Anatomy of Pharynx - Introduction

🧠 What is the Pharynx?

Pharynx is a long, muscular, funnel-shaped tube that serves as a shared passage for both the respiratory and digestive tracts.

📏 Dimensions of Pharynx:

• Structurally, it resembles an inverted cone.

• Length: Approximately 12 to 14 cm

Which is the widest and narrowest part of the Pharynx?

📍 Extent of the Pharynx

The pharynx extends from the pharyngeal tubercle at the base of the skull to the lower border of the cricoid cartilage, where it continues as the oesophagus.

⚙️ Functions of the Pharynx

• Respiration
• Digestion
• Middle Ear Ventilation
• Speech

🧱 Layers of the Pharyngeal Wall

The wall of the pharynx consists of five distinct layers (from inner to outer):

1- Mucosal Layer

• Nasopharynx - Lined with ciliated pseudostratified columnar epithelium (respiratory type)
• Oropharynx & Laryngopharynx - Lined with non-keratinized stratified squamous epithelium

2- Submucosal Layer (Lamina Propria)

• Connective tissue layer containing elastic fibers and gut-associated lymphoid tissue.
• Houses Waldeyer's Ring, an important lymphoid structure involved in local immunity.

What is the Waldeyer's Ring?

3- Pharyngobasilar Fascia (Pharyngeal Aponeurosis)

• Anchored to the skull base
• Becomes thickened near the base due to the absence of muscle, providing structural integrity.

4- Muscular Layer

• External circular muscles - Superior, Middle, and Inferior constrictors
• Internal longitudinal muscles - Stylopharyngeus, Salpingopharyngeus, Palatopharyngeus

To learn more about the Origin, Insertions, Nerve Supply and Action of all the muscles, please purchase the notes.

5- Buccopharyngeal Fascia

• Thin areolar tissue covering the constrictors
• Continues anteriorly with the fascia of the buccinator.
• Contains the Pharyngeal plexus of veins and nerves.

🔀 Divisions of the Pharynx

The pharynx is divided into 3 anatomical parts, based on their anterior communications:

1- Nasopharynx

• Located behind the nasal cavity
• Connects via the choanae

2- Oropharynx

• Located behind the oral cavity
• Connects via the oropharyngeal isthmus

3- Laryngopharynx

• Located posterior to the larynx
• Connects to the larynx via the laryngeal inlet