L66: esophagus and pharynx

MCQ: which animal may present difficulty in passing a nasogastric tube due to the presence of a pharyngeal diverticulum?

pigs

MCQ: what animals have skeletal muscle throughout their esophageal wall?

1. canine

2. bovine

3. caprine

why do ruminants have skeletal muscle throughout their esophageal wall?

to enable regurgitation for the rumination process

pharynx

a passage and that connects the nasal and oral cavities to the esophagus and larynx respectively.

what structure plays a crucial role in both digestion and respiration?

pharynx

what does crossing from ventral to dorsal of the oropharynx to esophagus allow for in digestion?

smooth swallowing of bolus

what is orange?

isthmus of fauces

what is yellow?

oral cavity

what is pink?

oropharynx

what is green?

esophagus

what is blue?

laryngopharynx

what is red?

epiglottis

what structure is caudal to the oral cavity?

oropharynx

what is the location of the oropharynx?

From Palatoglossal folds and arches, to the hyoid apparatus

what structure is caudal to the nasal cavity?

nasopharynx

where does the laryngopharynx have more obvious tubular construction?

at the beginning of the esophagus

Common Pharynx/intralaryngeal opening

the region where the oropharynx, nasopharynx, and laryngopharynx meet, facilitating the passage of air and food

what structures does the soft palate separate?

separates nasophaynx from oropharynx

what structure has to be lifted during swallowing and vomiting?

soft palate

what structure protects the airways during the act of swalliowing?

epiglottic cartilage

what does the epiglottic cartilage cover?

1. Oropharyngeal surface/lingual surface

2. Laryngeal surface

when is the only time the laryngopharynx will be open?

when bolus opens it for swallowing otherwise collapsed to prevent air from entering esophagus

what are the categories of the muscles of the pharynx?

1. pharyngeal constrictors

2. pharyngeal dilators

3. pharyngeal shorteners

what are the pharygeal constrictor muscles?

1. hyopharyngeus

2. thyropharyngeus

3. cricopharyngeus

what is the pharyngeal dilator muscle?

stylopharyngeus

what are the pharyngeal shortener muscles?

1. pterygopharyngeus

2. palatopharyngeus

the muscles of the pharynx are mainly associated with which structure?

laryngopharynx

function of pharyngeal dilators

enlarges the pharynx during swallowing, bolus will assist

function of pharyngeal constrictors

muscles contract to close passage of laryngopharynx and push food into esophagus

hyopharyngeus muscle location

hyoid appratatus to the pharynx

thyropharyngeus muscle location

thyroid cartilage of the larynx to the pharynx

cricopharyngeus muscle location

cricoid cartilage of larynx to pharynx

function of palatopharyngeus muscle

pulls pharynx forward and lifts soft palate slightly upward

function of pterygopharyngeus

pulls pharynx slowly forward when swallowing has been intiated

location of pterygopharyngeus muscle

pterygoid bone of the skull towards the pharynx

what is orange?

Pterygopharyngeus muscle

what is blue?

Palatopharyngeus muscle

what is pink?

Pterygopharyngeus muscle

what is orange?

Pterygopharyngeus muscle

what is yellow?

Hyopharyngeus muscle

what is green?

Thyropharyngeus muscle

what is pink?

Cricopharyngeus muscle

what provides motor innervation to the muscles of the pharynx (in order of the amount they play a role in i.e. 1= plays a major role)?

1. vagus nerve (CN X)

2. glossopharyngeal nerve (CN IX)

3. cranial root of the accessory nerve (CN XI) -very little role!

what provides sensory innervation to the muscles of the pharynx (in order of the amount they play a role in i.e. 1= plays a major role)?

1. glossopharyngeal nerve (CN IX)

2. vagus nerve (CN X)

3. trigeminal nerve (CN V)

what initates the swallowing reflex?

bolus reaching oropharynx region

what is 1?

external carotid artery

what is 2?

facial artery

what provides the major blood supply of the pharynx?

ascending pharyngeal artery

what is 3?

lingual artery

what is 4?

cranial laryngeal artery

what is 5?

cranial thyroid artery

what does the pharyngeal plexus and satellite veins drain into?

internal and external jugular veins

describe the pharynx in the horse

long and narrow for obligate nasal breathing

describe the soft palate in the horse

longer soft palate that lies beneath epiglottic cartilage which prevents oral breathing

what is the blue line showing?

opening of laryngopharynx should be somewhere along this line but cannot see because usually it is collapsed

what is pink?

soft palate

what is blue?

guttural pouch

what is green?

opening of auditory tube

what is the function of the auditory tube in horses?

connects middle ear to nasopharynx to help cool down blood going to the brain

what is the pharynx adapted for in ruminants?

rumination and prevention of aspiration during regurgitation

what is the process of rumination?

regurgitation, remastication, and reswallowing food

describe the pharynx of ruminants

have wider pharynx to allow swallowing of larger boluses

what is 13?

pharyngeal diverticulum

what does the soft palate of ruminants allow for?

limited oral breathing

what makes up the pharyngeal plexus?

1. vagus nerve

2. glossopharyngeal nerve

describe the microscopic anatomy of the nasopharynx

ciliated epithelium to trap and clear debris

describe the microscopic anatomy of the oropharynx and laryngopharynx

protective stratified squamous epithelium to withstand mechanical stress

what structure is this?

nasopharynx of the dog

what structure is shown?

oropharynx of dog

what can tonsils initate?

immune response, it is the first line of defense of the digestive system

what are the types of tonsil tissues?

1. pharyngeal 

2. palatine

3. lingual

4. paraepiglottic

which species have paraepiglottic tonsils?

pig and horse

location of lingual tonsils

embedded in the mucosa of the tongue (root)

which species have well developed lingual tonsils?

bovine and small ruminants

what are palatine tonsils associated with?

oropharyngeal surface

which species have palatine tonsils visible in the tonsilir fossa?

dogs and cats

which species have palatine tonsols?

dog, cat, horse, ruminants, pigs

where are palatine tonsils located in ruminants?

deep within the muosa (tonsillar sinus)

where are palatine tonsils visible in the pig?

soft palate

where are the pharyngeal tonsils?

associated with nasopharynx

what does it mean if the pharyngeal tonsil is tubal?

it is around the opening of the auditory tube

MALT

mucosa associated lymphoid tissue

what is the arrow pointing at?

palatine tonsils

what is the arrow pointing at?

palatine tonsils

which species have large palatine tonsils with deep crypts for antigen trapping?

ruminants and pigs

which species have scattered lymphoid tissue rather than a well-defined tonsillar structure?

horses

which species have deep crypts in the palatine tonsils making them more prone to tonsillitis?

dogs

MCQ: Which animal does not have clearly visible palatine tonsils?

horse

where does the esophagus extend from and to?

extends from cricoid cartilage to the cardia of the stomach

what parts is the esophagus broken down into?

1. cervical part

2. thoracic part

3. abdominal part

where does the esophagus move when you go down along the neck in the cervical region?

left lateral position

what is the esophagus?

tubular and muscular hollow organ that connects the pharynx to the stomach, allowing the passage of food and liquid

describe the location of the cervical part of the esophagus>

from the pharynx (Cricoid cartilage of the larynx) to the cardia of the stomach 

what muscles make up the cranial/upper esophageal sphincter in the cervical part of the esophagus? 

1. cricopharyngeus muscle

2. thyropharyngeus muscle

what is the location of the lower esophageal sphincter/ cardiac sphincter in the cervical part of the esophagus? 

at the opening into the stomach at the cardia of the stomach

what is the red arrow pointing to?

pharyngoesophageal limen

what muscles if constricted will close the passage of the laryngopharynx to allow food to go through the esophagus?

1. thyropharyngeus muscle

2. cricopharyngeus muscle

what is the location of the thoracic part of the esophagus?

from thoracic inlet to the esophageal hiatus of the diaphragm; within the mediastinum

what is the location of the abdominal part of the esophagus?

liver to left side of esophageal notch