Apparatus hyoideus
The hyoid apparatus is a chain of paired and unpaired bones suspended from the temporal bone of the skull. It consists of the basihyoid (with its lingual process), thyrohyoid, ceratohyoid, epihyoid, stylohyoid, and tympanohyoid. The apparatus supports the root of the tongue, the larynx, and the pharynx. Muscles attached to the hyoid move it forward or backward, which changes the position of the tongue and the diameter of the upper airway. In the horse the hyoid plays critical roles in swallowing, maintaining airway stability during exercise, and allowing normal tongue movement. Because the tongue and hyoid are linked to the poll and neck through muscles and fascia, tension or pain in this region can affect poll flexion and bit acceptance. Fractures of the hyoid bones can occur from trauma (kicks to the throat, falls, or dental procedures) and may compromise the airway or the ability to swallow.
Hyoid fractures are uncommon but can cause difficulty swallowing, swelling under the jaw, abnormal respiratory noise, or resistance to poll flexion. Upper-airway endoscopy and radiographs or CT are used for diagnosis. Soft-tissue dysfunction of the hyoid muscles can contribute to dorsal displacement of the soft palate or other dynamic airway problems.
Progressive fusion and thickening of the temporohyoid joint (where the stylohyoid articulates with the temporal bone). Can lead to fracture of the petrous temporal bone, damaging cranial nerves VII an
## Overview Fracture of the hyoid apparatus (the bony support of the tongue and larynx) is uncommon and usually traumatic. It can cause difficulty swallowing, throatlatch swelling, pain on manipulati
Difficulty swallowing, swelling under the jaw or throat, abnormal breathing noise, or sudden resistance to the bit or poll flexion after trauma should be evaluated. Keep the mouth and throat area free of unnecessary trauma during dental work and handling.
Progressive fusion and thickening of the temporohyoid joint (where the stylohyoid articulates with the temporal bone). Can lead to fracture of the petrous temporal bone, damaging cranial nerves VII and VIII. A serious, potentially life-threatening condition. Signs include: Sudden onset facial nerve paralysis (drooping ear, lip, eyelid); head tilt; difficulty swallowing; loss of balance (vestibular signs); may have history of ear discharge or previous mild episodes; can cause sudden death from basilar skull fracture; diagnosed on endoscopy of the guttural pouches or CT.
## Overview Fracture of the hyoid apparatus (the bony support of the tongue and larynx) is uncommon and usually traumatic. It can cause difficulty swallowing, throatlatch swelling, pain on manipulation, abnormal respiratory noise, and sometimes epistaxis. Resistance to poll flexion may be noted. ## Causes Trauma to the throat or tongue region, or excessive traction. ## Diagnosis Radiographs or computed tomography of the hyoid bones, endoscopy, and clinical signs of dysphagia or local pain. ## Treatment Conservative management with soft feeds and anti-inflammatories for stable fractures. Surgical repair is rarely required. Supportive care for dysphagia. ## Recovery and Prognosis Generally good for uncomplicated fractures. Persistent dysphagia worsens the outlook. ## Prevention Avoidance of throat trauma. Signs include: difficulty swallowing; swelling under the jaw or throat; pain on throat manipulation; abnormal respiratory noise; possible epistaxis
Hyoid fractures are uncommon but can cause difficulty swallowing, swelling under the jaw, abnormal respiratory noise, or resistance to poll flexion. Upper-airway endoscopy and radiographs or CT are used for diagnosis. Soft-tissue dysfunction of the hyoid muscles can contribute to dorsal displacement of the soft palate or other dynamic airway problems.
Difficulty swallowing, swelling under the jaw or throat, abnormal breathing noise, or sudden resistance to the bit or poll flexion after trauma should be evaluated. Keep the mouth and throat area free of unnecessary trauma during dental work and handling.
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