NOT true about Facial Vein is:
**Core Concept**
The facial vein is a superficial vein that plays a significant role in the venous drainage of the face. It is a continuation of the superior ophthalmic vein and ultimately drains into the internal jugular vein via the common facial vein.
**Why the Correct Answer is Right**
The facial vein is unique in that it has a valveless system, allowing it to drain blood from the face into the internal jugular vein against gravity. This is in contrast to most other veins, which rely on the presence of valves to prevent backflow. The facial vein also has a rich anastomotic network with other veins, including the anterior branch of the retromandibular vein, which can provide an alternative pathway for venous drainage.
**Why Each Wrong Option is Incorrect**
* **Option A:** The facial vein is not a tributary of the external jugular vein, which is incorrect. The facial vein actually drains into the common facial vein, which then merges with the internal jugular vein.
* **Option B:** The facial vein does not have a significant role in the drainage of the nasal cavity, which is incorrect. The facial vein does drain blood from the face, including the nasal cavity.
* **Option C:** The facial vein is not a tributary of the pterygoid venous plexus, which is incorrect. The pterygoid venous plexus is a network of veins that drains blood from the deep structures of the face.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the facial vein is a common site for parotid gland abscesses and fistulae, particularly in cases of parotiditis or trauma. The facial vein's valveless system and rich anastomotic network make it a unique and clinically relevant structure.
**Correct Answer:** A.