Anatomy and Physiology of Swallowing

• Understanding the anatomy and physiology of normal swallows is essential for speech-language pathologists to evaluate and treat swallowing disorders.
• Speech-language pathologists must identify abnormal elements of the swallow to create treatment plans to compensate for or improve function.
• The goal of dysphagia rehabilitation is to identify and treat abnormalities of feeding and swallowing to maintain safe nutrition and hydration.

Normal Swallowing

• Normal swallowing is a life-sustaining skill.
• Impaired swallowing is life-threatening.
• Swallow frequency is most common during meals.
• Swallow frequency is least frequent during other activities.
• An individual swallows approximately 580 times each day

What's Normal

• Duration and characteristics of each swallow depend on food volume and type, and voluntary control.
• The swallow duration differs between a bolus of pudding and a bolus of steak.
• There are four distinct phases that overlap during normal swallowing.
• Not all swallows involve all phases, particularly those involving saliva.
• Respiration and swallowing are reciprocal, meaning respiration halts with the pharyngeal phase.
• Complete control is maintained over swallows.
• Thirty-plus muscles under the control of five cranial nerves can convert a respiratory channel into a digestive tract and back within 500 milliseconds.

Anatomy of Normal Deglutition

• Normal deglutition involves the oral cavity, pharynx, larynx, and esophagus.
• The lips close anteriorly.
• Teeth (24 deciduous, 32 permanent): They help with mastication. The hard palate provides a surface for the tongue to push the bolus posteriorly. The soft palate and uvula come into contact with the tongue.
• The mandible assists in opening and closing the mouth.
• The tongue is responsible for bolus preparation.
• The faucial arches trigger the pharyngeal swallow.

Functional Components of Normal Swallowing

• The oral cavity is responsible for gathering food/liquids and preparing them for transit.
• Containment keeps food/liquid in the mouth and on the tongue.
• Closure after bolus take is completed with the Orbicularis Oris/lips.
• Adequate tension to assist in lip closure is completed with the Buccinators/cheeks .
• Bolus preparation involved the Teeth which helps in the mastication (if the bolus requires chewing)
• The Tongue drives to propel bolus posteriorly.
• Sulci close to channel the bolus.
• The soft palate lowers and contacts the tongue, creating a seal to prevent premature spillage.

Facial Muscles Relevant to Feeding

• This group of muscles helps to close the mouth (when using a spoon, cup, or straw) and contain the bolus.
• Relevant muscles include the Orbicularis Oris, Buccinator, Levator labii superioris, Levator anguli oris, Depressor anguli oris, Mentalis, Zygomaticus major, Zygomaticus minor, and Depressor labii inferiori

Mastication Muscles

• Keep the jaw fixed and support the tongue's effort.
• The jaw opens and closes.
• Openers use lateral pterygoid muscles which are the primary jaw opener and Suprahyoid muscles, including the digastric, mylohyoid, geniohyoid, and stylohyoid
• Closers use the Masseter, Medial pterygoid, and Temporalis muscles.
• All muscles attach to the body of the mandible anteriorly and the body of the hyoid bone posteriorly.

Floor of the Mouth Musculature

• Key muscles include the Mylohyoid, Geniohyoid, and Anterior belly of digastric.
• The sulci are natural cavities/spaces composed of the anterior and lateral (buccal) cavities.
• The sulci are important to swallowing as these spaces can collect food or liquid that remains after swallowing in patients with dysphagia.
• The spaces should be checked when doing an evaluation, and they are a functional component for normal bolus transfer.

Tongue Muscles

• Protruding muscles include the Genioglossus, which anchors the tongue to the alveolar ridge and helps with retraction, Transversus, and Verticalis.
• Bolus transfer anteriorly to posteriorly is achieved via the genioglossus.
• Retracting muscles include the Hyoglossus that depresses the tongue and elevates the hyoid and the Styloglossus that pulls the tongue up and back.
• Tongue base retraction: hyoglossus and styloglossus.
• The tongue comprises the oral tongue (1-5) and the pharyngeal (tongue base) (6).
• Oral tongue sections are the tip, blade, front, center, and back, which end at the circumvallate papillae.
• The oral tongue is active during speech and the oral stages of swallowing, controlled cortically/voluntarily.
• The pharyngeal tongue base (6) begins at the circumvallate papillae and ends at the hyoid bone
• It is active during the pharyngeal swallow, controlled involuntarily from the brainstem but with some voluntary control.
• Various papillae (filiform, foliate, vallate) house taste receptors.

Taste Receptors

• Taste receptors are located on both the oral tongue and tongue base for five basic tastes: sweet, sour, salty, bitter, and zest.
• Saliva is required to aid in grinding and chewing.
• Good hydration is important to maintain tongue function.

Salivary Glands

• Glands produce two fluid types to create saliva.
• Viscid fluids are mucus-like whereas serous fluids are watery.
• Parotid glands: produce serous fluid and are found between the cheeks and upper molars.
• Submandibular glands: produce more serous than viscid fluid and are located in the floor of the mouth.
• Sublingual glands: produce more viscid than serous fluid and are located in the floor of the mouth.
• Many small glands in the mucous membrane of the tongue, lips, cheeks, and roof of the mouth produce both.
• Purposes of saliva serve to maintain oral moisture, reduce tooth decay, assist in digestion, and neutralize stomach acid.

Mouth Roof

• The mouth roof is formed by the hard palate/maxilla, the velum/soft palate, and the uvula.
• The soft palate pulls down against the back of the tongue by the palatoglossus within the anterior faucial arch.
• Soft palate elevates & retracts to contribute to velopharyngeal closure by palatopharyngeus and elevating sealing the velopharyngeal port to swallow.

Pharynx

• The Pharynx is described as a crossroads that allows food and oxygen to pass into the human body.
• Where the pharnyx meets are four portals in the oral cavity, nasal cavity, trachea, and esophagus.
• The pharynx is composed of three parts: the nasopharynx, oropharynx, and hypopharynx or laryngopharynx

Functional Components of the Normal Swallowing Mechanism

• The oropharynx propels the bolus, using structures such as the soft palate, lateral pharyngeal walls, and base of the tongue.
• For proper velopharyngeal function (sealing off the nasopharynx), the soft palate elevates as the tongue propels the bolus posteriorly and also during the tongue elevation.
• The hypopharynx facilitates bolus propulsion and laryngeal closure using muscular propulsion from the pharyngeal constrictors, pyriform sinuses, and cricopharyngeal function/UES.
• For laryngeal closure, the hyoid elevates with closure of the glottis and ventricular folds.

Pharyngeal Cavity

• It begins at the posterior portion of nasal and oral cavities and ends at the UES
• Pharyngeal constrictors form posterior and lateral pharyngeal walls consisting of the superior, medial, and inferior pharyngeal constrictors
• The anterior wall of pharynx is comprised of ptyergoid plates/ sphenoid bone, a soft palate, the base of the tongue, the mandible, the hyoid bone, the thyroid, and cricoid cartilages.

Hyoid Bone

• The hyoid bone articulates by itself and forms the tongue's foundation, embedded in the base of the tongue, suspended by the floor of the mouth muscles.
• The hyoid bone articulates with no other bone.
• The hyoid bone is suspended from the hyoid bone by the thyrohyoid ligament and thyrohyoid muscle.
• If the hyoid elevates and moves forward, the larynx will move forward unless stabilized by other muscles

Hyolaryngeal Complex

• The hyoid moves upward via the mylohyoid and anterior digastric muscles.
• It is pulled downward by the sternothyroid, sternohyoid, and omohyoid.
• And pulls together Hyoid/Larynx via the Thyrohyoid.

Styloglossus and Hyoglossus

• They are utilized during Tongue Base Retraction and responsible for post pharyngeal walls' anterior bulging at the tongue base.
• Pharyngeal recesses are spaces (NOT STRUCTURES) most relevant to swallowing in the pharynx

Pharyngeal Recesses

• Valleculae: median glossoepiglottic fold, which is wedge shaped space between the base of the tongue and epiglottis
• Pyriform sinuses: lateral spaces or side pockets in the lower pharynx above the upper esophageal sphincter (UES). Spaces are formed between fibers of inferior constrictor and sides of thyroid cartilage.
• Food may fall and reside here before or after the swallow.

Cricopharyngeal Muscle

• Most inferior structure of the pharynx, attached to the cricoid lamina. The cricopharyngeal Muscle forms a valve into the esophagus called the cricopharyngeal region (CP).
• The pharyngeal Esophageal segment is also known as UES
• This sphincter remains tonic (closed and tight) when awake, loses tonic with sleep.
• The muscle prevents air from entering and reduces material backflow is reduced into the pharynx.
• it acts as a sphincter with a 2-4 cm zone of elevated pressure immediately prior to swallow and when the patient inhales to prevent air from going further down the digestive tract.
• The larynx is a major organ for respiration, phonation, and deglutition, specifically in the movement used to regulate food into the esophagus.
• Larynx closes tightly to generate the pressure needed to lift/bear down during swallowing, and functions as a valve that prevents food from entering the airway during the swallow

Laryngeal Vestibule

• It is the opening of the larynx, which includes the epiglottis, aryepiglottic folds, arytenoid cartilages and the termination point for where false vocal folds end.
• Epiglottis is the highest point on the larynx, rests against base of tongue.
• The epiglottis connects into hyoid bone by a ligament, with its base attaching to thyroid notch, and inverts during swallowing to protect airway
• The aryepiglottic folds form lateral walls.
• Tilt forwards during closure using Posterior Cricoarytenoid muscle which opens/abducts with Lateral Cricoartenoid, interarytenoid muscle.
• Finally the True Folds close for LAST LEVEL of AIRWAY PROTECTIONS.

Laryngeal Strap Muscles

• Strap muscles suspend the larynx and trachea in the neck.
• Permit larynx to elevate, pull anteriorly/forward and lower for various activities
• Should be able to palpate structures of the mandible, Thyroild notch/wings and cricoid and Sternal notch.

Muscles of Larynx

• Intrinsic portions include abduction via the Posterior Cricoarytenoid, and adduction via and Interarytenoid/ Thyroarytenoid.
• Esophagus transports bolus tot he stomach with muscle constriction.

Esophagus

• It transports bolus to stomach with UES and peristaltic waves.
• TE Wall TE Wall.
• The ES is made of 2 layers of inner (circular located in the upped part) and outer(longitudinal (more fo smooth muscle below)
• Neural control for swallowing follows both voluntary and involuntary control.
• researchers arguevisual appreciation may prep Bolous.
• The mandibular branch of the trigeminal nerve innervates the principle muscles of chewing behaviors The recurrent laryngeal nerve innervates laryngeal folds:
• The superior nerve provides touch and proprioception.

Muscles of Feeding

• buccinator works with the Modiolus
• Larynx: (CNX) innervates palate . Glossopharyngeal CN IX: sensory in oropharnyx. Hypoglossal.CN. XII Motor tongue
• Normal swallowing is initiated voluntarily. -Includes coordinated cranial nerves with in the medulla.
• Two scholars suggest cognative message helps stimulates saliva during bolous peration. Bolous is formed by the top ancherung to elvevloea rigage.

Triggering the Pharngeal SWallon

• The orat stage ends triggering SWallon when in passes the Faucial Arches with Medulla sensory process:
• During swallow larynx clevation closes with three Sphincters, closing TVC during the pharyngeal transit time. -The soft pellet elevates sealing cavities for TBR.
• Pressure rises.
• When TBR increases Bolous viscosith increases
• Pharnegeal transit: Is from time of the Manible passes the sphincter till the Bolus enters the esophagus
• The epiglottis directs food.
• Bolous is cleared with littler or no resudiue with wave contraction. Pharnagel transport increased with viscosity. When tongue base hits base the structures make complete content. Pulls it all down to LES. Bolous increases while respiration decreases
• Normal swallowing involves rapid acts, involving both voluntary and involuntary aspects that require complex neuromuscular control

This quiz covers the anatomy and physiology of swallowing, including the roles of the brainstem, muscles, and cranial nerves. It includes questions about the esophagus, the epiglottis, and the process of mastication. It also touches on related medical knowledge concerning the placement of a Tracheoesophageal Voice Prosthesis.