Cervical Spinal Muscles
Muscles of the Cervical Spine
Muscles of the cervical spine can be grouped according to the nerves which innervate them, or their action. The Sternocleidomastoid is a major muscle innervated by C2 and C3; extends and rotates the head and flexes the vertebral column. The Rectus Capitus Anterior and the Rectus Capitus Lateralis are also innervated by C2 and C3 with the former acting to flex the head and the latter bending the head laterally. The Longus Capitus also flexes the head and is innervated by C1-C3. The Scalenus flexes and rotates the neck and is innervated by the lower cervical nerves.
Other muscles in the cervical spine which act to rotate the head include the Obliquus Capitus Inferior which is innervated by the subocciptal nerve (C1) and rotates the Atlas (the first cervical vertebra). Innervated by C1-C5, the Semispinalis Capitus rotates the head and pulls it backward as does the Longissimus Capitus which is innervated by the middle and lower cervical nerves. The Longissiumus Cervicus and the Iliocostalis Cervicus are extensor muscles innervated by the middle and lower cervical nerves and the Spinalis Cervicus and Spinalis Capitus are also extensors but are involved in the rotation of the head in addition to its extension. Innervated by the suboccipital nerve (C1) the Rectus Capitus Posterioir Major extends and rotates the head whilst the Rectus Capitus Posterioir Minor simply extends the head without being involved in its rotation. C1 also innervates the Obliquus Capitus Superioir to extend and bend the head laterally.
The three remaining cervical spinal muscles are the Semispinalis Cervicis, the Splenius Cervicis, and the Longus Colli Cervicis. The first two of these are innervated by the middle and lower cervical nerves and the latter by C2-C7. The Splenius Cervicis extends the vertebral column whilst the Semispinalis Cervicis extends and rotates the vertebral column. Flexion of the cervical vertebrae is the responsibility of the Longus Colli Cervicis muscle
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Last Updated: 1/22/2011