to allow of particularization ; it is sufficient to say, they most of them run longitudinally. The 

 jugular veins run one on each side of the neck superficially, on the side of the trachea and windpipe, and 

 form the vessel usually bled from {fi^. 618 r). A few inches before they reach the angle of the jaw, each 

 divides to furnish the head. 



5717. The internal parts <tf tJie wcA are the vertebra;, within which passes the spinal marrow. The 

 carotid arteries pass up under the jugular veins, near the oesophagus {fig. 618 s). The trachea or wind- 

 pipe {fig. 618 g), is a large canal for the transmission of air, formed by alternate rings of membrane and 

 segments of cartilage, rendering it at once flexible, yet cylindrically hollow. The asophagus {figs. 616 h 

 ^ (il8), is the continuation of the funnel-like cavity of the pharynx. It is externally muscular, 

 and internallv membranous and cuticular, by which formation it is elastic, to allow of distension in 



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