Dalley, 10th Edition

129

Muscles of Back

Occipitalis Epicranial aponeurosis Obliquus capitis superior Rectus capitis posterior minor Posterior tubercle of atlas Rectus capitis posterior major Longissimus capitis External occipital protuberance Greater occipital nerve (C2)

Inferior nuchal line

Occipital bone

Superior nuchal line Occipital artery Obliquus capitis superior Digastric Longissimus capitis Suboccipital nerve (C1) Obliquus capitis inferior Greater occipital nerve (C2) Least (third) occipital nerve (C3)

2

C2

Greater occipital nerve (C2) Third occipital nerve (C3) Great auricular nerve (C2, C3) Lesser occipital nerve (C2, C3) Fourth cervical nerve (C4)

Spinous process of axis

Nerve C4

C3

Semispinalis capitis

Deep cervical vein Semispinalis cervicis

C4

Interspinales Spinous process of vertebra (C7)

C5

C6

(A) Posterior view

(B) Posterior view

FIGURE 2.44. Innervation of suboccipital region and posterior scalp. A. Dissection of posterior cervical region. B. Sensory innervation.

TABLE 2.13. NERVES OF POSTERIOR CERVICAL REGION, INCLUDING SUBOCCIPITAL REGION/TRIANGLES

Nerve

Origin

Course

Distribution

Suboccipital

Posterior ramus of spinal nerve C1 Runs between cranium and C1 verte bra to reach suboccipital triangle

Muscles of suboccipital triangle (no cutaneous distribution)

Greater occipital

Posterior ramus of spinal nerve C2 Emerges inferior to obliquus capitis inferior and ascends to posterior scalp

Skin over the neck and occipital bone

Lesser occipital

Anterior rami of spinal nerves C2–C3

Passes directly to skin

Skin of superior posterolateral neck and scalp posterior to external ear

Posterior rami, nerves C3–C7

Posterior rami of spinal nerves C3–C7

Pass segmentally to muscles and skin Intrinsic muscles of back and overlying skin (adjacent to vertebral column)

CLINICAL BOX MUSCLES OF BACK Back Strains, Sprains, and Spasms Adequate warm-up and stretching and exercises to increase the tonus of the “core muscles” (muscles of the anterolateral abdominal wall—especially the transversus abdominis—determined to play a role in lumbar stabilization) prevent many back strains and sprains, common causes of lower back pain. Back sprain is an injury in which only ligamentous tissue, or the attachment of ligament to bone, is involved, without dislocation or fracture. It results from excessively strong

contractions related to movements of the vertebral column, such as excessive extension or rotation. Back strain is a common injury in people who participate in sports; it results from overly strong muscular contraction. The strain involves some degree of stretching or microscopic tearing of muscle bers. The muscles usually involved are those producing movements of the lumbar IV joints, es pecially the erector spinae. If the weight is not properly balanced on the vertebral column, strain is exerted on the muscles. Using the back as a lever when lifting puts an enormous strain on the vertebral column and its ligaments and muscles. Strains can be minimized if the lifter crouches, holds the back

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