The multitude of mucus-secreting glands lubricate the entire oral cavity against the abrasive action of harsh feedstuffs. The anatomy and physiology of the salivary glands allow efficient use of saliva. The mandibular ducts course under the tongue to the sublingual papillae, which are poorly recognizable. In adult llamas, the papilla is located across from a point 1 centimeter (cm) dorsal to the gingival margin between the last upper premolar and the first molar. The duct moves medial to the buccinator muscle and empties into the mouth through a prominent papilla on the inside of the cheek. This differs from ruminants, in which the duct courses with the facial vessels along the ventral aspect of the masseter muscle. The parotid duct courses craniad along the lateral aspect of the masseter muscle, roughly following the orientation of the muscle fibers, and dorsal to the facial artery and vein. Some of these glands, namely, the sublingual glands, also secrete small amounts of serous fluid, but camelids appear to lack a large serous salivary gland in the mouth comparable with the inferior molar gland of sheep. Most of these are diffuse aggregates of secretory cells, not distinct tissue masses. 4, 5 Numerous mucus-secreting glands are located throughout the oral cavity, including the buccal, palatine, sublingual, and labial regions. Two large salivary glands are located along the caudal border of the vertical ramus of each hemimandible: (1) the parotid glands are the largest and most superficial and have a serous secretion, and (2) the ventromedially located mandibular glands have a mixed mucous–serous secretion. In spite of the unevenness, evidence that these points cause trauma or chewing disorders is rare. Points or ridges may develop on the lateral maxillary arcades and the medial mandibular arcade and may require filing. Although camelids chew with a rotary motion, they tend to have very uneven wear on the occlusal surface of their cheek teeth ( Figure 40-3 Mandibular cheek teeth are narrower compared with maxillary teeth, and mandibular arcades are closer together. The cheek teeth have closed roots and do not continue to grow after maturity.Īdult premolars are less than one quarter the size of molars and occasionally are absent or do not erupt. The frequency of patent infundibula appears to be low, but this condition is seen sporadically and may contribute to periapical infections. Of the premolars, only the second mandibular one has an infundibulum. All the lower cheek teeth have two roots (cranial and caudal), with the caudal root of the last molar consisting of two fused roots. The maxillary premolars have three roots (medial, craniolateral, and caudolateral), whereas the molars have four roots. Hybridization has confused this distinction somewhat. The incisors of llamas and guanacos are tapered toward the root, whereas the incisors of vicuñas and alpacas are rectangular, have an open root, and erupt continuously. 3 Alpaca and vicuña incisors have a narrower cutting surface with enamel only on the labial surface. Llama and guanaco incisors are covered in enamel and have a broad, flat cutting surface that works against the upper dental pad. The middle incisors depict malocclusion as well. Retained deciduous incisors in a camelid. Although it does not extend from the mouth nearly to the degree of the bovine tongue, the tip is reasonably motile, and the main muscular portion of the tongue creates a pronounced caudal dome that fills most of the caudal oropharynx. The tongue further impedes oral examination. The anterior oral mucosa is smooth and often has areas of pigmentation, whereas the buccal mucosa is papillated. The length and narrowness of the oral cavity makes visual examination difficult. The lower lip is less mobile and less sensitive than the upper lip.Ĭamelids have a small oral cavity with an elongated soft palate and narrow oropharynx. With its tactile qualities and mobility, this upper lip plays some of the role of the tongue in traditional ruminants. Each half can move independently, allowing camelids to fastidiously investigate potential food sources and then to procure choice foods. One anatomic feature that contributes to this ability is the labial cleft, or philtrum, which divides the upper lip into halves. Llamas and alpacas selectively graze high-quality plants in environments where overall nutrient availability is low.
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