In terms of origin and insertion, where is the origin of the frontalis muscle (frontal belly of the occipitofrontalis)?

• A. Zygomatic bone
• B. Epicranial aponeurosis (galea aponeurotica)
• C. Mastoid process of the temporal bone
• D. Mandibular fossa of the temporal bone

Answer: (B)

Verified step by step guidance

1. Understand that the frontalis muscle, also known as the frontal belly of the occipitofrontalis, is a muscle of facial expression primarily responsible for raising the eyebrows and wrinkling the forehead.
2. Recall that muscles have two key attachment points: the origin (usually the fixed or less movable point) and the insertion (the more movable point).
3. Identify that the frontalis muscle's origin is on the epicranial aponeurosis, also called the galea aponeurotica, which is a tough layer of connective tissue covering the top of the skull.
4. Recognize that the insertion of the frontalis muscle is on the skin of the eyebrows and forehead, allowing it to move these areas when it contracts.
5. Therefore, when asked about the origin of the frontalis muscle, the correct anatomical location to select is the epicranial aponeurosis (galea aponeurotica), not the bones listed such as the zygomatic bone, mastoid process, or mandibular fossa.