Dominic Stone
The zygomaticus major muscle is a facial muscle that extends diagonally from the zygomatic bone to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor muscle. The zygomaticus major muscle is responsible for smiling and emotional expression. It controls the way in which we smile, and research has shown its role in distinguishing between genuine and deliberate smiles.
| Characteristics | Values |
|---|---|
| Type | Facial muscle |
| Location | Cheek area |
| Origin | Zygomatic bone |
| Insertion | Angle of the mouth |
| Innervation | Zygomatic and buccal branches of facial nerve (CN VII) |
| Arterial Supply | Facial artery and its superior labial branch |
| Function | Elevation of the angle of the mouth; smiling, emotional expression, and speech |
| Dimples | May occur in bifid form, causing cheek dimples |
| Force | Average muscle can contract with a force of 200 g |
| Surgery | May be used in reconstructive surgery to replace lost tissue |
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What You'll Learn
- The zygomaticus major muscle is responsible for smiling
- It is one of two zygomatic muscles, the other being the zygomaticus minor
- It is innervated by the zygomatic and buccal branches of the facial nerve
- The muscle is involved in creating other facial expressions, such as disdain and contempt
- Variations in the zygomatic muscle can cause dimples
The zygomaticus major muscle is responsible for smiling
The zygomaticus major muscle is a thin, paired facial muscle that extends diagonally from the zygomatic bone (or cheekbone) to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor, and both lie next to each other in the cheek area.
The zygomaticus major muscle is also involved in distinguishing between genuine and deliberate smiles. Research using facial electromyography (fEMG) has shown that spontaneous smiles, which are often considered more genuine, are typically shorter in duration (around 4-6 seconds), have a slower offset, and are more symmetrical than deliberate smiles.
The muscle is innervated by the zygomatic and buccal branches of the facial nerve (CN VII) and supplied with arterial blood by the facial artery and its superior labial branch. The average zygomaticus major muscle can contract with a force of 200 g.
In some individuals, variations in the zygomaticus major muscle can cause cheek dimples when smiling. This occurs when the muscle divides into two parts, forming two separate bundles before inserting into the connective tissue of the mouth corner.
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It is one of two zygomatic muscles, the other being the zygomaticus minor
The zygomaticus major muscle is a thin, paired facial muscle that extends diagonally from the zygomatic bone to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor. Both muscles lie next to each other in the cheek area. The zygomaticus major muscle arises from the lateral surface of the zygomatic bone, also known as the cheekbone, and its origin site is located anterior to the zygomaticotemporal suture and lateral to the origin site of the zygomaticus minor muscle.
The main action of the zygomaticus major muscle is to elevate the angle of the mouth in the upward and lateral directions, creating facial expressions of pleasure or laughter. In synergy with the risorius muscle, the zygomaticus major produces the expression of smiling. This function is followed by the deepening of the nasolabial groove. The average muscle can contract with a force of 200 g.
The zygomaticus major muscle is innervated by the zygomatic and buccal branches of the facial nerve (CN VII) and is supplied with arterial blood by the facial artery and its superior labial branch. The facial artery and its accompanying vein run between the buccinator and zygomaticus major muscles. The zygomaticus major is classified as a buccolabial muscle, which means it facilitates speech and creates facial expressions.
Variations in the zygomaticus major muscle are known to cause dimples when smiling. The muscle sometimes divides into two parts, forming two separate bundles, resulting in cheek dimples. The split is known as the duplication or bifurcation of the zygomaticus major. Skin movements over the split result in dimples, such as when smiling. The zygomaticus major muscle may also be used in reconstructive surgery to replace lost tissue, such as with injuries to the lips.
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It is innervated by the zygomatic and buccal branches of the facial nerve
The zygomaticus major muscle is a thin, paired facial muscle that extends diagonally from the zygomatic bone (also known as the cheekbone) to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor. The zygomaticus major muscle is responsible for smiling and emotional expression. It controls the way in which we smile and is deemed the "laughing muscle".
The zygomaticus major muscle is innervated by the zygomatic and buccal branches of the facial nerve (CN VII). The facial nerve is the seventh cranial nerve, and it plays a crucial role in facial expression and movement. It emerges from the brainstem and passes through the skull to reach the muscles of the face. The zygomatic and buccal branches of the facial nerve specifically supply the zygomaticus major muscle with nerve impulses, enabling it to contract and create facial expressions.
The nerve supply provided by these branches of the facial nerve allows the zygomaticus major muscle to function properly and coordinate its movements with other muscles of the buccolabial group. This integration of muscles in the cheeks, lips, and chin enables a wide range of facial expressions and facilitates speech. The buccolabial group includes muscles such as the risorius, levator labii superioris, and depressor anguli oris, which work together to form the structure and carry out the functions of the cheeks and lips.
The zygomaticus major muscle is primarily responsible for pulling the angle of the mouth upward and laterally, creating the appearance of a smile. This movement also deepens and raises the nasolabial furrow, contributing to facial expressions such as smiling, disdain, contempt, or smugness. The contraction of this muscle is measured using facial electromyography (fEMG), which detects the electrical activity underlying muscle movement.
The innervation of the zygomaticus major muscle by the zygomatic and buccal branches of the facial nerve is essential for its function and allows for the complex movements and expressions that shape our emotional responses and interactions with others.
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The muscle is involved in creating other facial expressions, such as disdain and contempt
The zygomaticus major muscle is a thin, paired facial muscle that extends diagonally from the zygomatic bone to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor muscle. These muscles lie next to each other in the cheek area. The zygomaticus major muscle is responsible for creating facial expressions, such as smiles, and distinguishing between genuine and deliberate smiles.
The zygomaticus major muscle is involved in creating a range of facial expressions beyond just smiling. It works in conjunction with other muscles of facial expression that elevate the lip, such as the levator labii superioris alaeque nasi, levator labii superioris, and risorius. Together, these muscles can produce expressions of disdain, contempt, or smugness by raising the upper lip to bare the upper teeth and deepening and raising the nasolabial furrow.
The activation of the zygomaticus major muscle is associated with positive emotions and expressions of pleasure or laughter. However, research using fEMG (facial electromyography) has shown that its activation is not exclusively linked to positive emotions. For example, when activated in combination with other muscles, it can contribute to expressions of disdain or contempt.
The role of the zygomaticus major muscle in creating facial expressions is further influenced by the presence of cheek dimples. Individuals with cheek dimples typically have a variation of the zygomaticus major muscle, where it divides into two separate bundles before inserting into the connective tissue of the mouth corner. This division creates a split or bifurcation, resulting in the formation of dimples when smiling or expressing other emotions.
The zygomaticus major muscle is an essential component of our facial anatomy, contributing to our emotional expressions and how we relate to the world. By working in conjunction with other muscles, it enables us to convey a range of emotions, including disdain and contempt, beyond just smiling and laughter.
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Variations in the zygomatic muscle can cause dimples
The zygomaticus major muscle is a thin, paired facial muscle that extends diagonally from the zygomatic bone to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor. Both muscles lie adjacent to each other in the cheek area. The zygomaticus major muscle is responsible for raising the upper lip to bare the upper teeth and deepening the nasolabial furrow. It also works in conjunction with other muscles to produce facial expressions such as smiling, laughing, disdain, contempt, or smugness.
The formation of cheek dimples is often attributed to variations in the zygomaticus major muscle. Specifically, individuals with cheek dimples typically have a bifid zygomaticus major muscle, which means that the muscle is split into two fascicles that are partially or completely separate from each other but remain adjacent. This split can result in two insertion points instead of one, leading to the formation of dimples when the muscle contracts during smiling or other facial expressions.
The occurrence of bifid zygomaticus major muscle has been observed in anatomical studies, with an incidence rate of 34% in one particular study involving cadaver dissections. This variation in muscle morphology can provide a possible explanation for the presence of cheek dimples in certain individuals.
It is important to note that the inheritance pattern of cheek dimples can be unpredictable, and they are often classified as an irregular dominant trait. While dimples are generally considered a genetic trait, the specific mechanisms of their inheritance are not yet fully understood. Multiple genes may influence the presence of cheek dimples, and further research is needed to unravel the complex genetics underlying this trait.
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Frequently asked questions
The zygomaticus major is a thin, paired facial muscle that extends diagonally from the zygomatic bone (cheekbone) to the angle of the mouth. It is one of two zygomatic muscles, the other being the zygomaticus minor.
The main function of the zygomaticus major is to elevate the angle of the mouth in the upward and lateral directions, producing facial expressions such as smiling, disdain, contempt, or laughter. It is also involved in speech.
The zygomaticus major is often referred to as the "laughing muscle" or the "smiling muscle". When activated, it pulls the angle of the mouth upward and outward, creating the appearance of a smile. Research using fEMG (facial electromyography) has shown that this muscle is involved in distinguishing between genuine and deliberate smiles.
