The<unk><unk><unk>  is a thin, quadrilateral muscle, situated at the upper and back part of the thorax.
It arises by a thin and broad aponeurosis from the lower part of the ligamentum nuchae, from the spinous processes of the seventh cervical and upper two or three thoracic vertebræ and from the supraspinal ligament.
Inclining downward and lateralward it becomes muscular, and is inserted, by four fleshy digitations, into the upper borders of the second, third, fourth, and fifth ribs, a little beyond their angles.
Serratus posterior superior muscle
Splenius capitis muscle
Rectus abdominis muscle
Transversus abdominis muscle
Levatores costarum muscles
Abdominal internal oblique muscle
Levator scapulae muscle
Obturator internus muscle