Pharynx Anatomy and Functions

The Pharynx

• A wide muscular tube located behind the nose, mouth, and larynx.
• Divided into three parts: nasopharynx, oropharynx, and laryngopharynx.
• Plays a crucial role in breathing and swallowing.
• The wall of the pharynx is composed of five layers: mucosa, submucosa, pharyngobasilar fascia, muscular coat, and buccopharyngeal fascia.

Nasopharynx

• Situated behind the nose and above the lower border of the soft palate.
• Functions primarily as a respiratory passageway.
• Air passage remains patent due to rigid and non-collapsible walls.
• Lined by ciliated columnar epithelium.
• The mucous membrane receives blood supply and innervation.
• Communicates with the nasal cavity through the posterior nasal apertures.
• Communicates with the oropharynx at the pharyngeal isthmus.

Oropharynx

• Middle part is situated behind the oral cavity.
• Walls are formed by superior, middle, and inferior constrictors.
• Communicates with the nasopharynx via the pharyngeal isthmus.
• Communicates with the oral cavity via the oropharyngeal isthmus.
• The lateral wall houses the palatine tonsil located in the tonsillar fossa.

Laryngopharynx

• Lowest part is situated behind the larynx.
• Extends from the upper border of the epiglottis to the lower border of the cricoid cartilage.
• The anterior wall consists of the inlet of the larynx, cricoid, and arytenoid cartilages.

Muscles of the Pharynx

• Three constrictors: superior, middle, and inferior
  • Constrictors: Work together to propel food down the esophagus during swallowing.
  • Superior Constrictor: Originates from the pterygoid hamulus, pterygomandibular raphe, medial surface of the mandible, and side of the tongue.
  • Middle Constrictor: Originates from the stylohyoid ligament and horns of the hyoid bone.
  • Inferior Constrictor: Has two parts: thyropharyngeus and cricopharyngeus.
    • Thyropharyngeus: Originates from the oblique line of the thyroid lamina and cricothyroid muscle.
    • Cricopharyngeus: Originates from the cricoid cartilage.
  • Constrictors: Insert onto a median raphe on the posterior wall of the pharynx.
• Longitudinal muscles: stylopharyngeus, salpingopharyngeus, and palatopharyngeus.
  • Stylopharyngeus: Originates from the styloid process and inserts onto the inner surface of middle and inferior constrictors.
  • Salpingopharyngeus: Originates from the auditory tube and inserts onto the thyroid cartilage and inferior constrictor.
  • ** Palatopharyngeous:** Originates from the side of the hard palate and inserts onto the thyroid cartilage and blends with constrictor fibers.

Gaps Between Pharyngeal Muscles

• Above Superior Constrictor: Auditory tube, levator palati, ascending palatine artery.
• Between Superior and Middle Constrictor: Stylopharyngeus muscle, glossopharyngeal nerve
• Between Middle and Inferior Constrictor: Internal laryngeal nerve, superior laryngeal artery.
• Below Inferior Constrictor: Inferior laryngeal nerve.

Nerve Supply

• All muscles of the pharynx are innervated by the vagus nerve, except the stylopharyngeus muscle, which is innervated by the glossopharyngeal nerve.

This quiz explores the anatomy and functions of the pharynx, detailing its division into nasopharynx, oropharynx, and laryngopharynx. It also examines the structure of the pharyngeal walls and the roles these regions play in breathing and swallowing.