Deep Back Musculature

 

Splenius Muscles:

 

Splenius capitis

• Origin:

  1. lower portion of ligamentum nuchae

  2. spinous processes of C3-T3(4)

• Insertion:

  1. superior nuchal line

  2. mastoid process of temporal bone

• Action:

  1. bilateral contraction: extend head & neck

  2. unilateral contraction: rotate and laterally bend head & neck to the contracted (same) side

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Splenius cervicis

• Origin: spinous process of T3-T6

• Insertion: posterior tubercles of transverse processes of C2-C4

• Action:

  1. bilateral contraction: extend head & neck

  2. unilateral contraction: rotate and laterally bend head & neck to the contracted (same) side

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

 

Erector Spinae Muscles

 

Iliocostalis lumborum

• Origin: common tendinous origin: (same for all lower erector spinae)

  1. sacrum

  2. iliac crest

  3. spinous processes of lower thoracic & most lumbar vertebrae

• Insertion: lower border of angles of ribs (5)6-12

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Iliocostalis thoracis

• Origin: upper border of ribs 6-12 (medial to I. lumborum's insertion.)

• Insertion: lower border of angles of ribs 1-6 (sometimes transverse process of C7)

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Iliocostalis cervicis

• Origin: angles of ribs 1-6

• Insertion: transverse processes of C4-C6

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Longissimus thoracis

• Origin: common tendinous origin: (same for all lower erector spinae)

  1. sacrum

  2. iliac crest

  3. spinous processes of lower thoracic & most lumbar vertebrae

• Insertion:

  1. transverse processes of all thoracic vertebrae

  2. all ribs between tubercles and angles

  3. transverse processes of upper lumbar vertebrae

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Longissimus cervicis

• Origin: transverse processes of T1-T5(6)

• Insertion: transverse processes of C2-C6

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Longissimus capitis

• Origin:

  1. transverse and articular processes of middle and lower cervical vertebrae

  2. transverse processes of upper thoracic vertebrae

• Insertion: posterior aspect of mastoid process of temporal bone

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Spinalis thoracis

• Origin: common tendinous origin: (same for all lower erector spinae)

  1. sacrum

  2. iliac crest

  3. spinous processes of lower thoracic & most lumbar vertebrae

• Insertion: spinous processes T3(4)-T8(9)

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Spinalis cervicis

• Origin: spinous processes of C6-T2

• Insertion: spinous processes of C2 (and possibly extend to C3 or C4)

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Spinalis capitis

• Origin: spinous processes of lower cervical & upper thoracic vertebrae

• Insertion: between superior & inferior nuchal lines of occipital bone

• Action: (same for all erector spinae)

  1. bilateral:

     1. extension of vertebral column

     2. maintenance of erect posture (pneumonic = I Like Standing)

     3. stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity

  2. unilateral:

     1. lateral bend to same side

     2. rotation to same side

     3. opposite muscles contract eccentrically for stabilization

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

 

Transversospinal Muscles

 

Semispinalis thoracis

• Origin: transverse processes of T6-T12 vertebrae

• Insertion: spinous processes of upper thoracic & lower cervical vertebrae

• Action:

  1. bilaterally extends vertebral column, especially head and neck

  2. controls lateral flexion to side opposite contraction (eccentric for stability)

  3. maintains head posture

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Semispinalis cervicis

• Origin: transverse processes of T1-T6 vertebrae and can go down to lower thoracic

• Insertion: spinous processes of C2-T5(6)

• Action:

  1. bilaterally extends vertebral column, especially head and neck

  2. controls lateral flexion to side opposite contraction (eccentric for stability)

  3. maintains head posture

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Semispinalis capitus

• Origin:

  1. transverse processes of T1-T6

  2. articular processes of C4-C7

• Insertion: between superior & inferior nuchal lines of occipital bone

• Action:

  1. bilaterally extends vertebral column, especially head and neck

  2. controls lateral flexion to side opposite contraction (eccentric for stability)

  3. maintains head posture

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Multifidus

• Origin:

  • cervical region: from articular processes of lower cervical vertebrae

  • thoracic region: from transverse processes of all thoracic vertebrae

  • lumbar region:

    1. lower portion of dorsal sacrum

    2. PSIS

    3. deep surface of tendenous origin of erector spinae

    4. mamillary processes of all lumbar vertebrae

• Insertion: spinous process of all vertebrae extending from L5 - C2 (skipping 1-3 segments)

• Action:

  1. bilaterally extends vertebral column

  2. controls lateral flexion to side opposite contraction (eccentric for stability)

  3. unilaterally rotate vertebral bodies (column) to opposite side

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Long rotators

• Origin: transverse process of one vertebra

• Insertion: skips one vertebra to insert on the base of spinous process of vertebra above

• Action:

  1. rotate to opposite side

  2. bilateral extension

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Short rotators

• Origin: transverse process of one vertebra

• Insertion: base of spinous process of vertebra immediately above

• Action:

  1. rotate to opposite side

  2. bilateral extension

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

 

Segmental Muscles

 

Interspinalis

• Origin: spinous processes of each vertebra

• Insertion: to the spinous process of vertebra immediately above

• Action: extension of the vertebrae segments

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves

 

Intertransversi

• Origin: (A to A and B to B)

  • cervical region:

    1. from the anterior tubercle of transverse process

    2. from the posterior tubercle of transverse process

  • thoracic region: (poorly developed)

  • lumbar region:

    1. lateral aspect of the transverse process

    2. mamillary process

• Insertion:

  • cervical region:

    1. to the anterior tubercle immediately above

    2. to the posterior tubercle immediately above

  • thoracic region: (poorly developed)

  • lumber region:

    1. lateral aspect of the transverse process immediately above

    2. to the accessory process on the vertebra immediately above

• Action:

  1. laterally flexes each respective pair of vertebrae

  2. (also eccentric muscle contraction provides stability)

• Blood: muscular branches of the aorta

• Nerve: dorsal rami of spinal nerves