Muscles of Pharynx

💪 Muscles of the Pharynx

📘 Introduction

The Muscles of the pharynx form the third layer of the pharyngeal wall (after the mucosal and submucosal layers).

They are divided into two groups:

• Circular constrictor muscles
• Longitudinal muscles

🔄 Circular Constrictor Muscles

The circular muscles assist in the reflex act of swallowing, propelling the food bolus by a coordinated peristaltic wave into the esophagus.

There are three circular constrictor muscles:

• Superior constrictor
• Middle constrictor
• Inferior constrictor (further divided into thyropharyngeus and cricopharyngeus parts)

🔹 1- SUPERIOR CONSTRICTOR

📍 Origin:

• Pterygoid hamulus
• Posterior surface of medial pterygoid plate
• Pterygomandibular raphe
• Posterior end of the mylohyoid line of the mandible
• Side of the tongue

🎯 Insertion:

• Median pharyngeal raphe
• Base of the skull via pharyngobasilar fascia
• Overlaps with middle constrictor
• Gap for stylopharyngeus, styloglossus, glossopharyngeal nerve, lingual nerve

⚡ Nerve Supply:

• Pharyngeal plexus (via vagus nerve, CN X)

✅ Function:

• Constricts the uppermost part of the pharynx

🔹 2- MIDDLE CONSTRICTOR

📍 Origin:

• Inferior end of stylohyoid ligament
• Greater and lesser horns of hyoid bone

🎯 Insertion:

• Median pharyngeal raphe
• Overlaps lower superior constrictor
• Gap anteriorly covered by thyrohyoid membrane

⚡ Nerve Supply:

• Pharyngeal plexus (via vagus nerve)

✅ Function:

• Constricts the middle part of the pharynx

🔹 3- INFERIOR CONSTRICTOR

• Thickest of all constrictors

• Divided into:

  • Thyropharyngeus (oblique fibers)
  • Cricopharyngeus (horizontal fibers)

🔸 a. Thyropharyngeus

📍 Origin:

• Oblique line of thyroid cartilage
• Behind thyroid lamina and inferior horn

🎯 Insertion:

• Median pharyngeal raphe

🔸 b. Cricopharyngeus

📍 Origin:

• Lateral aspect of cricoid cartilage

🎯 Insertion:

• Encircles cricoid arch (does not fuse at the raphe)

⚡ Nerve Supply:

• Pharyngeal plexus (via vagus nerve)

✅ Function:

• Forms the upper esophageal sphincter

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🧵 Openings Between Constrictor Muscles

There are a few openings in between the Constrictor muscles:

• Above superior constrictor
• Between superior and middle constrictor
• Below cricopharyngeus

What are the structures passing through the openings between Constrictor muscles?

What structures pierce the Thyrohyoid membrane?

🧬 Longitudinal Muscles

The longitudinal muscles act as elevators and dilators of the pharynx.

There are three longitudinal muscles:

• Stylopharyngeus
• Palatopharyngeus
• Salpingopharyngeus

🔹 1. STYLOPHARYNGEUS

📍 Origin:

• Base of styloid process (temporal bone)

🎯 Insertion:

• Posterior superior thyroid cartilage
• Some fibers → lateral glossoepiglottic fold

⚡ Nerve Supply:

• Glossopharyngeal nerve (CN IX)

✅ Function:

• Elevates pharynx and larynx
• Assists peristalsis

🔹 2. PALATOPHARYNGEUSs

📍 Origin:

• Anterior: Hard palate
• Posterior: Palatine aponeurosis

🎯 Insertion:

• Posterior border of thyroid cartilage

⚡ Nerve Supply:

• Pharyngeal plexus (via vagus)

✅ Function:

• Elevates pharynx/larynx
• Forms posterior pillar of fauces
• Closes isthmus during swallowing
• Shapes soft palate

🔹 3. SALPINGOPHARNEGUS

📍 Origin:

• Lower part of pharyngotympanic tube

🎯 Insertion:

• Blends with palatopharyngeus

⚡ Nerve Supply:

• Pharyngeal plexus (via vagus)

✅ Function:

• Elevates pharynx
• Assists in eustachian tube opening