Pharynx: Muscles, Nerve and Blood Supply

• The objective is to describe the musculature, nerve and blood supply and venous and lymphatic drainage of the pharynx along with its clinical significance

Muscles of the Pharynx

• There are two categories of muscles in the pharynx
• There are 3 constrictor muscles
• There are 3 longitudinal muscles

Constrictor Muscles

• The constrictor include the: superior constrictor, middle constrictor, and inferior constrictor

Superior Constrictor

• The origin of the superior constrictor if from the posterior border of the medial pterygoid plate, the pterygoid hamulus, pterygomandibular raphe, the posterior end of the mylohyoid line of the mandible and the side of the tongue

Middle Constrictor

• The middle constrictor originates from the upper border of the greater cornu of the hyoid bone, the lesser cornu of the hyoid bone and the lower part of the stylohyoid ligament

Inferior Constrictor

• The thyropharyngeus originates from the oblique line and inferior horn of the thryoid cartillage
• The cricopharyngeus originates from the anterior arch of the cricoid cartilage

Insertion of Constrictors

• The superior constrictor inserts on the pharyngeal tubercle and pharyngeal raphe
• The middle and inferior constrictors insert on the pharyngeal raphe

Longitudinal Muscles

• Longitudinal muscles include the: stylopharyngeus, palatopharyngeus and salpingopharyngeus

Stylopharyngeus Muscle

• The styloharyngeus originates from the styloid process and passes between the superior and middles constrictors

Palatopharyngeus Muscle

• The palatopharyngeus arises from the upper surface of the palatine aponeurosis

Salpingopharyngeus Muscle

• The salpingopharyngeus arises from the lower part of the tubal elevation
• They all insert as a conjoined sheet to the posterior border of the lamina of the thyroid cartilage

Sinus of Morgagni

• The Large gap concave between the superior constrictor and the base of the skull
• Structures going trough it include: Auditory tube, Levator veli palatine muscle Ascending palatine artery

Nerve Supply of Pharynx

• All muscles, besides the stylopharyngeus, are supplied by the cranial part of the accessory nerve through the pharyngeal plexus
• The stylopharyngeus is supplied by the glossopharyngeal nerve
• Additionally, the inferior constrictor is supplied by branches from the external laryngeal and recurrent laryngeal nerves

Sensory Nerve Supply of Pharynx

• Nasopharynx is supplied by the maxillary nerve through the pterygopalatine ganglion
• Oropharynx is supplied by the IX nerve
• Laryngopharynx is supplied by the internal laryngeal nerve

Actions of Muscles

• Longitudinal muscles elevate the larynx and shorten the pharynx during deglutition
• Constrictor muscles contract reflexively during deglutition and induce a wave of peristalsis

Pharyngeal Function

• The thyropharyngeus is propulsive and the cricopharyngeus acts as a sphincter
• If there is neuromuscular incoordination and both parts contract simultaneously, the intrapharyngeal pressure rises (if the cricopharyngeus fails to relax when the thyropharyngeus contracts)
• The mucous membrane of the pharynx bulges through the dehiscence, forming a pharyngeal diverticulum, also called Zenker's Diverticulum

Killian's Dehiscence

• Killian's Dehiscence is in the the posterior wall of the pharynx, between the thyropharyngeus and cricopharyngeus part of the the inferior constrictor

Nerves and Vessels

• The recurrent laryngeal nerve and inferior laryngeal vessels pass below the inferior constrictor
• The internal laryngeal nerve and superior laryngeal vessels pass between the middle and inferior constrictors
• The stylopharyngeus muscle and glossopharyngeal nerve pass between the superior and middle constrictors