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==Introduction==

==Introduction==

The larynx is situated below where the [[Pharynx - Anatomy & Physiology|pharynx]] divides into the trachea and the [[Oesophagus - Anatomy & Physiology|oesophagus]]. It is contained partly within the rami of the mandible and extends caudally into the neck. '''Vocal folds''' and '''vestibular folds''' are present in the larynx and due to this, it is more commonly known as the voice box.

The larynx is situated below where the [[Pharynx - Anatomy & Physiology|pharynx]] divides into the trachea and the [[Oesophagus - Anatomy & Physiology|oesophagus]]. It is contained partly within the rami of the mandible and extends caudally into the neck. '''Vocal folds''' and '''vestibular folds''' are present in the larynx and due to this, it is more commonly known as the voice box.

The cartilageous larynx can be manually palpated in the living animal and is commonly implicated in respiratory conditions such as [[Diseases of the conducting airways#Laryngeal paralysis|roaring]].

The cartilagenous larynx can be manually palpated in the living animal and is commonly implicated in respiratory conditions such as [[Laryngeal Paralysis|roaring]].

==Structure==

==Structure==

The [[Pharynx - Anatomy & Physiology|pharynx]] is located rostrally to the larynx, whilst the trachea is located caudally. The larynx is suspended from the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]. It is bilaterally symmetrical and 'tube-shaped'and can be described as a '''musculocartilagenous organ'''.

The [[Pharynx - Anatomy & Physiology|pharynx]] is located rostrally to the larynx, whilst the trachea is located caudally. The larynx is suspended from the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]. It is bilaterally symmetrical and 'tube-shaped' and can be described as a '''musculocartilagenous organ'''.

The larynx moves position when the animal [[Deglutition|swallows]] due to its attachments to the [[Tongue - Anatomy & Physiology|tongue]] and the '''basihyoid bone''' of the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]] by the '''thyrohyoid membrane'''.

The larynx moves position when the animal [[Deglutition|swallows]] due to its attachments to the [[Tongue - Anatomy & Physiology|tongue]] and the '''basihyoid bone''' of the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]] by the '''thyrohyoid membrane'''.

===Ligaments===

===Ligaments===

Membranes and elastic ligaments attach the laryngeal cartilages, allowing attachment of the [[Epiglottis|epiglottis]] to the '''thyroid''' and '''cricoid cartilage'''. The first tracheal ring has attachment with the '''cricoid cartilage''' by the '''cricotracheal ligament'''.

Membranes and elastic ligaments attach the laryngeal cartilages, allowing attachment of the epiglottis to the '''thyroid''' and '''cricoid cartilage'''. The first tracheal ring has attachment with the '''cricoid cartilage''' by the '''cricotracheal ligament'''.

===Extrinsic musculature===

===Extrinsic musculature===

===Epiglottis===

===Epiglottis===

The [[Epiglottis|epiglottis]] is the rostral margin of the larynx.

The epiglottis is the rostral margin of the larynx. It is a flap of [[Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]] covered by mucous membrane. It forms the rostral boundary of the larynx and prevents food particles from entering the trachea. The epiglottis can return to its normal size and shape after distortion due to the vast amount of elastic fibres present within.

 

Avian species do not have epiglottis.

==The Cartilage of the Larynx==

==The Cartilage of the Larynx==

===Thyroid Cartilage===  

===Thyroid Cartilage===  

 

The thyroid cartilage is a [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] and forms most of the floor of the larynx. The fusion of the two lateral plates varies in different species. The rostral part forms the 'Adam's apple'. The thyroid cartilage articulates with the '''thyrohyoid bone''' and the '''cricoid cartilage'''. It becomes brittle as the animal ages.

The thyroid cartilage is a [[Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] and forms most of the floor of the larynx. The fusion of the two lateral plates varies in different species. The rostral part forms the 'Adam's apple'. The thyroid cartilage articulates with the '''thyrohyoid bone''' and the '''cricoid cartilage'''. It becomes brittle as the animal ages.

===Cricoid Cartilage===

===Cricoid Cartilage===

 

The cricoid cartilage is also a [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]]. It is signet ring shaped and is wider on the dorsal surface than the ventral surface. There is a crest on the midline of the dorsal surface and facets for '''arytenoid cartilages''' on the rostral edge. The cricoid cartilage articulates with the '''thyroid cartilage'''. It also becomes brittle as the animal ages.

The cricoid cartilage is also a [[Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]]. It is signet ring shaped and is wider on the dorsal surface than the ventral surface. There is a crest on the midline of the dorsal surface and facets for '''arytenoid cartilages''' on the rostral edge. The cricoid cartilage articulates with the '''thyroid cartilage'''. It also becomes brittle as the animal ages.

===Arytenoid Cartilage===

===Arytenoid Cartilage===

 

The arytenoid cartilage is also a [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]]. It is paired and articulates with the rostral part of the '''cricoid cartilage'''. A '''vocal process''' is present on the caudal surface where the vocal folds attach; a muscular process extends laterally and a corniculate process extends dorsomedially.

The arytenoid cartilage is also a [[Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]]. It is paired and articulates with the rostral part of the '''cricoid cartilage'''. A '''vocal process''' is present on the caudal surface where the vocal folds attach; a muscular process extends laterally and a corniculate process extends dorsomedially.

===Epiglottic Cartilage===

===Epiglottic Cartilage===

The epiglottic cartilage is an [[Bones and Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]], which is the most flexible and most rostral type of cartilage. The thinner stalk-like part, is attached to the root of the [[Tongue - Anatomy & Physiology|tongue]], the body of the '''thyroid cartilage''' and the '''basihyoid bone'''. The larger blade-like part lies behind the soft palate and points dorso-rostrally. During [[Deglutition|deglutition]], the large blade part of the '''epiglottic cartilage''' partially covers the entrance to the trachea.

The epiglottic cartilage is an [[Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]], which is the most flexible and most rostral type of cartilage. The thinner stalk-like part, is attached to the root of the [[Tongue - Anatomy & Physiology|tongue]], the body of the '''thyroid cartilage''' and the '''basihyoid bone'''. The larger blade-like part lies behind the soft palate and points dorso-rostrally. During [[Deglutition|deglutition]], the large blade part of the '''epiglottic cartilage''' partially covers the entrance to the trachea.

===Interarytenoid Cartilage===

===Interarytenoid Cartilage===

The interarytenoid cartilage is a nodule of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]]. It is located between the '''arytenoid cartilages''' dorsally.

The interarytenoid cartilage is a nodule of [[Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]]. It is located between the '''arytenoid cartilages''' dorsally.

===Cuneiform Process===

===Cuneiform Process===

The cuneiform process is formed by [[Bones and Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]]. It supports '''mucosal folds''' from the [[Epiglottis|epiglottis]] to the '''arytenoid cartilages'''. It is not present in all species and can be free or fused with the '''epiglottic cartilages'''.

The cuneiform process is formed by [[Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]]. It supports '''mucosal folds''' from the epiglottis to the '''arytenoid cartilages'''. It is not present in all species and can be free or fused with the '''epiglottic cartilages'''.

==The Vocal and Vestibular Folds==

==The Vocal and Vestibular Folds==

===Transverse arytenoid muscle===

===Transverse arytenoid muscle===

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==

==Laryngeal Pharynx==

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 (clearest in the canine, in other species it is harder to see the demarcation). 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|epiglottis]], arytenoid cartilages and the aryepiglottic folds.

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 (clearest in the canine, in other species it is harder to see the demarcation). 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.

==Function==

==Function==

Mucous glands are present in the larynx with a particularly high density in the ventricles. '''Stratified squamous epithelium''' is located rostrally around the laryngeal entrance, whilst '''ciliated pseudostratified columnar epithelium''' is elsewhere.

Mucous glands are present in the larynx with a particularly high density in the ventricles. '''Stratified squamous epithelium''' is located rostrally around the laryngeal entrance, whilst '''ciliated pseudostratified columnar epithelium''' is elsewhere.

See [[Bones and Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage histology]] for more information.

The epiglottis is covered by mucous membrane and contains irregular elastic fibres. They form a dense network of branching fibres around the chondrocytes and less dense branching fibres towards the perichondrium.

See [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage histology]] for more information.

See [[Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage histology]] for more information.

See [[Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage histology]] for more information.

 

[[Facial_Muscles_-_Musculoskeletal_-_Flashcards|Facial Muscles Flashcards]]

 

[[Pharynx_-_Musculoskeletal_-_Flashcards#The_Laryngeal_Pharynx_Flashcards|Larynx Pharynx Flashcards]]

 

[[Larynx_-_Musculoskeletal_-_Flashcards|Larynx Flashcards]]

==Links==

==Links==

[[Larynx - Pathology|Pathology of the Larynx]]

[[:Category:Larynx - Pathology|Pathology of the Larynx]]

[[Bones and Cartilage - Anatomy & Physiology|Cartilage - Anatomy & Physiology]]

[[Cartilage - Anatomy & Physiology|Cartilage - Anatomy & Physiology]]

[[Lungs Inflammatory - Pathology#Aspiration pneumonia|Aspiration Pneumonia]]

[[Aspiration Pneumonia|Aspiration Pneumonia]]

[[Larynx - Musculoskeletal - Flashcards|Larynx Flashcards]]

 

|flashcards = [[Facial_Muscles_-_Musculoskeletal_-_Flashcards|Facial Muscles]]<br>[[Pharynx_-_Musculoskeletal_-_Flashcards#The_Laryngeal_Pharynx_Flashcards|Larynx and Pharynx]]<br>[[Larynx_-_Musculoskeletal_-_Flashcards|Larynx]]

[[Epiglottis|The epiglottis]]  

|powerpoints = [[Bone and Cartilage Histology resource|Interactive tutorial on bone and cartilage histology, including the Larynx]]

 

|videos = [http://stream2.rvc.ac.uk/Anatomy/canine/head_neck/Pot0258.mp4 Lateral section through the head of a dog]

 

[http://stream2.rvc.ac.uk/Anatomy/canine/head_neck/Pot0258.mp4 Pot 258 Lateral section through the head of a dog]

[[Category:Respiratory System - Anatomy & Physiology]][[Category:Musculoskeletal System - Anatomy & Physiology]]

[[Category:Respiratory System - Anatomy & Physiology]][[Category:Musculoskeletal System - Anatomy & Physiology]]

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