Inferior Pharyngeal Constrictor (Thyropharyngeal Part)

Origin, Insertion, Action & Nerve

Attachments explained

The Inferior Pharyngeal Constrictor (Thyropharyngeal Part) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.

Action & function

When the Inferior Pharyngeal Constrictor (Thyropharyngeal Part) contracts, it produces the following movement: Constricts the pharynx to propel the bolus during swallowing.

As part of the Pharynx group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.

Nerve supply & clinical relevance

The Inferior Pharyngeal Constrictor (Thyropharyngeal Part) receives its nerve supply from the Vagus nerve (CN X) via the pharyngeal plexus and external laryngeal nerve.

Because a muscle can only contract when its nerve is intact, injury to the Vagus nerve can weaken or paralyse the Inferior Pharyngeal Constrictor (Thyropharyngeal Part), impairing the movements it normally produces (constricts the pharynx to propel the bolus during swallowing). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Inferior Pharyngeal Constrictor (Thyropharyngeal Part) (the OIANS method)

Learn the thyropharyngeal part as the diagonal upper half of the inferior constrictor, taking its origin from the oblique line of the thyroid cartilage and running back to the median raphe. Because all three constrictors share that raphe and overlap from below upward, picture the inferior constrictor wrapping outside the middle one, and you will recall both its telescoping arrangement and its bolus-propelling action at once.

Fix the clinical anatomy that makes this part worth knowing: its oblique fibres sit just above the horizontal cricopharyngeus, and the sparse muscle between them is Killian's dehiscence. Tie its dual innervation, the pharyngeal plexus plus the external laryngeal nerve, to this boundary, since it marks the transition to the sphincteric cricopharyngeal fibres that guard the oesophageal inlet.

Frequently asked questions

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