Inferior constrictor location
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Here is a thorough account of the inferior constrictor muscle location and related anatomy, drawn from Gray's Anatomy for Students and KJ Lee's Essential Otolaryngology:
Inferior Constrictor - Location & Attachments
Origin (anterior attachments)
The inferior constrictor has two heads, giving it two named parts:
| Part | Origin |
|---|---|
| Thyropharyngeus | Oblique line of the thyroid cartilage |
| Cricopharyngeus | Side of the cricoid cartilage |
A ligament also spans between the two cartilaginous attachments, crossing the cricothyroid muscle.
Insertion (posterior)
Fibers spread out posteriorly and attach to the pharyngeal raphe (the median fibrous band on the posterior midline of the pharynx).
Overlap and inferior extent
- The posterior part of the inferior constrictor overlaps the middle constrictor above it.
- Inferiorly, the muscle fibers blend with the esophageal wall.
Key Anatomical Relationships and Clinical Points
Cricopharyngeus (the lowest part):
- Acts as the upper esophageal sphincter (UES)
- Under tonic contraction at rest; relaxes during swallowing
- Is actively dilated by laryngeal elevation during deglutition
Narrowest part of pharynx: Where the inferior constrictor attaches to the cricoid cartilage - this brackets the narrowest portion of the pharyngeal cavity.
Killian dehiscence: A triangular weak point between the thyropharyngeus and cricopharyngeus parts of the inferior constrictor. This is where a Zenker's diverticulum can herniate posteriorly.
Laimer-Hackerman space: Gap between the posterior cricopharyngeus and esophageal musculature.
Killian-Jamieson space: Lateral dehiscence just inferior to the cricopharyngeus, through which branches of the inferior thyroid artery pass.
Gap above inferior constrictor (between middle and inferior constrictor): The internal laryngeal nerve and vessels pass through here, gaining access to the thyrohyoid membrane to enter the larynx.
Gap below inferior constrictor: The recurrent laryngeal nerve and inferior laryngeal vessels enter the larynx posterior to the inferior horn of the thyroid cartilage, deep to the inferior constrictor.
Sources: Gray's Anatomy for Students, p. 4356-4362 | KJ Lee's Essential Otolaryngology, p. 669
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