Erector Spinae Group

 The Erector Spinae group consists of three back muscles, commonly called 'the Erectors'.

Imagine a tree with 3 branches:

Spinalis

Longissimus

Iliocostalis 

 Together they span the back of your entire spine from the back of your skull (occiput) to the base of your spine (sacurm). Simply put - there's all kinds of attachment points and layers and I don't think I EVER got them memorized in school (!) Well it's time to tackle this group of three - one at at time! But first! As a group (heh) - so yeah! you may want to grab a cup of coffee for this one!

Erector Spinae Group: Attachment Points:

ORIGIN:  

Common tendon (the thoracolumbar fascia) that attaches to the posterior surface of the sacrum, iliac crest, spinous processes of the lumbar vertebrae (L1-L5) and last two thoracic vertebrae (T11-T12)

INSERTION:

Various Attachments at the posterior (back of the) Ribs, spinous & transverse processes of thoracic and cervical vertebrae, and mastoid process of temporal bone.

All together - Erector Spinae group:
Muscle Action(s):
  

UNILATERALLY (one side):

- ipsi-laterally flexes the vertebral column (spine) 
aka side flexion to the same side

side flexion
BILATERALLY (both left & right together)

- extends the spine (spine extension!)

*check out my video "6 movements of the spine" for another visual of side flexion and extension of the spine:

*be sure to checkout "breaking down the spine" to get a better idea of how the spine is divided up - and to get a visual of the transverse processes!

Read on if you dare explore in more detail...

THE BRANCHES! (mwahahahahahaaaaa)

1) Spinalis: 

Spinalis is the smallest of the three erectors and closest to the spine (spine-alis) 

AND can be divided two sections: 

a) Thoracis (the part near the T-spine) 

b) Cervicis (the part near the C-spine).

Together, a & b look like a backwards 'S' (for Ssspinalis!)

ATTACHMENT POINTS for:

a) Thoracis: 

Origin: spinous processes of upper lumbar and lower thoracic vertebrae

Insertion: spinous processes of upper thoracic vertebrae

b) Cervicis:

Origin: ligamentum nuchae, & the spinous process of C7

Insertion: spinous process of the cervicals (except C1!)

2) Longissimus: 

Longissimus is the thickest of the erectors and also the longest (the longgissimest! ;)

So long that IT can be divided into THREE more sections:

a)  Capitis (referring to the head/skull)

b) Cervicis (referring to the neck/cervix)

 c) Thoracis (referring to the thorax/trunk)  

  

ATTACHMENT POINTS for:

 a) Capitis & b) Cervicis:

Origin: transverse processes (TVPS) of upper five thoracic vertebrae (aka T1-T5)

Insertion: a) mastoid process of temporal bone b) TVPS of the the C-spine

 c) Thoracis:

Origin:  Common Tendon (thoracolumbar fascia/aponeurosis)

 Insertion:  lower nine ribs (ribs 4-12) and TVPS of thoracic vertebrae  

3) Iliocostalis: "from hip to rib"

Iliocostalis is the most lateral (furthest away from the spine)

and has long tendons that extend outwards from the hip onto the ribs - underneath the shoulderblades AND can be divided into three sections:

a) Cervicis

b) Thoracis

c) Lumborum

ATTACHMENT POINTS for:

 a) Cervicis & b) Thoracis:

Origin: posterior surface of all the ribs (1-12)

Insertion: a) TVPS of lower cervicals  b) posterior surface of ribs 1-6

 c) Lumborum:

Origin: common tendon (thoracolumbar fascia/aponeurosis)

  Insertion: TVPS of L1-L3 and the posterior surfaces of ribs 6-12

Whewf! Are you still there? We made it you guys!

Transverso-Spinalis Group

is a group of three deep back muscles that run along either side of your spine:

a) Multifidi

b) Rotatores

c) Semi-Spinalis Capitits

together they create the acronym "Mrs" ("Mrs. Transverso-Spinalis" is what helps me to remember ;)

As you can see above -these muscle's fibers run in a diagonal direction, and live underneath the Erector Spinae group, (which also run along the back of your spine - with vertical fibers -

which will explore next week!) 

Transverso-spinalis muscles attach long the entire length of the spine - which is divided into 3 segments: lumbar (lower), thoracic (mid) & cervical (neck). Each vertebrae in the spine have bony 'wings' coming off the sides called tranverse processes (TVPS for short)

  and guess what? This group gets its name transverso because all 3 branches of this group (MRS) have attachment points on the TVPS:

Muscle Attachment Points

Transverso-spinalis group runs along entire length of vertebral column (spine) and branches off into Multifidi, Rotatores, & Semi-spinalis Capitis:

            Origin:         Multifidi - sacrum & transverse processes of lumbar through cervical vertebrae

  

                                 Rotatores- transverse processes of lumbar through cervical vertebrae

                                 Semi-spinalis Capitis -  transverse processes of thoracic vertebrae & articular processes of lower cervicals (bony bumps at base of skull)

          Insertion:       Multifidi & Rotatores - spinous processes of lumbar to cervical vertebrae.
                                 
                                 Semi-spinalis Capitis - spinous processes of  upper thoracic & cervical spine to   base of skull (superior nuchal line of occiput)

Whewf! That is complex. Here's some visuals of the MRS to ease our brains ;)

 

So what do all these muscles DO anyway?

Tranverso-Spinalis Group Muscle Action(s):

Multifidi & Rotatores have the same actions:

Unilaterally (one side of spine only) : rotate spine to the opposite side (aka spinal twist)

Bilaterally (left and right sides working together) : extend the spine

Semi-spinalis capitis: 

extend the spine & head

Remember that the Mulitfidi & Rotatores on the left side help you rotate to the right and vice versa!

Rotation can also be done in a seated or standing position  (the above is just one example)

And here is and example of spine extension! Which can also be done seated or standing.

This is done with the help of All 3 branches of the Transverso-Spinalis Group.

And there you have it! Some deep back muscles you hardly ever hear about ! When it comes to back extension - Erector Spinae group often hogs the spotlight when it comes to back extension - more next week!

Internal Abdominal Obliques

Our obliques are part of our abdominal muscles. There are Internal and External obliques.

Today let's get to know the Internal!

Muscle Attachment point(s) :

Origin: Lateral 2/3 of the inguinal ligament, the iliac crest and the thoracolumbar fascia (connective tissue deep in the torso)

Insertion:  Internal surface of lower three ribs (10-12) and the abdominal aponeurosis

Muscle Action(s) :

-Unilaterally (one side only) : lateral flexion of spine to one side

                                             - also rotates spine to the same side

  

-Bilaterally (both sides -left & right together) : spinal flexion -
which is basically a sit up! Remember Rectus Abdominus ?

above: Lateral Flexion to one side. (In this case - to the right !)
aka Ipsi-lateral flexion
aka Side Flexion or 'C spine'

Above: Ispi Lateral Rotation of the spine
aka Lateral rotation to one side
aka "Spinal Twist to left or right"

Check out my video of the 6 movements of the spine for a
closer look at the above mentioned spine movements!

And stay tuned for a blog post that will really break down the 6 movements of the spine in further detail :)