Lectures

Suboccipital Muscles – Back Muscles

by Craig Canby, PhD
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    00:00 Now, we will shift our attention to a region of the posterior cervical area between the upper two cervical vertebrae and the occiput or the occipital bone of the skull. This region is referred to as the suboccipital region. We will highlight the four pairs of suboccipital muscles that reside here, we will define a geometric configuration, yet another triangle and we will identify a very important blood vessel that runs within this suboccipital triangle.

    00:40 But, the muscles that are of interest here in the suboccipital region will be our rectus capitis major or simply the rectus major, that’s this muscle here. This muscle that’s shorter and lie medial to it, is your rectus capitis posterior minor or simply rectus minor.

    01:04 We also have two muscles that are obliquely oriented. Here is your obliquus capitis inferior or simply the inferior oblique. This muscle that really is oriented more vertically than obliquely is your obliquus capitis superior or simply the superior oblique and your suboccipital triangle will be defined by the superior oblique, the rectus major and then your inferior oblique and here is your triangle, right in through here. The vertebral component that you see lying deeper within the triangle is a portion of the posterior arch of the first cervical vertebra and then running on the superior aspect of that arch we have our vertebral artery.

    02:09 Now, we will wanna understand the attachments, innervation and the actions of the individual suboccipital muscles. We will begin with the rectus capitis posterior major or simply rectus major. So again, the muscle shown here in the illustration, it’s going to take its point of origin from the spinous process of C2, this will be a very important landmark in this area. The point of insertion is onto the occipital bone and it’s going to be just on the lateral portion of the occipital bone below a line that’s called the inferior nuchal line. So, that will be this area of attachment or insertion right along here.

    02:58 These suboccipital muscle, as well as the other three, are innervated by branches of the same nerve. This would be the dorsal or posterior ramus of the first cervical nerve, it does have the name suboccipital. The action of the rectus major is to extend the head and it can rotate the head to the same side, so if the right rectus major contracting, it will rotate your head to the right or the same side.

    03:41 The rectus capitis posterior minor or simply rectus minor will have a more superior point of origin. It is originating from the posterior tubercle of the first cervical vertebra, it then has an insertion onto the occiput, just medial to the major and just below the inferior nuchal line.

    04:10 Innervation, we have already described, suboccipital nerve. Action of this muscle would be principally to extend the head, it’s too medial to really provide any rotation.

    04:26 We also have the inferior oblique. Its point of origin is from the spinous process of C2.

    04:37 It crosses superiorly and laterally and if we look at our bony landmark here laterally, that is the transverse process of the first cervical vertebra. Innervation, again, is suboccipital nerve and the action of this muscle is to rotate the skull to the same side, so if the right inferior oblique is contracting, shortening, you will rotate your skull to the right.

    05:08 The last muscle of this region is your superior oblique. It is taking origin from the transverse process of C1 as we can nicely see here, it ascends and attaches to the occipital bone of the skull and it’s going to have a more superior attachment to the occipital bone, it’s going to be above the inferior nuchal line, but below the superior nuchal line.

    05:34 Innervation, suboccipital nerve and it will help extend the head and will also help to bend it to the same side, if it’s working unilaterally. So, if the right one, as shown here, shortens, your skull will bend to the right.


    About the Lecture

    The lecture Suboccipital Muscles – Back Muscles by Craig Canby, PhD is from the course Abdominal Wall.


    Included Quiz Questions

    1. Suboccipital nerve.
    2. Long thoracic nerve.
    3. Thoracoabdominal nerves.
    4. Obturator nerve.
    5. Supratrochlear nerve.
    1. Posterior ramus of first cervical nerve.
    2. Anterior ramus of first cervical nerve.
    3. Posterior ramus of second cervical nerve.
    4. Anterior ramus of second cervical nerve.
    5. Anterior ramus of third cervical nerve.
    1. Spinous process of C-2.
    2. Spinous process of C-1.
    3. Spinous process of C-3.
    4. Spinous process of C-4.
    5. Spinous process of C-5.

    Author of lecture Suboccipital Muscles – Back Muscles

     Craig Canby, PhD

    Craig Canby, PhD


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