The Lateral Line

The Lateral Line


The Lateral Line (LL) (Fig. 5.1) brackets each side of the body from the medial and lateral mid-point of the foot around the outside of the ankle and up the lateral aspect of the leg and thigh, passing along the trunk in a ‘basket weave’ or crossed-shoelace pattern under the shoulder to the skull in the region of the ear (Fig. 5.2 A,B/Table 5.1).

Table 5.1

Lateral Line: myofascial ‘tracks’ and bony ‘stations’ (Fig. 5.2)

Bony stations   Myofascial tracks
Occipital ridge/mastoid process 19  
  17,18 Splenius capitis/sternocleidomastoid
1st and 2nd ribs 16  
  14,15 External and internal intercostals
Ribs 13  
  11,12 Lateral abdominal obliques
Iliac crest, ASIS, PSIS 9,10  
  8 Gluteus maximus
  7 Tensor fasciae latae
  6 Iliotibial tract/abductor muscles
Lateral tibial condyle 5  
  4 Anterior ligament of head of fibula
Fibular head 3  
  2 Fibulari muscles, lateral crural compartment
1st and 5th metatarsal bases 1  

Postural function

The LL functions posturally to balance front and back, and bilaterally to balance left and right (Fig. 5.3). The LL also mediates forces among the other superficial lines – the Superficial Front Line, the Superficial Back Line, all the Arm Lines, and the Spiral Line. The LL often acts to stabilize the trunk and legs in a coordinated manner to prevent buckling of the structure during activity.

The Lateral Line in detail

The LL manages to connect both the medial and the lateral side of the foot to the lateral side of the body. We begin – at the bottom again, simply as a convenience – with the joint between the 1st metatarsal and 1st cuneiform, about halfway down the foot on its medial side, with the insertion of the tendon of fibularis longus (Fig. 5.5). Following it, we travel laterally under the foot, and, via a channel in the cuboid bone, turn up toward the lateral aspect of the ankle.

The LL picks up another connection, the fibularis brevis, about halfway down the lateral side of the foot. (The peroneal muscles were recently renamed as the ‘fibularis’ muscles; despite a lifetime of habit, we will follow the new convention.) From its insertion at the base of the 5th metatarsal, the fibularis brevis tendon passes up and back to the posterior side of the fibular malleolus, where the two fibulari muscles comprise the sole muscular components of the lateral compartment of the lower leg (see Fig. 2.3, p. 68). Thus both sides of the metatarsal complex are strongly tied to the fibula, providing support for the lateral longitudinal arch along the way (Fig. 5.6).

General manual therapy considerations

Although both of the other ‘cardinal’ lines have both a right and a left side, the two Lateral Line myofascial meridians are sufficiently far from each other and from the midline to exert substantially more side-to-side leverage on the skeleton than either the SFL or the SBL, into both of which the Lateral Line blends at its edges (Fig. 5.2A). The LL is usually essential in mediating left side–right side imbalances, and these should be assessed and addressed early in a global treatment plan.

Common postural compensation patterns associated with the LL include: ankle pronation or supination, ankle dorsiflexion limitation, genu varus or valgus, adduction restriction/chronic abductor contraction, lumbar side-bend or lumbar compression (in bilateral LL contraction), side shift of the rib cage on the pelvis, shortening of depth between sternum and sacrum, and shoulder restriction due to over-involvement with head stability, especially in head forward posture.

The lateral arch

imageThe lateral band of the plantar fascia was included in the Superficial Back Line (Ch. 3, p. 78). Although it is technically not part of the LL per se, it merits a mention as a factor in lateral balance. If the lateral muscles are so short as to evert the foot, or the foot is pronated in any case, the lateral band of the plantar fascia, running from the outer lower edge of the calcaneus straight forward to the 5th metatarsal base, will commend itself to work in the side-lying position, spreading the tissue between the two attachments (DVD ref: Lateral Line, 10:27–13:00)image.

The fibulari (peroneals)

image imageThe depth of the fibularis longus tendon on the underside of the foot and the brevity of the fibularis brevis make it impossible to accomplish anything useful with the LL below the malleolus, so we begin with the lateral crural compartment (Fig. 5.7). Fibularis longus and brevis blend together in this compartment, which is bounded by septa on either side. The anterior septum can be found on a line that runs roughly between the lateral malleolus and the front of the head of the fibula. The posterior septum, between the fibulari and the soleus, can be traced from just in front of the Achilles tendon up to just behind the fibular head. (See the palpation section below for more detail.) These septa and the overlying crural fascia are good places to open to address all forms of compartment syndrome.

As well as direct work to open these septa, the fibular myofascial units themselves can be lengthened and softened by work at right angles to the muscle fiber direction: spreading the tissue of this compartment both to the anterior and the posterior of the lateral line with fingertips or knuckles, while the client moves through the dorsiflexion–plantarflexion range (DVD ref: Lateral Line, 12:51–19:12).image

The fibulari are often used posturally to prevent dorsiflexion, as in standing, and can create excessive eversion when they are too short.

The thigh

image imageAlthough the fibularis brevis originates on the lower half of the fibula, the longus (and thus the fascial compartment) and this train of the LL continue on up to the fibular head. The obvious, straight-ahead connection from this point is to continue on to the biceps femoris, and this myofascial meridian connection will be explored in the next chapter on the Spiral Line. The continuation of the LL, however, involves a different switch, going slightly anterior onto the anterior ligament of the head of the fibula onto the tibial condyle and blending into the broad sweep of the inferior fibers of the iliotibial tract (ITT) (Fig. 5.8A and B).

The ITT begins its upward journey here, starting from the lateral tibial condyle as a narrow, thick, and strong band that can be clearly felt on the lateral aspect of the lower thigh. Like the Achilles tendon, the ITT widens and thins as it passes superiorly. By the time it reaches the hip, it is wide enough to hold the greater trochanter of the femur in a fascial cup or sling (Fig. 5.9). The tension on the ITT sheet, which is maintained and augmented by the abductors from above and the vastus lateralis hydraulically amplifying from beneath, helps keep the ball of the hip in its socket when weight is placed on one leg. This arrangement also acts as a simple tensegrity structure. By acting as a ‘backstay’, some of the direct compressive stress of our body weight is taken off the femoral neck by the ITT, whose leverage can be augmented by a contraction of the underlying vastus lateralis.

The LL continues to widen above the trochanter, to include three muscular components: the tensor fasciae latae along the anterior edge, the superior fibers of the gluteus maximus along the posterior edge, and the gluteus medius, which attaches to the underside, the profound side, of the ITT’s fascial sheet (see Figs 5.3 and 5.4).

All these myofasciae tack down onto the outer rim of the iliac crest, stretching from the ASIS to the PSIS. This entire complex is used in the weighted leg in every step to keep the trunk from leaning toward the unweighted leg. In other words, the abductors are less often used to create abduction, but are used in every step to prevent hip adduction. This requires a stabilizing tension along the whole lower LL.

The iliotibial tract

image In terms of its role in the LL, the ITT can be considered to begin at a point at the bottom (the tibial condyle, but really the whole outside of the knee), spreading upward to three points at the top (the ASIS, PSIS, and the strong fascial attachment at the heavy middle portion of the iliac crest). Depending on the postural angle of the pelvis, it may be advisable to work the leading or following edge of the ITT more strongly. Left–right imbalances in ITT tone will be present in lateral tilts of the pelvis. Imbalance between the ITT and adductor muscles will be present in genu varum and valgum (laterally or medially shifted knees).

The ITT can be worked in a manner similar to the fibulari: with the client side-lying and the knee supported, the practitioner can work either up or down the ITT and associated abductors, spreading laterally from the lateral midline with knuckles or loose fists. Since fibers of the ITT are meshed with the circumferential fibers of the fascia lata, it can also be useful to work the side of the leg vertically. Use the flat of the ulna, placing one just under the iliac crest, the other just above the greater trochanter. Slowly but deliberately bring the lower elbow toward the knee, stimulating the ITT (though it is too tough to get much longer, so ‘stretching’ the ITT is stretching the truth). The client can help by bringing the knee forward and back (DVD ref: Lateral Line, 19:13–25:51). image

Searching fingers can assess: Is the anterior edge of the ITT thicker, more fixed, or tighter than the posterior edge? If so, then the angle of the forearm on the leg can be adjusted, as in changing the angle of a violin bow to sound another string, to emphasize either the anterior, middle, or the posterior portion.


image As we move from the appendicular portion to the axial portion of the LL, we face another derailment – a break with the general Anatomy Trains rules. The ITT – in fact, the whole lower LL – looks a bit like the letter ‘Y’ (Fig. 5.9). To follow the rules we would have to keep going up and out on the upper prongs of the ‘Y’ (as in Fig. 5.10A) with sheets or lines of myofasciae that continued to fan outward and upward from the ASIS and PSIS. We will find these continuations in the Spiral and Functional Lines (Chs 6 and 8). If, however, we look at how the myofascia arranges itself along the lateral aspect of the trunk from here on up, we find that the fascial planes cross back and forth in a basket weave arrangement (Figs 5.2 and 5.10B).

Although these sharp changes in direction break the letter of the Anatomy Trains rules, the overall effect of these series of ‘X’s (or diamonds, if you prefer) is to create a mesh or net which contains each side of the body as a whole – a bit like the old Chinese finger traps. The resultant structure is a wide net of a line that contains the lateral trunk from hip to ear (see Fig. 5.2).

Jun 11, 2016 | Posted by in ANATOMY | Comments Off on The Lateral Line

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