PHARYNX

PHARYNX

The pharynx is a long, tubular structure that plays a crucial role in the digestive and respiratory systems. It is a muscular tube that extends from the base of the skull to the esophagus and trachea. The pharynx is a common pathway for food, air, and sound.

• The pharynx is divided into three main parts: nasopharynx, oropharynx, and laryngopharynx.
• The nasopharynx lies above the soft palate and communicates with the nasal cavity.
• The oropharynx lies below the soft palate and contains the tonsils.
• The laryngopharynx lies below the hyoid bone and leads to the esophagus and trachea.
• The pharynx is lined by mucous membrane that produces mucus to lubricate food and air.
• The pharynx is innervated by the pharyngeal plexus, which receives fibers from the vagus, glossopharyngeal, and sympathetic nerves.
• The pharynx is supplied by the pharyngeal branches of the external and internal carotid arteries.
• The lymphatic drainage of the pharynx is through the pharyngeal nodes.

Developmental Process

• The pharynx develops from the foregut endoderm during embryonic development.
• The pharyngeal arches and pouches form around the pharynx during embryonic development.
• The pharyngeal arches give rise to the muscles of the pharynx, while the pharyngeal pouches give rise to the parathyroid glands and thymus.

Muscle Action Sequence

• The pharyngeal muscles contract in a sequence to push food into the esophagus.
• The sequence is as follows:
  • Step 1 → The superior constrictor muscle contracts to push food into the pharynx.
  • Step 2 → The middle constrictor muscle contracts to push food into the pharynx.
  • Step 3 → The inferior constrictor muscle contracts to push food into the esophagus.
• The pharyngeal muscles are also involved in swallowing and speaking.

Pharynx

The pharynx is a muscular tube that connects the nose and mouth to the esophagus. It is divided into three main parts: the nasopharynx, oropharynx, and laryngopharynx.

Parts of Pharynx and their features:

• Nasopharynx: It is the upper part of the pharynx that lies behind the nasal cavity. It contains the Eustachian tube and the pharyngeal tonsils.
• Oropharynx: It is the middle part of the pharynx that lies behind the oral cavity. It contains the palatine tonsils.
• Laryngopharynx: It is the lower part of the pharynx that lies behind the larynx. It is also known as the hypopharynx.

Constrictors of Pharynx:

The pharynx has four constrictor muscles: the superior constrictor, middle constrictor, inferior constrictor, and the stylopharyngeus muscle.

• Superior constrictor: It is the uppermost constrictor muscle of the pharynx. It is attached to the pterygomandibular raphe and the pterygoid hamulus.
• Middle constrictor: It is the middle constrictor muscle of the pharynx. It is attached to the pterygomandibular raphe.
• Inferior constrictor: It is the lowermost constrictor muscle of the pharynx. It is attached to the cricoid cartilage.
• Stylopharyngeus muscle: It is a small constrictor muscle of the pharynx. It is attached to the styloid process of the temporal bone.

Nerve Supply

• The pharyngeal plexus is formed by the pharyngeal branches of the vagus, glossopharyngeal, and sympathetic nerves.
• The pharyngeal plexus innervates the pharyngeal muscles and mucous membrane.
• The pharyngeal plexus also receives fibers from the hypoglossal nerve, which innervates the tongue.

Blood Supply

• The pharynx is supplied by the pharyngeal branches of the external and internal carotid arteries.
• The external carotid artery supplies the anterior part of the pharynx, while the internal carotid artery supplies the posterior part of the pharynx.
• The pharyngeal branches of the external carotid artery include the ascending pharyngeal artery and the tonsillar artery.

Lymph Drainage

• The lymphatic drainage of the pharynx is through the pharyngeal nodes.
• The pharyngeal nodes receive lymph from the pharyngeal mucous membrane and lymph from the surrounding tissues.
• The pharyngeal nodes drain into the deep cervical lymph nodes

Applied Anatomy:

• The pharynx is a common site for the formation of pharyngeal abscesses.
• The pharynx is also a common site for the formation of pharyngeal tumors.
• The pharynx is involved in swallowing and the transfer of food from the mouth to the esophagus.