DTSD 304 : Anatomy of Head and NeckDTSD 304 : Anatomy of Head and Neck

Wanida Wanida SripairojthikoonSripairojthikoonDepartment of Anatomy, Faculty of Dentistry

Mahidol University

Outline of contents

• Deglutition = Swallowing• Digestive system and its

organs• Definition of deglutition• Stages of deglutiton• Deglutition reflex• Deglutition disorder

Digestive system• Digestive system

– function to prepare food for cellular utilization

– involve following activities :

• ingestion • mastication • deglutition• peristalsis • digestion• absorption • defecation

•• Deglutition is one activity of Deglutition is one activity of digestive systemdigestive system

Organs of digestive system

•• Tubular gastrointestinal Tubular gastrointestinal tract (GI tract)tract (GI tract)– From mouth to anus, 6-9

meters long– Oral cavity, pharynx,

esophagus, stomach, small intestine, large intestine and anus

•• Accessory digestive Accessory digestive organsorgans– Salivary glands,

pancreas, liver and gall bladder

Deglutition = Swallowing

Deglutition iDeglutition is s the the complexcomplex processprocessthatthat movesmoves bolusbolus of foodof food fromfrommouthmouth throughthrough pharynxpharynx into into esophagus and then to esophagus and then to stomachstomach

Organs of deglutition and related structures

• During deglutition, the muscles of mouth, pharynx, larynx and esophagus coordinate properly in a complex process; to move food and liquid into stomach– Organs of deglutition

• Oral cavity• Pharynx

– (Nasopharynx)– Oropharynx– Laryngopharynx

• Esophagus • Stomach

• The airway is protected by correct movement of larynx, so that food and liquid not enter the airway– Related organ of deglutition

• Larynx

Digestive systemDigestive system && Respiratory systemRespiratory system

Oropharynx

Pharynx is the common pathway for air, food and drink

Oral cavity

Oral cavity, upper opening of digestive system, contains tongue and teeth

Palate

Palate, roof of mouth, separates nasal and oral cavities

Tongue

Tongue, aids in mastication, deglutition and speech

Pharynx

Pharynx, most of the time subserves respiration instead of deglutition

Larynx

Larynx, organ of voice, entrance to lower respiratory passage

Stages of deglutition

• Deglutiton is a continuous process from oral cavity to stomach, divide into 3 stages1.oral phase2.pharyngeal phase3.esophageal phase

First stage of deglutition• The first stage is voluntary

and initiate deglutition process– A mass of chewed,

moistened food, a bolus, is moved to the back of the oral cavity by the tongue

– The lip and buccal muscles help keep bolus from dispersing either anteriorlyout of oral cavity or laterally into oral vestibule

Oral phase

• Intact labial seal• Anterior to posterior tongue movement

Second stage of deglutition

• The second stage is involuntary and rapid– The entire process

occurs in less than 2 seconds

– Start from the point at where the deglutition reflex is triggered at the anterior faucial arch through the upper esophageal sphincter into the esophagus

– The bolus is propelled by pumping action of tongue base and constriction of pharyngeal muscles

Anterior faucial arch• Soft palate• Palatoglossal arch• Base of tongue

Pharyngeal phase

• Soft palate is elevated, sealing off the nasopharynx from oropharynx, prevent reflux of food into nasal cavity

• Initiation of pharyngeal peristalsis to pick up and carry the bolus

• Elevation and closure of larynx, to prevent food from entering airway

• Upper esophageal sphincter (cricopharyngeusmuscle) relaxation

Pharyngeal phase

Larynx is closed off to the bolus by several mechanisms:– Larynx is pulled upward and anteriorly by muscles of neck, cause

epiglottis to swing backward over the opening of larynx.– Closure of larynx at all 3 sphincters

• Epiglottis / aryepiglottic folds• False vocal folds• True vocal folds

– Cessation of respiration

Third stage of deglutition

• The third stage is alsoinvoluntary– 8-20 seconds transmit time– Start from the point where

the bolus enters the esophagus at the upper esophageal sphincter

– Until the bolus passes into stomach at the lower esophageal sphincter

• During third stage, combination of gravity and peristalsis, push the bolus from esophagus down to stomach

Deglutition • Oral phase : (a)• Pharyngeal phase : (b)• Esophageal phase :

(c), (d), (e)

Deglutition reflex• Deglutition reflex is mainly a protective reflex• Two main things take place during reflex

– A squeezing action squeezes the bolus with muscles that pull food down to the stomach. This action is called peristalsis.

– Larynx closes off to keep food out of the airway. The epiglottis folds down and the vocal folds shut.

Deglutition reflex

• Sensory impulsestransmitted as a result of stimulation of deglutition receptors on the fauces– Tonsils– Soft palate– Base of tongue– Posterior pharyngeal wall

• By the 7th, 9th and 10th

cranial nerves

Deglutition reflex

• Sensory impulses reach the deglutition centerdeglutition center in brain stem

• Motor function is mediated through the 5th, 9th, 10th and 12th

cranial nerves• To initiate muscle

contraction – Elevation of soft palate– Elevation and closure of

larynx– Peristalsis of pharynx and

esophagus.

Deglutition disorder

• Difficulty of deglutition is known as dysphagiadysphagia• Deglutition can be restricted if the muscle of the mouth,

pharynx, larynx or esophagus are weak or uncoordinated. – Tongue dysfunction – prevent normal bolus movement through the

oral cavity– Palatal dysfunction – nasal regurgitation during deglutition– Dysfunction of pharyngeal constrictors

• poor bolus propulsion through pharynx• Pooled bolus can then easily spill over into larynx

– Dysfuction of larynx – can cause aspiration. If larynx does not close off and tilt out of the way at the right moment, food or drink may get into airway.

– Dysfunction of upper esophageal sphincter - lead to difficultpassing from pharynx into esophagus

• Deglutition problem can lead to coughing, airway obstruction, pneumonia and even death

Essential requirements of deglutition

1. Preparation of suitable size and consistency of bolus

2. Prevention of bolus disperse during various phases of deglutition

3. Create pressure to propel bolus in forward direction4. Prevention of bolus to enter nasopharynx and

larynx 5. Rapid passage through pharynx to esophagus

during stop breathing6. Prevent reflux from stomach into esophagus7. Final clearance of residue from the tract

Eat and drink safety

• Deglutition is generally safest when the person is sitting straight, with head upright or slightly forward

• Must be awake and alert, without distractions such as television

• Allow more time to eat and drink• Always make sure that one mouthful has

gone before offering the next