Anatomy and Physiology of Swallowing: Difference between revisions
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=== Muscles === | === Muscles === | ||
Table 1 lists major muscles involved in the swallowing and their function. | |||
{| class="wikitable" | {| class="wikitable" | ||
|+'''Table 1. Muscles of the swallowing''' | |+'''Table 1. Muscles of the swallowing''' | ||
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=== Cranial nerves === | === Cranial nerves === | ||
Cranial nerves modulate swallowing execution.<ref>Costa MMB. [https://www.scielo.br/j/ag/a/KSKwC9f7JRqtDxntLyCbksS/?lang=en Neural Control of Swallowing]. Arq Gastroenterol. 2018 Nov;55Suppl 1(Suppl 1):61-75. </ref> | Cranial nerves modulate swallowing execution.<ref name=":2">Costa MMB. [https://www.scielo.br/j/ag/a/KSKwC9f7JRqtDxntLyCbksS/?lang=en Neural Control of Swallowing]. Arq Gastroenterol. 2018 Nov;55Suppl 1(Suppl 1):61-75. </ref>Table 2 summerises the function and the clinical relevance of the six cranial nerves involved in the swallowing. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+'''Table 2. Cranial nerves involved in swallowing''' | |+'''Table 2. Cranial nerves involved in swallowing''' | ||
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** premature posterior spill of the bolus to the pharynx | ** premature posterior spill of the bolus to the pharynx | ||
** post swallow oral residue | ** post swallow oral residue | ||
|- | |||
|'''The accessory nerve''' CN XI<ref name=":2" /> | |||
| | |||
* motor innervation of the striated portions of the pharynx, larynx and oesophagus in association with the vagus nerve | |||
* presence of parasympathetic fibres (general visceral efferent) accompanying the vagus nerve fibres | |||
* prevent pressure from returning to the oral cavity | |||
* elevates the palate and blocks the possible pressure escape from the oropharynx to the rhinopharynx | |||
| | |||
* Impairment of the accessory nerve can cause: | |||
** reduced vocal folds adduction | |||
|} | |} | ||
=== Anatomy structures === | === Anatomy structures === | ||
the nose | <blockquote>"Feeding and breathing share the same anatomy. "<ref name=":3">Matsuo K, Palmer JB. [[Coordination of Mastication, Swallowing and Breathing]]. Jpn Dent Sci Rev. 2009 May 1;45(1):31-40. </ref></blockquote>'''The nose and nasal cavity''': Breathing through the nose occurs during eating solids, since the mouth is engaged in processing the food and the lips are sealed to prevent the food from escaping anteriorly. Nasal air pressure oscillates with masticatory jaw movement and becomes, relative to atmospheric pressure, positive during jaw closing and negative during jaw opening. <ref name=":3" /> | ||
the | '''The oral cavity:''' tongue movement corresponds with cyclic jaw movement when the food is in the mouth. The tongue and the cheek reposition food laterally (tongue) and medially (cheek). <ref name=":3" /> | ||
the | '''The pharynx:''' a route for breathing, mastication and swallowing. The pharynx is dilated to maintain airway for breathing, and is constricted to provide space for bolus aggregation before the pharyngeal swallow.<ref name=":3" /> | ||
larynx and vocal folds | '''The larynx and the vocal folds:''' the posterior aspect of the larynx forms the anterior wall of the upper esophageal sphincter (UES). | ||
the pharynx | '''The upper oesophageal sphincter (UES):''' a kidney bean shaped space encompassed anteriorly by the larynx, posterolaterally by the pharyngoesophageal muscles, superiorly by the pharynx and inferiorly by the esophagus. <ref name=":1" /> | ||
the esophagus: | == Neural Coordination of Swallowing == | ||
Swallowing requires a coordinated contraction of muscles in the mouth, pharynx, upper esophageal sphincter, and upper esophagus via central control. Swallowing centres activate the voluntary motor centres and inhibit the respiratory centres - this prevents food from entering the [[/www.physio-pedia.com/Trachea and Larynx|trachea]]. There is also activation of the: | |||
* | * Reflex centres | ||
* | * Nuclei of the [[/www.physio-pedia.com/Cranial Nerves|cranial nerves]] that are involved in the movement of the tongue, larynx and pharynx | ||
== | See the swallowing flow chart for details: | ||
[[File:Swallowing flow diagram.jpg|center|thumb|400x400px]] | |||
== Swallowing Physiology == | |||
=== Drinking and Swallowing of Liquid === | |||
== Resources == | == Resources == |
Revision as of 16:12, 24 May 2024
Original Editor - User Name
Top Contributors - Ewa Jaraczewska and Jess Bell
Introduction[edit | edit source]
Deglutition is the process of swallowing which defines the movement of liquids or solids from the mouth to the stomach via the pharynx and esophagus. This process accommodates the changes in development as well as changes related to pathology associated with dysphagia. The elements of swallowing such as the suck, swallow, and breathing sequence evolve in the early stages of development and end with a conscious action of swallowing.[1] Multiple organ systems are involved in this process and include musculoskeletal system, neuromuscular system and respiratory system. Normal swallowing requires a coordinated effort of over thirty muscles [2], the central nervous system, and five cranial nerves.[3] Additionally the nose, the nassal cavity, the oral cavity, and the pharynx are key anatomy structures involved in this process. This article explores anatomy and physiology pertain to the process of normal swallowing.
Developmental Anatomy and Swallowing[edit | edit source]
Anatomical differences in the swallowing structures are present from infant, through older child, to adulthood. Alongside the anatomical changes , the swallowing adaptation occurs.
- jaw and oral cavity are small
- tongue takes up most of the capacity of the mouth
- no teeth
- sucking is possible by using the tongue, sucking pads, and sulci
- sucking pads provide stability
- lack of distinct oropharynx
- the size of the larynx is 1/3 of an adult larynx and is located higher in the laryngeal cavity
- the base of the tongue is close to the larynx
- vocal cords consists of 1/2 of cartilage
- the epiglottis and soft palate touch when at rest
- tongue lies at a lower position (floor of the mouth) because the mouth is bigger and the tongue sits behind the teeth
- the mandible extends down and forward
- the oral cavity expands
- the hyoid and larynx are positioned further down
- buccinators (cheek muscles) generate sucking mechanism
- the tongue pushes the food laterally to allow chewing with the teeth
- the sucking pads degenerate
- the pharynx lengthens vertically
- the nasopharynx becomes a 90-degree angle
- the epiglottis becomes wide and flattened
- the base of the tongue and the larynx separate by the age 4
- true vocal cords consist of no more than 1⁄3 of cartilage
- larynx starts to lower by the age of 2
Note: the changes listed above occur at the compromise of aspiration. These changes make the patient prone to aspiration but they are important for speech.[5]
Adult Anatomy and Swallowing[edit | edit source]
Muscles[edit | edit source]
Table 1 lists major muscles involved in the swallowing and their function.
Muscles | Function | |
---|---|---|
Tongue muscles[5] | Intrinsic tongue muscles:
|
|
Masticatory muscles[5] | Mylohyoid tensor veli palatini
Temporalis Medial and lateral pterygoid muscles |
|
Muscles of the neck[5] | Anterior belly of digastrics (ABD)
Posterior belly of digastrics (PBD) |
|
Soft palate and pharynx[5] | Levator veli palatine (LVP)
Salpingopharyngeous (SPh) Intrinsic laryngeal muscles (IL) |
|
Upper esophageal sphincter[6] | The extrinsic muscles:Anterior group:
The extrinsic muscles: Posterior group:
The intrinsic muscles:
|
The extrinsic muscles:Anterior group:
Posterior group:
The intrinsic muscles:
|
Cranial nerves[edit | edit source]
Cranial nerves modulate swallowing execution.[7]Table 2 summerises the function and the clinical relevance of the six cranial nerves involved in the swallowing.
Cranial nerves | Function | Clinical Relevance |
---|---|---|
The trigeminal nerve (TN)CN V |
|
|
The facial nerve (FN)CN VII |
|
|
The glossopharyngeal nerve (GN)CN IX |
|
|
The vagal nerve (VN) CN X |
|
|
The hypoglossal nerve (HN) CN XII |
|
|
The accessory nerve CN XI[7] |
|
|
Anatomy structures[edit | edit source]
"Feeding and breathing share the same anatomy. "[8]
The nose and nasal cavity: Breathing through the nose occurs during eating solids, since the mouth is engaged in processing the food and the lips are sealed to prevent the food from escaping anteriorly. Nasal air pressure oscillates with masticatory jaw movement and becomes, relative to atmospheric pressure, positive during jaw closing and negative during jaw opening. [8]
The oral cavity: tongue movement corresponds with cyclic jaw movement when the food is in the mouth. The tongue and the cheek reposition food laterally (tongue) and medially (cheek). [8]
The pharynx: a route for breathing, mastication and swallowing. The pharynx is dilated to maintain airway for breathing, and is constricted to provide space for bolus aggregation before the pharyngeal swallow.[8]
The larynx and the vocal folds: the posterior aspect of the larynx forms the anterior wall of the upper esophageal sphincter (UES).
The upper oesophageal sphincter (UES): a kidney bean shaped space encompassed anteriorly by the larynx, posterolaterally by the pharyngoesophageal muscles, superiorly by the pharynx and inferiorly by the esophagus. [5]
Neural Coordination of Swallowing[edit | edit source]
Swallowing requires a coordinated contraction of muscles in the mouth, pharynx, upper esophageal sphincter, and upper esophagus via central control. Swallowing centres activate the voluntary motor centres and inhibit the respiratory centres - this prevents food from entering the trachea. There is also activation of the:
- Reflex centres
- Nuclei of the cranial nerves that are involved in the movement of the tongue, larynx and pharynx
See the swallowing flow chart for details:
Swallowing Physiology[edit | edit source]
Drinking and Swallowing of Liquid[edit | edit source]
Resources[edit | edit source]
- bulleted list
- x
or
- numbered list
- x
References[edit | edit source]
- ↑ Panara K, Ramezanpour Ahangar E, Padalia D. Physiology, Swallowing. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541071/ [last access 23.05.2024]
- ↑ Umay E, Akaltun MS, Uz C. Association between swallowing muscle mass and dysphagia in older adults: A case-control study. J Oral Rehabil. 2023 Jun;50(6):429-439.
- ↑ Arvedson J, Lefton-Greif M, Reigstad D, Brodsky L. Clinical swallowing and feeding assessment. San Diego, CA: Plural Publishing; 2020.
- ↑ 4.0 4.1 Kaiser L, Park T. Feeding and Swallowing Development in Children. Graduate Independent Studies - Communication Sciences and Disorders 2020; 27.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Banerjee S. Anatomy and Physiology Significant to Dysphagia. Plus Course 2024
- ↑ Ramaswamy AT, Martell P, Azevedo R, Belafsky P. The upper esophageal sphincter: anatomy and physiology. Ann Esophagus 2022;5:30
- ↑ 7.0 7.1 Costa MMB. Neural Control of Swallowing. Arq Gastroenterol. 2018 Nov;55Suppl 1(Suppl 1):61-75.
- ↑ 8.0 8.1 8.2 8.3 Matsuo K, Palmer JB. Coordination of Mastication, Swallowing and Breathing. Jpn Dent Sci Rev. 2009 May 1;45(1):31-40.