Pharynx Flashcards
The pharynx is
a muscular tube that connects the oral and nasal cavity to the larynx and oesophagus.
Where does it begin
It begins at the base of the skull, and ends at the inferior border of the cricoid cartilage (C6). The pharynx is comprised of three parts (superior to inferior):
The pharynx is comprised of three parts (superior to inferior):
Nasopharynx
Oropharynx
Laryngopharynx.
The nasopharynx is found between
the base of the skull and the soft palate. It is continuous with the nasal cavity,
What does the nasopharynx do
performs a respiratory function by conditioning inspired air and propagating it into the larynx.
What is the nasopharynx lines with
This part of the pharynx is lined with respiratory epithelium; ciliated pseudostratified columnar epithelium with goblet cells.
What is respiratory epithelium
ciliated pseudostratified columnar epithelium with goblet cells.
The posterosuperior nasopharynx contains the
which enlarge between 3-8 years of age and then regress.
The oropharynx is the middle part of the pharynx, located between
the soft palate and the superior border of the epiglottis.
What structures does oropharynx include
- Posterior 1/3 of the tongue.
- Lingual tonsils – lymphoid tissue at the base of the tongue.
- Palatine tonsils – lymphoid tissue located in the tonsillar fossa (between the palatoglossal and palatopharyngeal arches of the oral cavity).
- Superior constrictor muscle
Waldeyer’s ring is
the ring of lymphoid tissue in the naso- and oropharynx formed by the paired palatine tonsils, the adenoid tonsils and lingual tonsil.
The oropharynx is involved in the voluntary and involuntary phases of
swallowing.
The most distal part of the pharynx, the laryngopharynx is located between
the superior border of the epiglottis and inferior border of the cricoid cartilage (C6). It is continuous inferiorly with the oesophagus.
The laryngopharnyx It is found posterior to the larynx and communicates with it via
the laryngeal inlet, lateral to which one can find the piriform fossae.
The laryngopharynx contains the
middle and inferior pharyngeal constrictors
The inferior pharyngeal constrictor is split into two parts
the thyropharyngeus and the cricopharyngeus.
This area between the two is a weak area in the mucosa
Normally during swallowing, the thyropharyngeus and cricopharyngeus work how
the thyropharyngeus contracts as the cricopharyngeus relaxes, allowing the bolus of food to be propelled into the oesophagus and preventing the intrapharyngeal pressure from rising.
If this coordinated relaxation of the cricopharyngeus does not occur what happens
the intrapharyngeal pressure tends to rise and pharyngeal mucosa forms a midline diverticulum in the area between the thyropharyngeus and cricopharyngeus. It is possible for food to accumulate here, leading to dysphagia.
There are two main groups of pharyngeal muscles
There are two main groups of pharyngeal muscles
The muscles of the pharynx are mostly innervated by the
vagus nerve – the only exception being the stylopharyngeus (glossopharyngeal nerve).
There are three circular pharyngeal constrictor muscles
the superior, middle and inferior pharyngeal constrictors. They are stacked like glasses, which form an incomplete muscular circle as they attach anteriorly to structures in the neck.
The circular muscles contract sequentially from superior to inferior to constrict the lumen and
propel the bolus of food inferiorly into the oesophagus.
Superior pharyngeal constrictor – the uppermost pharyngeal constrictor. It is located in the oropharynx.
Where does it originate and insert
Originates from the pterygomandibular ligament, alveolar process of mandible and medial pterygoid plate and pterygoid hamulus of the sphenoid bone.
Inserts posteriorly into to the pharyngeal tubercle of the occiput and the median pharyngeal raphe.
Middle pharyngeal constrictor – located in the laryngopharynx.
Where does it originate and insert
Originates from the stylohyoid ligament and the horns of the hyoid bone.
Inserts posteriorly into the pharyngeal raphe.
Inferior pharyngeal constrictor – located in the laryngopharynx. It has two components:
Superior component (thyropharyngeus) has oblique fibres that attach to the thyroid cartilage.
Inferior component (cricopharyngeus) has horizontal fibres that attach to the cricoid cartilage.
All pharyngeal constrictors are innervated by the
vagus nerve (CN X).
The longitudinal muscles are the
stylopharyngeus,
palatopharyngeus and
salpingopharyngeus.
What do the longitudinal muscles do
They act to shorten and widen the pharynx, and elevate the larynx during swallowing.
Stylopharyngeus – arises from where and inserts where
the styloid process of the temporal bone, inserts into the pharynx.
What innervates the Stylopharyngeus
Unlike the other pharyngeal muscles, it is innervated by the glossopharyngeal nerve (CN IX).
Palatopharyngeus – arises from and inserts in the
hard palate of the oral cavity, inserts into the pharynx
What is the Palatopharyngeus innervated by
Innervated by the vagus nerve (CN X).
Salpingopharyngeus – arises from and inserts where
arises from the Eustachian tube, inserts into the pharynx.
What is the Salpingopharyngeus innervated by
Innervated by the vagus nerve (CN X).
What does the also Salpingopharyngeus do
In addition to contributing to swallowing, it also opens the Eustachian tube to equalise the pressure in the middle ear.
Motor and sensory innervation of the majority of the pharynx (except nasopharynx) is achieved by the
pharyngeal plexus.
The pharyngeal plexus, which mainly overlies the middle pharyngeal constrictor, is formed by: (4)
Pharyngeal branches from the glossopharyngeal nerve (CN IX).
Pharyngeal branch of the vagus nerve (CN X).
Branches from the external laryngeal nerve.
Sympathetic fibres from the superior cervical ganglion.
Sensory innervation of the Nasopharynx
Maxillary nerve (CN V2)
Sensory innervation of the oropharynx
Glossopharyngeal nerve (CN IX)
Sensory innervation of the Laryngopharnx
Vagus nerve (CN X)
All the muscles of the pharynx are innervated by the What
EXCEPT FOR
vagus nerve (CN X), except for the stylopharyngeus, which is innervated by the glossopharyngeal nerve (CN IX).
Arterial supply to the pharynx is via branches of the
external carotid artery:
The branches of the external carotid artery which arteriole supply the pharynx (3)
Ascending pharyngeal artery
Branches of the facial artery
Branches of the lingual and maxillary arteries.
Venous drainage is achieved by the
pharyngeal venous plexus, which drains into the internal jugular vein.
What forms the ganglia on the sympathetic chains and vagus nerve?
A collection of neuron cell bodies
What is the name of the fused first thoracic and lower cervical sympathetic ganglia?
The stellate gangion
What structures are supplied by the superior laryngeal nerve?
Sensation to the inside of the larynx down to the vocal cords and the cricothyroid muscle.
Which special sensation is carried in the glossopharyngeal nerve?
Sensation to the inside of the larynx down to the vocal cords and the cricothyroid muscle.
What is the location of the carotid sinus and what sensation does it detect?
What is the location of the carotid sinus and what sensation does it detect?
Which structures lie immediately behind the pharyngeal wall?
A thin layer of loose areolar tissue and then the cervical vertebral bodies.
Which parts of the pharynx lie below the lower border of the mandible?
The hypopharynx.
