Septum transverse

Fig. 4.4a,b. A 33-year-old female patient with a history of partially resected longitudinal vaginal septum. Transverse oblique T2-weighted MR images (a) show complete duplication of the uterine horns (arrows), as well as two duplicated cervices (arrowheads). The cavities show their normal zonal anatomy. Note the longitudinal vaginal septum (b) which appears in 75% of uterus didelphys... 

Chondrocytes, transverse septum Poecilia reticulata C219, C494, JSB-1 65... 

Uterus didelphys maybe associated with alongitu-dinal (75%) or, more rarely, with a transverse vaginal septum, the latter causing obstructive hematome-trocolpos. Endometriosis as a result of retrograde menstruation may also occur in these conditions. A non-obstructive uterus didelphys is usually asymptomatic. 

Figure 40.4 Transverse serial sections of Aulacothyroides liardensis (Fig. 40.3, (13-16)) from Grey Beds (Karnian), Charlie Lake equivalent, NE British Columbia , MS 1655, D.V. Ager Collection. These show weak dental plates in the pedicle valve (sections 0.4—1.6), a septalium in the brachial valve (2.4-4.5), triangular crura at the extremities of the sep-talial plates (3.6, 4.5) and a long median septum, characters shared with Aulacothyroides bulkutensis Dagys (1965, fig. 65). Dimensions of specimen length 28.6 mm width 20.5 mm thickness 17.1 mm. Scale bar is 4 mm for sections 0.0-1.2 mm 6.25 mm for sections 1.6-9.7 mm.

Figure 40.9 Transverse serial sections of a specimen of Anarhynchia gabbi Ager. Early Jurassic, Bedford Canyon, Santa Ana Mountains, California, MS 1687, showing development of ventrally directed and ventrally arching crura anteriorly (sections 1.6-14.1), flat cardinal process (0.4) and teeth laterally inserted in sockets (1.6). The appearance of septalial plate-like developments from the crura to the floor of the brachial valve are only briefly seen (0.6, 0.8) and then weak remnants are seen on the floor of the valve (1.6). This structure is so small that it does not appear to be a double median septum or septalial plates, but a secondary thickening of shell material towards the posterior of the valve, below the crura. This same resemblance to a double septum is more clearly seen in Ager s sections (1968, fig. 7). Dimensions of specimen length 29+ mm width 31.4+ mm thickness 15.1 mm. Scale bar is 3 mm for sections 0.0-1.6 6.25 mm for sections 2.1 -14.1 I mm for details of crura (bottom row) 6.5-10.1.

Kaufmann-McKusick syndrome Hydrometrocolpos, transverse vaginal membrane, vaginal septum, postaxial polydactyly, cardiac anomalies, hypospadias Hydroureter, ureteral duplication, ectopic urethra, urogenital sinus, posterior urethral valves AR (236700), mutations in Bardet-Biedl type 6 BBS6 gene... 

Fig. 13.13. Ectopic ureterocele associated with a duplex kidney. Transverse scan through fetal bladder (B) showing a septum (arrowheads) that limits the ureterocele...

The volar (anterior) compartment of the forearm includes the flexor and pronator (antebrachial) muscles. It can be divided by a transverse septum into two layers deep and superficial (Boles et al. 1999). 

As a rule, an accurate and systematic US examination of the dorsal muscles of the forearm should begin at the level of the wrist, where their individual tendons are easily distinguished within the six compartments. Then, US scanning should be performed by shifting the transducer upward to depict the myotendinous junction and the belly of the appropriate muscle to be evaluated. This retrograde technique is particularly helpful, even for the experienced examiner, to increase confidence on establishing the identity of the forearm muscles. At the middle third of the dorsal forearm, the muscle bellies of the superficial and deep layers are divided by a transverse hyperechoic septum (Fig. 9.9). More deeply, the hyperechoic straight appearance of the interosseous membrane and the profile of the radial and ulnar shafts separate the dorsal compartment from the volar compartment (Fig. 9.9). 

Two space compartments can be considered in the lower leg anterolateral and posteromedial. They are separated by a plane passing through the tibia, the fibular shaft, a strong interosseous membrane connecting these bones and the posterior crural intermuscular septum, vdiich is located lateral to the fibula. The anterolateral compartment can be further subdivided into an anterior crural compartment and a lateral crural compartment separated by the anterior crural intermuscular septum, located between the extensors and the peroneal muscles. The posterolateral compartment includes two groups of muscles - superficial and deep - separated by the transverse crural intermuscular septum. A brief description of the normal and US anatomy of the anterolateral and posteromedial compartments is included here. 

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