Reading
- p. 56 - 99 (Suboccipital...)
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- p. 439 - 457
- p. 460 - 466 (Craniovertebral Joints)
- p. 470 - 476
- p. 480 - 492 (Suboccipital)
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- p. 271 - 287 (Craniovertebral...)
- p. 288 (Movements...) - 304 (Suboccipital...)
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Body Surface
The primary surface landmarks of the back are associated with the skull (external occipital protuberance), spine (spinous process T1, spinous process C7 and ligamentum nuchae), scapula (inferior angle, medial border, spine and acromion) and innominate (iliac crest and posterior superior iliac spine). The skin overlying the back is innervated by the medial and lateral branches of the dorsal rami of spinal nerves.
Skeleton and Joints
The spine is comprised of 7 cervical, 12 thoracic and 5 lumbar vertebrae, the sacrum and coccyx supported by the anterior longitudinal, posterior longitudinal, ligamenta flava, intertransverse, interspinous and supraspinous ligaments. There are facet (zygapophyseal) joints between adjacent superior and inferior articular processes, and symphases (intervertebral discs) between the adjacent vertebral bodies and sacrum. The spine moves in flexion, extension, lateral flexion and rotation.
Fascial Organization
The deep muscles of the back and trunk are covered by the thoracolumbar (deep) fascia. In the thorax the fascia overlies the erector spinae muscles and separates them from the superficial back muscles that help to connect the upper extremity to the trunk. The thoracolumbar fascia has three layers in the lumbar region of the back. The anterior layer attaches to the vertebral transverse processes and passes anterior to the quadratus lumborum muscle. The middle layer also attaches to the transverse processes and passes between the quadratus lumborum and erector spinae muscles. The posterior layer attaches to the vertebral spinous processes and passes posterior to the erector spinae muscles. Laterally, the thoracolumbar fascia gives origin to some of the muscles of the anterior abdominal wall.
Muscles
The muscles of the back are arranged in three layers, superfical (mentioned above), intermediate (accessory respiratory muscles) and deep (true muscles of the back). The deep (intrinsic) muscles are organized into two groups, the more superficial erector spinae (spinalis, longissimus and iliocostalis) muscles and the deeper transversospinalis (semispinalis, multifidus and rotatores) muscles. The transversospinalis muscles fill the trough between the transverse and spinous processes. Together the erector spinae muscles act to extend or laterally flex the spine. The transversospinalis muscles act to extend and rotate (contralateral) the spine.
Innervation
Branches of the dorsal rami of spinal nerves innervate the back muscles.
Blood Supply
Dorsal branches of the various intersegmental (lateral sacral, lumbar, posterior intercostal and vertebral) arteries supply the back.
Anatomical Spaces or Features
The triangle of auscultation is bounded by the inferior fibers of the trapezius, superior fibers of the latissimus dorsi and inferior fibers of the rhomboid muscles. The lumbar triangle is bounded by the latissimus dorsi and external oblique muscles, and the iliac crest.