Final answer:
The vertebra prominens corresponds to the C7 vertebra, characterized by a prominent spinous process that is typically palpable at the base of the neck.
Step-by-step explanation:
The vertebra prominens is indeed the designation for the C7 vertebra, which is known for having a distinctive, long, and non-bifid spinous process. This vertebra can usually be palpated at the base of the neck and is commonly felt by running a finger down the posterior midline of the neck until you encounter the prominent spinous process of C7. Contrastingly, the C3-C6 vertebrae typically exhibit a bifid spinous process. The C7 is not located near the manubrium of the sternum, and it is often quite palpable in individuals, making statement 2 incorrect. Statement 3 is somewhat true as the C7 vertebra does roughly align with the scapula's inferior border when the arms are at the sides, but it is more accurate to say that it is located at the base of the neck. Therefore, the most accurate statements about the vertebra prominens are that it is the spinous process of C7 and it can generally be felt upon palpation.