Anatomical basis of modern thoracotomies: the latissimus dorsi and the "serratus anterior-rhomboid" complex.

The latissimus dorsi and the "serrato-rhomboid" complex are the muscles most often involved in present-day thoracotomies for lung surgery. The present anatomic study emphasizes: the continuity between the serratus anterior and the rhomboid levator scapulae mass as a wide muscular sheet with a deep common fascia, extending the serrato-thoracic space (of Gillis) to the vertebral column as the rhomboserrato-thoracic space (the levator scapulae is situated higher up, above the ordinary thoracotomy); the presence of a "composite fascia" in the posterior angle between the seratus anterior and the rhomboid; the long costal attachment area and the presence of two differently oriented layers for the muscular digitations of the middle and inferior parts of the serratus anterior. With a rich vascular supply from multiple sources, the serratus anterior and latissimus dorsi are two large flat muscles with a single longitudinal nervous pedicle proceeding from the brachial plexus. To avoid esthetic (winged scapula) and functional sequelae, it is imperative to safeguard this single innervation as far as possible : by halting division of the serratus anterior before reaching its neurovascular pedicle in lateral or anterolateral thoracotomy, and by transecting the latissimus dorsi very low down in standard postero-lateral thoracotomy. The other muscles are simply freed and retracted.