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The neck muscles support the head and enable a wide range of movements, including rotation. There are about 30 neck muscles, which extend from the base of the skull and jaw down to the shoulder blades and collarbone. These muscles work together with tendons and ligaments to support and move the neck and head. The neck muscles can be broadly categorised into anterior, lateral (prevertebral), and posterior muscles. The splenius capitis and splenius cervicis muscles, for instance, can extend, laterally flex, and rotate the head. The sternocleidomastoid muscle, commonly called the SCM, is a large muscle that helps protect fragile structures within the neck and also assists in head rotation and tilting the chin.
| Characteristics | Values |
|---|---|
| Sternocleidomastoid | Ipsilateral flexion and contralateral rotation of the neck at the cervical spine |
| Semispinalis capitis and cervicis | Extension of the head, cervical, and thoracic spine by bilateral contraction; ipsilateral lateral flexion of the head, cervical, and thoracic spine by unilateral contraction; contralateral rotation of the head, cervical, and thoracic spine by unilateral contraction |
| Rotatores cervicis | Extension of the spine by bilateral contraction, lateral flexion of the spine by unilateral contraction |
| Trapezius | Lateral flexion and contralateral rotation of the head when acting unilaterally, and extension of the head when acting bilaterally |
| Splenius muscles | Extension of the head when contracted bilaterally, unilateral contraction produces lateral flexion and rotation of the head to the same side |
| Scalene muscles | Flex, laterally flex, and rotate the head |
| Longus capitis | Weak flexor of the head when acting bilaterally, unilateral contraction produces ipsilateral rotation of the head |
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What You'll Learn
- Sternocleidomastoid muscles help with head rotation and tilting the chin
- Splenius muscles extend, laterally flex, and rotate the head
- Semispinalis muscles extend, flex, and rotate the head, cervical, and thoracic spine
- Trapezius muscles help extend the head and rotate/turn it
- Scalene muscles work together to flex, laterally flex, and rotate the head
Sternocleidomastoid muscles help with head rotation and tilting the chin
The sternocleidomastoid (SCM) muscle is a powerful neck muscle that helps with head rotation and tilting the chin. It is one of the largest and most superficial cervical muscles, originating at the manubrium of the sternum and the clavicle, and inserting at the mastoid process of the temporal bone of the skull. The SCM muscle has dual innervation by the accessory nerve (CN XI) and anterior rami of spinal nerves C2 and C3. It plays a crucial role in neck flexion, neck extension, and head rotation, with its function depending on whether it acts alone or in conjunction with its contralateral counterpart.
When the SCM muscle contracts unilaterally, it produces lateral flexion of the neck on the same side and rotates the head to the opposite side. This means that when you turn your head to the left or right, the SCM muscle on the opposite side contracts to facilitate this movement. Additionally, unilateral contraction of the SCM muscle can also cause lateral rotation of the head to the same side, resulting in a tilt of the chin toward the shoulder on that side.
On the other hand, when both sides of the SCM muscle contract simultaneously, it results in flexion of the neck, bringing the head toward the chest. This movement is often observed when we tilt our head forward, lowering our chin toward our chest. The SCM muscle is also essential for maintaining posture and stabilizing the neck, even when we are not actively moving our head.
Injuries, tension, and tightness in the SCM muscle can lead to neck stiffness, pain, and conditions such as torticollis, where the head naturally tilts or turns to one side. Treatment options for SCM-related issues include conservative approaches such as stretching, physical therapy, hot and cold therapy, massage, and osteopathic manipulation. In more severe cases, surgery may be required to address structural damage or tumours affecting the SCM muscle.
In summary, the sternocleidomastoid muscle plays a significant role in head rotation and tilting movements, as well as neck flexion and extension. Its function depends on its unilateral or bilateral contraction, and it works in conjunction with other neck muscles to facilitate these movements. Proper care and management of the SCM muscle are important to avoid pain, stiffness, and associated conditions.
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Splenius muscles extend, laterally flex, and rotate the head
The splenius muscles are a group of superficial muscles in the neck that originate at the midline and run laterally and superiorly to their insertions. These muscles include the splenius capitis and splenius cervicis. The splenius capitis originates from the spinous processes of the vertebrae, specifically C7-T3, and inserts onto the head region, attaching to the mastoid process of the temporal bone. On the other hand, the splenius cervicis originates on the spinous processes of the vertebrae T3-T6 and extends onto the cervical region, inserting on the transverse processes of the vertebrae C1-C3.
These splenius muscles have important functions in neck and head movements. When contracted bilaterally, they work together to extend the head and neck. In contrast, unilateral contraction of these muscles results in lateral flexion and rotation of the head to the same side. This means that when only one of these muscles contracts, it contributes to turning the head to that specific side.
The splenius muscles are not the only ones involved in rotating the head. Other muscles, such as the semispinalis capitis and semispinalis cervicis, also play a role in head rotation, in addition to their functions in lateral flexion and extension of the head.
In summary, the splenius muscles, particularly the splenius capitis and splenius cervicis, are crucial for extending, laterally flexing, and rotating the head. Their bilateral and unilateral contractions produce specific movements that allow us to turn and extend our heads, contributing to our overall ability to interact with our environment.
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Semispinalis muscles extend, flex, and rotate the head, cervical, and thoracic spine
The semispinalis muscles, as the name suggests, are a group of muscles that attach at one end to the spinous processes. The semispinalis muscles include the semispinalis capitis, the semispinalis cervicis, and the semispinalis thoracis.
The semispinalis capitis originates from the articular processes of vertebrae C4-C7 and the transverse processes of vertebrae T1-T6 or T7. It then courses upwards to insert between the superior and inferior nuchal lines of the occipital bone. The semispinalis cervicis arises from the transverse processes of vertebrae T1-T6 and inserts onto the spinous processes of vertebrae C2-C5. The semispinalis thoracis originates from the transverse processes of T6 to T10 and inserts onto the spinous processes of C6 to T4.
The semispinalis muscles work together to bilaterally extend the spine. Unilaterally, they contribute to the lateral flexion of the same side and rotation to the opposite side. The semispinalis capitis contributes to the extension, lateral flexion, and rotation of the head on the neck, as well as movement of the cervical spine (neck). The semispinalis cervicis and thoracis contribute to the extension, lateral flexion, and rotation of the cervical and thoracic spine.
The semispinalis muscles are contracted when the spine and head are extended, such as in the ustrasana (camel) yoga pose. They are lengthened when the spine and head are flexed.
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Trapezius muscles help extend the head and rotate/turn it
The trapezius muscles are two large, triangular muscles located on either side of the upper back. They get their name from the trapezoid shape they form when viewed together. These muscles are involved in the movement of the head, neck, and upper back, and help maintain and adjust posture.
The trapezius muscles are involved in several functions, including:
- Head extension: When both the left and right trapezius muscles contract simultaneously (bilateral contraction), they cause the head to extend or move backward.
- Head rotation: When acting unilaterally, the trapezius muscles produce lateral flexion and rotation of the head to the opposite side. This means that the head turns to the side that is opposite to the contracting muscle.
- Neck movement: The trapezius muscles help in neck extension, tilting, and rotation.
- Shoulder movement: The trapezius muscles are involved in elevating the shoulders, lifting the arms out to the side, and rotating the shoulder blades upward.
- Posture maintenance: These muscles play a crucial role in maintaining and adjusting posture, such as standing up straight or bending the upper back forward.
It is important to note that the actions of the trapezius muscles depend on the direction of contracting fibres. For example, the descending (upper) fibres contribute to elevating the scapula, while the ascending (lower) fibres are responsible for depressing or lowering the medial part of the scapula.
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Scalene muscles work together to flex, laterally flex, and rotate the head
The scalene muscles are a group of three pairs of muscles in the lateral neck: scalenus anterior, scalenus medius, and scalenus posterior. Sometimes, a fourth muscle, the scalenus minimus, is present behind the lower portion of the scalenus anterior. These muscles work together to flex, laterally flex, and rotate the head.
The scalenes are involved in several actions involving the neck, as well as the act of inhalation. During inhalation, the scalenes help elevate the ribs, while other muscles, like the diaphragm, expand the thoracic cavity. The scalenes are also involved in neck flexion, or the action of bringing the chin down toward the chest.
The scalenes are quite easy to injure or irritate as they are constantly working. Whiplash, a common injury in car accidents, occurs when the head snaps back and forth, causing distortion of the neck muscles, including the scalenes.
The degree of head rotation determines which scalene is targeted. To target the scalenus posterior, turn your face toward the pulling arm; to target the scalenus anterior, turn your face away from the pulling arm; and to target the scalenus medius, look straight up or slightly toward the pulling arm.
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Frequently asked questions
The muscles that are responsible for rotating the head include the splenius muscles, the erector spinae, the semispinalis muscles, the sternocleidomastoid, the scalene muscles, the suboccipital muscles, the trapezius, and the levator scapulae.
The splenius muscles extend the head when contracted bilaterally, while unilateral contraction produces lateral flexion and rotation of the head to the same side.
The erector spinae is a group of muscles that attach along the back of the spine. They play a key role in supporting posture, rotating the neck, and extending the neck backward.
The semispinalis muscles are responsible for the extension, lateral flexion, and contralateral rotation of the head, cervical, and thoracic spine.
The sternocleidomastoid muscle, commonly called the SCM, helps in head rotation and tilting the chin. It also assists in protecting the fragile structures within the neck.
