Prevertebral neck muscles (belong topographically to the group of deep neck muscles but act mainly on the cervical spine) Short nuchal and craniovertebral joint muscles (suboccipital muscles) They are innervated by cranial nerves (the trapezius by the accessory nerve) and were incorporated secondarily into the trunk wall (see p. Other muscles that have migrated to the trunk, such as the trapezius, are derived from the mesenchyme of the branchial arches (branchial musculature). Examples are the thoracohumeral muscles anteriorly, the spinohumeral muscles laterally and posteriorly, and the spinocostal muscles. Besides the muscles of the trunk wall, the back and thorax also contain muscles of the shoulder girdle and upper limb that migrated to the trunk during the course of development (nonintrinsic back and thoracic muscles). In the broad sense, they include the muscles of the pelvic floor (which form the inferior boundary of the abdominopelvic cavity) and the diaphragm (which separates the thoracic and abdominal cavities). The muscles of the trunk wall in the strict sense consist of the intrinsic back muscles and the muscles of the chest and abdominal wall. 2.1 The Muscles of the Trunk Wall: Their Origin and Function
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