Erector Spinae 

3 muscles that make up this complex

Erector Spinae is the Prime mover of back extension

Made up of 3 Muscles:

1. Iliocostalis

2. Lonissimus

3. Spinalis

Muscle of Vert Column

O – Iliac crests, inferior 6 ribs, ribs 3-6

I – Angles of ribs, C6-C4.

A – Extend vertebral column; maintain posture; bends column to same side

Muscle of Vert Column

O – Transverse process of lumbar through cervical vertebrae

I – Transverse process of thoracic or cervical vertebrae; mastoid process of temporal bone

A – Extend vertebral column, bends to same side; extends head and turns face to same side

Muscle of Vert Column

O – Upper lumbar and lower thoracic vertebrae

I – Upper thoracic and cervical vertebrae

A – Extend vertebral column

Muscle of Vert Column

O – Transverse process of C7-T12

I – Occipital bone and spinous processes of cervical and T1-T4

A – Extends vertebral column and head (rotates to opposite side); acts with SCM of opposite side

Muscle of Vert Column

O – Transverse process of lumbar and lower thoracic vertebrae

I - Spinous process of lumbar and thoracic vertebrae

A – Stabilize spine

Muscle of Vert Column

O – Iliac crest and lumbar fascia

I – Transverse process of upper lumbar and 12^th rib  

A – Flexes vertebral column laterally when acting separately; when pair acts together, lumbar spine is extended and 12^th rib flexed; assists in forced inspiration

Muscle of Neck

O – Manubrium of sternum and medial clavicle

I – Mastoid process of temporal bone and nuchal line of occipital

A – Head flexion; alone each muscle rotates head towards shoulder and tilts or laterally flexes head to its own side

Muscle of Neck

O – Transverse process of cervical vertrbrae

I – Anterolaterally on first 2 ribs

A – Elevates first 2 ribs (inspiration); flex and rotates neck

Muscle of Anterior and Lateral Abdominal Wall

O – Pubic crest and symphysis

I – Xiphoid process and costal cartlages of ribs 5-7

A – Flex and rotate lumbar vertebrae; fix and depress ribs, stabilize pelvis during walking, increase intra-abdominal pressure

Muscle of Anterior and Lateral Abdominal Wall

O – Outer surface of lower 8 ribs

I – Anterior aponeurosis into linea alba; some into pubic crest and tubercle and iliac crest

A – Aid rectus abdominus; trunk rotation, lateral flexion

Muscle of Anterior and Lateral Abdominal Wall

O – Lumbar fascia, iliac crest, and inguinal ligament

I – Linea alba, pubic crest, last 3-4 ribs

A – Aids rectus abdominus; trunk rotation, lateral flexion

Muscle of anterior and lateral abdominal wall

O – Inguinal ligament, lumbar fascia, cartlages of last 6 ribs; iliac crest

I – Linea alba, oubic crest

A – Compress Abdominal contents

Intrinsic Muscle of Back

O – Spinous process of C7-T6

I – Mastoid process and occipital bone

A – Extend or hyperextend head; when activated on one side, head is rotated and bent laterally to same side

Intrinsic Muscle of Back

O – Spinous process of C7-T6

I – Transverse process of C2-C4

A – Works in conjunction with splenius capitis

Muscle of Anterior Thorax

O – Anterior surfaces of ribs 3-5

I – Coracoid process of scapula

A – Draws scapula forward and downward

Muscle of the Anterior Thorax

O – Ribs 1-8

I – Entire anterior surface of vertebral border of scapula

A – Prime mover to protract the scapula

Muscle of Anterior Thorax

O – Costal cartilage of rib 1

I – Inferior surface of clavicle

A – Stabilizes the pectoral girdle

Posterior Thorax Muscle

O – Occipital bone

I – Continuous insertion along acromion and spine of scapula

A – Stabilizes, raises, retracts, and rotates scapula

Muscle of Posterior Thorax

O – Transverse processes of C1-C4

I – Medial border of scapula

A – Elevates and adducts the scapula

Muscle of Posterior Thorax

Rhomboids: Minor

O – Spinous processes of C7-T1

Major

O – Spinous processes of T2-T5

I (Both) – Medial border of scapula

A (Both) – Retract the scapula (“squaring the shoulders”)