Anatomy of the Pharynx

Vertebral level of the hard palate

C1

Vertebral level of the angle of the mandible

C2

Vertebral level of the cricoid cartilage

C6

Vertebral level of the thyroid cartilage

C4/5

Vertebral level of the hyoid bone

C3

What is the pharynx

common superior muscular chamber of the aero-digestive stream

How can we enter the pharynx anteriorly

via the nose or mouth

Which vertebral level does the pharynx split

C6

What does the pharynx split into

larynx- airways

oesophagus -digestive stream

What happens to the digestive stream and airways in the pharynx

-they cross over one another

Which vertebral level does the digestive stream and airways cross

C6

Explain why the crossing of pathways is important clinically

disorders of swallowing such as injury to the brain and trauma to intra-oral structures makes the crossing of pathways dangerous and increase risk of aspiration int he airways

Why is it important that the pathways cross

Where does the pharync begin

base of the skull

Where does the pharynx terminate

lower border of the cricoid cartilage

Describe the shape/dimensions of the pahrynx

-funnel shaped

-12 cm long

-greatest width of 5cm, tapers to a width of 1.5cm at the upper oesophagus

What are the 3 main divisions of the pharynx

nasopharynx

oropharynx

laryngopharynx/ hypopharynx

Location of the nasopharynx

above the soft palate

Superior and inferior boundary of the nasopharynx

superior- skull base

inferior- level of the soft palate (superior border of the uvula)

Anterior and posterior boundary of the nasopharynx

anterior- choanae (posterior nares/ posterior nasal aperture)

posterior- pharyngeal wall/ nasopharyngeal tonsil, C1 vertebral level

What are adenoids

-nasopharyngeal tonsilds that become enlarged

What is the nasopharynx lined with

ciliated pseudostratified squamous epithelium/ upper respiratory epithelium

Location of the oropharynx

behind the oral cavity and tongue

superior and inferior boundary of the oropharynx

supeior- inferior border of the soft palate

inferior- superior edge of the epiglottis

anterior and posterior border of the oropharynx

anterior- oropharyngeal isthmus/ oral cavity

posterior- pharyngeal wall C2/C3 vertebrae

Borders of the laryngopharynx

superior- inferior border of the epiglottis

inferior- lower border of the cricoid cartilage

anterior- larngeal inlet

posterior- pharyngeal wall

Contents of the oropharynx from anterior to posterior

anterior tonsialla pillar (palatolossal arch)

palatine tonsil (sits in the tonsillar fossa)

posterior tonsiallr pillar (palatopharyngeus arch)

What lines the pharynx

lineed by mucous membranes which are continuous with all the chambers with which it communicates

What is the submucosa of the pharynx known as

-pharyngobasilar fascia

-strong fibrous sheet which lines the muscles of the pharynx internally

Which fascia covers the muscles of the pharynx externally

buccopharyngeal fascia

How is the pharynx separated posteriorly from the vertebral column and prevertebral muscles and fascia

-by loose areolar tissue of the retropharyngeal space

How many muscles of the pharynx are there

6 muscles

What are the 6 muscles known as collectively

the pharyngeus complex of muscles

What are the 6 muscles of the pharynx

superior constrictor

middle constrictor

inferior constrictor

stylopharyngeus

palatopharyngeus

salpingopharyngeus

Origins of the superior constrictor muscle

-lower 1/3 of the posterior border of the medial pterygoid plate and its hamulus

-pterygomandibular raphe

-mylohyoid line of the mandible

-side of the root of the tongue

Describe the direction of the fibres of the superior constrictor muscle

-the fibres radiate upwards and downward

Insertion point of the superior constrictor muscle

-inserting in the pharyngeal raphe and by the upper most fibres into the pharyngeal tubercle

What is the sinus of morgagni

-non muscular area lateral to the pharyngeal tubercle in which the pharyngeal wall is made up mostly of the pharyngobasilar fascia

-occurs as the upper border of the superior constrictor doesn’t reach the skull base except at the midline

Origin of the stylopharyngeus muscle

-medial aspect of the base of the styloid process

What passes between the superior pharyngeal constrictor and middle pharyngeal constrictor?

-stylopharyngeus muscle

-glossopharyngeal nerve

Describe the arrangement of the constrictor muscles and stylopharyngeus muscls

-lower part of the superior constrictor is overlapped by the middle constrictor

-stylopharyngeis muscle passes between the superior and middle constrictors at the lateral pharyngeal wall

Direction of the fibres of the stylopharyngeus muscle

downwards

medial

Insertion of the stylopharyngeus muscle

-posterior and superior borders of the thyroid cartilage and spreads out under the mucosa of the pharynx

Which nerve innervates the stylopharyngeus muscle

the gloospharyngeal nerve

What is the significance of the palatopharyngeus muscle in relation to the oral cavity

-forms the palatopharyngeal arch

What are the 2 layers of the palatopharyngeus muscle in the palate

-1 layer that sits posterosuperior to the levator veli palatini

-1 antero-inferior to the levator veli palatini

Insertion of the palatopharyngeus msucle

-inserts into the posterior border of the thyroid cartilage and into the posterior wall of the pharynx

Origin of the salpingopharyngeus muscle

-arises from the lower border of the auditory tube

Insertion of the salpingopharyngeus muscle

-converges on the palatopharyngeus muscle and blends with it in the pharyngeal wall

Which nerve innervates the muscles of the pharyngeal wall

-the pharyngeal plexus

-except the stylopharyngeus which is innervated by the stylopharyngeus nerve (CNIX)

-the inferior constrictor also receives additional innervation from the external branch of the superior laryngeal nerve (CNX)

Location of the pharyngeal plexus

-formed on the middle constricotr muscle

-opposite the greater horn of the hyoid bone

What is the pbaryngeal plexus formed by

-CNIX

-CNX

-superior cervical ganglion

What are the 3 phases of swallowing

-oral phase

-pharyngeal phase

-esophageal phase

Explain the mechanims of swallowing

-food is pushed from oral cavity to the oropharynx (tongue and suprahyoid muscles elevate hyoid and larynx, soft palate elevates and seals off the nasopharynx, superior constrictors contract)

-food bolus passes into laryngopharynx by aid of middle and inferior constrictors

-larynx protected by (overhanging tongue, epiglottis, vocal cords)

-cricopharyngeus (upper oesophageal sphincter) relaxes

What is Zenker’s Diverticulum

-mucosal outpouching through a weak area just above the upper oesophageal sphincter (cricopharynegus muscle) in the posterior wall of the pharynx

What is Killian’s Dehiscence/triangle

-a triangular area in the posterior wall of the pharynx, located just above the upper oesophageal sphincter (in the same spot where zenker’s diverticulum)

-a potential weak spot where Zenker’s diverticulum is most likely to occur

What is the piriform fossa

-a recess on either side of the laryngeal inlet

Clinical significance of the piriform fossa

-foreign bodies such as fish bodies often get stuck there

What is the piriform fossa bounded by

medially by the aryepiglottic fold

laterally by the thyroid cartilage and thyrohyoid membrane