QS Study

An auditory tube is the ventilation tube between the pharynx and middle ear. It is a canal that connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity. The main function of this tube is ventilation of the middle ear and protection of equalized air pressure on both sides of the tympanic membrane or eardrum.

Length: 3-3.8cm.

Parts: It consists of two parts –

  1. Cartilaginous part – medial 2/3rd. 2.
  2. Bony part – lateral 1/3 rd.

Course:

From its opening in the anterior wall of the tympanic cavity, bony part of the tube runs in a downward, forward and medially towards the nasopharyngeal end. The osseous part lies within petrous part of temporal bone. The two parts form 1600 with each other.

In the resting stage, the auditory tube lies collapsed. On Chewing, swallowing and yawing, the tube opens due to contraction of the tensor and levator palati muscles.

Auditory Tube 1

Fig: Auditory Tube

Muscles associated with auditory tube:

  1. Tensor palati.
  2. Levator palati.
  3. Tensor tympani.
  4. Salpingo-pharyngeous.

In an adult, the auditory tube is mainly opened by tensor palati and levator palati.

Clinical importance

  1. It controls the ventilation of the middle ear cleft and maintains the equilibrium or pressure on two sides of the tympanic membrane.
  2. It helps in the drainage of the middle ear.
  3. It protects from nasopharyngeal air pressure and secretions.
  4. It controls the pressure within the middle ear, making it equal with the air pressure outside the body.
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