SS - PALATE & PHARYNX

PHARYNX - DEFINITION

DEFINITION

• Pharynx is a muscular tube of connective tissue/mucosal → ‘musculo-tendinous tube’

• It is 12cm = divided into 3 parts

• Cone-shaped

• Oesophagus = food pipe

• Pharynx = function of carrying food AND air 

• Where sphenoid bone & occipital bone meet, its union is called the basisphenoid or Basi oxyford. At this point, there is an elevation = pharyngeal tubercle  

EXTENDS FROM

• Nasal cavities (pharyngeal tubercle of occipital bone) 

• Vocal folds (cricoid cartilage at the level of C6) 

PHARYNX SPLIT INTO 3 PARTS

1. Nasopharynx: the choanae connects the nasal cavity to nasopharynx

2. Oropharynx: the fauces connect the oral cavity to oropharynx

3. Laryngopharynx: the aditus laryngitis (laryngeal inlet) connects the larynx to laryngopharynx

TERMINOLOGY

• Fauces - region between the anterior faucial pillar (palatoglossal arch) & posterior faucial pillar (palatopharyngeal arch) 

• Palatoglossal arch connect posterior ⅓ of tongue to anterior ⅔ of tongue

• Palatine tonsil is within the fauces

• Velum = soft palate

STRUCTURE OF PHARYNX 1 - INNER MUCOUS MEMBRANE

• Innermost layer will always secrete something.

• It is a mucous membrane which has palatine glands and pharyngeal glands to pour out secretions inside.

STRUCTURE OF PHARYNX 2 - PHARYNGEAL APONEUROSIS

• This is the middle CT layer

• Dense CT sleeve

• Attached to base of the skull, hyoid & thyroid cartilage

• Gives attachment to many pharyngeal muscles

• Strengthened posteriorly by fibrous band = median raphe

• Next to mucosa (1st layer) you have submucosa (2nd layer) which is made up of connective tissue. Major component of CT = collagen. This layer has more condensation of collagen & expansile collagenous tissue.  

• Aponeurosis is important because it forms the structure of the attachment to muscles.

STRUCTURE OF PHARYNX 3 - MUSCLE LAYER

• External circular muscles 

• 3rd layer is what you can see. Two types…   

1. External Longitudinal muscles = the external ones that are getting attached from the bones above.  They act to shorten and widen the pharynx, and elevate the larynx during swallowing

• Stylopharyngeus

  —> Originates from the styloid process of the temporal bone and inserts onto the pharyngeal wall.

  —> Innervated by glossopharyngeal nerve (IX) 

• Palatopharyngeus

  —> Originates from the hard palate of the oral cavity and inserts onto the pharyngeal wall.

  —> Innervated by the vagus nerve (X)

• Salpingopharyngeus

  —> Originates from the Eustachian tube and inserts onto the pharyngeal wall.

  —> Innervated by the vagus nerve (X)

  —> In addition to contributing to swallowing, it also opens the Eustachian tube to equalise the pressure in the middle ear.

2) Circular muscles = muscles that try to get attached from CT, and then get attached back to median raphe proper.  Constrictors of the pharynx… 

• Superior

• Median

• Inferior  

FUNCTIONS OF PHARYNX

1. Act as a passageway for food: from oral cavity to oropharynx.

2. Act as a passageway for air: from nasal or oral cavity through pharynx into larynx and trachea.

• valve needed to prevent inhalation of food (soft palate)

• muscles perform in such a way that food does not regurgitate back  

3. Equalise air pressure between middle ear and atmosphere via opening of auditory tube

• To mitigate against high altitude pressures = yawn or swallow or suck a popsicle to put pharyngeal muscles into contraction. 

• This is because there's a tube that connects the nasopharynx to the middle ear cavity. 

• This tube is called an auditory tube or eustachian tube, pressure in both should be equalised, other ways if the pressure in the middle ear cavity is higher, you get an uncomfortable feeling. Tympanic membrane**  

• Basically, nasopharynx is guarded by muscles, and those muscles try to neutralise the pressure acting in the middle ear cavity.  

4. Function in swallowing: moves bolus toward esophagus

5. Function in speech

• alteration of vocal tract shape → change in resonance

• constriction of vocal tract → change air flow → turbulence.

6. Protective function

• palatine tonsil = lymphoid aggregation. This is suitable for an immune defence mechanism = protective in nature. 

PROTECTIVE FUNCTION OF PHARYNX

• Pharynx is exposed to allergens/bacteria in air and food

  • Tonsils part of early immune system

  • aggregations of lymphoid tissue in oral and pharyngeal cavities.

  • contains 3 sets which form a ring around the oral cavity.

1. Palatine

• between palatoglossal and palatopharyngeal arches

• largest in children, shrink after puberty

2. Lingual

• root of tongue
  

3. Pharyngeal (adenoids)

• posterior nasopharynx

PHARYNGEAL TONSIL/ADENOID GROWTH

• Size and growth may affect acoustic properties of vocal tract

  • Peaks at 2yrs 

  • Then static peak 

  • Then declines 

  • In adults (usually above 15yrs) you don't see adenoids anymore 

• Hypertrophy can obstruct nasopharynx

• Mask short soft palate

FUNCTIONS OF PHARYNX IN ARTICULATION

• Elevate pharynx as a whole (so elevate larynx)

• Change length of resonating column of air above larynx

  • Decreased length (via relatively elevated larynx) associated with higher pitch

  • increased pharynx length with lower pitch

• Changing lung volume affects pharynx

  • increased lung volume exerts a greater downward pull on the larynx via the trachea – lengthens pharynx and lowers pitch.

• Fine control of pitch occurs in the larynx via laryngeal muscle

NASOPHARYNX

• Nasal cavity communicates with nasopharynx through choanae

• Static in size & shape as it has bone on top & bottom (limits mobility)

• Resonating chamber

• Respiration

• Equalise air pressure

• Auditory tube links nasopharynx & middle ear cavity 

• Lymphoid aggregation in roof of nasopharynx = adenoids. Infection that comes to nasopharynx will be trapped by adenoids. This will make them enlarged and block nasal cavity, affecting speech & breathing only through the mouth. Children will always have their mouths open.  

OROPHARYNX

• Oral cavity communicates with oropharynx through fauces

• Dynamic

• Mobile soft palate & tongue

• Soft palate will be easily trying to control oropharyngeal isthmus so food doesn't regurgitate in nasal cavity, acts like a valve going up and down 

• Respiration & digestion

• Resonating chamber

• Voiced fricatives are produced with larger pharynx 

LARYNGOPHARYNX

• Larynx communicates with laryngopharynx through laryngeal inlet

• Inferior - aditus laryngitis (entrance to larynx) at C6

• Sits behind the larynx & seated just behind laryngeal inlet

• Modifies laryngeal tone

• Helps with digestion
  

  VALLECULAE & EPIGLOTTIS

• Openings around the epiglottis reduce the risk of food entering the lungs

• Valleculae spaces =  space between tongue & epiglottis ‘formed by the attachment of the tongue base to the epiglottis via the glossoepiglottic folds’ (like ‘valley’)

• Epiglottis = anterior part of laryngeal inlet which has elastic cartilage which folds back & tried to close when food enters the oral cavity, otherwise food will pass into larynx & trachea   

  PIRIFORM RECESS

• Pyriform sinus recess = On either side of laryngeal inlet in laryngopharynx, there are 2 extensions = 'piriform recess' ‘between aryepiglottic fold and thyroid cartilage’

  – directs bolus laterally and away rom larynx towards oesophagus

• Piriform recess = where fish bones/chicken bones may get stuck, or some people try to smuggle drugs in this sinus 'smugglers pouch' 
  
  
  

  

CT DEFINITION

• Aponeurosis: thin sheet of connective tissue that provides attachment for muscles

• Raphe: union of two lateral halves

PHARYNGEAL MUSCLE ATTACHMENTS:

• Pharyngeal aponeurosis

• Between mucous and muscular layers of pharynx

  • Attached to occipital bone

  • Continuous laterally with palatine aponeurosis

• Pharyngeal raphe

  • Extends from the pharyngeal tubercle on the occiput to the posterior oesophagus

  • Narrow band of connective tissues at posterior joining of the pharyngeal constrictor muscles

MUSCLES OF PHARYNX - EXTERNAL LAYER:

• External layer consisting of 3 constrictors

• Circular muscles with fixed points

1. Superior constrictor

• pharyngeal tubercle, pharyngobasilar fascia & pterygomandibular raphe to pharyngeal raphe

  2. Middle constrictor

• Hyoid to pharyngeal raphe

3. Inferior constrictor

i. Thyropharyngeus – thyroid cartilage to pharyngeal raphe

ii.Cricopharyngeus – cricoid cartilage to opening of oesophagus

• Posterior attachment to pharyngeal raphe

PHARYNX & SWALLOWING

• Sequential constriction of pharynx helps to push the bolus down into the oesophagus

  • This is considered an involuntary phase in swallowing (second stage)

  • Cricopharyngeus is generally contracted acting as a sphincter

PHARYNX & ARTICULATION

• Pharyngealization is a secondary articulation ie. simultaneous articulation at two different places by which the pharynx or epiglottis is constricted during the articulation of the sound.

  • Does not appear in English - appears in arabic language 

LONGITUDINAL MUSCLE - STYLOPHARYNGEUS

ACTION	ATTACHMENT
Elevates & opens pharynx	Styloid process Pharyngeal constrictor+post thyroid cartilage Basically in between superior constrictor & inferior constrictor

LONGITUDINAL MUSCLE - PALATOPHARYNGEUS

ACTION	ATTACHMENT
Can either…  Elevate pharynx with raised soft palate - contraction narrows oropharynx and with uvula prevents food re-entering mouth Lower soft palate	Anterior hard palate & midline soft palate Post margin thyroid Forms the posterior fauces (palatopharyngeal arch)   Anterior to this is palatine tonsil & palatoglossal arch  Blends the pharynx to help with pharynx elevation

LONGITUDINAL MUSCLE - SALPINGOPHARYNGEUS

ACTION	ATTACHMENT
Elevates lateral walls of pharynx Equalises pressure between auditory canal and pharynx	Medial Eustachian tubes to posterior thyroid region

PALATE

• Consists of hard palate and soft palate (velum)

• Hard palate:

  • Separates nasal and oral cavities.

  • Formed by the palatine process of maxilla and palatine bones.

• Two bones meet at the intermaxillary suture (or median palatine suture)

FEATURES OF HARD PALATE

• Palatal vault (arch)

  • height of vault affects acoustics

  • variable

• Rugae

  • ridges of mucous membrane

  • facilitate articulation through an increased surface area

SOFT PALATE (VELUM) - ROLES

• Creates a flexible opening between the nasal cavity and the oral cavity = made of mucous membrane so mobile

The soft palate is raised (elevated) to close the entrance to the nasal cavity during: Swallowing (Prevent food entering nasopharynx) Many speech sounds Blowing

The soft palate is lowered (depressed) to open the entrance to the nasal cavity during: Some speech sounds (sing , nigh) Breathing

SOFT PALATE DEPRESSORS

PALATOGLOSSUS - Anterior Faucial Pillar Depresses soft palate Lifts tongue Narrows pharynx  Pulls palate down

PALATOPHARYNGEUS Depresses soft palate Narrows pharynx Elevates pharynx

SOFT PALATE ELEVATORS

TENSOR VELI PALITINI Elevates soft palate Hook around hamulus Tenses soft palate Dilates eustachian tube 'L' shaped  Changes direction due to strong bony protrusion = hamulus  TVP connects to medial pterygoid plate (more lateral than LVP)

LEVATOR VELI PALITINI Elevates soft palate Raise soft palate Retracts soft palate Comes from petrous part of temporal bone

FURTHER MUSCLES INVOLVED IN SOFT PALATE CLOSURE

• Musculus uvulae

  • Bunches and shortens with contraction

• Superior constrictor

  • Pulls the posterior pharyngeal wall forwards to meet the soft palate

VELOPHARYNGEAL CLOSURE

• The role of the velopharyngeal closure is to vary the degree of acoustic coupling between the oral and nasal cavities.

• Velopharyngeal closure is necessary for the production of "oral stops" sounds - raising soft palate to posterior pharyngeal wall prevents air from exiting through the nasal cavity.

  • Impound air pressure within the oral cavity for the production of plosive consonants.

  • Complete closure of velum against pharynx walls required for wind instrumentalists to avoid air leak through nose.

  • 3 speech sounds require depressed soft palate – m/n/ng.

• Inadequate velopharyngeal closure → nasalised vowels and weak plosives

• Continuous sphincter type arrangement at the superior pharynx.

• Soft palate closes the ‘roof’ above this opening

VELOPHARYNGEAL CLOSURE IS ACHIEVED BY….

1. Palatal movement

Elevate (LVP) and tense (TVP) soft palate

2. Anterior movement of posterior pharyngeal wall

Superior constrictor around C1

3. Inward or medial movement of the lateral walls of the nasopharynx

Superior constrictor, buccinator and orbicularis oris

• NOTE = 

  • Small space at beginning of pharynx & end of palate that needs to be closed when there is swallowing procedure happening. Superior constrictor is coordinated by pterygomandibular raphe. 

  • All these muscles act in a coordinated way so that the gap present most superiorly is closed = velopharyngeal closure  help superior constrictor come anteriorly so that space is closed.  

NERVE SUPPLY OF PALATE - MOTOR

• All the muscles of the palate are supplied by Cranial nerve X (vagus) 

• Except for tensor veli palatini = supplied by mandibular branch of trigeminal(Vmand)

NERVE SUPPLY OF PHARYNX - MOTOR

• All the muscles of the pharynx are supplied by Cranial nerve X (vagus)

• Except for stylopharyngeus which is supplied by Cranial nerve IX (glossopharyngeal)

LARYNGEAL ELEVATORS

• Supra hyoid muscles

  • geniohyoid, digastric, thyrohyoid (infra), mylohyoid, and stylohyoid muscles

LARYNGEAL DEPRESSORS

• Infrahyoid (strap) muscles)

  • sternohyoid, sternothyroid, omohyoid