Victor Forge
The human head and neck contain a variety of muscles that serve important functions, including movement of the head, neck, eyes, and mouth, as well as facial expressions. The neck muscles, including the sternocleidomastoid and trapezius, are responsible for gross motor movements of the head and neck, allowing for flexion, extension, and rotation. The head also contains muscles of facial expression, such as the orbicularis oculi, which closes the eye, and the orbicularis oris, which moves the lips. The tongue is another important muscle in the head, receiving motor innervation from the hypoglossal nerve. The muscles of mastication, including the masseters and temporalis, are associated with jaw movements. These muscles, along with the extra-ocular muscles and the muscles of facial expression, contribute to the diverse functions of the head and neck.
| Characteristics | Values |
|---|---|
| Muscles of the head | The tongue, muscles of facial expression, extra-ocular muscles, and muscles of mastication |
| Muscles of facial expression | Frontalis, orbicularis oculi, orbicularis oris, buccinator, zygomaticus, corrugator supercilia, nasalis, procerus, depressor septi nasi |
| Muscles of mastication | Masseters, temporalis, medial pterygoid, lateral pterygoid |
| Neck muscles | Sternocleidomastoid, trapezius, erector spinae, iliocostalis, longissimus, spinalis, multifidus, interspinales, intertransversarii |
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What You'll Learn
Neck muscles control head movement
The neck is a complex structure of bones, muscles, nerves, blood vessels, and connective tissues. The neck muscles are part of a musculoskeletal system that connects the base of the skull to the torso. The neck muscles support the head and enable a range of movements, including moving the head, chewing, swallowing, and breathing. The neck muscles also protect other neurovascular structures necessary for sustaining life.
The cervical spine, or neck, is the most flexible part of the spine, allowing for large movements to scan our surroundings. The primary motions of the OA joint in the cervical spine are flexion and extension. The cervical spine also aids in swallowing and helps elevate the rib cage during inhalation. The vertebral bodies protect the spinal cord and vertebral arteries.
The neck muscles are innervated by various cervical nerves and their branches, as well as cranial nerves. Efferent nerves carry impulses from the spinal cord, causing muscles to contract and controlling cervical movements. The sternocleidomastoid muscle, for example, laterally flexes and rotates the head. The splenius muscles, including the splenius capitis and splenius cervicis, can extend, laterally flex, and rotate the head.
The posterior neck muscles, including the suboccipital and transversospinalis muscles, are primarily responsible for head movements like extension. The suboccipital muscles, located just below the occipital bone at the base of the skull, help extend the head in different directions. The transversospinalis muscles enable head movements like forward and backward movement, side-to-side tilting, and stabilisation of the spine.
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Eyes contain intrinsic and extrinsic muscles
The human eye contains intrinsic and extrinsic muscles that work together to enable vision. These muscles control eye movement, eye alignment, and how much light enters the eye.
Extrinsic eye muscles, also known as extraocular muscles, are attached to the outside of the eyeball and control the movement and position of the eyes. There are six extrinsic muscles that work in pairs to move the eyes in different directions. Four of these are straight (rectus) muscles, and two are oblique muscles. The rectus muscles include the superior rectus, which controls upward movement, the inferior rectus, the medial rectus, which moves the eye inward, and the lateral rectus, which moves the eye outward. The superior oblique and inferior oblique muscles work like pulleys, extending forward and threading through small bony openings in the eye socket.
Intrinsic eye muscles, on the other hand, are located within the eye and are responsible for focusing the eye and controlling the amount of light that enters through the iris. These muscles include the ciliary muscle, iris sphincter, and radial pupil dilator muscles. They enable the eye to focus on near objects and adjust the amount of light entering the eye.
Together, the extrinsic and intrinsic muscles work in harmony to facilitate vision and allow us to perceive the world around us accurately.
It is important to note that these eye muscles are subject to various disorders, which can be mild or severe. In severe cases, eye muscle surgery may be recommended to address the issue and restore normal eye function.
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Zygomaticus major muscles enable facial expressions
The human face has well-developed muscles that allow for a wide range of facial expressions. Facial muscles are unique in that they mostly connect bones to skin, rather than bones to other bones. The zygomaticus major is one such muscle, and it plays a crucial role in enabling facial expressions.
The zygomaticus major is a thin, paired facial muscle that extends diagonally from the zygomatic bone to the angle of the mouth. It is part of a group of muscles known as the buccolabial group, which control the shape and movements of the mouth and lips. This muscle works in conjunction with other muscles of facial expression to elevate the lip, curling it to produce facial expressions such as smiling, disdain, contempt, or smugness.
The zygomaticus major muscle also deepens and raises the nasolabial furrow and pulls the angle of the mouth superolaterally. In coordination with other buccolabial muscles, it facilitates speech and creates facial expressions. For example, when working in conjunction with the risorius muscle, the zygomaticus major contributes to laughing, which is why they are often referred to as the "laughing muscles."
The zygomaticus major muscle is also important in reconstructive surgery. Due to its role in elevating the upper lip and exposing the upper teeth, it can be used to replace lost tissue in cases of injuries to the lips.
In summary, the zygomaticus major muscle is a key player in enabling facial expressions, particularly those involving the movement of the upper lip and the angle of the mouth. By working in harmony with other facial muscles, it helps us convey a wide range of emotions and feelings through our facial expressions.
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Buccinator muscles compress the cheeks
The buccinator muscle is a facial muscle that is responsible for compressing the cheeks and expelling air between the lips. It is also involved in mastication and holding food in the mouth while chewing. Additionally, it plays a role in various facial expressions, such as whistling, blowing a kiss, or sucking on a lemon. The muscle is located deep within the facial muscles and can contribute to the appearance of lines, wrinkles, and sunken cheeks if not properly treated.
The buccinator muscle is the main component of the cheeks, along with a considerable amount of subcutaneous fat. It arises from the outer surfaces of the alveolar processes of the maxilla and mandible, corresponding to the three pairs of molar teeth. The muscle fibres converge toward the angle of the mouth, where the central fibres intersect each other, with those from below being continuous with the upper segment of the orbicularis oris, and those from above with the lower segment. The upper and lower fibres are then continued forward into the corresponding lip without decussation.
The buccinator muscle is not considered an expressive muscle, but rather a muscle used for chewing. However, because many other muscles overlay and intermingle with it, it is involved in several facial expressions. For example, the act of compressing the cheeks can be the precursor to whistling, blowing a kiss, or sucking on a lemon.
The buccinator muscle also has another interesting function: expelling the air from the inflated vestibule while playing a wind instrument such as the trumpet. This is why the buccinator muscle is also called the "trumpet muscle".
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The occipitofrontalis muscle moves the scalp and eyebrows
The occipitofrontalis muscle is a wide, two-bellied muscle that spans the dome of the skull. It is composed of two muscle bellies, or two physiologically and anatomically different muscles: the frontal belly and the occipital belly. The bellies are connected by a thick fibrous sheath called the epicranial aponeurosis (galea aponeurotica). The function of the occipitofrontalis muscle is to move the scalp and eyebrows.
The occipital belly of the occipitofrontalis muscle moves the scalp forwards, while the frontal belly lifts the eyebrows and moves the scalp backward. The frontal belly is responsible for elevating the eyebrows, while the corrugator supercilii, orbicularis oculi, and procerus muscles play a role in depressing the eyebrows. The frontalis muscle is the only muscle that raises the eyebrows, and it is necessary for conveying emotions and nonverbal communication.
The antagonist muscles to the frontalis muscle are the orbicularis oculi, corrugator, and procerus muscles. The frontalis, corrugator, procerus, and orbicularis muscles all have cutaneous insertions and have a confluence at the glabella and the orbital rim. The balance between these muscles determines the eyebrow position and shape. The corrugator muscle is below the frontalis and the orbicularis muscles and has a bony origin from the medial orbital rim.
The occipitofrontalis muscle is generally regarded as one muscle, but it appears to be composed of two physiologically and anatomically different muscles that separately affect the positions of the eyebrow and hairline. The occipital belly and the galea aponeurotica may create a deep musculoaponeurotic system anchored to the occipital bone, which may facilitate the retraction of the superficial musculoaponeurotic system. The deep musculoaponeurotic system may pull the scalp backwards, while the superficial musculoaponeurotic system lifts the eyebrow and pulls the scalp forwards.
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Frequently asked questions
The muscles in the head include the tongue, muscles of facial expression, extra-ocular muscles, and muscles of mastication.
Facial expression muscles are located in the subcutaneous tissue. They attach to the skin and contract to show emotions such as surprise, disgust, anger, and fear. These muscles can be divided into three groups: orbital, nasal, and oral.
Examples of muscles of facial expression include frontalis, orbicularis oculi, orbicularis oris, corrugator supercilia, nasalis, procerus, depressor septi nasi, buccinator, zygomaticus major, and zygomaticus minor.
