2- The pharynx تهاني.pdf

7/30/2019 2- The pharynx .pdf

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Dr. Tahani Abualteen

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The pharynx

Pharynx: A funnel shaped fibromuscular tube extends

from the base of skull & continues below with

esophagus at the level of C6

** Pharynx is 3 times larger than the larynx

which only extends between C4-C6

** Funnel = wide superiorly and narrow

inferiorly

Divided into 3 parts:o Nasal upper third behind the nasal cavitynasopharynx

o Oral middle third behind the oral cavityoropharynx

o Laryngeal lower third behind the larynx laryngeopharynx Walls of Pharynx:

Anterior wall:o Deficiento Communicates with nose, oral cavity and larynx

Lateral & Posterior Walls:o Muscleso Mucous membraneo Fibrous covering

Muscles of Pharynx: 6 Muscles (3 constrictors & 3 elevators) 3 constrictors:

o Superior, middle & inferioro They make the lateral & posterior walls of the pharynxo

They run in a circular direction in a superior-posterior orientation (upward & backward)and attached or inserted posteriorely to a pharyngeal raphe** Pharyngeal raphe = fibrous band extending from pharyngeal tubercle on the basilar part

of the occipital bone downward toward the esophageousat the level of C6 and it is the site of

insertion for all pharyngeal constrictors

o They are called constrictors because the successive contraction of these muscles produces theaction of swallowing

** When a bolus of food is swallowed, first it gets into the first part of the pharynx and by the

action of the superior constrictor it gets down, then it gets into the middle part of the pharynx

and by the action of the middle constrictor it gets down, and then it gets into the last part ofthe pharynx and by the action of the inferior constrictor it gets down into esophageous


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o They are funnel shaped muscles and forthis reason the pharynx is funnel shaped as

well

o They overlap each other in the directionof inferior to superior

so that middleconstrictor lies outside the lower part of

superior constrictor, and the inferior

constrictor lies outside the lower part of

middle constrictor

o Superior pharyngeal constrictor: Origin = pterygoid hamulus of

medial pterygoid plate,

pterygomandibular raphe,

posterior end of mylohyoid line of

mandible and side of tongue

Insertion = pharyngeal raphe Action = constrict wall of pharynx during swallowing Innervation = pharyngeal plexus

** Hamulus = hook-like process that curves laterally from the lower end of medial

pterygoid plate

** Pterygomandibular raphe or ligament = ligamentous band that is attached superiorly

to the hamulus of medial pterygoid plate , and inferiorly to the posterior end of

mylohyoid line of mandible

- Its posterior border gives attachment to the superior pharyngeal constrictor muscle - Its anterior border gives attachment to the Buccinator muscle- The Pterygomandibular raphe or ligament is a very important structure in the dental

practicebecause its the landmark where to give the inferior dental block anesthesia

"ID block" (in order to anaesthetize the inferior alveolar nerve before it enters the

mandibular foramen and thus anesthetizing all posterior teeth to do fillings or RCT or

extractions)

- The needle is placed lateral to the pterygomandibular raphe and medial to theramus of the mandible penetrating the Buccinator muscle into the infratemporal

fossa (needle can be inserted up to 2.5 cm)- In the infratemporal fossa, the posterior division of the mandibular nerve gives 3

sensory branches: the anterior one is lingual nerve, the middle one is inferior

alveolar nerve and the posterior one is the Auriculotemporal nerve

- When anesthetizing the inferior alveolar nerve in the ID block technique you willalso anaesthetize the lingual nerve and an indication that the ID block is working is

to ask the patient if he feelsnumbness/paresthesia on his tongue or not

** Medial pterygoid plate gives attachment for one muscle (superior pharyngeal

constrictor muscle) while lateral pterygoid plate gives attachment for 2 mastication

muscles (medial & lateral pterygoid muscles)


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o Middle pharyngeal constrictor: Origin = stylohyoid ligament and great & lesser horns of hyoid bone Insertion = pharyngeal raphe Action = constrict wall of pharynx during swallowing

Innervation = pharyngeal plexuso Inferior pharyngeal constrictor:

The largest constrictor This constrictor consists of 2 parts:

o Superior part Thyropharyngeus o Inferior part Cricopharyngeus

Origin:o Thyropharyngeus oblique line of thyroid cartilage of larynxo Cricopharyngeus one side of cricoid cartilage of larynx

Insertion:o Thyropharyngeuspharyngeal rapheo Cricopharyngeuscontralateral (opposite) side of cricoid cartilage

Action = constrict wall of pharynx during swallowing Innervation = pharyngeal plexus

** 3 muscles are attached to the oblique line of thyroid cartilage: sternothyroid,

thyrohyoid and upper part of inferior pharyngeal constrictor muscle

** Fibers of superior part of inferior constrictor (thyropharyngeus) run in a superior-

posterior orientation (upward & backward) and thus participate in the process of

swallowing

** Fibers of inferior part of inferior constrictor (cricopharyngeus) run in a horizontal

orientation (only backward) and thus they are important for something else other than

swallowing which is acting like a superior esophageal sphincter and so when this part

contracts, it closes the opening between the pharynx up and the esophageous below

preventing food regurgitation (vomiting or reflux)


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o Killians Dehiscence: Dehiscence = gap orsplit ortearing Inferior constrictor muscle consists

of 2 parts:

-

Superior propulsive part =thyropharyngeus

- Inferior sphincteric part =cricopharyngeus

A weak area presents between the 2parts of inferior constrictor muscle

on the posterior pharyngeal wall

because of the different orientation

of the fibers of these 2 parts

(thyropharyngeus going upward &

backward while cricopharyngeus going only horizontally backward)

Clinical significance ofKillians dehiscence:- Mucous membrane covering inferior constrictor muscle in the region of the dehiscence

may protrude giving rise to a pharyngeal pouch (or Pharyngoesophageal

diverticulum) where the smooth food can stickproducing uncomfortable sensation

and difficulty in swallowing (dysphagia)

o Pharyngeal Pouch (Pharyngoesophageal diverticulum): Outpouching of pharyngeal mucosa in the region of Killians dehiscence between

thyropharyngeus & cricopharyngeus parts of the inferior constrictor muscle 3 elevators:

o Stylopharyngeus muscle: Origin = styloid process Insertion = posterior Border of thyroid cartilage Pass in the gap between superior and middle pharyngeal constrictors Innervation = glossopharyngeal nerve (IX)

o Palatopharyngeus muscle: Origin = Palatal aponeurosis (of soft palate) Insertion = posterior border of thyroid cartilage Innervation = pharyngeal plexus This muscle is covered with a mucous membrane which becomes the palatopharyngeal fold

o Salpingopharyngeus muscle: Salpnig = tube Origin = Auditory tube "pharyngotympanic tube, Eustachian tube" (medial end) Insertion = blends with Palatopharyngeus Innervation = pharyngeal plexus When this muscle contracts, it opens the pharyngeal opening of the Eustachian tube which

function to balance air pressure between middle and external ears (balance the airpressure on both sides of the tympanic membrane) like what happens when chewing a gum


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** All of these muscles help elevate the pharynx & larynx during swallowing & speaking

** Innervation for all pharyngeal muscles is by the Vagus nerve via the pharyngeal

plexus EXCEPT the Stylopharyngeus muscle which is innervated by the

glossopharyngeal nerve

** Pharyngeal plexus = network of nerves formed by cranial nerves IX, X and XI(Glossopharyngeal, Vagus and accessory nerves) on the wall of the pharynx and it is

responsible for the motor supply of the pharynx (mainly the Vagus nerve component)

** Sensory supply of the pharynx comes from the glossopharyngeal nerve


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Interior of larynx: Nasopharynx:

o Posterior to nasal cavity & above soft palateo Lined by pseudostratified ciliated epithelium

(respiratory epithelium)o Contains:

Pharyngeal tonsil (adenoid)aggregation of lymphoid tissue in the

submucosa of the roof of nasopharynx

** Inflammation of the Pharyngeal tonsils

is called Adenoiditis

Pharyngeal opening of Eustachian tube found on thelateral wall of nasopharynx oneither side

Tubal tonsil aggregation of lymph nodules in the submucosa of the lateral wall ofnasopharynx around the opening of Eustachian tube** This aggregation of lymph nodes protects the auditory tube and the middle ear from any

infection (otitis media) entering the nasopharynx from the nose

Tubal elevation & Salpingopharyngeus fold** Tubal elevation elevated ridge at the opening of the Eustachian tube

** Salpingopharyngeus fold mucous membrane covering of Salpingopharyngeus

muscle becomes this fold


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Oropharynx:o Posterior to oral cavity&opens to it

through the oropharyngeal isthmus

o Located between the soft palatesuperiorly and the posterior 3

rd

of thetongue & Vallecula inferiorly "floor"

at the level ofC2-C3** Soft palate separates nasopharynx

above from oropharynx below

** Anterior 2/3s of tongue is located

in the oral cavity, while the posterior

1/3 of the tongue is located in the

oropharynx

** In the submucosa of the posterior 1/3

of tongue there's aggregation of lymph

nodules called the lingual tonsils

o The floor is made by the posterior 1/3 oftongue & Vallecula

** Vallecula is a depression between

epiglottis cartilage and posterior 1/3 of

tongue that prevents swallowing of sharp

foreign objects

o The roofis made by the soft palateo Lined by stratified Sequamous epitheliumo Contains:

Palatine tonsils:- Aggregation of lymph nodules in

the submucosa of the lateral wall

of the oropharynx between

palatoglossal and palatopharyngeal folds in the Tonsillar bed over the superior

pharyngeal constrictor

muscle

** Palatine tonsils arelocated in the oropharynx

- Relations of palatinetonsils:

Anteriorly:palatoglossal fold

Posteriorely:palatopharyngeal

fold

Superiorly: softpalate


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Inferiorly: posterior 1/3 of tongue & Vallecula Medially: cavity of oropharynx Laterally: superior constrictor muscle (which forms the Tonsillar bed)

- Palatine tonsils are the most common tonsilsto get inflamed** Palatoglossal fold represents the demarcating line between oral cavity andoropharynx (anything anterior to it is located in the oral cavity and anything posterior

to it is located in the oropharynx)

** We have talked about 4 groups of Tonsils:

1- Pharyngeal tonsilsroof of nasopharynx2- Tubal tonsilslateral wall of nasopharynx3- Palatine tonsilslateral wall of oropharynx4- Lingual tonsils floor of oropharynx

o Tonsillitis & Tonsillectomy: Tonsillitis = inflammation of the (palatine) tonsils (palatine, since they are the most

common tonsils to get inflamed)

Inflammation of pharyngeal tonsil is called adenoiditis Tonsillitis may be:

- Acute caused by viral infection "e.g. EBV, HSV, Influenza virus" leading toswelling and redness the patient suffers from sore throat, fever, dysphagialast

for 6 days treatment will be non-steroidal anti-inflammatory drugs "e.g.

Ibuprofen"

- Chronic caused by bacterial infection "e.g. hemolytic streptococcus group A" leading to pus or exudate last for 3 weeks treatment will be systemic antibiotics"e.g. amoxicillin"

Tonsillectomy = removal of palatine tonsils - Rationale: because the patient is suffering from continuous episodes of inflammations- Indication:

Old indications: 7 episodes of tonsillitis per year Or5 episodes per year for 2years (10 times)

Recent indications: 3 episodes per year for 3 years (9 times) despite treatment** Some argue that tonsillectomy is unnecessary surgery & may be dangerous

because you remove one source of immunity (first line of defense)** Others argue that chronically inflamed tonsils are a site of recurrent infection

besides they interrupt normal daily activities

Laryngeopharynx:o Posterior to larynxo Extends from epiglottis to cricoid Cartilage o At vertebral level C4-C6o Lined by stratified Sequamous epithelium


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o Contains: Piriform fossa:

- (Piriform = pear shaped)- Asmall depression or recess on each

side of the laryngeal inlet- Bounded: Medially quadrangular

membrane "aryepiglottic

membrane" Laterally thyroid cartilage

- Function prevents swallowing offoreign and sharp objects "e.g. fish

bones" not to cause severe injuries to

esophagus

- Internal laryngeal nerve (a branchfrom superior laryngeal nerve) passes

in the Piriform fossajust beneath the

mucous membrane and then

penetrates the thyrohyoid membrane and gets inside the larynx

Gag Reflex: Gag reflex happens when we work on posterior teeth or when we try to insert a denture and by

mistake we touch the soft palate (roof of oropharynx) or the posterior 1/3 of tongue (floor of

oropharynx) and after that the patient tries to vomit The touching has induced irritation that caused the sensory signals to travel along the

glossopharyngeal nerve to the Vagus nerve which will then induce contraction of pharyngeal

constrictors via pharyngeal plexus in an opposite order (inferior middle superior)

** Involved both sensory & motor innervations of pharynx working together

** Sensory stimulation of pharyngeal mucosa (via IX) leads to contraction of pharyngeal

musculature (from XI via X to pharyngeal plexus) Pharyngeal Gaps:

4 gaps to allow structures to get inside oroutside the pharynx

o Above superior Constrictor muscle: Eustachian tube Ascending palatine artery (a branch

offacial artery that supplies

the soft palate)

Tensor veli palatini Levator veli palatini


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o Between superior & middle Constrictormuscles:

Stylopharyngeus muscle Glossopharyngeal nerve

o Between middle & inferior Constrictormuscles: Internal laryngeal nerve Superior laryngeal artery

(supplies larynx above vocal fold)

o Below inferior Constrictor muscle: Inferior laryngeal artery (supplies

larynx below vocal fold)

Recurrent laryngeal nerve Waldeyers Tonsillar Ring:

Pharyngeal Tonsil single, roof of nasopharynx Tubal Tonsils pair, on lateral Walls of nasopharynx Palatine Tonsils pair, on lateral Walls of oropharynx Lingual Tonsil single, floor of oropharynx

Innervation of The Pharynx: Sensory:

o Nasopharynx: maxillary nerve (V2)o Oropharynx: glossopharyngeal nerve (IX)o Laryngeopharynx: Vagus nerve (X)

Motor:o Pharyngeal plexus to all muscles of pharynx Stylopharyngeus which is innervated by

glossopharyngeal nerve (IX)

2- The pharynx تهاني.pdf

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