Superficial Back Line (SBL)

Myofascial Meridian

Authors
Affiliations

Doctor of Physical Therapy

B.S. in Kinesiology

Doctor of Physical Therapy

B.A. in Neuroscience

Overview

The SBL runs from the plantar foot up the posterior body to the head and wrapping anteriorly to the brow1. There are 2 distinct pieces: toes to knees and knees to brow1. The SBL is likened to a “carapace”1.

Postural Function

Posturally, the SBL helps support the body to attain a fully upright standing position1. The SBL assists extension and prevents flexing into the fetal position1.

Since the SBL primarily plays postural roles, its associated muscles have an increased proportion of slow-twitch (type I) muscle fibers which excel at endurance1.

Since humans spend most of their waking hours fully upright, the SBL is placed under constant load due to postural demand1. As a result, the fascia adapts to these demands by thickening and creating extra-heavy fascial sheets and bands, as exemplified by the plantar fascia, achilles tendon, within the hamstrings, sacrotuberous lig., thoracolumbar fascia, the “cables” of the erector spinae muscles, and the nuchal lig.1.

Note

Although the SBL primarily performs extension, a notable exception is the knee joint1.

The SBL muscles of the hamstring and gastrocnemius function to flex the knee1. Posturally, the SBL assists full upright stance at the knee through its interlocking tendons at the posterior knee which assist the cruciate ligaments1.

Common postural compensations

  • Ankle dorsiflexion limitation1
  • Knee hyperextension1
  • Hamstring shortness (overuse often due to compensation for dysfunctional deep hip stabilizers)1.
  • Anterior pelvic shift1
  • Sacral nutation1
  • Lordosis1
  • Extensor widening in thoracic flexion1
  • Cervical hyperextension due to Suboccipital limitation1
  • Anterior shift or rotation of the occiput on the atlas (C0-C1)1.
  • Eye–spine movement (oculo-motor reflex) disconnection1

Movement Function

Other than the knee joint, the SBL primarily functions to create extension or hyperextension1.

Development

During development, the fetus is in the “fetal position,” and the SBL does not develop much in this position1.

As babies, we begin to lie in prone and begin to utilize the SBL to extend our neck and head to look around1. Babies progressively use more distal parts of the SBL moving from just neck to belly, seat, knees, and feet1.

Details

The SBL is a cardinal myofascial line1. It acts primarily in the sagittal plane: limiting flexion or creating extension1.

There are 2 SBLs: right SBL and left SBL1.

Table 1: superficial back line: Myofascial ‘tracks’ and bony attachments1
Bony Attachments Myofascial tracks
frontal bone, supraorbital ridge 13
12 Galea aponeurotica/ epicranial fascia
Occipital ridge 11
10 Sacrolumbar fascia / erector spinae
Sacrum 9
8 Sacrotuberous ligament
Ischial tuberosity 7
6 Hamstrings
Femoral condyles 5
4 Gastrocnemius and Achilles tendon
Calcaneus 3
2 Plantar fascia and short toe flexors
Plantar surface of toe phalanges 1

Toes to Heel

The most distal bony attachment is at the plantar toes1. The first myofascial track is composed of the plantar fascia and the tendons of the 4 short toe flexors (see Table 2)1.

Table 2: Short Toe Flexor OIAN
Muscle Origin Insertion Innervation Action

The 4 short toe flexors and plantar fascia form 5 distinct bands blend into 1 single aponeurosis and attach onto the anterior-inferior aspect of the calcaneus1. There is a 6th band known as the “lateral band” which runs from the 5th metatarsal base1.

These fascia and their respective muscles pull across the bottom of the foot to create a “bow-string” with the longitudinal arches1. This bowstring mechanism aproximates the two ends and keep the proper relationship between the triangulation of the heel, 1st metatarsal head and 5th metatarsal head1.

Examination

Assess the foot by observing the triangulation between the heel, 5th metatarsal and 1st metatarsal1.

If the medial foot (Heel to 1st MT)

Heel to Knee

Knee to Hip

Hip to Sacrum

Sacrum to Occiput

Occiput to Supraorbital Ridge

Poly and Monoarticular muscles

Expresses and locals # Bony Attachments Stations

Distal Hamstrings

Separating the Hamstrings

Knee rotation

Plantar fasciitis

Heel Spurs

Test

Forward bend

Derailment

Sacrotuberous ligament

Sacrotuberous ligament

Erector spinae fascia

Suboccipital Muscles

Suboccipitals

Scalp

Neurocranium relationship

General Movement Treatment Considerations

Overall stretches

Specific treatments

Palpation

The SBL and the Waves of the Spine

Is There a Deep Back Line?

References

1.
Myers TW. Anatomy Trains. 4th ed. Elsevier; 2021.

Citation

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