Question

multiple select question
select all that apply
which is a thick muscle that extends from the upper chest to the mastoid behind the ear?
masseter
x sternocleidomastoid muscle
scalene muscle
trapezius

Explanation:

Analyze the anatomical description

The question asks for a thick muscle extending from the upper chest to the mastoid process behind the ear. The upper chest attachments include the sternum (sterno-) and clavicle (cleido-), while the insertion is on the mastoid process (-mastoid).

Evaluate the given options

• Masseter: A muscle of mastication originating from the zygomatic arch and inserting into the mandible.
• Sternocleidomastoid muscle: A major neck muscle with two heads originating from the manubrium of the sternum and the clavicle, inserting onto the mastoid process of the temporal bone. This matches the description perfectly.
• Scalene muscle: A group of three pairs of muscles in the lateral neck originating from the cervical vertebrae and inserting into the first two ribs.
• Trapezius: A large superficial back muscle extending from the occipital bone and spine to the shoulder girdle.

Confirm the correct selection

The sternocleidomastoid muscle is the only option that matches the origin (upper chest/sternum and clavicle) and insertion (mastoid process behind the ear).

Answer:

• Masseter
• Sternocleidomastoid muscle (Correct answer)
• Scalene muscle
• Trapezius