Guttural Pouches - Anatomy & Physiology

()Map CARDIORESPIRATORY SYSTEM (Map)

Equine Guttural Pouch - Copyright David Bainbridge

Introduction

The Guttural Pouch is present only in members of the order Perissodactyla (nonruminant ungulates: horses; tapirs; rhinoceros) and another small band of small mammels including Hyraxes, certain bats and a South American mouse.

The guttural pouch, also known as the Auditory Tube Diverticulum is a long, slitlike opening connecting the nasal cavity and middle ear which dilates to form pouches which can have a capacity of 300-500ml in the domestic horse.

Structure

• The Guttural Pouch is located below the cranial cavity, towards the caudal end of the skull.
• It is covered laterally by the Pterygoid muscles, parotid and mandibular glands. The floor lies mainly on the pharynx. It is moulded to the Stylohyoid muscle which divides the medial and lateral compartments.
• The Guttural Pouch has close association with many major structures including several cranial nerves (Glossopharyngeal, Vagus, Accessory, Hypoglossal), the Sympathetic Trunk and the External and Internal Carotid Arteries. The pouch directly covers the temporohyoid joint.
• The pouch has an extremely thin wall which is lined by respiratory epithelium which secretes mucous. This normally drains into the pharynx when the horse is grazing.

Function

• The Guttural Pouch is a mechanism for cooling the cerebral blood supply after exercise, due to it's close connection with the Internal Carotid Artery.

Species Differences

• The Gutteral pouch is present only in members of the order Perissodactyla (nonruminant ungulates: horses; tapirs; rhinoceros) and another small band of small mammels including Hyraxes, certain bats and a South American mouse

References

• Dyce, K.M., Sack, W.O. and Wensing, C.J.G. (2002) Textbook of Veterinary Anatomy. 3rd ed. Philadelphia: Saunders.