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!