Healthcare and Medicine Reference
In-Depth Information
The Lateral Line
The LL picks up another connection, the peroneus
brevis, about halfway down the lateral side of the foot.
From its insertion at the base of the 5th metatarsal, the
peroneus brevis tendon passes up and back to the pos-
terior side of the fibular malleolus, where the two pero-
neal muscles comprise the sole muscular components of
the lateral compartment of the lower leg (see Fig. 2.3, p.
66). 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).
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 shoelace pattern under the
shoulder to the skull in the region of the ear (Fig. 5.2
A,B/Table 5.1).
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 (bilateral LL
contraction), rib cage shift on pelvis, shortening of depth
between sternum and sacrum, shoulder restriction due
to over-involvement with head stability.
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 fixes the
trunk and legs in a coordinated manner to prevent buck-
ling of the structure during any activity with the arms.
Movement function
The LL participates in creating a lateral bend in the body
- lateral flexion of the trunk, abduction at the hip, and
eversion at the foot - but also functions as an adjustable
'brake' for lateral and rotational movements of the trunk
(Fig. 5.4).
The Lateral Line in detail
The lateral arch
The lateral band of the plantar fascia was included in
the Superficial Back Line (p. 76). Although it is techni-
cally not part of the LL per se, it merits a mention as a
factor in lateral balance. If the peroneal compartment is
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,
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 cunei-
form, about halfway down the foot on its medial side,
with the insertion of the tendon of peroneus 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 peroneal muscles were
recently renamed as the 'fibularis' muscles. Here we use
both terms interchangeably.)
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