Hyoid Apparatus - Anatomy & Physiology

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Introduction

The hyoid apparatus holds the larynx in place and supports the pharynx and tongue from the skull.

It is made up of 5 different bones which vary in length and size depending on the species.

Hyoid Apparatus in situ - Copyright Nottingham

Structure and Function

• Attached to the temporal region of the skull by a synchondrosis

• Palpable through pharynx

• Visible when the pharynx is viewed through the mouth

• Basihyoid is palpable within the intermandibular space

• Sternohyoid muscle pulls hyoid caudally

• Geniohyoid muscle pulls hyoid rostrally

Hyoid Apparatus Drawing - Copyright nabrown

The hyoid bones

• Basihyoid
  • Lingual process present in some species which protrudes into the roof of the tongue
  • Unpaired

• Stylohyoid
  • Articulates with base of skull at petrus temporal
  • Articulates with thyroid cartilage of larynx
  • Paired

• Epihyoid
  • Paired

• Keratohyoid
  • Paired

• Thyrohyoid
  • Paired

Species Differences

Carnivores

• Stylohyoid bones not palpable

Equine

• Epihyoid small

• Lingual process present

• Well developed stylohyoid muscle

Ruminants

• Lingual process present

Porcine

• Lingual process present