A morphological comparison of the human lumbar multifidus by chemical dissection

Abstract

This anatomical study describes the morphology of the human lumbar multifidus muscle through gross and chemical dissection of fresh cadavers. Previous morphological descriptions were analyzed with regard to fascicular divisions and cleavage planes. Gross dissection was performed on the lumbar multifidus of four fresh adult human cadavers and four preserved cadavers. Gradual chemical dissection using nitric or formic acid was used for connective tissue digestion to enhance the documentation of muscle fiber direction. Results revealed four distinct layers of the lumbar multifidus separated by cleavage planes. The superficial layer was more extensive than previously described with bony attachments at both the origin and insertion at several vertebral levels. The attachments of the second through fourth layers differed in that distinct cleavage planes between the various fascicles were not found with chemical dissection. The lumbar multifidus has a multipennate fiber arrangement, and the fascicles between the various layers inter-attach. Inter-fascicle attachment differs with the description by Macintosh et al of distinct cleavage planes between and within the fascicles of each layer. Accurate anatomical knowledge of the fascicles of the lumbar multifidus is integral for defining the actions of this complex lumbar muscle. This study supports the clinical belief that the multifidus has a significant role in control and stabilization of the lumbar spine in multiple planes of action. The multipennate arrangement of this muscle with fascicular inter-attachment supports the clinical premise that the multifidus is activated in a variety of positions and can potentially produce and mediate intersegmental mobility and provide proprioception.

Keywords: Chemical Dissection; Lumbar Region; Multifidus; Muscles.

FIGURE 1

Multifidus as depicted in Gray's Anatomy (1918).

FIGURE 2

Dorsal view of multifidus in fresh cadaver-blunt dissection only. Arrow pointing to pin on L1 spinous process.

FIGURE 3

Lateral views of multifidus-blunt dissection.

FIGURE 4

Superficial layer: SP=Spinous Process, SAP=Superior Articular Process.

FIGURE 4A

Superficial layer; origin: mamillary process; insertion: spinous processes.

FIGURE 4B

Resection of superficial layer; fresh cadaver.

FIGURE 5

Superficial layer; pins depicting the natural separation of layers one and two.

FIGURE 6

Fascicles of the second layer of the multifidus. 2F=Tendon and fascicle of second layer originating from L2 spinous process. 2FA=Tendon and fascicle of second layer originating from L1 spinous process. Fascicles from 2FA interdigitate with fascicle 2F. 2FB=Tendon and fascicle of second layer originating from L3 spinous process receiving fascicles from 2F. Not pictured: Interdigitation of muscle fibers to the layer ventral to the second layer or 3F fascicles.

FIGURE 7

Layer 2 post-chemical dissection fresh cadaver. 2F=Tendon and fascicle of second layer originating from L1 spinous process. 2FA=Tendon and fascicle of second layer origination from T12 spinous process. Fascicles from 2FA interdigitate with fascicle 2F. 2FB=Tendon and fascicle of second layer originating from L2 spinous process receiving fascicles from 2F.

FIGURE 8

Second and third layers post-chemical dissection fresh cadaver. 2F=Second-layer tendon and fascicle. 3F=Third-layer fascicle, muscular in origin from spinous process.

FIGURE 9

Layer 3 fascicles interdigitating with fascicles above and below.

FIGURE 10

Second- and third-layer fresh cadaver. 2F=Second-layer tendon and fascicle. 3F=Third-layer fascicle, muscular in origin from spinous process.

FIGURE 11

Layer 3 fascicle-muscular attachment. 2F= Second-layer tendon and fascicle. 3F= Third-layer fascicle, muscular in origin from spinous process.

FIGURE 12

Fourth layer. Interlaminar fibers.