Changes

The transverse arytenoid muscle is innervated by the '''caudal laryngeal nerve''', a branch of the vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]). It completes the '''muscular sphincter arrangment''' and spans the '''arytenoid cartilages'''.

The transverse arytenoid muscle is innervated by the '''caudal laryngeal nerve''', a branch of the vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]). It completes the '''muscular sphincter arrangment''' and spans the '''arytenoid cartilages'''.

==Laryngeal Pharynx==

===Extrinsic Musculature===

 

The laryngeal pharynx is the largest part of the [[Pharynx - Anatomy & Physiology|pharynx]]. It is wide rostrally and narrows caudally. The laryngeal pharynx joins the [[Oesophagus - Anatomy & Physiology|oesophagus]] at the mucosal folds. The lumen is closed at rest by the roof and walls falling towards the floor. The floor of the laryngeal pharynx contains the opening into the larynx - epiglottis, arytenoid cartilages and the aryepiglottic folds.

The hyoepiglotticus is a bilobed muscle that originates on the basihyoid bone and inserts ventrally on the epiglottis. In horses, contraction of the hyoepiglotticus muscle pulls the epiglottis toward

 

the basihyoid bone, depressing it against the soft palate. This enlarges the airway during inspiration. Additionally, contraction of the muscle stabilizes the epiglottis during inspiration, preventing its prolapse through the glottis.

==Function==

===Function===

The larynx protects the trachea in [[Deglutition|swallowing]], preventing aspiration of foreign material. During swallowing, the larynx is moved rostrally causing the epiglottis to partially cover the laryngeal entrance. Solid foods are carried over the laryngeal entrance by the muscles of the [[Pharynx - Anatomy & Physiology|pharynx]]. Fluids are deflected by the epiglottis. Closure of the glottis also prevents food passing down the larynx. The reflex stimulation of the mucosa promotes the coughing reflex.  

The larynx protects the trachea in [[Deglutition|swallowing]], preventing aspiration of foreign material. During swallowing, the larynx is moved rostrally causing the epiglottis to partially cover the laryngeal entrance. Solid foods are carried over the laryngeal entrance by the muscles of the [[Pharynx - Anatomy & Physiology|pharynx]]. Fluids are deflected by the epiglottis. Closure of the glottis also prevents food passing down the larynx. The reflex stimulation of the mucosa promotes the coughing reflex.  

The larynx also allows the passage of air to the lungs and increases the intra-abdominal pressure. The glottis can widen by adduction of the vocal folds when breathing is vigorous. In addition to this, the larynx is used for vocalisation.

The larynx also allows the passage of air to the lungs and increases the intra-abdominal pressure. The glottis can widen by adduction of the vocal folds when breathing is vigorous. In addition to this, the larynx is used for vocalisation.

==Vasculature==

===Vasculature===

'''Laryngeal branch of the superior thyroid artery''' supplies the rostral larynx and is a branch of the '''carotid artery'''.

'''Laryngeal branch of the superior thyroid artery''' supplies the rostral larynx and is a branch of the '''carotid artery'''.

'''Laryngeal branch of cricothyroid artery''' branches from the '''superior thyroid artery'''.

'''Laryngeal branch of cricothyroid artery''' branches from the '''superior thyroid artery'''.

==Innervation==

===Innervation===

The larynx is innervated by branches of the '''vagus nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]).  

The larynx is innervated by branches of the '''vagus nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]).