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!

Quadratus Lumborum

Quadratus Lumborum (QL) : 

often referred to as our 'Hip Hiker' muscle ! Can also be seen as a really deep abdominal muscle

OR a really deep back muscle so I guess it's in the middle of us!

(image on left c/o Trail Guide to the Body)

QL muscle attachment points:

QL attaches to the top of our hip (close to the spine) then climbs up the lumbar spine (vertebrae) and finally attaching to our 12th (bottom) rib :

More specifically/officially:

 

Origin: the medial half of the inferior border of the 12th rib* and the transverse processes of the Lumbar vertebrae 1-4**

Insertion:  Iliac crest and ilio-lumbar ligament***

Break it down further:

* medial half meaning closer to our spine (instead of away from it)  and inferior border meaning underneath. The 12th rib is shorter than the rest and is considered a 'floater' as this rib does not wrap around your torso attaching to the front like the higher ribs.

**the transverse processes (aka TVPS) of our vertebrae are the bones that stick out on either side (kinda like wings!) Often when a muscle attaches to sides of our spine like that - the muscle will help bend to the side (aka lateral flexion)

***iliac crest aka the top curve of our hip & the ilio-lumbar ligament spans between the hip bone to the lumbar vertebrae bone.

(original image on left c/o Trail Guide to the Body)

QL Muscle Actions:

Unilaterally (each QL on their own):

 

a-laterally tilts the pelvis (aka hip hike)

b-lateral flexion of spine (vertebral column) to the same side (a side bend)

c- assists in extension of the spine (aka a back bend)

these movements are moving the trunk of our body and the movement is happening at the spinal joints.

 (hiking of the right hip - right QL is shortening with each hike)

(Lateral (side flexion) to the Left side)

Bilaterally (both QLs together) :

When breathing - QLs secure (hold down) the 12th rib during inspiration (inhalation) and forced exhalation.

Another way to look at it - is that QL is in a shortened state any time we bring our hip and ribs closer together - this is encouraged when we sit and especially when we don't stand up straight.

One QL gets shortened in Scoliosis 

(a postural condition when one hip hikes, creating an 'S' curve or our spine)

scoliosis image via Gary Leung

Personally I've had on and off issues with my Right QL for years. It basically feels like a dull, low right back pain).  It only goes away when I exercises regularly/consistently - and of course regular massage, heat application and posture awareness! (I have a  nasty habit of favouring one hip / leg when standing, and crossing my legs when sitting - helping encourage my own hip hike over time!)  

All of this  makes me a huge fan of receiving and GIVING deep low back massage (!)

Serratus Posterior Inferior

Remember last week's Serratus Posterior Superior ? Well there is also an inferior!

Serratus Posterior Inferior

Serratus: jagged looking like a knife. Posterior: on the back.  Inferior: below

This muscle lives in your lower back attaching from the lower spine onto the lower ribs and instead of a xmas tree shape (or upside down 'V')  like last week's  Superior,  

Serratus Posterior Inferior is a V- Shape.

Muscle Attachment Points:

breakdown of terminology below:

 

Origin: spinous processes of T11-L2

Insertion: posterior surfaces of ribs 9-12

*spinous processes are the bony bumps that stick out from the back of your spine (aka vertebral column) our spine is divided into segments called vertebrae. T refers to the thoracic spine (mid back where ribs attach) & L refers to our lumbar spine - basically our low back.

(I will fully breakdown the spine in a future post) In conclusion - many many muscles attach to the spinous processes on the vertebrae of our spine :)

Serratus Posterior Inferior

Muscle Actions:

depresses ribs 9-12 at the sc/cs joints

this muscle simply depresses ribs 9-12 during exhalation. It is pretty much stabilizing our lower ribs against the pressure of the pull of the diaphragm.

This subtle movement happens at the sterno-costal and costo-spinal joints*

*our ribs can elevate (rise) and depress (lower) at the front & back of our ribcage. The front is where the sternum (breastbone) & ribs (costals) meet aka sterno-costal joints
And on the back - costo-spinal joints: is where ribs connect to our spine

So for muscle actions I've really been enjoying making little stop-motion vids - however the subtle movement of this particular muscle (which is really a stabilzer more than anything!) is tough to capture! For example see last week's vid for serratus posterior superior (!)

Until our Next Muscle Monday!