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After having described the surgical anatomy of the lumbar region, with particular regard to the relationships with pleura and peritoneum, as well as to the course of the nervous structures of the region (12th intercostal, ileohypogastric and ileoinguinal), the authors describe the possible complications related with the surgical approaches to the lumbar region. Pathogenesis of post-operatory pains and parietal hypotonies is especially evaluated; these complications may be caused by section, ligature or compression of one or more nervous trunks. The authors conclude that the respect of the anatomic structures located in the lumbar region represents the best way in order to prevent most complications related to lumbotomies.

To date, the lesions of the popliteal system, which are responsible for the so-called postero-lateral knee instability, are still an imperfectly known chapter of knee conditions. We retrospectively analyzed 215 consecutive MR examinations performed May-August 1991 to evaluate MR capabilities in correctly depicting both the normal anatomy and the pathologic conditions of the popliteal system. Using our standard protocols for knee study and two different magnets (0.064 and 0.5 T), we identified 23 lesions of the popliteus and of its meniscal and peritoneal insertions, and 17 lesions involving also other capsular and ligamentous structures of the knee. Coronal T1-weighted images were the best ones to correctly identify normal knee anatomy, whereas sagittal T2-weighted images were more sensitive in detecting popliteal lesions. Our results had clinical or surgical confirmation in all cases.

The authors conducted a macroscopic anatomical study of the metatarsophalangeal joints of the middle toes in order to add to our knowledge of the anatomy and physiology of this structure. Anatomical observations reveal the foot's lack of transverse ligamentous formations (as the sagittal bundle in the hand) connecting the extensor tendon to the glenoid plate. Consequently, the containment of the extensor tendon above the metatarsophalangeal joint is considerably less stable in the foot than in the hand, since it is entrusted to the posterior portion of the interossei muscles and the deep and superficial retinacula (all formations which run in a prevalently oblique direction). Hyperextension of the metatarsophalangeal joint causes the posterior portion of the interossei muscles, bound to the extensor tendon, to slide proximally, straightening the fibers and loosening the structures that stabilize the extensor tendon. The tendon can then easily shift in a lateral direction with respect to the rotation axis of the metatarsophalangeal joint, acquiring a valgus action. Even though the metatarsophalangeal joint is equipped with strong collateral ligaments, the valgus action of the extensor tendon eventually overcomes the resistance of both these and the weaker connections to the plantar aponeurosis of the foot and the extensor tendons. In conclusion, the lack of structures to provide passive stabilization of the extensor tendon in the metatarsophalangeal joints of the toes makes the foot particularly susceptible to multiple-toe deformity.

The authors have examined an anatomical preparation of a human upper limb preserved in the Anatomical Museum in Bologna. The specimen was formed by bone, fibrous formations, musculus biceps brachii and musculus coracobrachialis. The soft parts were kept in situ and dried by mummification. The humerus showed abnormalities at its proximal extremity (Fig. 1) and the muscles displayed fibrous varieties: a) a fibrous sheet (Fig. 1, 2) connected the caput brevis of the musculus biceps brachii to the articular capsule of the shoulder joint; b) an aponevrosis (Fig. 1, 3) connected the musculus coracobrachialis to the same articular capsule and the humerus. These observations were discussed from an evolutionary and functional point of view.

Following a previous note on the musculus obliquus externus, attention is now directed to the obliques internus and the transversus in an assessment of the anatomical formations of the groin, in the light of doubts concerning their constitution expressed in the recent literature, and in a critical appraisal of the hernioplasty techniques proposed. Data from the cadaver, which appear to be of particular interest, show muscle-aponeurosis fissures in both the obliquus parvus and the obliquus externus; these may be the cause of recurrent hernias. The differences in the extent of the muscle and aponeurosis portions of the obliquus internus and the greater or lesser area of the trigonum inguinale, which is covered by aponeurotic fibres of the transversus, are regarded as important factors in the genesis of inguinal hernia.

The morphology of Hunter's canal was examined, together with behaviour of the sheath of the femoral vessels and the relations between this sheath and the walles of the canal. A search was made for morphological and anatomotopographical features capable of explaining early and intense degenerative arteriopathy and the reasons why this is a level of choice for segmentary forms. The extent, constitution and behaviour of the adductor canal are explained. It is shown that, under normal conditions, the sheath is independent of the canal walls. Mechanical influences on the corresponding segment of the artery may be attributable to early inflammation or sclerosis of the cell milieu of the adductor canal.

Continence depends not only on correct muscular function but also on the integrity of the suspensory structures of the anal canal, the latter being the subject of this study performed on embryological and adult specimens. The role of the perineal body as an insertion tendon common to all the striated muscles (pubo-coc-cygeus, superficial striated sphincter) which anchor the anal canal to the surrounding structures is pointed out. The characteristic behaviour of the longitudinal muscle that links the striated musculature to the visceral cylinder is also described.

The problem of muscle evolution among Invertebrates has been considered, mainly in obliquely strated fibers of Annelida and in trasversally striated fibers of Insecta. In both groups the morphological variations run parallel to the functional requirements; similar modulations, in fact, have been observed in fast and slow acting muscle fibers independently from the basic pattern of Insecta and Annelida fibers. Fast acting muscles are characterized by a lesser diameter of myosin filaments and a low thin-to-thick filament ratio. On the contrary, the slow acting muscles show a greater diameter of the myosin filaments and a higher thin-to-thick filament ratio. These observations agree with the hypothesis of a common origin of almost all muscular systems.

In the light of recent publications where common hernia repair techniques are defined as unanatomical and unphysiological, a study of the anatomy of the inguinal region has been undertaken layer by layer on cadavers. The first note analyses the most superficial layer of the inguinal region, namely the external oblique muscle. Having described the dissection technique, the most significant data regarding this formation are examined. Although the correctness of the data given in anatomy textbooks is confirmed in the majority of cases, study of necroptic findings highlights a number of factors which are misunderstood or have been insufficiently analysed. Findings included vibices of the external oblique aponeurosis, to which no pathogenetic importance is attributed with respect to inguinal hernia, as well as the presence of an internal tunic of Lauth's ligament which was not easy to strip away from the posterior surface of the external oblique muscle and, finally, localization variations of the external inguinal ring. The secondary involvement of the aponeurosis of the external oblique muscle in the genesis of inguinal hernia is confirmed along with its importance as a reinforcement in hernia repair operations, the containment function proper being performed by the posterior wall. A subsequent note will deal with this.