Macroscopic anatomy of the auditory tube diverticulum (guttural pouch) in the thoroughbred equine–a silicon mold approach.

This research article investigates the structure and characteristics of the guttural pouches (auditory tube diverticulum) in thoroughbred horses using a silicon mold method. The study also explores their anatomical relationship with surrounding bones, muscles, nerves, and arteries.

Study Methodology

• The researchers began by inspecting the anatomical connection between the guttural pouches and the surrounding bones and muscles in the horse’s head.
• They then constructed a silicon mold to better understand the three-dimensional features of the guttural pouches and examine how major arteries and nerves are distributed around these structures.
• The volume of the silicon mold was measured by submerging it in water, allowing researchers to determine the size of the guttural pouches.

Anatomical Location of Guttural Pouches

• The guttural pouches are found dorso-posteriorly to the posterior pharynx, the part of the throat at the back of the horse’s mouth. They are rostrally in contact with the Os sphenoidale bone and ventrally with the pharynx and esophagus. The pouches are also caudally linked to the Articulatio atlantoaxialis, a joint located at the upper neck vertebral column.
• The left and right guttural pouches were found to have almost equal capacities in each of the horses examined.

Associated Arteries and Nerves

• The A. carotis interna, cranial ganglia of cervical nerves, and cervical Truncus sympathicus, as well as several key nerves such as N. vagus, N. glossopharyngeus, N. hypoglossus, and Radices spinales of the N. accessorius, were present in a mucosal crease extending from the top of the guttural pouches down to the middle of the rear wall.
• The N. facialis and N. mandibularis nerves were both found to originate from specific foramen and travel along the roof of the lateral recess and different sides of the guttural pouches, respectively.

Lymph Nodes and Guttural Pouch Capacity

• The researchers noted the presence of lymph nodes scattered on the mucosal surface of the guttural pouches. These nodes created tiny indentations, the size of millet seeds, visible on the surface of the silicon mold.
• The study found a significant size disparity between adult horses and foals, with adult guttural pouches found to be three times larger (472 +/- 12.4 cm3) than in foals (145 +/- 9.4 cm3).

This comprehensive exploration of the equine guttural pouches provides valuable insight into their anatomy and relationship with surrounding structures, contributing to a more detailed understanding of equine head anatomy.