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Pharynx II : External features - Constrictors
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Medical students and healthcare professionals seeking a practical, specimen-based understanding of pharyngeal anatomy and its clinical relations.
TL;DR
This video provides a detailed anatomical dissection of the pharynx, focusing on its external musculature and constrictor muscles. It explains the structural relationships, attachments, and key landmarks like the pharyngeal raphe and the sinus of Morgagni.
Key Takeaways
- The pharynx is a funnel-shaped musculomembranous tube extending from the base of the skull to the pharyngoesophageal junction at the lower border of the C6 vertebra.
- Unlike the rest of the gastrointestinal tract, the pharynx features an inner longitudinal muscle coat and an outer circular muscle coat, the latter consisting of three constrictor muscles.
- The pharyngeal constrictors overlap one another posteriorly and insert into a midline fibrous structure known as the pharyngeal raphe, which attaches superiorly to the pharyngeal tubercle.
- The superior constrictor muscle attaches to the pterygomandibular raphe, which serves as a shared point of origin for both the superior constrictor and the buccinator muscle.
- The sinus of Morgagni is a weak space above the superior constrictor muscle where the pharyngobasilar and buccopharyngeal fasciae meet, allowing structures like the Eustachian tube to pass.
- The middle constrictor muscle originates from the greater horn of the hyoid bone and the stylohyoid ligament, comprising the ceratopharyngeus and chondropharyngeus muscle components.
- A distinct anatomical gap exists between the superior and middle constrictor muscles, which provides a pathway for the stylopharyngeus muscle and the glossopharyngeal nerve to enter the pharynx.
In This Video
- 00:00Introduction to Pharyngeal Anatomy
The video introduces the external features and musculature of the pharynx, focusing on the constrictor muscles and their anatomical relations.
- 01:45Relations and Extent of Pharynx
This section details the lateral relations of the pharynx, including the carotid sheath, and defines its extent from the skull base to C6.
- 03:42Musculature and Longitudinal Muscles
The pharynx features a unique muscle arrangement with an inner longitudinal layer, consisting of the salpingopharyngeus, palatopharyngeus, and stylopharyngeus muscles.
- 04:40The Pharyngeal Constrictor Muscles
The outer circular layer comprises three overlapping constrictor muscles that attach to the midline pharyngeal raphe for structural support.
- 06:01Superior Constrictor and Sinus of Morgagni
The superior constrictor attaches to the pterygomandibular raphe, while the sinus of Morgagni provides a passage for the Eustachian tube and other structures.
- 09:00Middle Constrictor and Stylopharyngeus
The middle constrictor arises from the hyoid bone, and the gap between it and the superior constrictor allows the glossopharyngeal nerve to pass.
Questions & Answers
What is the extent of the pharynx?
The pharynx is a musculomembranous tube extending from the base of the skull down to the pharyngoesophageal junction, which corresponds to the lower border of the C6 vertebra.
What are the three constrictor muscles of the pharynx?
The three constrictor muscles are the superior constrictor, the middle constrictor, and the inferior constrictor.
What is the pharyngeal raphe?
The pharyngeal raphe is a midline fibrous structure that extends from the pharyngeal tubercle on the basilar occiput down to the pharyngoesophageal junction, serving as the insertion point for the pharyngeal constrictor muscles.
What is the sinus of Morgagni?
The sinus of Morgagni is a deficient space above the superior border of the superior constrictor muscle, covered by the pharyngobasilar and buccopharyngeal fasciae, through which structures like the Eustachian tube pass.
What structures pass between the superior and middle constrictor muscles?
The stylopharyngeus muscle and the glossopharyngeal nerve pass through the space between the superior and middle constrictor muscles to enter the pharynx.
How does the pharyngeal muscle arrangement differ from the rest of the GIT?
Unlike the rest of the gastrointestinal tract, which has an inner circular and outer longitudinal muscle coat, the pharynx has an inner longitudinal muscle coat and an outer circular muscle coat.
Key Terms
- Buccopharyngeal fascia — The fascia covering the posterior aspect of the pharynx and the muscles surrounding it.
- Pharyngobasilar fascia — A layer of fascia that covers the muscles of the pharynx deep to the superior constrictor.
- Pterygomandibular raphe — A fibrous band attaching the buccinator muscle anteriorly and the superior constrictor muscle posteriorly.
- Pharyngeal tubercle — A bony prominence on the under surface of the basilar occiput where the pharyngeal raphe attaches superiorly.