Pharynx: Anatomy and Function

• The pharynx is a tube-shaped structure in the head and neck region, serving as a part of both the digestive and respiratory systems.
• It extends from the base of the skull to the level of the 6th or 7th cervical vertebrae.
• The pharynx consists of three parts: the nasopharynx, oropharynx, and laryngopharynx.
  • The nasopharynx is behind the nasal cavity.
  • The oropharynx is behind the oral cavity.
  • The laryngopharynx is behind the larynx.
• Structures posterior to the pharynx include the prevertebral plate of the cervical fascia, prevertebral muscles, and the cervical spine.
• The retropharyngeal space between the pharynx and fascia contains lymph nodes.

Nasopharynx

• The nasopharynx functions as part of the respiratory system.
• It is located between the base of the cranium and the 3rd cervical vertebra.
• The choanae connect the nasopharynx with the nasal cavity.
• The pharyngeal opening of the auditory tube is located on the lateral wall of the nasopharynx.
• The auditory (Eustachian) tube connects the pharynx to the tympanic cavity, regulating pressure in the middle ear.
• The torus tubarius, made of cartilage from the auditory tube, surrounds the tube opening superiorly and posteriorly.
• The vault (fornix) refers to the upper part of the pharynx.
• The pharyngeal tonsil (adenoid), an immune system organ, sits between the superior and posterior walls of the pharynx.
• The tubal tonsil is located near the pharyngeal opening of the auditory tube and the soft palate.
• The pharyngeal and tubal tonsils are components of the Waldeyers-Pirogovs lymphoepithelial ring, which also includes the lingual tonsil, two palatine tonsils, and two tubal tonsils.

Oropharynx

• Occupies the middle section of the pharynx.
• Connects to the oral cavity via the faucium (fauces).
• It can be found at the level of the third cervical vertebra.

Laryngopharynx

• Situated behind the larynx.
• Transitions into the esophagus.

Pharyngeal Wall

• The pharyngeal wall is composed of several layers: the mucosa (mucous membrane), submucosa containing pharyngeal glands, the pharyngobasilar fascia, pharyngeal muscles, and the buccopharyngeal fascia.
• The pharyngobasilar fascia forms the base of the pharyngeal wall.
• It attaches to the base of the occipital bone and other bones at the skull's base.
• The inner side is covered by mucosa, and the outer side by pharyngeal muscles.
• Pharyngeal muscles are grouped into constrictors (circular) and dilators (longitudinal).

Constrictor Muscles

• The constrictor muscles are divided into superior, middle, and inferior constrictors.
• The superior constrictor muscle originates from the medial plate of the pterygoid process of the sphenoid bone, running downward and backward to connect with the contralateral muscle.
• The middle constrictor muscle originates from the greater and lesser horns of the hyoid bone and connects with the opposite muscle on the posterior pharyngeal wall.
• The inferior constrictor muscle originates from the lateral surface of the thyroid cartilage plate and the laryngeal cartilage, connecting with the contralateral muscle.
• The left and right muscle fibers connect on the posterior wall to form the pharyngeal raphe.
• Contraction of the constrictor muscles narrows the pharyngeal cavity.

Dilator Muscles

• The dilator muscles are arranged longitudinally.
• The stylopharyngeal muscle runs from the styloid process and attaches to the pharyngeal wall.
• The palatopharyngeal muscle is located in the palatopharyngeal arch of the soft palate.

Buccopharyngeal Fascia

• The outermost layer of the pharyngeal wall is the buccopharyngeal fascia.

The pharynx is a tube in the head and neck, part of the digestive and respiratory systems. It has three parts: the nasopharynx, oropharynx, and laryngopharynx. Posterior to the pharynx are muscles, the cervical spine, and lymph nodes.