Netter's Back and Spinal Cord Muscular System

1

splenius capitis muscle 

• Origin: Nuchal ligament and spinous processes of C7–T3

• Insertion: Mastoid process and superior nuchal line

• Action: Extends, rotates, and laterally flexes head

2

splenius colli muscle 

• Origin: Spinous processes of T3–T6

• Insertion: Transverse processes of C1–C3

• Action: Extends, rotates, and laterally flexes neck

3

rhomboid minor muscle (cut) 

• Origin: Spinous processes of C7–T1

• Insertion: Medial border of scapula at spine

• Action: Retracts and stabilizes scapula

4

serratus posterior superior muscle 

• Origin: Nuchal ligament and spinous processes C7–T3

• Insertion: Superior borders of ribs 2–5

• Action: Elevates ribs; possibly proprioceptive

5

rhomboid major muscle (cut) 

• Origin: Spinous processes of T2–T5

• Insertion: Medial border of scapula

• Action: Retracts and rotates scapula

6

serratus posterior inferior muscle 

• Origin: Spinous processes T11–L2

• Insertion: Inferior borders of ribs 9–12

• Action: Depresses ribs; possibly proprioceptive

7

erector spinae muscles

• Origin: Posterior iliac crest, sacrum, lumbar vertebrae

• Insertion: Ribs, vertebrae, and skull (varies by component)

• Action: Extends and laterally flexes vertebral column; stabilizes posture

8

thoracolumbar fascia (posterior layer)

9

spinous process of T12 vertebra

10

latissimus dorsi muscle 

• Origin: Spinous processes T7–L5, thoracolumbar fascia, iliac crest, ribs 9–12

• Insertion: Intertubercular sulcus of humerus

• Action: Extends, adducts, and medially rotates arm

11

spinous process of C7 vertebra

12

trapezius muscle 

• Origin: Occipital bone, nuchal ligament, spinous processes C7–T12

• Insertion: Lateral clavicle, acromion, scapular spine

• Action: Elevates, retracts, rotates scapula; extends neck

13

semispinalis capitis muscle 

• Origin: Transverse processes of C4–T6

• Insertion: Between superior and inferior nuchal lines

• Action: Extends head; minimal rotation

1

splenius capitis muscle 

• Origin: Nuchal ligament and spinous processes of C7–T3

• Insertion: Mastoid process and superior nuchal line

• Action: Extends, rotates, and laterally flexes head

2

splenius colli muscle 

• Origin: Spinous processes of T3–T6

• Insertion: Transverse processes of C1–C3

• Action: Extends, rotates, and laterally flexes neck

3

semispinalis capitis muscle 

• Origin: Transverse processes of C4–T6

• Insertion: Between superior and inferior nuchal lines

• Action: Extends head; minimal rotation

4

supraspinatus muscle 

• Origin: Supraspinous fossa of scapula

• Insertion: Greater tubercle of humerus

• Action: Initiates arm abduction (first 15°)

5

teres minor and major muscle 

• Origin: Minor: lateral scapula; Major: inferior angle of scapula

• Insertion: Minor: greater tubercle; Major: medial intertubercular sulcus

• Action: Minor: lateral rotation; Major: adduction, medial rotation

6

erector spinae muscle

• Origin: Posterior iliac crest, sacrum, lumbar vertebrae

• Insertion: Ribs, vertebrae, and skull (varies by component)

• Action: Extends and laterally flexes vertebral column; stabilizes posture

7

gluteus maximus muscle 

• Origin: Ilium, sacrum, coccyx, erector spinae aponeurosis

• Insertion: Gluteal tuberosity of femur and iliotibial tract

• Action: Extends and laterally rotates thigh; increases thoracolumbar fascia tension

8

thoracolumbar fascia

9

latissimus dorsi muscle 

• Origin: Spinous processes T7–L5, thoracolumbar fascia, iliac crest, ribs 9–12

• Insertion: Intertubercular sulcus of humerus

• Action: Extends, adducts, and medially rotates arm

10

deltoid muscle

• Origin: Lateral third of clavicle, acromion, spine of scapula

• Insertion: Deltoid tuberosity of humerus

• Action: Abducts arm; anterior fibers flex/medially rotate; posterior fibers extend/laterally rotate

11

trapezius muscle 

• Origin: Occipital bone, nuchal ligament, spinous processes C7–T12

• Insertion: Lateral clavicle, acromion, scapular spine

• Action: Elevates, retracts, rotates scapula; extends neck

1

rhomboid major muscle 

• Origin: Spinous processes of T2–T5

• Insertion: Medial border of scapula

• Action: Retracts and rotates scapula

2

rhomboid minor muscle 

• Origin: Spinous processes of C7–T1

• Insertion: Medial border of scapula at spine

• Action: Retracts and stabilizes scapula

3

spinal accessory nerve (CN XI) (innervates trapezius muscle)

4

trapezius muscle (reflected) 

• Origin: Occipital bone, nuchal ligament, spinous processes C7–T12

• Insertion: Lateral clavicle, acromion, scapular spine

• Action: Elevates, retracts, rotates scapula; extends neck

5

posterior cutaneous branches (medial branches of dorsal rami of C4-T6 spinal nerves)

6

latissimus dorsi muscle 

• Origin: Spinous processes T7–L5, thoracolumbar fascia, iliac crest, ribs 9–12

• Insertion: Intertubercular sulcus of humerus

• Action: Extends, adducts, and medially rotates arm

7

posterior cutaneous branches (lateral branches of dorsal rami of T7-12 spinal nerves)

8

thoracolumbar fascia

9

gluteus maximus muscle 

• Origin: Ilium, sacrum, coccyx, erector spinae aponeurosis

• Insertion: Gluteal tuberosity of femur and iliotibial tract

• Action: Extends and laterally rotates thigh; increases thoracolumbar fascia tension

10

spinous process of T12 vertebra

1

serratus posterior superior muscle 

• Origin: Nuchal ligament and spinous processes C7–T3

• Insertion: Superior borders of ribs 2–5

• Action: Elevates ribs; possibly proprioceptive

2

serratus posterior inferior muscle 

• Origin: Spinous processes T11–L2

• Insertion: Inferior borders of ribs 9–12

• Action: Depresses ribs; possibly proprioceptive

3

iliocostalis lumborum muscle 

• Origin: Lumbar transverse processes and thoracolumbar fascia

• Insertion: Angles of lower ribs and iliac crest

• Action: Extends and laterally flexes vertebral column

4

longissimus thoracis muscle 

• Origin: Lumbar transverse and accessory processes

• Insertion: Thoracic transverse processes and ribs

• Action: Extends and laterally flexes trunk

5

spinalis thoracis muscle 

• Origin: Spinous processes of T11–L2

• Insertion: Spinous processes of upper thoracic vertebrae

• Action: Extends thoracic spine

6

iliocostalis thoracis muscle 

• Origin: Upper borders of lower six ribs

• Insertion: Upper six ribs and C7 transverse process

• Action: Extends vertebral column

7

longissimus colli muscle 

• Origin: Transverse processes of T1–T5

• Insertion: Transverse processes of C2–C6

• Action: Extends and laterally flexes neck

8

spinalis colli muscle 

• Origin: Spinous processes of upper thoracic vertebrae

• Insertion: Spinous processes of cervical vertebrae

• Action: Extends cervical spine

1

semispinalis capitis muscle 

• Origin: Transverse processes of C4–T6

• Insertion: Between superior and inferior nuchal lines

• Action: Extends head; minimal rotation

2

splenius capitis and colli muscles

3

rectus posterior minor capitis muscle 

• Origin: Posterior tubercle of C1

• Insertion: Medial part of inferior nuchal line

• Action: Extends head; stabilizes atlanto-occipital joint

4

oblique superior capitis muscle 

• Origin: Transverse process of C1

• Insertion: Occipital bone (between nuchal lines)

• Action: Extends and laterally flexes head

5

rectus posterior major capitis muscle 

• Origin: Spinous process of C2

• Insertion: Inferior nuchal line (lateral part)

• Action: Extends and rotates head to same side

6

oblique inferior capitis muscle 

• Origin: Spinous process of C2

• Insertion: Transverse process of C1

• Action: Rotates atlas and head to same side

7

spinous process of C7 vertebra

8

longissimus colli muscle 

• Origin: Transverse processes of T1–T5

• Insertion: Transverse processes of C2–C6

• Action: Extends and laterally flexes neck

9

longissimus thoracis muscle 

• Origin: Lumbar transverse and accessory processes

• Insertion: Thoracic transverse processes and ribs

• Action: Extends and laterally flexes trunk

10

serratus posterior inferior muscle 

• Origin: Spinous processes T11–L2

• Insertion: Inferior borders of ribs 9–12

• Action: Depresses ribs; possibly proprioceptive

11

spinalis thoracis portion of the erector spinae

• Origin: Spinous processes of T11–L2

• Insertion: Spinous processes of upper thoracic vertebrae (T1–T8, variable)

• Action: Extends thoracic spine; maintains upright posture

1

erector spinae muscle

• Origin: Posterior iliac crest, sacrum, lumbar vertebrae

• Insertion: Ribs, vertebrae, and skull (varies by component)

• Action: Extends and laterally flexes vertebral column; stabilizes posture

1

rotatores colli muscle (longi; breves) 

• Origin: Transverse processes of cervical vertebrae

• Insertion: Lamina/spinous process 1–2 levels above

• Action: Extend and stabilize spine

2

rotatores thoracis muscle (longi; breves) 

• Origin: Transverse processes of thoracic vertebrae

• Insertion: Spinous processes 1–2 levels above

• Action: Extend and stabilize spine; may assist rotation

3

levatores costarum muscle (breves; longi) 

• Origin: Transverse processes of C7–T11

• Insertion: Ribs below (1 or 2 segments)

• Action: Elevates ribs, may aid respiration

4

multifidus lumborum muscles 

• Origin: Posterior sacrum, PSIS, mammillary processes

• Insertion: Spinous processes 2–4 segments above

• Action: Extends, stabilizes vertebrae, resists shear

5

multifidus thoracis muscles 

• Origin: Transverse processes of thoracic vertebrae

• Insertion: Spinous processes 2–4 segments above

• Action: Extends and stabilizes thoracic vertebrae

6

semispinalis thoracis muscle 

• Origin: Transverse processes of T6–T10

• Insertion: Spinous processes of upper thoracic/cervical vertebrae

• Action: Extends thoracic spine

7

semispinalis capitis muscle 

• Origin: Transverse processes of C4–T6

• Insertion: Between superior and inferior nuchal lines

• Action: Extends head; minimal rotation