In human anatomy, how many pairs of major salivary glands are present in an adult, secreting saliva into the mouth?

Introduction:
Saliva plays a key role in digestion and oral health. It is secreted by several salivary glands located around the mouth. Knowing the number and names of the major salivary gland pairs is a basic requirement in human anatomy. This question asks you to recall how many pairs of these major salivary glands are present in humans.

Given Data / Assumptions:
- The question refers to pairs of major salivary glands, not minor glands scattered in the mucosa. - Options range from three to eight pairs. - We assume a normal adult human without developmental anomalies. - The major salivary glands are parotid, submandibular (also called submaxillary) and sublingual.

Concept / Approach:
Humans have three pairs of major salivary glands: a pair of parotid glands in front of the ears, a pair of submandibular glands beneath the jaw and a pair of sublingual glands under the tongue. Each pair consists of a left and a right gland that secrete saliva into the oral cavity through ducts. In addition, there are many minor salivary glands in the mucous membranes of the mouth, but these are not usually counted in the basic number of pairs. Therefore, the correct answer is three pairs of major salivary glands.

Step-by-Step Solution:
Step 1: List the major salivary glands: parotid, submandibular and sublingual. Step 2: Recognise that each of these exists as a pair, one on the left and one on the right side of the head and neck. Step 3: Count the pairs: one pair of parotid glands, one pair of submandibular glands and one pair of sublingual glands. Step 4: Total the number of pairs: 1 + 1 + 1 = 3 pairs of major salivary glands. Step 5: Compare this with the options and select three pairs as the correct answer.

Verification / Alternative check:
Anatomy textbooks and dental science references consistently list three major salivary gland pairs with descriptions of their locations and ducts: Stensen's duct for parotid, Wharton's duct for submandibular and multiple ducts of Rivinus for sublingual glands. Clinical discussions of salivary gland disorders such as mumps primarily involve the parotid glands, confirming their status as major glands. No reliable source suggests four, six or eight pairs of major salivary glands as normal anatomical structures.

Why Other Options Are Wrong:
Four pairs: More than the recognised number of major salivary gland pairs; there is no additional distinct major gland beyond the three listed. Six pairs: Would imply six different named major glands, which is not supported by standard anatomical classification. Eight pairs: Greatly exceeds the normal number and is not anatomically accurate.

Common Pitfalls:
Some learners may count the many small minor salivary glands in the lips, cheeks and palate and become confused about the total number. Others might misremember whether submandibular and sublingual glands are counted separately. To avoid these mistakes, focus on the three named major pairs and remember the simple list parotid, submandibular and sublingual, adding up to three pairs in total.

Final Answer:
Humans have Three pairs of major salivary glands: parotid, submandibular and sublingual.