In human beings, how many pairs of major salivary glands are present that open into the mouth cavity?

Introduction / Context:
Salivary glands play an important role in the digestive system by secreting saliva, which helps in lubrication, digestion of starch, and maintaining oral hygiene. This question asks about the number of major pairs of salivary glands present in humans. It is a straightforward recall question from human anatomy and physiology.

Given Data / Assumptions:

• The question refers to major salivary glands.
• We are asked about the number of pairs.
• Minor salivary glands in the mucosa are not being counted.

Concept / Approach:
Humans have three pairs of major salivary glands. These are the parotid glands located near the ears, the submandibular glands located beneath the lower jaw, and the sublingual glands located under the tongue. Each pair secretes saliva through ducts opening into the oral cavity. Although numerous minor salivary glands exist in the lining of the mouth, the classical question in exams focuses on these three major paired glands.

Step-by-Step Solution:
Step 1: List the major salivary glands: parotid, submandibular, and sublingual. Step 2: Note that each of these exists on both sides of the mouth as a left and right gland, forming a pair. Step 3: Count the pairs: one pair of parotid, one pair of submandibular, and one pair of sublingual. Step 4: Conclude that there are three pairs in total.

Verification / Alternative check:
Anatomy diagrams of the head and neck region clearly label the three major salivary glands and show their ducts opening into the mouth cavity. Each type is present on both sides, confirming that there are three pairs. No standard reference lists a different number of major pairs.

Why Other Options Are Wrong:

• Option B (4): This would imply an extra major pair, which does not exist in standard human anatomy.
• Option C (6) and Option D (8): These numbers are far higher than the known number of major salivary gland pairs.

Common Pitfalls:
Sometimes students may confuse the number of individual glands with the number of pairs. Since each pair consists of two glands, the total number of major salivary glands is six, but they are still counted as three pairs. Exam questions usually ask for pairs, so reading the wording carefully is important.

Final Answer:
Humans have three pairs of major salivary glands that open into the mouth cavity.