How does the anatomy of the platysma muscle contribute to the formation of neck bands according to the chapter?

The platysma muscle contributes to neck bands by contracting, which creates vertical folds extending from the mandible to the clavicles. Increased resting tone in the platysma with age also contributes to these bands.

The platysma muscle is a broad muscle covering the anterior and lateral neck and the lower face. It originates from the pectoralis and deltoid muscles, extends over the clavicle, and inserts into various regions of the lower face. Neck bands, or platysmal bands, are vertical folds resulting from the contraction of the platysma muscle. These bands become more evident with activities like straining or speaking animatedly. As people age, the resting tone of the platysma muscle increases, further contributing to the formation of these bands. Botulinum toxin treatment targets the anterior neck platysma muscle to inhibit its contraction, thereby reducing neck band formation and improving neck contour.