ligamentous- muscular support

lower Back pain syndrome


ligamentous- muscular support




FIGURE 25. Sensorimotor aspect of
nerve rool Within the intervertebral
foramen the motor roots are smaller
than the sensory and are inferior and
posterior near the disc

terior (motor) root. Thes" remain separate until encountering the ganglion

of the sensory root, at which point they merge into a single

funiculus. In their further descent and outward migration the motor

(nerve roots are concentrated anterioinferiorly in the funiculus (Fig. 25

The nerve roots and their dural sleeves are attached loosely to the

foramina and are permitted to move. The nerve axons have plasticity

but the dura has no elasticity. Traction distally or dorsally pulls the

entire nerve fiber-dura complex in either direction. The nerve roots

intrinsically elongate, whereas the dura increases in tension. This will

be discussed further in the chapter on disc herniation

Within the foramen the nerve and its sheath occupies 35 to 50 percent

of the space. The remainder of the foramen is filled with loose areolar

connective tissue, adipose tissue, arteries, veins, lymphatics, and the

(recurrent nerve of Luschka (Fig. 26

Upon emergence from the foramen, the nerves divide into their

anterior and posterior primary division, sending immediately a branch

to the facet joints (Fig. 27). Within the foramen only the dura innervated

by the recurrent nerve of Luschka is apparently pain-sensitive. The

posterior longitudinal ligament also innervated by this nerve is likewise

sensitive

We have ascertained which tissues within the functional unit are

capable of eliCiting pain, and we have depicted the static erect spine by

combining and superimposing the functional units. Now we must make

our upright person move and, in moving, the normal must be established

so that deviations capable of causing pain can be understood

LIGAMENTOUS-MUSCULAR SUPPORT

Consideration of the periarticular tissues and muscular influence on

the kinetic spine involves once again a discussion of the static spine

FIGURE 26. Dura accompanying nerve root through intervertebral foramen with its

innervation by the recurrent meningeal nerve. 1 and 2 proceed to the anterior dural

sheath, illustrating the sensitivity of that portion of the dura. The posterior dural sheath

with no innervation is insensitive. 3. Innervation which is cnpabJe of pain supplies the

posterolongitudinal ligament

.because a balanced erect static spine requires minimal muscular effort

Physiologic erect balance is essentially a ligamentous function relieved

by intermittent small muscular contractions that are triggered by

proprioceptive reflexes of the joints and ligaments. The muscles of an

erect but relaxed man are electromyographically silent except for those

in the gastrocnemius groups. The calf muscles which balance the leg at

the ankle joint are the only continually active muscular group affecting

posture.

Ligamentous support is effortless and thus not fatiguing. Excessive

or prolonged ligamentous stress ;s relieved by muscular contraction

and, as muscular effort is fatiguing, is held to a minimum for economy of

energy expenditure. Good posture requires balance between

FIGURE 27. Division o f nerve roots. Upon emergence from the foramen, the roots

divide into the anterior primary division and the posterior primary division. A small

articular branch is sensory to the facets

ligamentous support and minimal, yet adequate, muscle tone. Improper

posture or prolonged stress from awkward positions causes

protracted ligamentous strain resulting in discomfort. Strain may arise

.because of muscular fatigue which no longer affords ligamentous relief

.For proper posture, the static spine is dependent on the pelvic angle

The pelvis is held in ligamentous balance by the anterior hip joint and

the "Y" ligament. This "Y" ligament, the iliopectineal ligament, is a

fibrous reinforcement of the anterior portion of the hip joint that prevents

hyperextension of the hip. In erect stance, man "leans forward on

this ligament."

The knee joint can similarly be "locked" in extension when it relies

on the posterior popliteal tissue that prevents overextending the

knees. This position eliminates the need for any muscular effort on the

part of the quadriceps femoris. The lumbar spine can "lean" on the

,anterior-longitudinal ligament and the abdominal wall. The ankle joint

however, cannot be "locked" in any position so that muscular effort is

required constantly.

The pelvis is further supported by the tensor fascia latae. These

fascial bands mechanically assist the "Y" ligaments as well as limit

lateral shift of the pelvis. Their course from the iliac crests downward

and backward to insert at the iliotibial band at the knee lends itself well

(to reinforcing the "Y" ligament and helps lock the knee (Fig. 28

The pelvic angle is the key to ligamentous posture. Rotation of the

pelvis will initiate a total unlocking of all the balancing joints and

necessitate muscular effort

FICURE 28. Static spine support. The relaxed person leans on his ligaments: the

iHofemorai ligament, ("yo, ligament of Bigelow), the anterior longitudinal ligament, and

the posterior knee ligaments. The ankle cannot be "locked," but by leaning forward only

a few degrees the gastrocnemius must contract to support the entire body. Relaxed erect

posture is principally ligamentous with only the gllstroc.soJeus muscle group active

To study the erect person functioning in anterior-posterior plane, it is

best to view him from the rear because it will then be possible to see the

deviations from the normal in their relation to an imaginary vertical

.line

The upright supporting beams of the pelvic floor are the legs, and if

the parallel legs are equal in length the supported platform will be

horizontal. If the tibia and femurs of both legs are in direct alignment

and of equal length, the femoral heads must be equidistant from the

ground, and the transverse axis through the femoral heads must be

FICURE 29. Spinal alignment fronl anterior·posterior aspecl Anterior·posterior view of

the erect human spine. With both legs equal in length the spine supports the pelvis in a

level horizontal plane and the spine, taking off at a right (9Cklegree) angle, ascends in a

straight line. The facets shown in the enlarged drawing on the right show their parallel

alignment and proper symmetry in this erect position

FIGURE 30. Pelvic obliquity and its relationship to spinal alignmenl Anterior view of

,an oblique pelvis due to a leg-length discrepancy. Owing to pelvic slant in a lateral plane

the spinal take-off is at a lateral angle. The flexible spine will curve in an attempt to

compensate, and the facets of the curving spine will become asymmetrical in relationship

to each other

horizontal. Balanced between these two points the pelvis will rotate

.around a level axis

In the static spine a level pelvis viewed from behind will reveal the

spine ascending from the pelvic base at right angles and so continuing

cephalad will find the head perched in direct mid-line over the center

of the sacral point (Fig. 29). This head-pelvic center relationship obviously

presupposes a straight spine.

A structurally straight spine of adequate flexibility will permit symmetrical

bilateral side-bending. When we recall that lateral spine

movement occurs in the thoracic region and not in the lumbar area, an

equal degree of bending to the left or to the right will demand that the

.midpoint be level. This action requires a truly vertical lumbar spine

Symmetry in the act of Side-bending requires lateral flexibility of the

spine. As no significant lateral bending occurs in the lumbar spine the

angle of take-off from the lumbar spine at the pelvic level will determine

the amount of correction the dorsal spine must take to effect a

return to the center of gravity.

Another important factor is leg-length discrepancy which will cause a

pelvic obliquity. The causes of leg-length differences are numerous. A

unilateral genu valgum or unilateral genu recurvatum will cause the

side involved to be of shorter length. A unilateral leg-length discrepancy

can result from fractures, articular disease, amputation per se or

,from an improperly fitted prosthesis. Childhood diseases (such as osteochondrosis

poliomyelitis, and hip dysplasia), that may impair unilateral

leg growth, can lead to unequal leg lengths in adult life. The

effect of leg-length difference on the pelvic level has an apparent

influence on the static spine when it is seen from the anterior-posterior

position, and the obliquity of the pelvis has an equal effect on the

(kinetic spine (Fig. 30