Ph. Vaysse

Vertebral pedicle anatomy in relation to pedicle screw fixation: a cadaver study.

New techniques to stabilize and correct the thoracic and lumbar spine have been developed in recent years. In view of the wide variety and complexity of fixation devices, the optimum configuration of spinal instrumentation systems needs to be defined. Linear and angular measurements of both vertebral pedicles were made in ten complete thoracic and lumbar cadaveric spines using callipers and a goniometer. The vertical interpedicular distance gradually increased along the spine up to L5. The transverse interpedicular distance was larger at both ends of the spine. Pedicular height gradually increased from T1 to L5, plateauing between T3 and T9, being widest at the thoracolumbar junction. Pedicular width was greatest at the three junctional regions of the spine. The sagittal pedicular angle decreased along the length of the spine to zero at L5. The transverse pedicular angle decreased from T1 to T12 and then increased to L5.Of the pedicular measurements only width limits the diameter of fixation screws. The vertical interpedicular distance determines the distance between the holes of plates, while the length of the transfixator is related to the transverse interpedicular distance. The pedicular angles enable triangulation of screws and determine the stability of the fixation.

Contribution to the study of the tributaries and the termination of the external jugular vein

SummaryThe dissection of 100 external jugular veins in 50 cadavers was the object of this anatomic study. A certain number of notions concerning the afferent veins, the mode of termination and the valvular system of this vessel were defined. 1)Afferent veins. Along its pathway toward the deep venous system, the external jugular vein successively received: the transverse cervical vein in 88 cases (88%), usually opposite the intersection of the external jugular vein with the dorsal border of the sterno- cleidomastoid muscle; the suprascapular vein in 47 cases (47%); the anterior jugular vein in 46 cases (46%); the cervical vein or anastomosis with the latter in 13 cases (13%). 2)Mode of termination. Forty-three subjects presented a symmetric mechanism. 100 anastomoses can be classed into three types: in 60 cases (60%), the external jugular vein flowed into the jugulo-subclavian venous confluence; in 36 cases (36%), in to the subclavian vein at a distance from its junction with the internal jugular vein; in 4 cases (4%) in to the trunk of the internal jugular vein. 3)Study of the valves. There were studied in 25 subjects (50 external jugular veins). The valves were found in the ostial and paraostial position in 49 out of 50 veins.RésuméCette étude anatomique repose sur la dissection de 100 vv. jugulaires externes chez 50 cadavres. Elle a permis de préciser un certain nombre de notions concernant les veines afférentes, le mode de terminaison et le système valvulaire de ce vaisseau. 1)Veines afférentes. Le long de son trajet vers le sytème veineux profond, la v. jugulaire externe reçoit successivement: la v. cervicale transverse dans 88 cas (88 %), habituellement en regard du croisement de la v. jugulaire externe avec le bord dorsal du m. sterno-cléido-mastoïdien ; la v. supra-scapulaire dans 47 cas (47 %); la v. jugulaire antérieure dans 46 cas (46 %) ; la v. céphalique ou une anastomose avec celle-ci dans 13 cas (13 %). 2)Mode de terminaison. Quarante trois sujets présentent un dispositif symétrique. Les 100 abouchements peuvent être classés en trois types : dans 60 cas (60 %) la v. jugulaire externe se déverse dans le confluent veineux jugulo-subclavier ; dans 36 cas (36 %), dans la v. subclavière à distance de sa réunion avec la v. jugulaire interne ; dans 4 cas (4 %) dans le tronc de la v. jugulaire interne. 3)Etude des valvules. Recherchées chez 25 sujets (50 vv. jugulaires externes), les valvules ont été retrouvées dans 49 cas sur 50 en position ostiale ou paraostiale.

Microsurgical anatomy of the internal vertebral venous plexuses

Few studies have been done about the venous vascularization of the spine since neuroradiologic studies in the 1960s and 70s. The aim of this study was to clarify the topography of the internal vertebral venous plexuses in relation to the posterior longitudinal ligament and the dura. The relationships of the vv. were studied at different levels of the spine. The internal vertebral venous system of seven cadavers was injected with a blue bicomponent silicon rubber. It consisted with an anterior and a posterior venous plexus. At the cervical level, the anterior longitudinal vv. are located in a dehiscence of the periosteal layer, in the lateral part of the spinal canal. At each level, they joined the contralateral one at the midline by a retrocorporeal v. located behind the posterior longitudinal ligament. No vv. were found in the epidural space. There was a major development of the retrocorporeal v. of the axis, but it did not receive any venous drainage from the vertebral body. At the thoracic and lumbar levels, the anterior venous plexuses remain within a dehiscence of the periosteal layer, which is thinner. The retrocorporeal vv. become pre-ligamentous. We did not find any posterior venous plexuses at the cervical level, but they were evident at the thoracic level and became more voluminous and sinusoidal in the lumbar region.

Contribution to the study of the venous vasculature of the penis

The penile veins are thought to be responsible for some erectile disorders. The aim of this study was to describe the anatomy and function of these veins. The venous systems of 25 cadaveric penises were studied by various anatomic and histologic techniques. The superficial veins arising from the tegumentary layers drain into the superficial dorsal vein which in three-quarters of cases empties into the left great saphenous vein. The veins of the deep internal system, running below the deep fascia of the penis, emerge from the erectile bodies and can be divided into two systems, one anterosuperior and the other posteroinferior. The anterosuperior system comprises the veins of the glans which will form the deep dorsal vein the latter receives blood from the medial portion of the corpus spongiosum and from the free portion of the corpora cavernosum mainly via the circumflex veins. It ends in the pre-prostatic plexus. The posteroinferior system, issuing from the posterior portion of the erectile bodies, is composed of the bulbar, cavernous and crural veins which drain towards the pre-prostatic plexus and the internal pudendal veins. Anastomoses link the two networks, superficial and deep. Study of the structure of the veins of the deep system reveals the presence of muscular cushions, which we have shown to have adrenergic innervation. These findings are compared with those of the literature, which show variations which are mainly of number. The place of veins in the mechanism of erection is discussed.

Functional anatomy of the medial ligamentous complex of the elbow. Its role in anterior posterior instability.

Abstract The question remains unanswered regarding the role of repair of medial ligament injuries associated with subluxation of the elbow and non-reconstructable radial head fracture and whether or not this will decrease the risk of chronic instability and cubitus valgus. The goal of this study was to define the role of the medial ligamentous complex of the elbow in elbow instability and to describe the anatomy of the complex in 35 fresh-frozen cadaver elbows. We documented medial ligamentous complex anatomy and compared our results to those in the literature. 25 elbows were dissected in order to describe the different bundles of the medial ligament complex and to precise the positions of the elbow that placed each in tension section of the different ligamentous bundles was done to study the role of each in elbow stability. 10 other elbows were dissected and used for the ligamentous section studies which were performed subcutaneously. We found two bundles at the level of the anterior portion and termed them superficial and deep. Section of the anterior bundle lead to posterior subluxation of the elbow at 30-100° flexion in both supination and pronation. Posterior subluxation was obtained after an anterior capsulotomy medial epicondylectomy did not compromise the stability of the elbow after a complete section of the insertion of the deep fibers of the anterior bundle. Elements thus required for stability of the elbow are integrity of the articular surface of the humerus and the ulna, and the anterior bundle of the medial ligamentous complex.