Anatomy & Stretching 101 The Intrinsic Muscles of the Spine

Anatomy and Stretching 101

Muscles of Back Most body weight lies anterior to the vertebral column, especially in obese people; consequently, the many strong muscles attached to the spinous and transverse processes of the vertebrae are necessary to support and move the column.

There are two major groups of muscles in the back. The extrinsic back muscles include superficial and intermediate muscles that produce and control limb and respiratory movements, respectively.

The intrinsic (deep) back muscles include muscles that specifically act on the vertebral column, producing its movements and maintaining posture.

The section below will focus on the intrinsic back muscles.

Note/tip. Because of the number and complexity of the intrinsic spinal muscles, we have chosen not to provide images of all of them. Rather, we have provided examples. Use your anatomy software program to explore each region. Click in individual muscles, isolate them, highlight them, strip layers away or use labels to explore their origins, insertions and actions.

Intrinsic Back Muscles • The intrinsic back muscles are grouped into superficial, intermediate, and deep layers according to their relationship to the surface.

• The intrinsic back muscles (muscles of back proper, deep back muscles) are innervated by the posterior rami of spinal nerves • Act to maintain posture and control movements of the vertebral column • These muscles which extend from the pelvis to the cranium, are enclosed by deep fascia that attaches medially to the nuchal ligament, (see image A) the tips of the spinous processes of the vertebrae, the supraspinous ligament, (see image B) and the median crest of the sacrum.

• The fascia attaches laterally to the cervical and lumbar transverse processes and the angles of the ribs.

• The thoracic and lumbar parts of the deep fascia constitute the thoracolumbar fascia. (See image C) It extends laterally from the spinous process and forms a thin covering over the intrinsic back muscles in the thoracic region and a strong thick covering for muscles in the lumbar region.

IMAGE A

Image A. The Nuchal ligament is analogous to the supraspinous ligament of the lower spinous vertebrae.

IMAGE B

Image B. The supraspinous ligament joins the tips of the spinous processes from C7 to the sacrum and limits flexion.

IMAGE C

Image C. The thoracolumbar/lumbodorsal fascia is part of the back fascia that covers the thoracic and lumbar regions. It has a posterior and middle layer that encloses the muscles between them. The erector spinae are enclosed between the posterior and middle layers.

Superficial layer • The splenius muscles (L. musculi splenii) are thick and flat and lie on the lateral and posterior aspects of the neck covering the vertical muscles somewhat like a bandage, which explains their name (L. splenion, bandage) (Image 1).

• The splenius muscles arise from the midline and extend superolaterally to the cervical vertebrae (splenius cervicis, Image 3) and cranium (splenius capitis Image 2).

• The splenius muscles cover and hold the deep neck muscles in position.

• The superficial layer of intrinsic muscles and information on their attachments, nerve supply, and actions is provided in Table 1.

IMAGE 1

IMAGE 2

IMAGE 3

Image 2. Splenius capitis

Image 3. Splenius cervicis

Table 1. Superficial layer of intrinsic back muscles Muscle Splenius

Proximal Attachment

Distal Attachment

Nuchal ligament and spinous processes of C7T3 or T4 vertebrae

Splenius capitis: fibres run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone Splenius cervicis: tubercles of transverse processes of C1C3 or C4 vertebrae

Nerve Supply Posterior rami of spinal nerves

Main Action Acting alone: laterally flex neck and rotate head to side of active muscles Acting together: extend head and neck

Intermediate layer • The massive erector spinae muscles lie in a “groove” on each side of the vertebral column between the spinous processes centrally and the angles of the ribs laterally • The erector spinae are the chief extensors of the vertebral column and are divided into three parallel columns (note, not layers) : The iliocostalis forms the lateral column (image 4), the longissimus forms the intermediate column, and the spinalis forms the medial column, • Each column is divided regionally into three parts according to the superior attachments (e.g., iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis). See example image 4.

• The common origin of the three erector spinae columns is through a broad tendon that attaches inferiorly to the posterior part of the iliac crest, the posterior aspect of the sacrum, the sacroiliac ligaments, and the sacral and inferior lumbar spinous processes.

• The erector spinae are often referred to as the “long muscles” of the back.

• In general, they are dynamic (motion-producing) muscles, acting bilaterally to extend (straighten) the flexed trunk.

• The muscles of the intermediate layer and their attachments, nerve supply, and actions is provided in Table 2.

Table 1. Superficial layer of intrinsic back muscles Muscle Erector spinae Iliocostalis Longissimus Spinalis

Proximal Attachment Arises by a broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacroiliac ligaments, sacral and inferior lumbar, spinous processes, and supraspinous ligament

Distal Attachment Iliocostalis: lumborum thoracis, cervicis; fibres run superiorly to angles of lower ribs and cervical transverse processes Longissimus: thoracis, cervicis, capitis; fibres run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions, and to mastoid process of temporal bone.

Spinalis: thoracis, cervicis, capitis; fibres run superiorly to spinous processes in the upper thoracic region and to cranium

Nerve Supply Posterior rami of spinal nerves

Main Action Acting bilaterally: extend vertebral column and head; back is flexed, control movement via eccentric contraction Acting unilaterally: laterally flex vertebral column

IMAGE 4

Image 4. Each column is divided regionally into three parts according to the superior attachments (e.g., iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis).

IMAGE 5

Intermediate layer • D eep to the erector spinae is an obliquely disposed group of much shorter muscles, the transversospinales muscle group consisting of the • Semispinalis Image 6 • Multifidus Image 7, 8, 9 and • Rotatores Image 10 • These muscles originate from transverse processes of vertebrae and pass to spinous processes of more superior vertebrae. They occupy the “gutter” between the transverse and the spinous processes and are attached to these processes, the laminae between them, and the ligaments linking them together .The semispinalis is the superficial member of the group. As its name indicates, it arises from approximately half of the vertebral column.

Image 5. Iliocostalis lumborum

Table 3. Deep layers of intrinsic back muscles Muscle Transversospinalis Semispinalis Multifidus Rotatores (brevis and longus)

Proximal Attachment Transverse processes Semispinalis: arises from transvers processes of C4-T12 vertebrae Multifidus: arises from posterior sacrum, posterior superior iliac spine of ilium, aponeurosis of erector spinae, sacroiliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of T1-T3, articular processes of C4-C7 Rotatores: arise from transverse processes of vertebrae; best developed in thoracic region

Distal Attachment Spinous processes of more superior vertebrae Semispinalis: thoracis, cervicis, capitis fibres run superomedially to occipital bone and spinous processes in thoracic and cervical regions, spanning 4-6 segments Multifidus: thickest in lumbar region; fibres pass obliquely superomedially to entire length of spinous processes, located 2-4 segments superior to proximal attachment Rotatores: fibres pass superomedially to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or 2 segments (longus) superior to vertebrae of attachment

Nerve Supply Posterior rami of spinal nerves

Main Action Extension Semispinalis: extends head and thoracic and cervical regions of vertebral column and rotates them contralaterally Multifidus: stabilizes vertebrae during local movements of vertebral column Rotatores: stabilize vertebrae and assist with local extension and rotatory movements of vertebral column; may function as organs of proprioception

IMAGE 6

Image 6. The right side of the spine displays a section of the semispinalis of the deep layer, with the erector spinae cut away. On the left are the more superficial erector spine which lie over the top.

IMAGE 7

Image 7, 8 & 9.

The multifidus muscles span the length of the spine, filling the gutter between the spinous and transverse processes.

IMAGE 8

IMAGE 9

IMAGE 10

Image 9.

The multifidus running from the sacrum cranially to the skull.

Image 10.

The rotatores muscles are the deepest of the transversospinalis group.

They are present thought out the spine but more develop in the thoracic region.

Table 4. Minor deep layer Proximal Attachment

Distal Attachment

Interspinales

Superior surfaces of spinous processes of cervical and lumber vertebrae

Intertransversarii

Levatores costarum

Muscle

Nerve Supply

Main Action

Inferior surfaces of spinous processes of vertebra superior to vertebra of proximal attachment

Posterior rami of spinal nerves

Aid in extension and rotation of vertebral column

Transverse process of cervical and lumbar vertebrae

Transverse processes of adjacent vertebrae

Posterior and anterior rami of spinal nerves1

Aid in lateral flexion of vertebral column; acting bilaterally, stabilize vertebral column

Tips of transverse processes of C7 and T1-T11 vertebrae

Pass inferolaterally and insert on rib between tubercle and angle

Posterior rami of C8-T11 spinal nerves

Elevate ribs, assisting respiration; assist with lateral flexion of vertebral column

1 Most back muscles are innervated by posterior rami of spinal nerves, but a few are innervated by anterior rami.

Anterior intertransverse muscles of the cervical region are supplied by anterior rami.

IMAGE 11

• The interspinalis muscles run from C3 to L5 Image 11 • Extend the neck and trunk • Travel superiorly to the vertebrae that are located on vertebral segment superior to their origin site.

• Information on origin function insertion can be found in table 4

Image 11. Interspinalis muscles

IMAGE 12

The intertransversarii muscles • Divided into 3 portions • Cervical • Thoracic • Lumbar • Originate from and insert into the transverse processes of adjacent vertebrae • Information on origin function insertion can be found in table 4 • Image 12

Image 12. The intertransversarii muscles

IMAGE 13

Levatores costarum • A series of small muscles that lie within the internal aspect of the posterior thoracic cage.

See image 13.

• Fibers pass in an inferolateral direction, parallel to the external intercostal muscles • Divided into two groups • Levatores costaurm breve originate from the transverse processes of C7 to T11 vertebrae inserting immediately below the vertebrae from which they originate • Levatores costaurm longi originate from transverse processes of T8 to T10 inserting into the upper margins of the ribs, two ribs below their origin • Information on origin function insertion can be found in table 4.

Image 13. Levatores costaurm longi and breve

Summary • The intrinsic back muscles have superficial, intermediate, and deep layers • The deep layer is further subdivided into major and minor categories • The intrinsic back muscles specifically act on the vertebral column • The deep layers have a greater proprioceptive function. Proprioception refers to the sense of self movement and body position.

Stretches The Posterior Stretch • Standard: Beginner • Spring Tension: Light - Medium • Muscle Emphasis: All spinal extensors from superficial to deep, hamstrings, calves, adductor magnus, gluteus maximus, latissimus dorsi

A

A & B. How to stretch Sit with feet on lower position.

Align feet with sit bones.

Slowly try to straighten legs to POT. Take chin toward chest.

B

B. How to contract Press feet down into reformer.

C

C. How to restretch Straighten legs further.

What to watch out for: • Moving carriage out too fast.

• Not taking chin to chest.

• Too much flexion in thoracic

spine and legs still bent.

The Posterior Stretch 2.0 • Standard: Beginner • Spring Tension: Light - Medium • Muscle Emphasis: All spinal extensors from superficial to deep, hamstrings, calves, adductor magnus, gluteus maximus, latissimus dorsi

A

A & B. How to stretch Sit with hands and balls of feet on foot bar. Align feet with sit bones.

Slowly try to straighten legs to POT. Take chin toward chest.

B

B. How to contract Press feet down into foot bar.

Try to lift chest to straighten spine.

C

C. How to restretch Straighten legs fully if possible.

What to watch out for: • Moving carriage out too fast.

• Not taking chin to chest.

• Too much flexion in thorax

and legs still bent.

The Dangler • Standard: Any • Spring Tension: Heavy • Muscle Emphasis: Entire posterior spinal muscles, posterior disks, posterior portion of internal obliques, transversus abdominus, quadratus lumborum

A

A. How to stretch

Clasp carriage and then shoulder rests as pictured. Allow legs to hang or dangle.

Hold for 90 seconds.

B

How to breathe

Take deep abdominal breaths to expand abdominal region.

What to watch out for: • Lifting head or feet, which engages spinal muscles.

• Shallow breathing.

• Coming out of the stretch too quickly.

The Dangler FLEXION HOW TO STRETCH: Photo A - Lie over box with pubic bone off the edge - Allow head and knees to drop completely - Take deep abdominal breaths

C

A

HOW TO CONTRACT: Photo B - Imagine pressing legs and head/upper back to ceiling

PARTNER VARIATION: Photo D - Allow legs and upper body to dangle - Contract by pushing pelvis/chest up into partner resistance - Restretch by hanging further - Deep abdominal breaths are important

D

HOW TO RESTRETCH: Photo B - Let hips and head drop down to floor - Allow legs to float as much as possible

B

Major muscles stretched Erector spinae Rhomboids

Photo C - Stronger versions with less floor contact - Instructions as above

Hamstring Spine Combo FLEXION

C

HOW TO STRETCH: Photo A - Bend one knee and drop it out to the side - Clasp opposite foot slide leg away to POT - Partner to press on pelvis towards neutral position

A

HOW TO CONTRACT: Photo B - Press heel of foot into floor - Press ball of foot into hand

B

Major muscles stretched Hamstrings Calves Erector spinae Gluteus maximus

HOW TO RESTRETCH: Photo C - Straighten leg if possible - Partner to roll pelvis forwards as much as possible - Lower chest and head onto leg

Foam Roller Mermaid LATERAL FLEXION HOW TO SET UP: Photo A - Straighten legs and place ankles onto roller - Balance body on hand and elbow

A

HOW TO STRETCH/CONTRACT: Photo B - Lift chest by pressing arm straight - Press both feet down into floor

B

VARIATION: Photo D - Roll top hip forward

D

VARIATION: Photo E - Roll top hip back

E

Major muscles stretched HOW TO RESTRETCH: Photo C - Further straighten both arms - Move supporting arm closer to body

C

Hip abductors Oblique abdominals Quadratus lumborum Multifidi

Floor Side Bend LATERAL FLEXION HOW TO STRETCH: Photo A - Abduct one leg - Bend other leg - Place elbow inside straight leg - Use arm to pull trunk towards straight leg - Roll top shoulder backwards above bottom shoulder - Reach arm overhead - Partner (if you have one) to press down on hip to keep it anchored to mat - Partner to press trunk further into side bend

C

HOW TO CONTRACT: Photo A - Press shoulders back into partner

VARIATION: Photo D - Roll top shoulder forwards so spine is rotated and bent sideways (lateral flexion)

A

D

HOW TO RESTRETCH: Photo B - Use bottom arm to pull trunk further laterally - Reach top arm towards foot - Partner to press hip down and shoulder/spine further sideways

Major muscles stretched

B

VARIATION: Photo C - Bend straight leg and place support underneath - Bend top arm at elbow

Oblique abdominals Latissimus dorsi Quadratus lumborum

Seated Side Bend LATERAL FLEXION

C

HOW TO STRETCH: Photo A - Sit on box and clasp box strap with hand - Lean to same side as arm holding box strap - Reach other arm overhead - Position top shoulder above bottom one - Partner to press down on hip and press spine into side bend HOW TO CONTRACT: Photo A - Press spine back towards upright position/ middle

A

HOW TO RESTRETCH: Photo B - Lean further to side - Partner to press down on hip and press spine into side bend

B

VARIATION: Photo C - Roll top shoulder backwards - Roll top shoulder forwards (see photo B)

Major muscles stretched Oblique abdominals Quadratus lumborum Latissimus dorsi Erector spinae Multifidi

The Mermaid • Standard: Beginner/Intermediate • Spring Tension: Light - Medium • Muscle Emphasis: Oblique abdominals, quadratus lumborum, intercostals, abductors

A

A & B. How to stretch Slide carriage out and sit in center.

Place top leg/foot on top of bottom leg/foot. Align feet, hips, hand, ensure top hip above bottom hip.

Slide carriage in to POT to find stretch.

B

B. How to contract Press hands and feet down into floor.

C

C. How to restretch Slide carriage in further.

Deepen inhalations as much as possible.

What to watch out for: • Not aligning top hip with feet.

The Seated Side Bend • Standard: Beginner/Intermediate • Spring Tension: Light - Medium • Muscle Emphasis: Oblique abdominals, quadratus lumborum, intercostals, latissimus dorsi, erector spine one side, long head of triceps

A

A. How to stretch Push carriage out and keep both sit bones on carriage.

Reach arm over and bend spine and rib cage away from footbar.

B

A. How to contract Imagine pressing outside shoulder away from footbar.

C

B & C. How to restretch Slide carriage out a little further.

Deepen inhalations as much as possible.

Bend spine and head to side as much as is comfortable.

The Standing Banana • Standard: Intermediate /Advanced • Spring Tension: Medium • Muscle Emphasis: Oblique abdominals, quadratus lumborum, intercostals, latissimus dorsi, abductors of hip A

A. How to stretch Push carriage away, straighten botton leg. Align hand on footbar with bottom hip and foot. Support arm at roughly 90 degrees to spine.

B. Shift top foot to position shown for greater support.

C. Lower hips.

B

C. How to contract Press hips up.

C

C. How to restretch Lower hips further.

Deepen inhalations as much as possible.

What to watch for • Pushing carriage out too far.

• Not lowering hips enough.

• Not aligning body

as described above.

Variations

A

B

(A) Roll top hip forward (B) and backward to shift stretch around.

Conclusion The stretches that require no equipment can be found in my book “StretchFit: Safe Effective Stretches for Every Body,” on Amazon books.

The final stretches on the Pilates reformer is from “Stretching on the Pilates Reformer: Essential Cues and Images” on Amazon books.