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Larynx - Anatomy & Physiology (view source)
Revision as of 17:42, 29 December 2010
, 17:42, 29 December 2010no edit summary
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 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]].
[[Image:Larynx Anatomy.jpg|thumb|right|250px|Anatomy of the Larynx - Copyright Nottingham]]
[[Image:Larynx Anatomy.jpg|thumb|right|250px|Anatomy of the Larynx - Copyright University of Nottingham]]
[[Image: Annotated horse larynx.JPG|thumb|right|250px|Annotated horse larynx- Copyright RVC]]
[[Image: Annotated horse larynx.JPG|thumb|right|250px|Annotated horse larynx- Copyright RVC]]
==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]]. The larynx is bilaterally symmetrical and 'tube-shaped', it 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 attatchment of the [[Epiglottis]] to the '''thyroid''' and '''cricoid cartilage'''. The first tracheal ring has attatchment with the '''cricoid cartilage''' by the '''cricotracheal ligament'''.
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'''.
===Extrinsic musculature===
===Extrinsic musculature===
===Glottic cleft===
===Glottic cleft===
The '''glottic cleft''' (rima glottidis) is surrounded by the '''arytenoid cartilages''' dorsally and '''vocal folds''' ventrolaterally. It varies in size and is diamond shaped. The glottic cleft disappears when the glottis is closed. Vocal folds run caudodorsally. The '''infraglottic cavity''' extends from the caudal section of the '''arytenoid cartilages''' into the lumen of the trachea. It is fixed in size.
The '''glottic cleft''' (rima glottidis) is surrounded by the '''arytenoid cartilages''' dorsally and '''vocal cords''' ventrolaterally. It varies in size and is diamond shaped. The glottic cleft disappears when the glottis is closed. Vocal folds run caudodorsally. The '''infraglottic cavity''' extends from the caudal section of the '''arytenoid cartilages''' into the lumen of the trachea. It is fixed in size.
===Epiglottis===
===Epiglottis===
The [[Epiglottis]] is the rostral margin of the larynx.
The [[Epiglottis|epiglottis]] is the rostral margin of the larynx.
==The Cartilage of the Larynx==
==The Cartilage of the Larynx==
===Thyroid Cartilage===
===Thyroid Cartilage===
[[Image:Thyroid cartilage.jpg|thumb|right|250px|Thyroid Cartilage - Copyright nabrown RVC]]
[[Image:Thyroid cartilage.jpg|thumb|right|250px|Thyroid Cartilage - Copyright nabrown RVC]]
The thyroid cartilage is [[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 thyriod cartilage articulates with the '''thyrohyoid bone''' and the '''cricoid cartilage'''. It becomes brittle as the animal ages.
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.
===Cricoid Cartilage===
===Cricoid Cartilage===
[[Image:Cricoid cartilage.jpg|thumb|right|250px|Cricoid Cartilage - Copyright nabrown RVC]]
[[Image:Cricoid cartilage.jpg|thumb|right|250px|Cricoid Cartilage - Copyright nabrown RVC]]
The cricoid cartilage is also [[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 egde. The cricoid cartilage articulates with the '''thyroid cartilage'''. It also becomes brittle as the animal ages.
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.
===Arytenoid Cartilage===
===Arytenoid Cartilage===
[[Image:Arytenoid cartilages.jpg|thumb|right|250px|Arytenoid Cartilages - Copyright nabrown RVC]]
[[Image:Arytenoid cartilages.jpg|thumb|right|250px|Arytenoid Cartilages - Copyright nabrown RVC]]
The arytenoid cartilage is also [[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. (elastic 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. <font color = 'red'>(elastic cartilage)</font color>
===Epiglottic Cartilage===
===Epiglottic Cartilage===
[[Image:Epiglottic cartilage.jpg|thumb|right|250px|Epiglottic Cartilage - Copyright nabrown RVC]]
[[Image:Epiglottic cartilage.jpg|thumb|right|250px|Epiglottic Cartilage - Copyright nabrown RVC]]
The epiglottic cartilage is [[Bones and Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]]. It is flexible and the most rostral type of cartilage. The thinner stalk-like part is attached to the root of the [[Tongue - Anatomy & Physiology|tongue]], 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 [[Bones and Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage]]. <font color = 'red'>It is flexible and the most rostral type of cartilage. </font color>The thinner stalk-like part is attached to the root of the [[Tongue - Anatomy & Physiology|tongue]], 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===
===Cuneiform Process===
===Cuneiform Process===
The cuneiform process is [[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 [[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 Vocal and Vestibular Folds==
==The Vocal and Vestibular Folds==
===Vestibular folds===
===Vestibular folds===
The vestibular folds are made of (slightly stiffer) elastic ligaments. The '''vestibular ligaments''' are rostral to the '''vocal ligament'''. The vestibular folds run caudodorsally, rostral to the vocal folds with the ligament positioned medially and the '''vocalis muscle''' laterally. Fat surrounds vocalis muscle. The vestibular folds differ as they do not form the glottis.
The vestibular folds are made of (slightly stiffer) elastic ligaments. The '''vestibular ligaments''' are rostral to the '''vocal ligament'''. The vestibular folds run caudodorsally, rostral to the vocal folds with the ligament positioned medially and the '''vocalis muscle''' laterally. <font color = 'red'>The vestibular folds differ as they do not form the glottis.
</font color>
==Intrinsic Musculature==
==Intrinsic Musculature==
===Cricothryroid muscle===
===Cricothyroid muscle===
The cricothyroid muscle is innervated by the '''cranial laryngeal nerve''', a branch of the vagus nerve. ([[Cranial Nerves - Anatomy & Physiology|CN X]]) It moves the '''cricoid''' and '''arytenoid''' cartilages caudally to tense the vocal folds.
The cricothyroid muscle is innervated by the '''cranial laryngeal nerve''', a branch of the vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]). It moves the '''cricoid''' and '''arytenoid''' cartilages caudally to tense the vocal folds.
===Dorsal cricoarytenoid muscle===
===Dorsal cricoarytenoid muscle===
===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'''. It 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'''.
[[Image:Pharynx Anatomy.jpg|thumb|right|250px|Pharynx Labelled - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
[[Image:Pharynx Anatomy.jpg|thumb|right|250px|Pharynx Labelled - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
==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, but 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|epiglottis]], arytenoid cartilages and the aryepiglottic folds.
==Function==
==Function==
The larynx protects the trachea in [[Deglutition|swallowing]], preventing aspiration of foreign material. During [[Deglutition|swallowing]], the larynx is moved rostrally causing the [[Epiglottis|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|epiglottis]]. Closure of the glottis also prevents food passing down the larynx. The relfex 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 inferior thyroid artery''' supplies the caudal larynx and is branching from the '''subclavian artery''' from the '''thyrocervical trunk'''.
'''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]]).
'''Cranial laryngeal nerve''' has two branches. The internal branch innervates the mucosa and the external branch innervates the '''cricothyroid muscle''' and constricts the [[Pharynx - Anatomy & Physiology|pharynx]].
The internal branch innervates the mucosa and the external branch innervates the '''cricothyroid muscle''' and constrictors of the [[Pharynx - Anatomy & Physiology|pharynx]].
'''Caudal (recurrent) laryngeal nerve''' innervates the intrinsic muscles of the larynx (except the cricothyroid muscle).
==Lymphatics==
==Lymphatics==
==[[Species Differences in Laryngeal Structure|Species Differences]]==
==[[Species Differences in Laryngeal Structure|Species Differences]]==
The variation of the laynx between species is significant. More information can be found by clicking [[Species Differences in Laryngeal Structure|here]].
The variation of the larynx between species is significant. More information can be found by clicking [[Species Differences in Laryngeal Structure|here]].
==Histology==
==Histology==
Mucous glands are present in the larynx. In the ventricles, there is a high density of mucous glands. '''Stratified squamous epithelium''' is located rostrally around the laryngeal entrance, whilst '''ciliated pseudostratified columnar epithelium''' can be located 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.
See [[Bones and Cartilage - Anatomy & Physiology#Elastic Cartilage|elastic cartilage histology]] for more information.
[[Bones and Cartilage - Anatomy & Physiology|Cartilage - Anatomy & Physiology]]
[[Bones and Cartilage - Anatomy & Physiology|Cartilage - Anatomy & Physiology]]
[[Lungs Inflammatory - Pathology#Aspiration pneumonia|Aspiratory Pneumonia]]
[[Lungs Inflammatory - Pathology#Aspiration pneumonia|Aspiration Pneumonia]]
[[Larynx - Musculoskeletal - Flashcards|Larynx Flashcards]]
[[Larynx - Musculoskeletal - Flashcards|Larynx Flashcards]]
[[Category:Respiratory System - Anatomy & Physiology]][[Category:Musculoskeletal System - Anatomy & Physiology]]
[[Category:Respiratory System - Anatomy & Physiology]][[Category:Musculoskeletal System - Anatomy & Physiology]]
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