Thorax (1953), 8, 282.

AN ANATOMICAL AND SURGICAL STUDY OF THEEXTRA-THORACIC FASCIA

BY

MICHEL LATARJET AND PIERRE JUTTINFrom the Anatomy Department of the Faculty of Medicine of Lyons and the National Institute of Hygiene

(RECEIVED FOR PUBLICATION MARCH 6, 1953)

Under the title of "Fascia Exo-Thoracique,"Gabrielle, Latarjet, and Michaud (1947) havedescribed an extremely thin, homogeneous, andcontinuous fascial layer which covers the surfaceof the thoracic cage, posteriorly and laterally. Thisis a well-known surgical fact and is frequently usedin suturing the resulting costo-intercostal incisionsof thoracotomies. However, the literature doesnot effectively describe this fascia either in thesense of its possessing recognizable morphologicalcharacteristics, or those histological propertieswhich render valuable service to the thoracicsurgeon.The classical papers, French, English, American

or German, describe a plane of cleavage interposedbetween a posterior muscular plane (levatorscapulae, rhomboids, and serratus magnus) andthe costo-intercostal surface anteriorly. Further-more, this space was supposedly brought intoexistence by the incessant movements of thescapula upon the thoracic wall. This gave birth tothe idea of a pseudo-articulation which wasdescribed and called the "l'articulation scapulo-thoracique" by Miramond de Laroquette (1909).It has since remained the classical description.

This study will show that the interposed spaceis bounded by two layers: one is posterior andcovers the anterior surface of the rhomboids andthe serratus magnus; the second is anterior andrests upon the costo-intercostal surface. Thissecond layer will henceforth be referred to as the" extra-thoracic fascia" by analogy with the"endo-thoracic fascia" which is interposedbetween the parietal pleura and the costo-inter-costal surface.

ANATOMICAL PROCEDURES

If the posterior integuments, the trapezius andlatissimus dorsi are reflected exposing the levatorscapulae, the rhomboids, and the scapula, it is seenthat the scapula is covered by the supra- and infra-spinatus and their aponeuroses. It is prolonged

inferiorly by the inferior portion of the serratusmagnus. The rhomboids are reflected medially totheir spinal origins by cutting the muscle at itsscapular insertions. In order to obtain a betterview of the region, it is necessary to reflectlaterally the scapula with its attached muscles, thusexposing the entire posterior region of the thoraciccage. In the median plane are the outlines of thetransverse vertebral processes and the heads of theribs, irrespective of the deep muscles of the back.Slightly laterally, the fibres of the serratus muscles,posterior, superior, and inferior, reunited by theaponeuroses of the deep muscles, are seen. How-ever, the latter muscles and the aponeuroses arethemselves covered by a recognizable fascial layer,extremely thin and transparent medially, thicker,with minute, irregular eruptions of adipose tissuelaterally: this is the extra-thoracic fascia.

BOUNDAREESThe boundaries are illustrated in Figs. 1, 2, 3,

and 4.

MEDIAL.-The medial limit originates in theregion of the vertebral attachments of the rhom-boid and latissimus dorsi, generally extending onlyto the beginning of the ninth thoracic vertebra.

LATERAL.-The lateral limit merges at theanterior insertions of the serratus anterior, that is,the fascia, beginning at the lateral portion of thesecond rib, descends obliquely downwards andanteriorly towards the mid-axillary line, which itreaches at the eighth rib; the lateral limit extendslower than the medial limit.These limits, lateral and medial, mark the route

by which the extra-thoracic fascia merges with themore superficial aponeuroses (Fig. 1). Thus, inthe region of origin of the rhomboid (medial limitof the fascia) there is a continuation with theaponeurosis covering the anterior surfaces of therhomboid, which itself is continuous with that ofthe serratus magnus. Fig. 1 demonstrates this

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EXTRA-THORACIC FASCIA 283

FIG. 1.-Horizontal section of the thoracic wall (sixth dorsal vertebra).(1) Latissimus dorsi; (2) rhomboid; (3) iliocostalis; (4) serratusdorsalis cranialis; (5) serratus anterior; (6) subscapularis;(7) infraspinalis. The interrupted line marks the route by whichthe extra-thoracic space (8) merges with the more superficial -5aponeurosis.

Fio. 2.-Sagittal section of the thoracic wall, through the scapula.(1) Trapezius; (2) supraspinalis; (3) infraspinalis; (4) latissimus'dorsi; (5) serratus anterior; (6) subscapularis; (7) aponeurosisof the serratus anterior; (8) extra-thoracic fascia.

FIG. 3.-Sagittal section of the thoracic wall medial to the scapula.(1) Trapezius; (2) latissimus dorsi; (3) rhomboid; (4) levator 9,scapulae; (5) extra-thoracic fascia.

Flo. 4.-Sagittal section of the thoracic wall, medial, and inferior tothe scapula. (1) Trapezius; (2) latissimus dorsi; (3) extra- 7thoracic fascia. The crosses show, upwards, the extra-fascialspace, downwards and anterior, the sub-fascial space.

FIG. 1.

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MICHEL LATARJET and PIERRE JUTTIN

continuity, as well as the space between them whichseparates the anterior muscles of the scapula fromthe thoracic cage. The practical and anatomicalimportance of this space will be discussed later.SUPERIOR.-At first glance, the extra-thoracic

fascia appears to follow the posterior surface ofthe scalenus posterior, but in reality, and dissectiondemonstrates this very clearly, the fascia lies asfollows.Above the scapula it merges superiorly and

posteriorly with the aponeurosis of the trapezius(Fig. 2). Medially to the scapula the fibresrun upwards and posteriorly to merge withthe aponeurosis enveloping the levator scapulae(Fig. 3). Thus, in addition to the closing off of thespace medially and laterally by the medial andlateral limits of the extra-thoracic fascia, its fusionwith the aponeurosis of the trapezius and thelevator scapu!ae limits the space superiorly.INFERIOR.-The inferior border of the extra-

thoracic fascia runs parallel to the body of theninth rib or, less frequently, the ninth intercostalspace. Thus its course is obliquely downwardsand lateral and it is covered by the anterior surfaceof the latissimus dorsi medially and of the serratusmagnus laterally. The inferior border is morecomplex, and here the extra-thoracic fascia dividesinto two sheets (Fig. 4): (1) the deep sheet, whichis thinner than the superficial, merges with thethoraco-lumbar region; (2) the superficial sheet,more resistant, unites with the anterior part of theaponeurosis of the latissimus dorsi medially andthat of the serratus magnus laterally. Thus unionwith these different aponeuroses inferiorly closesthe infero-posterior line of the retro-thoracic space.By assimilating the other limits this space appearsas an irregular, enclosed space.

MORPHOLOGYThe extra-thoracic fascia should be studied on

the living man or the fresh cadaver. Injectedspecimens cause this fascia to lose individualityand it becomes confused with its underlying struc-tures. In the living body, the extra-thoracic fasciais easily identified by its characteristic appearance.Its composition is not homogeneous, being thinsuperiorly (on the posterior surface of the scalenusand the superior digitations of the serratusmagnus), it thickens from above downwards, athickening caused by a lamination of layers. Thethickening can be seen at thoracotomy whichcauses a change in the texture of the fascia.Before the incision the fascia blends with thesurrounding elements, but several minutes after-

wards the fascia condenses and thickens, offeringa solid grip to the forceps. Another property,which manifests itself on incision, is its elasticity.It is shown by the enlargement of the space be-tween the two lips of the incision, which seem todisappear under the neighbouring muscles.The extra-thoracic fascia is a strong membrane

and this has an important surgical bearing. Afterdeveloping to its maximum thickness between thefifth and eighth ribs, the fascia thins out again inthe region of the ninth rib. The splitting, whichwas described previously, further decreases itsthickness, resulting in a membraneous appearance.This membrane is not to be considered a part ofthe extra-thoracic fascia but a prolongation of thelumbar aponeurosis. Medially, in the region ofthe deep muscles of the back, the fascia is thin.However, on its way to the lateral aspect of thethoracic wall, it thickens quickly to its maximum,which it maintains anteriorly.

MICROSCOPIc ANATOMYSections taken from different regions were

examined histologically for their constituentelements and their relationship to neighbouringfascia. Impressed by the elasticity of the extra-thoracic fascia in vivo, the sections were stainedwith Weigert-safran as well as with haematoxylinand eosin.CONSTITUENT ELEMENTS.-The extra-thoracic

fascia is composed of fatty connective tissue (ring-shaped), well vascularized, and rich in elastic fibres.The blood vessels are numerous posteriorly, butrelatively rare near the surface normally in contactwith the thoracic cage. The elastic fibres are dis-posed singly and in bundles, and, some long andthin, others short and squat, tend to orientatethemselves parallel to the laminae of the fascia, buteach differs in direction from the neighbouringlaminae (Fig. 5).The histological arrangement explains the

solidity and elasticity of the extra-thoracic fascia.It also explains its reactions to inflammation andsuppuration.

RELATION TO NEIGHBOURING FASCIAE.-It iseasily deduced that the extra-thoracic fascialies between two cellular spaces which are broughtinto existence by its presence (Fig. 6). The spacescan be divided into the space separating the super-ficial muscular plane from the fascia and the spaceinterposed between the fascia and the thoraciccage. The extra-thoracic fascia is independent andcan slide smoothly between the muscles and theosteo-muscular wall. The existing space betweenfascia and thorax has also an importance medially.

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EXTRA-THORACIC FASCIA '85

FIc. 6.-(1) Bone (rib); (2) periosteum; (3) extra-thoracic fascia; (4) extra-fascial space; (5)

aponeurotic layer.

FIG. 7.-Vertical section of the thoracic wall: theclosure of the ssound after thoracotomnv withrib resection. (1) Parietal pleura; (2) peri-osteuni of the resected rib; (3) extra-thoracicfascia; (4) muscular layer; (5) skin. The threadwshich goes through the pleura, the intercostal

i:~iffk>̂>muscles, and the extra-thoracic fascia closes thesub-fascial space (6). prosiding extensiveemphysema upssards and dossNnswards.

FIG. D.

Fic,. 7.FIG. 6.

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MICHEL LATARJET and PIERRE JUTTIN

THE POSTERIOR THORACIC SPACES

Depending upon their position, the spaces canbe called the extra-fascial space and the sub-fascialspace.EXTRA-FASCIAL SPACE.-This lies between the

muscular plan of the levator scapulae, the rhom-boid, the serratus magnus on the one hand, andthe extra-thoracic fascia on the other. Further-more, the splitting and junctions of its limitsresult in a virtually closed pocket of fairly largedimensions (Fig. 1). This can be made evident bylifting up the scapula, exposing a triangular spacelimited at its summit by the digitation of theserratus magnus supero-laterally and the scalenusposterior supero-medially. The apex is coveredposteriorly by the levator scapulae. After passingthe superior border of the first rib the apexbecomes horizontal or at least strongly oblique infront and above (Fig. 3).The medial side of the triangle lies against the

spinal processes which yield attachment to therhomboids. It is also superficial to the "deepmuscles of the back" and, arriving at the ninthrib, this line forms a curve to join with the basisof the triangle.The lateral side runs obliquely downwards and

forwards following the anterior insertions of theserratus magnus, but, at the eighth rib, changesdirection to curve backwards.The basis is concave from above downwards,

hence the border crosses the posterior axillary linein the region of the ninth rib. Here, the serratusmagnus has already disappeared and the spaceforms an inferior " cul de sac " which lies againstthe anterior surface of the latissimus dorsi. Inthe extra-fascial space the appearance of the extra-thoracic fascia is variable. Between the scapulaand the spinal processes the sheet is easilyseparated. Anterior to the scapula and serratusmagnus, a variable mass of connective tissueunites the anterior aponeurosis of this muscle andthe extra-thoracic fascia. Miramon de Laroquettehas described the various aspects of this space as" seldom free, more often interrupted by connec-tive tissue adhesions which, in order to expose theposterior aspect of the ribs, must be cut byscissors."

SUB-FASCIAL SPACE.-This is not a closed spaceas the above, but simply a plane of cleavage.Hence its communication with the neighbouringspaces is of importance. Laterally and mediallythe fascia is fastened to the muscles with which it isin contact. Above and below it communicatesfreely with the following regions. Above it opens

into the space beneath the superficial cervicalaponeurosis, and, by a narrow opening, com-municates with the space which separates the firstdigitation of the serratus magnus from the superiorfibres of the serratus posterior and superior, andbelow it continues into the region beneath themuscles of the thoraco-lumbar region, inferior tothe ninth rib (Spitalier and Aubrespy, 1950).

SURGICAL VALUE OF THE EXTRA-THORACICFASCIA

CLOSURE OF THE THORAX.-The gap of a thora-cotomy must be sealed hermetically. Parietalemphysema, mediastinal disequilibrium, inabilityto maintain pulmonary collapse after an extra-pleural pneumolysis, are some of the consequencesof any suture which allows air to escape.Different procedures are required after a thora-cotomy with or without costal resection.

Thoracotomy without Costal Resection.-Oneor more ribs are sectioned posteriorly, and to closethe resulting gap it is necessary to approach theadjacent ribs in order to suture the intercostalmuscles. The orientation of the muscle fibres andthe fragility of their aponeurosis render this sutureprecarious. To reinforce it the surgeon oftenbinds the two adjacent ribs. The intercostal nervescannot support this trauma without pain. In orderto prevent this pain and yet obtain a sound suture,the surgeon must use other methods, and we pro-pose reinforcement by the extra-thoracic fascia.

Thoracotomy with Costal Resection.-In thiscase, the suture is supported by the costal peri-osteum which was carefully guarded during theosseous resection. However, at times it is damagedby the blades of the retractor. Again, in extra-periosteal pneumolysis, its resistance is diminishedby the intercostal separation.

Thoracotomy with Temporary Section.-Ahinge is produced by leaving the rib attached to thesupero-posterior part of the periosteum. Thisoperation gives the rib a strong attachmentsuperiorly, but does not hold it in place laterally.The superficial muscles do not hold the ribagainst the thoracic wall.Thus, no matter which technique is utilized, the

surgeon needs a supplementary suture to ensurethat the gap is closed. Quite often surgeons,without identifying or naming the extra-thoracicfascia, have made use of it to reinforce the primarysuture.The extra-thoracic fascia must be used system-

atically. After first closing the gap, the thread isbrought back, the needle sewing the extra-thoracic

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EXTRA-THORACIC FASCIA

fascia and the intercostal wall together. It appearsuseless to suture the fascia alone: air which escapesfrom the primary suture spreads into the sub-fascial space, and passes into the supra-clavicularregion above and the lumbar region below. Bycontrast, by suturing this fascia as we suggest (Fig.7) the sub-fascial space is closed and the spreadof emphysema prevented. Furthermore, this suturereinforces the coherence of the musculo-periostealsuture. Unfortunately the extra-thoracic fascia isthinnest in the region where it could be most useful,i.e., at the postero-medial angle of the ribs. How-ever, it is possible to make use of the serratusposterior and superior or the levatores costorum,muscles which can be conserved on removal of therib. Certain surgeons prefer to use a thin sectionof the rhomboid muscle to reinforce the suturesabove the sixth rib. We prefer to use the extra-thoracic fascia, which is simpler, more certain, andanatomically correct.

UTILIZATION OF THE EXTRA-FASCIAL SPACE.This space is, above all, useful in the postero-lateral thoracoplasty. On sectioning the trapeziusand rhomboid to reflect the scapula, the surgeonexposes this space. After having cut the frequentconnective tissue adhesions between the extra-thoracic fascia and the aponeurosis of the serratusmagnus, he uncovers the costo-intercostal surfacecovered by the same fascia. After the ribs havebeen resected, -the floor of the space, i.e., the extra-thoracic fascia, loses its continuity and adheres tothe collapsed lung, forming a concave depression.The depression varies in depth with the extensive-ness of the resection. Inevitably, it is in this con-cavity that blood-stained serum collects. Certainsurgeons consider this fluid a valuable counter-acting agent against secondary expansion of thelung. However, most operative techniques drainthe extra-fascial space, not only to avoid inflam-matory fluids but, above all, to obtain as soon aspossible a remodelling of the soft tissues coveringthe collapsed lung. Since the angle of inclinationof the space follows the ninth rib, the drainage, tobe completely successful, must originate at theeighth rib. In practice, the surgeon fixes the

drainage slightly lateral to the posterior axillaryline at the outer edge of the highest remaining rib.But, the extra-fascial space reaches lower, betweenthe thoracic wall and the superficial muscles. Insuch a drainage, the fluids, which tend to descendto the level of the ninth rib, accumulate below thedrain. It is impossible to drain the spaceefficiently at this level, but if the drainage tube isplaced close to the lateral axillary line near theanterior part of the eighth rib, free drainage resultsbecause of the favourable slope.

Post-operative healing shows that the extra-fascial space has closed. Dense connective tissueappears, making it difficult to find the space againin a second-stage thoracoplasty or in an operationfor unsuccessful apical collapse. This space is, attimes, the seat of suppuration, complicationswhich arise after thoracoplasties or thoracotomies.By making use of the described limits of the extra-fascial space, it is possible to follow the evolutionof a suppuration and, at the same time, to drain iteffectively.

SUMMARY

The anatomy and microscopy are described of afascial layer, which is named the " extra-thoracicfascia," between the muscles of the posteriorthoracic wall and the costo-intercostal structures.

It is the floor of a closed space made of con-nective tissue, whose lower level is, backwards,along the ninth rib.The extra-thoracic fascia covers the sub-fascial

space, which communicates freely with the neigh-bouring regions, i.e., the supra-clavicular regionabove, and the lumbar region below.The extra-thoracic fascia, sealed with the costo-

intercostal plane, enforces effectively the closure ofthoracotomies.The extra-fascial space must be recognized, and

eventually drained.

REFERENCESGabrielle, H., Latarjet, M., and Michaud, P. (1947). Lyon chir., 42

101.Miramond de Laroquette (1909). Rev. Orthop., ser 2, 10, 311.Spitalier and Aubrespy (1950). Marseille chir., 2, 223.

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