Facial Muscles - Lower Group

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Introduction

Located underneath the skin of the face and scalp are a group of 20 flat skeletal muscles. These muscles of facial expression, also named craniofacial muscles, are found in the subcutaneous tissue and emanate from bone or fascia, to attach onto the skin. They are a group of muscles that exclusively attach to skin and by contracting, the muscles pull on the skin and create movements of the face, such as smiling, grinning and frowning. Therefore, these muscles are commonly called muscles of facial expression, or mimetic muscles. All of the facial muscles are innervated by the facial nerve (CN VII) and vascularised by the facial artery.

The facial muscles are located around facial openings (mouth, eye, nose and ear) or extend over the skull and neck. Hence, they are divided into several groups;

• Muscles of the nose (nasal group)
• Muscles of the cranium and neck (epicranial group)
• Muscles of the external ear (auricular group)
• Muscles of the mouth or oral group (buccolabial group)

More specifically the oral group are accountable for movements of the mouth and lips. Such movements are necessary in singing and whistling and give emphasis to vocal communication.

Description

There is a total of eleven facial muscles that create movement at the mouth and their functions include:

• Lifting up and everting the upper lip: levator labii superioris, levator labii superioris alaeque nasi, risorius, levator anguli oris, zygomaticus major and zygomaticus minor muscles.
• Lowering and everting the lower lip: depressor labii inferioris, depressor anguli oris and mentalis muscles.
• Closing the lips: orbicularis oris muscle.
• Compacting the cheek: buccinator muscle.

Each muscle is described individually below;