Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Internal maxillary artery in ox is extraosseous.
Reason (R) : In ox, alar canal is absent.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true and (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Ruminants lack several cranial canals found in other species.
Since the alar canal is absent in the ox, the maxillary artery does not enter a bony canal, keeping its path extraosseous (outside the bone).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The maxillary artery (formerly known as the internal maxillary artery) is the main continuation of the external carotid artery, providing blood supply to the deep structures of the face, nasal cavity, and teeth.
Its anatomical path varies across domestic species due to differences in skull osteology, particularly the presence or absence of the alar canal.

Step 2: Detailed Explanation:
Let us analyze the comparative anatomy of the maxillary artery and the alar canal:
- Alar Canal: The alar canal is a short bony tunnel in the sphenoid bone of the skull.
- Species Variations:
- In the horse and dog, the alar canal is present. The maxillary artery passes through this canal, making a portion of its course intraosseous.
- In the ox (ruminants), the alar canal is completely absent.
- Anatomical Course in the Ox: Because there is no alar canal in the ox, the maxillary artery does not run through a bony tunnel. Instead, it runs an extraosseous course along the lateral surface of the pterygoid bone, passing directly toward the infraorbital canal.
Therefore, the assertion is correct, the reason is correct, and the absence of the alar canal in the ox directly explains why the artery's course is extraosseous.

Step 3: Final Answer:
Both (A) and (R) are true, and (R) is the correct explanation of (A). This corresponds to option (A).