Serratus Posterior is triangular shaped thin muscle located into the deep side of rhomboids muscles. There are two muscles of serratus posterior, superior and the inferior. The two muscles are considered as a part of the auxiliary back muscles, implying that they moved to the back over the span of embryogenesis.
The former is located at the upper part of the posterior chest and Serratus back predominant is a thin quadrilateral muscle, which emerges by a thin aponeurosis from the lower some portion of the nuchal tendon, the spines of the seventh cervical and upper a few thoracic vertebrae and their supraspinous tendon, while the second is V-shaped and located in center of the lower back, at the lowest point it becomes thicker even, it is a thin region and it pulls down the lower ribs.
Anatomy of Serratus Posterior:
The superior area is located in the upper thoracic or up to fourth vertebrae in while the inferior region is located in lower some portion of the ligamentum nuchae, and the cervical and thoracic spines. Inferior originates up to eleventh thoracic vertebrae.
Superior raises the ribs in inspiration, in contrast, inferior lower ribs in expiration and helps to move upward and downward the ribs during exhaling.
It is inserted into the strands of the Superior drive in an inferolateral bearing, connecting to ribs 2-5. It is inserted into the upper borders and external surfaces of the second, third, fourth and fifth ribs. In contrast, inferior inserted into borders and outer surfaces of the lower four ribs.
Superior is innervated by the ventral rami of the second, third, fourth and fifth intercostals nerves. Inferior innervated by the ventral rami of the ninth, tenth, eleventh and twelfth thoracic spinal nerves.
Nerve Supply of Serratus posterior:
They both are supplied by the intercostal nerves deriving from the front rami of the spinal nerves.