A manual of veterinary physiology.

  • Smith, Frederick, 1857-1929.
Date:
1907
Catalogue details

Licence: Public Domain Mark

Credit: A manual of veterinary physiology. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    second act of deglutition. The length of the soft palate prevents food or water being returned by the mouth when once they have entered the pharynx, so that in vomiting, or in cases of sore throat, the food, water, or other material is returned by the nostrils. The action of the epiglottis in the closure of the glottis has been much discussed. We have described it as being forced over the opening by the base of the tongue and the advancing larynx ; but the epiglottis is not essential to swallowing, for an animal can swallow when it has been removed, and even when one of the arytenoid cartilages has been excised. With a finger in the larynx it can easily be demonstrated that the part tightly and forcibly closes during the second stage of swallowing, the vocal cords and arytenoids being brought so close together that the glottis is perfectly air-tight. It has been pointed out that animals usually swallow with a flexed neck, as in this position the epiglottis is behind the soft palate and in the most favourable position to be applied over the glottis ; it has also been shown that when the head is extended the epiglottis is in the mouth, viz., anterior to the soft palate. We have found it in this position in the horse, and judging from the fact that in a state of nature the horse and ox swallow with an extended and not with a flexed neck, it is probable that in feeding oft' the ground the epiglottis is anterior to the soft palate. During the third stage of deglutition the bolus can be seen slowly travelling down the channel of the neck; if liquid however be passing, the movement is very rapid, for as many as sixty swallows may be made in a minute. Both in eating and drinking the third act of deglutition can occur against gravity; this is because it is a muscular act. The whole process of deglutition is considerably assisted by the salivary secretion. When this has been experimentally diverted swallowing only occurs with difliculty and very slowly. The oesophagus of the horse is found to differ consider- ably from that of most other animals. It is composed for the greater part of its length of red striated muscle,