Back/Abdomen Muscles

Exam 3

Splenius Capitis

O - Nuchal ligament and C7-T4 TPs

I  - Mastoid process, occipital bone

A - Bilaterally: extends head/neck. Unilaterally: bends head, rotates head

I  - Dorsal Rami

Splenius Cervicis

O - T3-T6 SPs

I - C1-C3 TPs

A - Bilaterally: extends head/neck. Unilaterally: bends head, rotates head

I  - Dorsal Rami

Iliocostalis

Cervicis, Thoracis, Lumborum

O - Iliac crest, sacrum, ribs

I - Thoracolumbar fascia, ribs, cervical vertebrae

A - Bilaterally: Extends vertebral column

Unilaterally: Laterally flexes vertebral column

I - Dorsal Rami

Longissimus

Capitis, Cervicis, Thoracis

O - Thoracodorsal fascia, transverse + cervical vertebrae

I  - Vertebrae, mastoid process

A - Bilaterally: Extends vertebral column

Unilaterally: Laterally flexes vertebral column

I - Dorsal Rami

Spinalis

Capitis, Cervicis, Thoracis

O - SPs

I  - SPs

A - Bilaterally: Extends vertebral column

Unilaterally: Laterally flexes vertebral column

I - Dorsal Rami

Semispinalis

O - Thoracic TPs 

I  - Cervical/Thoracic SPs

A - Bilaterally: Extends vertebral column

Unilaterally: Contralateral vertebral column rotation

I  - Dorsal Rami

Multifidus

O - Sacrum, TPs of cervical/thoracic/lumbar vertebrae

I  - SPs of lower cervical/thoracic/lumbar vertebrae

A - Bilaterally: Extends vertebral column

Unilaterally: Contralateral vertebral column rotation

I  - Dorsal Rami

Rotatores

O - TPs of C2-sacrum

I - Lamina immediately above vertebrae of origin

A - Bilaterally: Extends vertebral column

Unilaterally: Contralateral vertebral column rotation

I  - Dorsal Rami

Levatores Costarum

*Important for breathing

O - TPs of C7-T11

I  - Ribs

A - Elevates ribs, minor thoracic rotation

I  - Dorsal Rami

Interspinales

O - SPs

I  - SPs

A - Extension of vertebral column

I  - Dorsal Rami

Intertransversarii

O - TPs

I  - TPs

A - Lateral flexion of vertebral column

I - Dorsal Rami

Superficial Back Muscles

Trapezius

Latissimus Dorsi

Levator Scapulae

Rhomboids Major

Rhomboids Minor

Serratus Posterior Superior

Serratus Posterior Inferior

Superficial Layer of Deep Back Muscles

Splenii muscles

Splenius Capitis

Splenius Cervicis

Intermediate Layer of Deep Back Muscles

Erector spinae muscles

Iliocostalis

Longissimus

Spinalis

Deep Layer of Deep Back Muscles

Transversospinal muscles

Semispinalis

Multifidus

Rotatores

Deepest Layer of Deep Back Muscles

Segmental muscles

Levatores Costarum

Interspinalis

Intertransversarii

Intercostals

O - Inferior border of ribs

I - Superior border of inferior rib

A - Extenal: elevate ribs

Internal/Innermost: depress ribs

I - Intercostal nn.

Transverse Thoracis

O - Posterior surface of sternum

I - Deep surface of costal cartilages 2-6

A - Depress ribs

I - Intercostal nn.

Subcostalis

O - Deep surface of lwoer ribs

I - Superior borders of ribs 2-3 above origin

A - Depresses ribs

I - Intercostal nn.

Rectus Abdominis

O - Xiphoid process and costal cartilages 5-7

I  - Pubic bone and pubic symphysis

A - Trunk flexion, posterior pelvic tilt, compresses abdominal viscera

I  - Thoracoabdominal nn. T6-T12

External Oblique

O - Ribs 5-12

I - Linea alba, pubic tubercle, iliac crest

A - Bilateral: Trunk flexion, compresses abdominal viscera

Unilateral: Contralateral trunk rotation, ipsilateral lateral trunk flexion

I  - Thoracoabdominal nn. T6-T12

Internal Oblique

O - Ribs 10-12 and linea alba

I - Iliac crest and inguinal ligament

A - Bilateral: Trunk flexion, compresses abdominal viscera

Unilateral: Ipsilateral trunk rotation, ipsilateral lateral trunk flexion

I - Thoracoabdominal nn. T6-T12

Transverse Abdominis

O - Costal cartilages 7-12, iliac crest, inguinal ligament

I  - Pubic crest, linea alba, pectinial line

A - Bilateral: compresses abdominal viscera

Unilateral: Ipsilateral trunk rotation

I  - Thoracoabdominal nn. T6-T12 

Quadratus Lumborum

O - Lumbar TPs and 12th rib

I  - Iliac crest

A - Bilateral: Trunk extension

Unilateral: Ipsilateral trunk lateral flexion, hip hiking

I - T12-L4

Psoas Minor

O - T12-L1 Vertebral bodies and discs

I - Pectin Pubis

A - Hip flexion, posterior pelvic tilt

I  - Anterior rami L1

Psoas Major

O - T12-L5 Vertebral bodies and discs

I  - Lesser trochanter 

A - Hip flexion, Hip ER, Trunk flexion

I  - Anterior Rami L1-L3

Iliacus

O - Iliac fossa

I  - Lesser trochanter

A - Hip flexion, Hip ER, Trunk flexion

I  - Femoral n. L2-L3