Iliocostalis

You guys...I've been slack on my Muscle Monday posts the past couple of weeks! My apologies, but today we will begin again. We'll talk about the Iliocostalis in horses.

L O C A T I O N:
The Iliocostalis is a very deep muscle that lies next to the longissimus, stretching the full length of the spine. Parts of it start in the lumbar area and other segments continue to the third rib. The segments of the iliocostalis all run forward and down.
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F U N C T I O N:
The muscle helps in extension of the spine. It helps in fixation of the vertebral column or lateral movement when only one side contracts.
The iliocostalis helps in expiration, since it pulls the ribs backwards, but it has more effect on the spine. Like the longissimus dorsi, if all the segments contract at once, it helps extend (hollow) the spine. If only one side all contracts at once, it assists in lateral bending. But segmented muscles don't all have to act at the same time. Usually different segments contract at different times. You can actually feel these muscles on your horse. If you stand beside him and put your fingers on his dorsal spinous processes about the level of the last few ribs, then pull down and out lightly, you will be running your fingers over the longissimus dorsi. Out about six or eight inches or so from the spine, you kind of "bump off" the edge of the longissimus, but then there is another smaller bump of muscle before you get down onto the ribs themselves. That smaller bump is made up of the caudal serratus dorsalis and the iliocostalis muscles. How well you will feel this depends a whole lot on how much fat cover your horse has. Thinner horses are much easier to feel than fatter ones.
P R O B L E M S:
Since the Iliocostalis runs the length of the spine, it can be a factor that can be overlooked when it comes to saddle fit. Back pain and restricted spinal movement can be symptoms of an underlying issue.
Make sure you are working on your horse's core muscles to help strengthen these muscles. Lateral work and hill work can be great additives to any workout!
Next week we'll go into the longissimus dorsi!