Morphological Classification of the Muscular Tubercles of the Vertebrae

Transcription

1 Okajimas Folia Anat. Jpn., 58(4-6) : , March 1982 Morphological Classification of the Muscular Tubercles of the Vertebrae By TATSUO SATO and SUSUMU NAKAZAWA Department of Anatomy, School of Medicine, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113, Japan -Received for Publication, December 26, Key words : Vertebrae, Tubercles, Paravertebral muscles. Summary : Presacral vertebrae, excluding the atlas and axis, obtained from fifty dried vertebral columns were carefully examined to detect the muscular tubercles derived from the attachments of the paravertebral muscles. On the basis of the divisions of these muscles, the tubercles may be classified as follows : (1) tubercles of the median attachments of the back muscles observed at the tips of the spines, (2) tubercles of the lateral attachments of the medial series of the intrinsic back muscles, corresponding to the mamillary processes, observed on the posterior aspect of the cervical articular column and on the upper surfaces of the thoracic transverse processes, (3) tubercles of the lateral series of the intrinsic back muscles and of the posterior laterovertebral muscles, corresponding to the cervical posterior tubercles, observed at the lower surfaces of the thoracic transverse processes, and divided into two in the lumbar region, the accessory processes and the tubercles on the fronts of the costal processes, (4) tubercles of the anterior laterovertebral muscles and of the lateral attachments of the prevertebral muscles, corresponding to the cervical anterior tubercles, observed in the lumbar region at the tips of the costal processes, (5) tubercles of the medial attachments of the prevertebral muscles which exist as small tuberosities of the longus colli on the cervical vertebrae, as tuberculi musculi longi colli (Krmpotic) on the upper thoracic vertebrae and as tuberosities of the psoas major on the lumbar vertebral bodies. Illustrations of typical examples of the above tubercles are provided at the end of the report. In general, the form of a bone is strongly influenced by its surrounding structures. Of these structures, muscles are the most important element. In this study we are concerned with the formation of elevations on the surface of the vertebral column. Most of these elevations take the form of small tubercels, derived from the tendinous attachments of the paravertebral muscles. Since these muscles are divided into several longitudinal series, the tubercles may also be classified accordingly. Thus, the present study was undertaken with the 1167

2 1168 T. Sato and S. Nakazawa intention of locating and classifying the muscular tubercles. In this paper we report our findings on the muscular tubercles of the presacral vertebrae, exclusive of the atlas and axis (C3-L5). Our findings on the atlas, axis and sacrum will be published in a further paper. Materials and Methods This report is based on the examination of fifty dried vertebral columns from the collection in the Department of Anatomy at Tokyo Medical and Dental University. Of these, thirty-six were male and eight female, ranging from 18 to 70 years of age, while the other six were of unknown sex and age. A special dissection were performed on an adult male cadaver in order to obtain anatomical details of the arrangement and attachment of the paravertebral muscles. 3) small processes formed by traction of the attachments of the intrinsic muscles of the back : processus mamillaris et accessorius in the lumbar region. The processes of the third group are different from the former two in that they are muscular processes (Wood Jones 1911) or muscular tubercles, which, contrary to common opinion, do sometimes appear on the cervical and thoracic vertebrae as well as the lumbar. In order to investigate and to classify the muscular tubercles of the vertebrae systematically, we thought special atten- Observations and Discussion The fundamental elements of a vertebra are the body and arch, from which some processes project. In the "Nomina Anatomica" the following seven processes are recognized : a) processes spinosus b) processus transversus c) processus articularis superior d) processus articularis inferior e) processus costarius f) processus mamillaris g) processus accessorius These processes are morph logically classified as follows : 1) processes contributing to the formation of the intervertebral joints : processus articulares superior et inferior ; 2) processes situated in accordance with the horizontal and the dorsal median septa from the point of view of comparative anatomy : processus spinosus, transversus, et costarius ; Text-Fig. 1. Diagram showing the typical course and manner of attachment of the paravertebral muscles and possible location of muscular tubercles derived from these muscles.

3 Classification of Muscular Tubercles of Vertebrae 1169 tion should be paid to the composition and direction of the paravertebral muscles. Since each series of paravertebral muscles follows an obliquely longitudinal course, the muscular tubercles may appear predominantly along the longitudinal lines of the medial and lateral attachment margins of that muscle series (Text-Fig. 1). Therefore, classification of the paravertebral muscles is required before investigating the sites of muscular tubercles. The paravertebral muscles are divided into three groups, the post-, latero- and pre-vertebral, according to their relative positions to the transverse processes (Text-Fig. 2). The postvertebral muscles are subdivided into the extrinsic back muscles, and the medial and lateral series of the intrinsic back muscles. The laterovertebral muscles are traversed by the ventral primary rami of the spinal nerves, which subdivide them into posterior and anterior muscles. Therefore, the paravertebral muscles may be classified as follows (Text-Fig. 3 & Table 1) : Text-Fig. 2. Diagrammatic transverse section through a cervical vertebra showing the arrangement of the paravertebral muscles. A: Gross division of the paravertebral muscles into three groups. B: Components of the three muscle groups.

4 1170 T. Sato and S. Nakazawa Text-Fig. 3. Diagrams showing the arrangement of the paravertebral muscles and the possible location of tubercles derived from these muscles in the cervical, thoracic, and lumbar regions. A-i : Gross division of the paravertebral muscles into three groups. A-u: Components of the three muscle groups. B-i : Location of the muscular tubercles. B-u: Detailed analysis of the tubercles.

5 Classification of Muscular Tubercles of Vertebrae 1171 Table 1. Morphological Classification of the Muscular Tubercles of the Vertebrae (C3-L5). 1. Muscular tubercles of the median attachments of the extrinsic and intrinsic back muscles On the lateral side of the tip of each spinous process, one or more small tubercles or tuberosities may be observed (Plate I). These elevations can be divided theoretically into three groups : 1) the tubercles of the tendinous sheets of the extrinsic back muscles, i.e., the trapezius, latissimus dorsi, rhomboideus, and serrati posteriores ; 2) those of the superficial median attachments of the lateral series of the intrinsic back muscles, i.e., the splenius and longissimus thoracis ; 3) those of the median attachments of the medial series of the intrinsic back muscles, i.e., the spinalis, semispinales thoracis et cervicis, and the multifidus. Usually, the tubercles formed by these three muscle groups fuse, and it is very difficult to distinguish one from the other. 2. Muscular tubercles of the lateral attachments of the medial series of the intrinsic back muscles The most typical examples of the muscular tubercles in this series are the mamillary processes on the lumbar vertebrae, from which the multifidus originates. Since the medial series of the intrinsic back muscles continues to the thoracic and cervical regions, we suggest that tubercles homologous with the mamillary processes may also be observed there. The tubercles are often found on the lower thoracic vertebrae at the roots of their transverse processes (Th10 Th12 in Plate 11), and may occasionally be observed in the middle thoracic region at the same points. On the cervical vertebrae, especially on C5 and C6, prominent muscular tubercles, deriving from the multifidus, are sometimes found between the superior and inferior processes, i.e., on the surface of the so-colled articular column (C5.C6 in Plate 1). These processes, if well-developed, are

6 1172 T. Sato and S. Nakazawa cone-shaped, and their pointed ends are directed cranially and slightly towards the medial. 3. Muscular tubercles of. the lateral series of the intrinsic back muscles and of the posterior laterovertebral muscles Typical examples of the tubercles in this series are the posterior tubercles of the cervical vertebrae and the accessory processes of the lumbar vertebrae. The posterior tubercles are derived from the attachments of the splenius, iliocostalis, and longissimus, and from the scaleni medius et posterior. Indistinct elevations corresponding to the posterior tubercles may also be observed at the lower surfaces of the transverse processes of the upper and middle thoracic vertebrae (Plates ifi & IV). In the lower thoracic region these elevations gradually increase in prominence and at the level of Th10 or Thll take the form of distinct tubercls. In the lumbar vertebrae they are called accessory processes, and serve the medial tendons of the longissimus thoracis. In addition to these processes, small tuberosities are observed at the tips of the costal processes for the lateral tendons of that muscle and for the quadratum lumborum (Plate IV). 4. Muscular tubercles of the anterior laterovertebral muscles and of the lateral attachments of the prevertebral muscles Typical examples of the tubercles in this series are the anterior tubercles of the cervical vertebrae. These are derived from the attachments of two muscle groups : the scalenus anterior belonging to the anterior laterovertebral muscles, and the longi capitis et colli of the prevertebral group (Plate V). In 05 and C6, especially in the latter, the marks of attachment are sometimes divided into two (C6 in Plate V) : 1) the lateral tuberosities of the longus capitis and the scalenus anterior ; 2) the medial indistinct tuberosities of the superior and inferior oblique portions of the longus colli. In the thoracic region no corresponding marks are observed because the front surfaces of the transverse 'processes are articulated with the ribs. In the lumbar region the corresponding tuberosities, for the lateral origin of the psoas major, are observed at the central anterior portions of the costal processes (Plate V ). 5. Muscular tubercles of the medial. attachments of the prevertebral muscles The longus colli is situated on the anterior surface of the cervical vertebral column lateral to the anterior longitudinal ligament. The lower extremity of the muscle is attached by a strong tendinous slip to the bodies of the first two or three thoracic vertebrae. A prominent tubercle derived from this tendinous slip may sometimes be observed on the body of Th2 (Plate VI). This type of tubercle has already been reported by Krmpoti6 (1954) and labelled the "tuberculum musculi longi colli". A typical example of this tubercle is shown in Plate 6, in which another slight tubercle in Th3 is also illustrated. Also proceeding from the longus colli are other small tuberosities on the anterolateral surfaces of the bodies of the lower cervical vertebrae (Plate V). In the lumbar vertebrae, the corresponding tuberosities are observed at the upper and lower lateral parts of each vertebral body. These tuberosities are derived from the medial origin of the psoas major (Plate V).

7 Classification of Muscular Tubercles of Vertebrae 1173 Abbreviations for all Figures ant. laterovert. mm. : anterior laterovertebral muscles extr. back mm.: extrinsic back muscles i : insertion ilioc. : iliocostalis ilioc. cap. : iliocostalis capitis ilioc. cerv. : iliocostalis cervicis intr. back mm. : intrinsic back muscles laterovert. mm. : laterovertebral muscles lat. dor. : latissimus dorsi lat. series : lateral series 1ev. scap. : levator scapulae lgss. : longissimus lgss. cap. : longissimus capitis lgss. cerv.: longissimus cervicis lgss. thor. : longissimus thoracis long, cap. : longus capitis long. cob.: longus colli med. series : medial series mf multifidus : origin pars ant. : anterior part pars obl. inf. : inferior oblique part pars obl. sup. : superior oblique part pars post. : posteiror part pars vert. : vertical part post. laterovert. mm. : posterior laterovertebral muscles postvert. mm.: postvertebral muscles prevert. mm. : prevertebral muscles proc. acc. : accessory process proc. mam. : mamillary process psoas : psoas psoas ma j. : psoas major psoas mm.: psoas minor quadr. lumb.: quadratus lumborum rhom. : rhomboideus r. ventr. : ramus ventralis scal. ant. : scalenus anterior scal. med. : scalenus medius scal. post. : scalenus posterior ser. post. serratus posterior sp : spinals spl: splenius spl. cerv. : splenius cervicis sp.-ssp.: spinalis and semispinalis ssp : semispinalis ssp. cap. : semispinalis capitis ssp. cerv. : semispinalis cervicis tbc. ilioc. : tubercle of the iliocostalis tbc. ilioc.-lgss. : tubercle of the iliocostalis and the longissimus tbc. laterovert.: tubercle of the laterovertebral muscles tbc. lat.-ser. : tubercle of the latissimus dorsi and the serratus posterior inferior tbc. lgss.: tubercle of the longissimus tbc. lgss. thor. : tubercle of the longissimus thoracis tbc. long. cap. : tubercle of the longus capitis tbc. long. col. : tubercle of the longus colli tbc. mf. : tubercle of the multifidus tbc. postvert. : tubercle of the postvertebral muscles tbc. prevert. : tubercle of the prevertebral muscles tbc. scal. ant. : tubercle of the scalenus anterior tbc. scal. med.-post. : tubercle of the scaleni medius and posterior tbc. ssp. cap. : tubercle of the semispinalis capitis tbc. ssp.-mf. : tubercle of the semispinalis and the multifidus tbc. trap.-rhomb.-ser. : tubercle of the trapezius, the rhomboideus and the serratus posterior superior tbc. trap.-spl. : tubercle of the trapezius and the splenius tbs. ilioc. : tuberosity of the iliocostalis tbs. lgss. thor. : tubersity of the longissimus thoracis tbs. long. cob.: tuberosity of the longus colli tbs. quad. : tuberosity of the quadratus lumborum tbs. pso. : tuberosity of the psoas major tbs. quad. : tuberosity of the quadratus lumborum tend. lat. : lateral tendon tend. med. : medial tendon tend. orig. : tendon of the origin trap. : trapezius References 1) Krmpotie, J.: tiber ein Erkennungszeichen des II. Brustwirbels. Z. Anat. Entwickl.-Gesch., 118: , ) Wood Jones, F.: Some nerve markings on the lumbar vertebrae. J. Anat. (London), 47 : , 1911.

8 1174 T. Sato and S. Nakazawa Explanation Plate of Figures I A dissection of the medial series of the intrinsic back muscles, with some examples of the tubercles derived from the medial attachments of these muscles.

9 Plate 1175 I T. Sato and S. Nakazawa

10 1176 T. Sato and S. Nakazawa Plate II A dissection of the medial series of the intrinsic back muscles, with some examples of the tubercles derived from the lateral attachments of these muscles.

11 Plate 1177 II T. Sato and S. Nakazawa

12 1178 T. Sato and S. Nakazawa Plate III A dissection of the lateral series of the intrinsic back muscles and the posterior laterovertebral muscles, with some examples of the tubercles derived from these muscles in the cervical and the upper thoracic regions.

13 Plate 1179 III T. Sato and S. Nakazawa

14 1180 T. Sato and S. Nakazawa Plate IV A dissection of the lateral series of the intrinsic back muscles, with some examples of the tubercles derived from these muscles in the middle and lower thoracic and the lumbar regions.

15 Plate 1181 IV T. Sato and S. Nakazawa

16 1182 T Sato and S. Nakazawa Plate V A dissection of the anterior laterovertebral muscles and the prevertebral muscles, with some examples of the tubercles derived from these muscles.

17 Plate 1183 V T. Sato and S. Nakazawa

18 1184 T. Sato and S. Nakazawa Plate VI A dissection of the longus colli with some examples of the tubercles derived from this muscle.

19 T. Sato and S. Nakazawa 1185 Plate VI