Labeled Horse Skull Anatomy Pharyngeal

labeled horse skull anatomy pharyngeal

Labeled Horse Skull Anatomy Pharyngeal

The pharynx is a bottleneck in the upper airway that is formed dorsally by the corniculate cartilages and laterally by the vocal folds. It is ventrally lined with laryngeal mucosa that may resemble a grape-sized cluster of pimples, or a cobblestone-like appearance, depending on age and/or existent pathology. The aditus laryngis can be closed or open (see fig below).

Laryngeal innervation of the equine skull is supplied by the ipsilateral recurrent laryngeal nerve (RLN). The motor neurons of the RLN are located in the nucleus ambiguus, a loosely organized column of cells within the ventrolateral part of the caudal brainstem. Until recently, it was thought that these motor neurons were distributed uniformly throughout the nucleus; however, it has been shown that they are primarily concentrated in the area of the aditus laryngis, which is the site of the rostral protrusion of the laryngeal cartilages.

Similarly, the sensory neurons of the RLN are scattered throughout the caudal part of the medulla oblongata. The afferent input to the nasopharynx from these motor and sensory neurons is relayed via the medial palatine nerve and the lateral palatine nerve (see fig below). These sensory neurons are also situated in the nucleus ambiguus, but they are mainly scattered in the region of the rostral protrusion of aditus laryngis, where the acoustic window of aditus laryngis is located.

The equine skull is a relatively large bone with many ridges and crests that are reflected on the surface of the brain. These crests are important landmarks that can be identified when examining the skull under magnification. The cranial vault of the equine skull is very long and contains the internal and external carotid arteries. The internal carotid artery runs briefly on the caudal surface of the guttural pouch, and may hemorrhage into the pouch if eroded by infection (see Clinical Notes below). The external carotid artery stays on the lateral surface of the pharyngeal wall.

In addition to the aforementioned structures, the skull contains the sinuses and a lingual thyroid gland. A lingual thyroid gland is the dominant gland of the pharynx and produces hormones that control salivary secretions. The sinuses and lingual thyroid are also involved in regulating the respiratory and digestive tracts.

In BOVINE, the mouth has a nasolabial plate that is rigid and hairless (not like in EQUINE). The mandibular incisors are flattened shovel shaped teeth that lack an infundibulum. In addition, there are numerous (and easily palpable) lymph nodes under the chin that run near the linguofacial v. and the ramus of the mandible. Young horses often have prominent temporary tuberosities on the ventral border of the mandible that are remnants of deciduous teeth P3 and P4. These are not to be confused with fractures.