Step 1: Understanding the Question:
The question asks to identify a specific anatomical structure marked in a radiographic image of the neck region, likely a contrast study or a soft tissue X-ray. Step 2: Detailed Explanation:
Anatomy of the Pharynx: The hypopharynx (laryngopharynx) extends from the superior border of the epiglottis to the inferior border of the cricoid cartilage. It consists of three main parts: the pyriform sinuses, the post-cricoid area, and the posterior pharyngeal wall.
Pyriform Sinus: The pyriform sinuses are two pear-shaped mucosal recesses located on either side of the laryngeal orifice. They are bounded medially by the aryepiglottic fold and laterally by the thyroid cartilage and thyrohyoid membrane.
Radiological Identification: On an anteroposterior (AP) view of the neck, especially during a barium swallow or when air-filled, the pyriform sinuses appear as symmetrical lateral pouches or recesses. The arrows in the image point to these lateral air-filled or contrast-filled spaces lateral to the laryngeal inlet.
Clinical Significance: The pyriform sinus is a common site for the entrapment of foreign bodies (like fish bones) and a frequent site for the development of hypopharyngeal squamous cell carcinoma.
Differentiation:
- Thyroid Cartilage: This is the large shield-like structure forming the laryngeal prominence; it is more anterior and central.
- Epiglottis: A leaf-shaped flap of cartilage that projects upwards behind the tongue and in front of the laryngeal inlet.
- Vallecula: These are the depressions between the base of the tongue and the epiglottis, located superior to the pyriform sinuses.
Step 3: Final Answer:
Based on the anatomical location lateral to the larynx in the AP view, the marked structure is the Pyriform sinus.
