Pharynx Flashcards
what are the pharynx
The pharynx is a muscular tube that connects the nasal cavities to the larynx and oesophagus. It is common to both the gastrointestinal and respiratory tracts.
where is the pharynx begin
It begins at the base of the skull and ends inferiorly to the cricoid cartilage (C6)
what is pharynx comprised
the nasopharynx, oropharynx and laryngopharynx (from superior to inferior).
where are the two types of the muscle that form the pharynx
There are two types of muscles that form the walls of the pharynx – longitudinal and circular.
what are both types of pharyngeal innervated by
Both types are innervated by the vagus nerve, except for the stylopharyngeus, which is innervated by the glossopharyngeal nerve.
desribe the circular musclar
The circular muscles contract sequentially from superior to inferior to constrict the lumen and propel the bolus of food inferiorly into the oesophagus.
They are stacked like glasses and are an incomplete muscular circle, anteriorly attaching to structures in the neck.
They are all innervated by the vagus nerve (CN X):
Superior pharyngeal constrictor is found in the oropharynx.
Runs from the pterygoid hamulus, pterygomandibular raphe, the mandible and the side of the tongue to the pharyngeal tubercule of the occiput.
Middle pharyngeal constrictor is found in the laryngopharynx.
Originates from the stylohyoid ligament and the horns of the hyoid to the pharyngeal raphe.
Inferior pharyngeal constrictor is found in the laryngopharynx and has two components. The superior component (thyropharyngeus) has oblique fibres that attach to the thyroid cartilage and the inferior component (cricopharyngeus) has horizontal fibres that attach to the cricoid cartilage.
describe the longitudinal
The longitudinal muscles shorten and widen the pharynx, and elevate the larynx during swallowing.
Stylopharyngeus: from the styloid process of the temporal bone to the pharynx, innervated by the glossopharyngeal nerve (CN IX)
Palatopharyngeus: from hard palate of the oral cavity to the pharynx, innervated by the vagus nerve (CN X)
Salpingopharyngeus: from the Eustachian tube to the pharynx, innervated by the vagus nerve (CN X). In addition to contributing to swallowing, it also opens the Eustachian tube to equalize the pressure in the middle ear with the atmosphere.
innervation of the pharynx
Innervation of the majority of the pharynx is achieved by the pharyngeal plexus, which comprises of:
Branches of the glossopharyngeal nerve (CN IX)
Branches of the vagus nerve (CN X)
Sympathetic fibres of the superior cervical ganglion.
Sensory: Each of the three sections of the pharynx have a different innervation:
The nasopharynx is innervated by the maxillary nerve (CN V2).
The oropharynx by the glossopharyngeal nerve (CN IX).
The laryngopharynx by the vagus nerve (CN X).
Motor: All the muscles of the pharynx are innervated by the vagus nerve (CN X), except for the stylopharyngeus, which is innervated by the glossopharyngeal nerve (CN IX).
blood supply of the pharynx
Arterial supply is via branches of the external carotid artery: ascending pharyngeal, lingual, facial and maxillary arteries.
veinous drainge of the parynx
Venous drainage is achieved by the pharyngeal venous plexus, which drains into the internal jugular vein.
desribe the nasophaynx
The nasopharynx is found between the base of the skull and the soft palate, it is a continuation of the nasal cavity. It performs a respiratory function by conditioning inspired air and propagating it to the larynx.
This part of the pharynx is lined with respiratory epithelium: ciliated pseudo-stratified columnar epithelium with goblet cells.
The postero-superior nasopharynx contains the adenoid tonsils, which are large between the ages of 3-8 and then regress.
desribe the oropharynx
the oropharynx is the middle part of the pharynx, located between the soft palate and the superior border of the epiglottis. It contains the following structures:
Posterior 1/3 of the tongue.
The lingual tonsils – Located inferiorly to the tongue.
The palatine tonsils – Found in the tonsillar fossa between the palatoglossal and palatopharyngeal arches of the oral cavity.
Superior constrictor muscle
The oropharynx is involved in the voluntary and involuntary phases of swallowing.
desribe the larynogopharynx
the most distal part of the pharynx, this is located between the superior border of the epiglottis and inferior border of the cricoid cartilage (C6), at which point it becomes continuous with the oesophagus. 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.
