QS Study

The pharynx is a wide muscular tube situated behind the nose, the mouth and the larynx. It is a part of the upper respiratory tract. It is a five-inch-long tube that starts near our nose and ends at our windpipe. It receives food and air from the mouth, and air from the nasal cavities.

Location: It’s situated behind the cavities of nose, mouth and the larynx with which it interacts.

Boundary

Superiorly

The base of the skull, including the posterior part of the body of the sphenoid and the basilar part of the occipital bone.

Inferiorly:

Constant with the esophagus in the level of lower border of cricoid cartilage anteriorly and lower border of C6 vertebra posteriorly. It is continuous with the oesophagus at the level of the 6th cervical vertebra.

  • Posteriorly: It is related to prevertebral fascia.
  • Anteriorly: It communicates with the nasal cavity, the oral cavity, and the larynx.

On each side: It is attached to the –

  1. The medial pterygoid plate.
  2. The pterygomandibular raphae.
  3. The Mandible.
  4. The tongue.
  5. The hyoid bone.
  6. The thyroid and cricoid cartilages.

It communicates on each side with the middle air cavity through the auditory tube.

Pharynx 1

Fig- Parts of the pharynx

Parts:

The cavity of the pharynx is divided into.

  1. The nasal part (nasopharynx) – It is found between the base of the skull and the soft palate. It is continuous with the nasal cavity and performs a respiratory function.
  2. The oral part (oropharynx) – It is the middle part of the pharynx, located between the soft palate and the superior border of the epiglottis.
  3. The laryngeal part (laryngopharynx) – It is located between the superior border of the epiglottis and inferior border of the cricoid cartilage. It is continuous inferiorly with the oesophagus.

Nerve supply:

The pharynx is supplied by the pharyngeal plexus of nerves. The plexus is formed by –

  1. The pharyngeal branch of the vagus nerve.
  2. The pharyngeal branch of the glossopharyngeal nerve.
  3. The pharyngeal branches of the superior cervical sympathetic ganglion.

Motor fibers are derived from the cranial accessory nerve through the branches of the vagus, supply all muscles of pharynx except stylopharyngeus which is supplied by the glossopharyngeal nerve. Sensory fibers from the pharynx mostly pass through the glossopharyngeal nerve and partly by the vagus nerve.

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