Zygomaticus Major vs Synkinesis: When Smiling Doesn’t Feel Right

A smile is one of the most powerful and sincere expressions of human communication. However, even this simple gesture can turn into complex problems after facial paralysis or nerve damage. At this point, while the zygomaticus major muscle shapes the facial expression as the main actor of the smile, errors in nerve healing can lead to involuntary muscle movements called “synkinesis”. This causes the smile to look unnatural, asymmetry in facial expressions and loss of control. A smile that does not look right is not only an aesthetic problem, but also has negative effects on social interaction and psychological health. In this article, the functions of the Zygomaticus Major muscle, the causes, symptoms and treatment options of synkinesis will be examined in detail. Our aim is to understand this complex condition and guide you to achieve healthy facial movements.

Role of the Zygomaticus Major Muscle

The zygomaticus major muscle has an important place among the facial mimic muscles and plays a critical role especially in the creation of smile and facial expression. This muscle extends from the cheekbone (zygomatic bone) to the corner of the mouth and when contracted, it pulls the corner of the mouth upwards and outwards. This movement creates a natural and sincere smile. In this context, the proper functioning of the Zygomaticus Major contributes to a lively, warm facial expression and effective social communication. In addition, its neural control is provided by a branch of the facial nerve (nervus facialis). Therefore, any nerve damage or muscle weakness can impair the function of this muscle and cause the smile to appear asymmetrical or inadequate. Especially in cases such as facial paralysis, affecting the Zygomaticus Major muscle prevents a person from fully reflecting their emotional expressions and can lead to difficulties in social interaction. Therefore, a good understanding of the anatomy and function of the muscle has an important place in the treatment of facial expression disorders.

Why does synkinesis of the zygomaticus major muscle occur?

Synkinesis of the zygomaticus major muscle is a complication that usually occurs during the nerve recovery process after facial paralysis. When the facial nerve is damaged, the nerve fibers have to rebuild themselves and reconnect to the muscles. However, this healing process is not always flawless; the nerve wires can be misdirected and involuntarily stimulate the Zygomaticus Major muscle as well as other facial muscles. This disrupts the natural movement patterns of the muscles and leads to involuntary contractions. For example, when a person wants to smile, the eyelid muscles may involuntarily contract along with the Zygomaticus Major muscle, causing the eyes to close involuntarily. At the same time, these misconnections of nerves disrupt the coordination of facial movements and prevent the smile from looking natural and symmetrical. Therefore, nerve recovery after facial paralysis should be closely monitored and the risk of synkinesis should be minimized with appropriate treatment.

How Does Synkinesis of the Zygomaticus Major Muscle Develop?

Synkinesis of the zygomaticus major muscle develops as a result of incorrect nerve connections during the recovery process of the nerves after facial paralysis. Normally, facial nerves control different muscle groups separately and in a coordinated manner. However, when nerve damage occurs in facial paralysis, the nerve wires may have directional errors as they reconstruct themselves. In this case, the nerve wires can send the wrong nerve impulses to different muscles than the target muscles. Especially in muscles that enable smiling, such as the Zygomaticus Major muscle, this incorrect connection of the nerves causes involuntary contractions. For example, when a person wants to smile, not only the Zygomaticus Major muscle but also the eyelid muscles contract involuntarily, leading to asymmetry in facial movements and facial expression disorders.

The development of facial synkinesis depends on factors such as the extent of nerve damage, the effectiveness of interventions in the healing process and the timeliness of rehabilitation. With early diagnosis and treatment, the effects of these incorrect nerve connections can be reduced and facial function can be restored.

How to recognize synkinesis of the zygomaticus major muscle?

Synkinesis of the Zygomaticus Major muscle is recognized when involuntary contractions and asymmetry are noticed in the patient's facial movements. Especially when smiling, normally only the Zygomaticus Major muscle that pulls the corner of the mouth up and out is active, but in case of synkinesis, the eyelid muscles or other facial muscles involuntarily contract in addition to this muscle. This is manifested by the patient involuntarily closing their eyes when smiling or experiencing muscle spasms on one side of the face.

During a clinical examination, the doctor carefully observes the patient's facial movements and assesses which muscles are working involuntarily. In addition, electrophysiological tests such as electromyography (EMG) examine nerve and muscle function by measuring the electrical activity of the muscles. In this context, EMG supports the diagnosis of synkinesis by showing whether nerves are sending impulses to the wrong muscles. In addition, when the patient's complaints and clinical findings are evaluated together, synkinesis in the Zygomaticus Major muscle can be clearly identified. Thus, the correct treatment plan can be created.

Symptoms of Synkinesis in the Zygomaticus Major Muscle

There are certain symptoms in cases of synkinesis in the zygomaticus major muscle. These symptoms vary according to the course of the disease. If it is necessary to discuss these symptoms in detail, they are as follows;

• Involuntary and concomitant contraction of the eyelid during smiling (blinking or closing)
• Facial asymmetry, abnormal movements on one side of the face, especially when smiling
• Involuntary muscle spasms and a feeling of muscle stiffness
• Loss of control of facial expressions and unnatural movements
  Involuntary contraction of other muscles during speaking, eating or facial expressions
• Uncoordinated coordination of the smile and the expression appears artificial
• Muscle fatigue or discomfort
• Limitation of movement and weakness on the affected side of the face

Diagnostic Process of Synkinesis in the Zygomaticus Major Muscle

The diagnostic process of synkinesis in the Zygomaticus Major muscle begins with the patient's complaints and clinical evaluation. At this point, the specialist carefully examines the movements of the facial mimic muscles and evaluates the signs of involuntary contraction and coordination disorder, especially in the area where the Zygomaticus Major muscle functions. During the examination, the patient's facial movements are observed and an electromyography (EMG) test can be applied to support the diagnosis; EMG measures the electrical activity of the muscles and reveals whether the nerves are sending impulses to the wrong muscle groups. In addition, methods such as video recording and photo analysis can be used to examine facial movements in detail.

In this process, related branches such as neurologists, plastic surgeons or physical therapists work together and adopt a multidisciplinary approach. Accurate diagnosis is critical for the creation of an effective treatment plan.

Treatment Options for Synkinesis in the Zygomaticus Major Muscle

There are different treatment options for synkinesis in the zygomaticus major muscle. However, these treatment options are evaluated according to the course of synkinesis. In this context, the treatment options for synkinesis in the Zygomaticus major muscle are as follows;

• Physical Therapy and Facial Exercises: Special exercise programs are applied to increase muscle coordination and reduce involuntary contractions.
• Botulinum Toxin (Botox) Injections: With Botox application for facial paralysis, muscle activity is temporarily suppressed and involuntary movements are taken under control.
• Electrostimulation: Electrical impulses can be applied to support the muscles to work properly.
• Surgical Intervention: In rare and severe cases, surgical methods such as nerve transfer or muscle decompression may be preferred.
• Multidisciplinary Approach: The collaboration of neurologists, plastic surgeons and physical therapists increases the success of treatment.
• Psychological Support: Counseling and support programs are recommended for the social and psychological effects of facial expression disorders.
• Selective Neurolysis: Selective neurolysis is a method of surgically selectively cutting or destroying nerve branches to prevent involuntary muscle contractions. This method is especially preferred in cases of severe synkinesis that do not respond to other treatments.

If you are experiencing synkinesis in the zygomaticus major muscle, you can contact Dr. Berke Özücer and his team, who are experts in facial synkinesis.