Part 2 book “Clinical anatomy - A problem solving approach” has contents: Vertebral column, cranial meninges, middle meningeal artery and pituitary gland, development of central nervous system, white matter of cerebrum, olfactory nerve and pathway, vestibulocochlear nerve, and other contents. | S E C T I O N VERTEBRAL COLUMN AND SPINAL CORD, CRANIAL CAVITY AND BRAIN 53 DEEP MUSCLES OF BACK Chapter Contents ♦♦ DEEP MUSCLES OR INTRINSIC MUSCLES OF BACK • Nerve Supply • Classification of Postvertebral Muscles • Erector Spinae or Sacrospinalis • Suboccipital Triangle • Vertebral Artery • Vertebral Vein • Subclavian Steal Syndrome • Vertebral Angiography Nerve Supply The splenius consists of splenius capitis and splenius cervicis muscles. i. The splenius capitis takes origin from the lower half of the ligamentum nuchae and spines of the seventh cervical and upper three to four thoracic vertebrae. It is inserted into the mastoid process and the lateral third of superior nuchal line. (Note: The splenius capitis appears in the upper part of the floor of the posterior triangle of the neck). ii. The splenius cervicis takes origin from the spines of third to sixth thoracic vertebrae and is inserted into the posterior tubercles of the transverse processes of the upper two to three cervical vertebrae. All deep muscles of back receive nerve supply from the dorsal rami of the spinal nerves. Actions DEEP MUSCLES OR INTRINSIC MUSCLES The deep or intrinsic muscles of the back are a complex group of muscles extending from the sacrum to the skull. They are collectively called the postvertebral muscles and are very well developed in human being. In upright position the weight falls in front of the vertebral column because the line of gravity passes in front of it. Therefore, the postural tone of the postvertebral muscles is responsible for maintaining the normal curvatures of the vertebral column. Classification of Postvertebral Muscles From superficial to deeper level the muscles are classified in four groups: 1. Splenius muscle is the one in which the muscle fibers are directed upward and laterally. ii. Erector spinae group of muscles are those in which the muscle fibers run vertically. iii. Transversospinalis group is the one in which muscle fibers run
