Corpus: Mimic musculature

The mimic muscles are a group of muscles in the facial region that connect to the skin above them, enabling physical expression of emotions and moods through their movement.

The mimic muscles develop from the embryonic pharyngeal arches, especially the second arch, and are innervated by branches of the facial nerve. Most of these muscles originate from the cranial bones or subcutaneous tissue, attaching to the skin via elastic end tendons. These muscles generally lie within the subcutaneous fat layer without a fascia, except for the buccinator muscle, which is covered by the buccopharyngeal fascia.

The mimic muscles can be grouped by their location and direction. Below is a breakdown of these muscles by facial region:

3.1. Frontal and epicranium

• Occipitofrontalis muscle
  • Frontal belly
  • Occipital belly
• Temporoparietal muscle

Together, the occipitofrontalis and temporoparietal muscles are referred to as the epicranius muscles.

3.2. Eye

• Orbicularis oculi muscle
• Corrugator supercilii muscle
• Depressor supercilii muscle

3.3. Nose

• Nasalis muscle
• Depressor septi muscle
• Procerus muscle
• Levator labii superioris alaeque nasi muscle

3.4. Mouth

• Superficial layer
  • Orbicularis oris muscle
  • Depressor anguli oris muscle
  • Risorius muscle
  • Mentalis muscle
  • Levator labii superioris muscle
  • Greater zygomatic muscle
  • Lesser zygomatic muscle
• Deep layer
  • Buccinator muscle
  • Depressor labii inferioris muscle
  • Levator anguli oris muscle

The levator labii superioris alaeque nasi muscle and the lesser zygomatic muscle are also attributed to the levator labii superioris muscle in the anatomical literature and then addressed as the angular and zygomatic head of this muscle.

3.5. Other

• Platysma

3.6. Ear muscles

The ear muscles are also sometimes categorized as part of the mimic muscles. These include:

• Anterior auricular muscle
• Posterior auricular muscle
• Superior auricular muscle
• Minor helical muscle
• Major helical muscle
• Tragicus muscle
• Antitragicus muscle
• Transversus auricular muscle
• Oblique muscle of auricle

All mimic muscles are innervated by branches of the facial nerve (cranial nerve VII).

The mimic muscles enable essential functions like closing the eyelids and mouth. They also play a significant role in shaping the lips and oral cavity, which affects speech articulation. More broadly, these muscles are vital for facial expressions, making them essential for non-verbal communication.

Mimic muscle function is altered in several clinical conditions, such as facial nerve palsy, which paralyzes one side of the face. In tetanus, facial muscles may produce the characteristic expression known as risus sardonicus.

• Artnatomy - the mimic musculature in action