Zygomaticus major muscle

Zygomaticus Major Muscle

The Zygomaticus Major Muscle is a facial muscle that plays a crucial role in the expression of emotions, particularly in smiling and laughing. Originating from the zygomatic bone, it extends downwards and medially, inserting into the corners of the mouth. This muscle is innervated by the facial nerve (Cranial Nerve VII), allowing for voluntary and involuntary movements associated with facial expressions.

Anatomy

The Zygomaticus Major Muscle originates from the lateral aspect of the Zygomatic Bone, just below the zygomatico-orbital foramen. It travels obliquely downward and medially, passing over the Zygomaticus Minor Muscle when present, and inserts into the skin and muscle at the corner of the mouth, blending with fibers of the Orbicularis Oris Muscle.

Function

The primary function of the Zygomaticus Major is to elevate and draw the angle of the mouth superiorly and laterally. This action is predominantly seen during smiling and laughing, making it an essential muscle for facial expressions of joy and happiness. Through its contraction, the Zygomaticus Major pulls the upper lip upwards and outwards, creating the characteristic smile.

Innervation

The Zygomaticus Major is innervated by the buccal branch of the Facial Nerve (Cranial Nerve VII). This nerve provides the motor innervation necessary for the muscle to contract and perform its function in facial expression.

Clinical Significance

Damage to the Facial Nerve can result in paralysis of the Zygomaticus Major Muscle, leading to a loss of the ability to smile on the affected side of the face. This condition is often seen in Bell's Palsy, a temporary paralysis of the facial muscles. Additionally, cosmetic procedures and surgeries involving the face may target or affect the Zygomaticus Major due to its role in facial expressions.

See Also

• Facial Muscles
• Facial Nerve
• Zygomatic Bone
• Bell's Palsy

References

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  Zygomaticus major muscle illustration from 1909
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  Animation of the zygomaticus major muscle
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  Zygomaticus major muscle