Intermediate Back Muscles – Back Muscles

00:01 Now, we want to shift our attention to the intermediate muscle group and there are only two muscles that occupy this layer of the back musculature, and these would be the serratus posterior superior and the serratus posterior inferior. Both those muscles are shown here, here is the superior one and then your inferior fellow is shown down here in the lower thoracic and lumbar region.

00:35 The attachments, the innervation and the actions of the serratus posterior muscles, for example your superior serratus posterior shown in through here is going to originate from the lower portion of the ligamentum nuchae as we can see there and the spinous processes of C7 downwards to T3, the insertion is going to be on the ribs that we see along here.

01:08 Ribs 2 through 5 generally will be the insertion points, there is some variability here. Innervation will be by the anterior rami of your upper thoracic spinal nerves and the action of the superior serratus posterior is to assist with respiration, it will help pull the ribs superiorly.

01:35 The inferior one shown here, the inferior serratus posterior is going to originate from the spinous processes of the Serratus posterior inferior will originate from the spinous processes of T11, T12 T10 as well as the first three lumbar vertebrae.

01:56 It’s going to attach to ribs 9 through 12 typically. Innervation is by the anterior rami of the relative nerves in this region and the action is to assist in depressing the ribs, pulling them downwards and these muscle slips may also oppose the action of the diaphragm when it’s contracting during inspiratory movements.