Deep Intrinsic Back Muscles

00:01 Let's continue talking about the intrinsic back muscles by looking at the deep layer.

00:08 So here we see the semispinalis, multifidus, interspinales and a very descriptive muscle called rotatores.

00:20 We also have the intertransversarii and levatores costarum.

00:28 Together, all of these little muscles are considered the transversal spinal muscle group.

00:37 Let's look at the multifidus a little bit closer in terms of its origins and insertions.

00:43 So they'll attach to the mammillary processes of the lumbar vertebra, to the transverse processes of the thoracic vertebra, and articular processes of the cervical vertebra.

00:56 And then attached to the spinous processes of all the vertebra from L5 to C2.

01:02 Now let's look at the attachments of the semispinales.

01:06 We see we have origins on the transverse processes of the thoracic vertebra as well as the articular processes of the cervical vertebra.

01:14 And then they'll attach to the spinous processes of the thoracic and cervical vertebra as well as the occipital bone around the area of the nuchal lines.

01:24 Let's take a closer look at the small muscle known as rotatores.

01:28 We have to zoom in because these are pretty small muscles.

01:32 We see we have attachments from the transverse process to the adjacent spinous process.

01:40 The intertransversarii area are also very small.

01:44 And as their name implies, they're attaching to the transverse processes of the contiguous vertebrae.

01:52 Inter spinalis, also very small, and we can see their attachments are from the spinous processes of the contiguous vertebrae.

02:02 Levatores costarum, it's a very descriptive name and the costarum tells us a little bit about where they're located.

02:09 And we see there at the transverse processes of the thoracic vertebrae, going out to the ribs below the vertebra that they originate from.

02:19 Transversospinalis muscles altogether when we're talking about the innervation come from the dorsal rami of the spinal nerves in that area.

02:30 In terms of function, we have extension of the vertebral column.

02:35 And very importantly, because they're very small, and attaching to adjacent vertebra, it's stabilization of the vertebral column.

02:43 Not quite a movement, but it's an important function for maintaining posture overall.