Zygomaticus Major

Definition

The zygomaticus major is a facial muscle that originates from the zygomatic bone and inserts into the angle of the mouth, playing a key role in the movement and expression of the lips and cheeks. This muscle is an important component of the axial musculature of the head, neck, and back.

5 Must Know Facts For Your Next Test

1. The zygomaticus major muscle is responsible for pulling the corners of the mouth upward and laterally, resulting in a characteristic smile expression.
2. This muscle is innervated by the buccal branch of the facial nerve (cranial nerve VII), which controls the voluntary movement of the facial muscles.
3. Contraction of the zygomaticus major muscle, along with the zygomatic minor and orbicularis oculi muscles, is associated with the Duchenne smile, a genuine and spontaneous expression of happiness.
4. Weakening or paralysis of the zygomaticus major muscle can lead to an asymmetric smile or facial asymmetry, which may be a symptom of certain neurological conditions.
5. The zygomaticus major muscle is often used as a target for botulinum toxin injections to treat conditions such as excessive grinning or undesirable facial expressions.

Review Questions

• Describe the anatomical location and function of the zygomaticus major muscle.
  • The zygomaticus major muscle originates from the zygomatic bone and inserts into the angle of the mouth. Its primary function is to pull the corners of the mouth upward and laterally, contributing to the expression of a smile. This muscle is an important component of the axial musculature of the head and plays a crucial role in facial expressions and movements.
• Explain the innervation and clinical significance of the zygomaticus major muscle.
  • The zygomaticus major muscle is innervated by the buccal branch of the facial nerve (cranial nerve VII), which controls the voluntary movement of the facial muscles. Weakening or paralysis of this muscle can lead to an asymmetric smile or facial asymmetry, which may be a symptom of certain neurological conditions. Additionally, the zygomaticus major muscle is often targeted for botulinum toxin injections to treat conditions such as excessive grinning or undesirable facial expressions.
• Analyze the role of the zygomaticus major muscle in the Duchenne smile and its implications for emotional expression.
  • The contraction of the zygomaticus major muscle, along with the zygomatic minor and orbicularis oculi muscles, is associated with the Duchenne smile, a genuine and spontaneous expression of happiness. This type of smile is considered a marker of authentic emotional expression, as it involves the activation of both the voluntary and involuntary facial muscles. The zygomaticus major's contribution to the Duchenne smile highlights its importance in the communication and interpretation of genuine emotional states, which has significant implications for understanding human behavior and social interactions.

Related terms

Zygomatic Bone:

The zygomatic bone, also known as the cheekbone, is a paired bone located on the lateral aspect of the face that forms the prominence of the cheek.

Risorius:

The risorius is a small facial muscle that originates from the fascia over the parotid gland and inserts into the angle of the mouth, contributing to the movement of the lips during facial expressions.

Orbicularis Oris:

The orbicularis oris is a circular muscle that surrounds the lips and plays a crucial role in various oral functions, such as pursing the lips, whistling, and speaking.