Dominic Stone
Smiling is viewed across cultures as a sign of friendliness, especially when greeting someone. The human face has 43 muscles, most of which are controlled by the seventh cranial nerve, also known as the facial nerve. While it is hard to tell exactly how many muscles are used when smiling, it is possible to determine the minimum number of muscles used in the most insincere, subtle, restrained, mouth-only smile. There are five muscle pairs (or 10 total muscles) that accomplish this. The zygomaticus major is the muscle most responsible for our smile and is often referred to as the smile muscle. It works in conjunction with up to 43 other facial muscles to provide a wide array of smiles.
| Characteristics | Values |
|---|---|
| Number of muscles involved in a smile | 10-43 |
| Main muscles involved | Zygomaticus major and minor |
| Other muscles involved | Orbicularis oris, depressor anguli oris, levator labii superioris, risorius, corrugator supercilii, procerus, orbicularis oculi |
| Nerve involved | Facial nerve (VII) |
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What You'll Learn
The zygomaticus major is the most responsible for our smile
Smiling is viewed across cultures as a sign of friendliness, especially when greeting someone. While there are differing views on the number of muscles involved in smiling, it is known that the zygomaticus major is the most responsible for our smile. This muscle works in conjunction with up to 43 other facial muscles to produce a wide range of smiles.
The zygomaticus major is a strap of facial muscle below the cheekbones that pulls up the corners of the mouth. It is part of a group of muscles known as the zygomatic muscles, which also includes the zygomaticus minor. These muscles work together to pull the orbicularis oris (the circular muscle of the mouth) upwards to form a smile.
The zygomaticus major is also responsible for the formation of cheek dimples. In people without dimples, this muscle travels from the zygomatic bone in one cluster to connect to the corner of the mouth. However, in people with dimples, the zygomaticus major splits into two bundles before connecting to the mouth, forming a bifid zygomaticus major muscle. This split causes one bundle to connect to the corner of the mouth, while the other connects slightly below, creating a dimple.
The zygomaticus major is not just involved in smiling but also plays a role in other facial expressions. For example, in Bell's palsy, the depressor anguli oris muscle can sometimes activate alongside the zygomaticus major, resulting in an asymmetrical smile. In this case, the depressor anguli oris muscle, which pulls the mouth corner downwards, can overpower the zygomaticus major, leading to a "crooked" smile.
In summary, the zygomaticus major muscle is the primary muscle responsible for our smile. It works in conjunction with other facial muscles to produce a variety of smile configurations and is also involved in the formation of cheek dimples and certain facial expressions.
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The zygomaticus minor also works to form a smile
Smiling is a complex process that involves the coordination of many facial muscles. While the zygomaticus major is often referred to as the "smiling muscle", it is not the only muscle involved in forming a smile. The zygomaticus minor, along with the major, also plays a crucial role in creating a smile.
The zygomaticus minor is one of the 43 muscles in the human face that contributes to our facial expressions. These muscles are controlled by the seventh cranial nerve, also known as the facial nerve (VII). When activated, these muscles send signals to the brain that we are smiling.
The zygomaticus minor, in particular, works together with the zygomaticus major to pull the orbicularis oris (the circular muscle of the mouth) upwards. This action results in the upturning of the corners of the mouth, which is a key component of a smile. The zygomaticus minor helps to create the curvature of the lips that we associate with a smile.
Additionally, the zygomaticus minor can contribute to the formation of dimples in the cheeks. While the presence of dimples depends on the structure of the zygomaticus major, the minor muscle can influence the appearance of dimples during a smile. This occurs when the zygomaticus major splits into two bundles before connecting to the mouth, with one bundle connecting slightly below to form a dimple.
In summary, the zygomaticus minor is an important muscle that assists in forming a smile by working in conjunction with the zygomaticus major to pull the corners of the mouth upwards and create the characteristic curvature of the lips. Its involvement in smile formation can also influence the presence of dimples in some individuals.
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The risorius pulls the corners of the mouth outward
Smiling is viewed across cultures as a sign of friendliness, especially when greeting someone. The risorius muscle, also known as the "smiling muscle", is one of the muscles responsible for this action. It is a slender and narrow facial muscle that belongs to the buccolabial group of muscles. It is found in the superficial layer of the facial muscles, on either side of the lips, overlying the buccinator muscle.
The risorius muscle is a narrow bundle of muscle fibres that originates at the fascia of the lateral cheek, passing over the parotid gland, the superficial masseter, and platysma muscles, before inserting into the skin at the angle of the mouth. It works in conjunction with other muscles to create facial movement, pulling the corners of the mouth outward and upward to form a smile. This movement also aids in producing other facial expressions such as smirking, grinning, and frowning.
The risorius muscle is innervated by the facial nerve, specifically by one of its branches known as the buccal branch or the marginal mandibular branch. It receives its arterial blood supply from the facial artery and the transverse facial artery, which are branches of the external carotid artery. The facial and transverse facial veins drain deoxygenated blood from the risorius muscle, with the facial vein draining into the common facial vein and then into the internal jugular vein.
The risorius muscle is not present in all individuals and is believed to be unique to African great apes and humans, evolving from our common ancestor. It is an important muscle for facial expressions and can be targeted through cosmetic surgical procedures or facial exercises to alleviate sagging or drooping in the area.
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The depressor anguli oris pulls the mouth corners downward
Smiling is viewed across cultures as a sign of friendliness, especially when greeting someone. While there is no definitive number for how many muscles it takes to smile, it is believed that there are 43 muscles in the face, most of which are controlled by the seventh cranial nerve, also known as the facial nerve. The facial nerve splits into five primary branches: temporal, zygomatic, buccal, mandibular, and cervical. These branches control the movement of the muscles that control the mouth.
The depressor anguli oris (DAO) is responsible for pulling the corners of the mouth down and expressing emotions such as sadness or questioning. It is sometimes referred to as the "sadness muscle" because of its association with frowning. When the DAO is overactive or weak, it can cause a person to appear as if they are frowning even when their face is at rest. Issues with this muscle can also make it difficult to smile, resulting in a lopsided smile or excessive frowning.
Congenital hypoplasia of the DAO muscle can cause facial asymmetry at birth, with one corner of the mouth failing to move downward when the child cries. In rare cases, this condition can also affect adults, making it difficult to express emotions through the mouth.
To address issues with the DAO muscle, some people choose cosmetic procedures such as Botox to relax the depressor and allow the elevators to become more active. By blocking the nerve signals that cause the muscle to contract, Botox can help elevate the corners of the mouth and create a more positive facial expression. However, it is important to note that the effectiveness of these procedures may vary, and some individuals may require regular injections to maintain the desired results.
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The levator labii superioris pulls the upper lip up
Smiling is viewed across cultures as a sign of friendliness, especially when greeting someone. While there is no definitive number for how many muscles it takes to smile, it is believed that 10 muscles are used in the most insincere, subtle, restrained, mouth-only smile.
The levator labii superioris (LLS) is one of the muscles responsible for pulling the upper lip up during a smile. This muscle sits beneath the orbicularis oculi on the medial portion of the zygomatic bone, just in front of the zygomatic major muscle. It connects to the subcutaneous tissue of the upper lateral lip muscle.
The LLS is a thin, quadrilateral muscle that begins at the infraorbital margin of the maxilla and extends toward the upper lip. It integrates into the upper lip's muscle mass, the orbicularis oris, and works in conjunction with the upper lip's other muscles to elevate and evert the upper lip. By contracting, the LLS helps other buccolabial muscles elevate and invert the upper lip, exposing the maxillary teeth and deepening the nasolabial lines.
The LLS also plays a role in creating facial expressions of disgust, sadness, disdain, and seriousness. It is involved in nasal flaring, retching, and other oral movements. Additionally, the LLS contributes to the depth and contour of the nasolabial fold, which can be modified by the LLS and LLSAN.
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Frequently asked questions
The zygomaticus major is the muscle most responsible for our smile. It works in conjunction with up to 43 other facial muscles to produce a wide array of smiles.
The other muscles involved in smiling include the orbicularis oris, the zygomaticus minor, the risorius, the levator labii superioris, and the depressor anguli oris.
The zygomaticus major is the muscle that pulls up the corners of the mouth. It is located below the cheekbones.
It is generally believed that it takes 17 muscles to smile, but some sources claim it takes 26 or even 43. However, it is difficult to determine the exact number of muscles involved in a smile as it can vary depending on the individual and the type of smile.
There are three main types of smiles: reward smiles, affiliative smiles, and dominance smiles. Reward smiles are symmetrical hoists of the zygomaticus muscles with a slight eyebrow lift and sharp lip pulling. They are often used with babies or to express joy. Affiliative smiles are used to communicate tolerance, acknowledgment, or a bond and are characterized by a wide, thin upturn of the mouth with pressed lips and no exposed teeth. Dominance smiles signify status and are used to manage social hierarchies. They are lopsided and sneering, often paired with raised brows and lifted cheeks.
Yes, even a fake smile can fool your brain into thinking you are happy. Activating the muscles associated with smiling can trigger the release of endorphins, which are the body's natural painkillers and are associated with positive emotions.
