Dalley, 10th Edition

127

Muscles of Back

The four small muscles of the suboccipital region lie deep (anterior) to the semispinalis capitis muscles and consist of two rectus capitis posterior (major and minor) and two obliquus muscles. All four muscles are innervated by the posterior ramus of C1 , the suboccipital nerve . The nerve emerges

as the vertebral artery courses deeply between the occipital bone and the atlas (vertebra C1) within the suboccipital tri angle . Details concerning the boundaries and contents of this triangle and the attachments of the suboccipital muscles are illustrated in Figure 2.41 and described in Table 2.10.

2

Occipital region

Suboccipital region (deep)

Proximal Distal Muscle attachments

Suboccipital triangles

Posterior cervical region

Occipital bone

Trapezius ( 1 )

Semispinalis capitis ( 2 )

Rectus capitis posterior minor ( 5 ) Suboccipital nerve (C1)

1

3

2

Inferior nuchal line

4

Rectus capitis posterior major ( 6 ) Posterior atlantooccipital membrane

Sternocleidomastoid ( 3 ) Obliquus capitis superior ( 4 ) Longissimus capitis ( 7 )

5

6

7

Posterior arch (C1)

5

Suboccipital nerve (C1)

Transverse process (C1)

8

6

Vertebral artery

Obliquus capitis inferior ( 8 )

8

Transverse process (C2) Spinal ganglion (C2)

Splenius Semispinalis capitis Trapezius Greater occipital nerve (C2)

Vertebral artery

Semispinalis cervicis Interspinales

Posterior view

FIGURE 2.41. Suboccipital muscles and suboccipital triangle.

TABLE 2.10. SUBOCCIPITAL MUSCLES AND SUBOCCIPITAL TRIANGLE Suboccipital Muscles

Muscle

Origin

Insertion

Rectus capitis posterior major

Spinous process of vertebra C2

Lateral part of inferior nuchal line of occipital bone

Rectus capitis posterior minor

Posterior tubercle of posterior arch of vertebra C1 (atlas)

Medial part of inferior nuchal line of occipital bone

Obliquus capitis inferior

Spinous process of posterior arch of vertebra C2 (axis)

Transverse process of vertebra C1 (atlas)

Obliquus capitis superior Copyright © 2027 Wolters Kluwer. Unauthorized reproduction of the article is prohibited. Transverse process of vertebra C1 Occipital bone between superior and inferior nuchal lines

Suboccipital Triangle

Aspect of Triangle

Structures

Superomedial boundary

Rectus capitis posterior major

Superolateral boundary

Obliquus capitis superior

Inferolateral boundary

Obliquus capitis inferior

Floor

Posterior atlantooccipital membrane and posterior arch of vertebra C1 (atlas)

Roof

Semispinalis capitis

Contents

Vertebral artery and suboccipital nerve