The sagittal grooves of the middle nasal turbinate determine paradoxical curvatures and bifidities.

BACKGROUND: Paradoxical curvature of the middle nasal turbinate (MT) is a common anatomic variant, usually found and reported on coronal CT slices. However, less attention has been paid to the sagittal groove (SG) which is determining it. AIM: The study aimed to determine paradoxical curvatures and bifidities in the sagittal groves of middle nasal turbinate. MATERIAL AND METHOD: A retrospective CBCT study on the archived files of 52 adult patients was performed. RESULTS: Different patterns of MT bifidity were found: (1) unilateral bifid MTs; (2) bifid and trifid MTs and "wandering" single SGs; (3) bilateral bifid middle turbinates and double SGs, (4) bilateral false bifid appearance due to middle and superior turbinates fusion and (5) bifid concha bullosa media. Digital "dissections" of patients' files allowed us to conclude that paradoxical curvature as well as bifidity of MTs relate to the placement and number of the SGs on the MTs. Such SGs were previously documented in prenatal MTs since the 14th week, as well as in pædiatric patients. CONCLUSIONS: It seems reasonable to speculate that paradoxical curvature, as well as bifidity of MT, this later being previously undocumented, are just adult vestiges of the primitive MT morphology. Nevertheless, documentation of the MT morphology should not rely exclusively on coronal CTs, as combined morphologies of that turbinate could occur.

Rare anatomic variation: Giant unilateral concha bullosa superior.

The lateral nasal wall attaches the nasal turbinates, which could be, either pneumatized, or paradoxically curved. The turbinate pneumatization-concha bullosausually indicates the pneumatization of the middle turbinate. However, concha bullosasuperior (CBS) is also, although rare, anatomic possibility of variation. We report here a case of unilateral giant septated CBS, which was not, to our knowledge, previously reported. The case was documented in Cone Beam Computed Tomography (CBCT). Subtle pneumatizations of inferior turbinates were found bilateral, as also were the middle conchae bullosae. The left concha bullosasuperior was very large (17.43/5.34mm), dropping down between the left middle turbinate and the contralaterally deviated nasal septum, and contacting the paradoxical curvature of the middle turbinate on that side. An incomplete oblique septum divided it incompletely into anterior and posterior chambers, it was communicating with a posterior ethmoid air cell, and was draining in the superior meatus. Care should be taken not to misdiagnose a giant CBS as a middle turbinate pneumatization, in order not to misjudge surgical corridors. Therefore, a careful anatomic CT or CBCT diagnosis would be of use for the plan of treatment.

Vertical and sagittal combinations of concha bullosa media and paradoxical middle turbinate.

Common anatomic variants of the middle nasal turbinate include its pneumatization (i.e. concha bullosa media) and its paradoxical curvature. We report here two cases of differently combined variations of the middle turbinate which were documented in cone beam computed tomography (CBCT). The first report presents the vertical combination of a double or septated lamellar concha bullosa with the paradoxical curvature of middle turbinate. This combined variant associated (coincidental findings): ipsilateral paradoxical superior turbinate and contralateral paradoxical middle turbinate, concha bullosa superior and concha bullosa suprema. In the second case was found the sagittal combination of successive anterior concha bullosa media and posterior paradoxical curvature of the middle turbinate. An ethmoidal sinolith was found embedded in lamella basalis. The contralateral superior turbinate was pneumatized. These rare findings demonstrate that sound knowledge of possible anatomical variations, supported by a complete use of the tools available for the CBCT documentation of cases, is able to enrich the picture of human anatomic variations, with a direct impact on clinical and surgical practice. The septa-containing lamellar concha bullosa and paradoxical middle concha combination is a variation that affects surgical practice.

'Magic' nucleus 42Si.

Nuclear shell structures--the distribution of the quantum states of individual protons and neutrons--provide one of our most important guides for understanding the stability of atomic nuclei. Nuclei with 'magic numbers' of protons and/or neutrons (corresponding to closed shells of strongly bound nucleons) are particularly stable. Whether the major shell closures and magic numbers change in very neutron-rich nuclei (potentially causing shape deformations) is a fundamental, and at present open, question. A unique opportunity to study these shell effects is offered by the 42Si nucleus, which has 28 neutrons--a magic number in stable nuclei--and 14 protons. This nucleus has a 12-neutron excess over the heaviest stable silicon nuclide, and has only one neutron fewer than the heaviest silicon nuclide observed so far. Here we report measurements of 42Si and two neighbouring nuclei using a technique involving one- and two-nucleon knockout from beams of exotic nuclei. We present strong evidence for a well-developed proton subshell closure at Z = 14 (14 protons), the near degeneracy of two different (s(1/2) and d(3/2)) proton orbits in the vicinity of 42Si, and a nearly spherical shape for 42Si.

Bifid and secondary superior nasal turbinates.

The lateral nasal wall contains the nasal turbinates (conchae) which are used as landmarks during functional endoscopic surgery. Various morphological pos- sibilities of turbinates were reported, such as bifidity of the inferior turbinate and extra middle turbinates, such as the secondary middle turbinate. During a retrospective cone beam computed tomography study of nasal turbinates in a patient we found previously unreported variants of the superior nasal turbina- tes. These had, bilaterally, ethmoidal and sphenoidal insertions. On the right side we found a bifid superior turbinate and on the left side we found a secondary superior turbinate located beneath the normal/principal one, in the superior nasal meatus. These demonstrate that if a variant morphology is possible for a certain turbinate, it could occur in any nasal turbinate but it has not been yet observed or reported.

The ultrastructural anatomy of the nuclear envelope in the masseter muscle indicates its role in the metabolism of the intracellular Ca+.

Specific ultrastructural anatomy of masticatory muscles is commonly referred to a general pattern assigned to striated muscles. Junctional feet consisting of calcium channels of the sarcoplasmic reticulum (i.e. the ryanodine receptors, RyRs) physically connected to the calcium channels of the t-tubules build triads within striated muscles. Functional RyRs were demonstrated in the nuclear envelopes of pancreas and of a skeletal muscle derived cell line, but not in muscle in situ. It was hypothesized that ryanodine receptors (RyRs) could also exist in the nuclear envelope in the masseter muscle, thus aiming at studying this by transmission electron microscopy. There were identified paired and consistent subsarcolemmal clusters of mitochondria, appearing as outpockets of the muscle fibers, usually flanking an endomysial microvessel. It was observed on grazing longitudinal cuts that the I-band-limited mitochondria were not strictly located in a single intermyofibrillar space but continued transversally over the I-band to the next intermyofibrillar space. It appeared that the I-band-limited transverse mitochondria participate with the column-forming mitochondria in building a rather incomplete mitochondrial reticulum of the masseter muscle. Subsarcolemmal nuclei presented nuclear envelope-associated RyRs. Moreover, t-tubules were contacting the nuclear envelope and they were seemingly filled from the perinuclear space. This could suggest that nucleoplasmic calcium could contribute to balance the cytosolic concentration via pre-built anatomical routes: (i) indirectly, via the RyRs of the nuclear envelope and (ii) directly via the communication of t-tubules and sarcoplasmic reticulum through the perinuclear space.

Z = 50 shell gap near 100Sn from intermediate-energy Coulomb excitations in even-mass 106-112Sn isotopes.

Rare isotope beams of neutron-deficient 106,108,110Sn from the fragmentation of 124Xe were employed in an intermediate-energy Coulomb excitation experiment. The measured B(E2,0(1)(+)-->2(1)(+)) values for 108Sn and 110Sn and the results obtained for the 106Sn show that the transition strengths for these nuclei are larger than predicted by current state-of-the-art shell-model calculations. This discrepancy might be explained by contributions of the protons from within the Z = 50 shell to the structure of low-energy excited states in this region.

Probing shell structure and shape changes in neutron-rich sulfur isotopes through transient-field g-factor measurements on fast radioactive beams of 38S and 40S.

The shell structure underlying shape changes in neutron-rich nuclei near N = 28 has been investigated by a novel application of the transient-field technique to measure the first-excited-state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

Measurement of excited states in (40)Si and evidence for weakening of the N=28 shell gap.

Excited states in (40)Si have been established by detecting gamma rays coincident with inelastic scattering and nucleon removal reactions on a liquid hydrogen target. The low excitation energy, 986(5) keV, of the 2(1)(+) state provides evidence of a weakening in the N=28 shell closure in a neutron-rich nucleus devoid of deformation-driving proton collectivity.

Quadrupole deformation of the self-conjugate nucleus 72Kr.

We report on the first determination of the absolute B(E2;0+(1)-->2+(1)) excitation strength in the N=Z nucleus 72Kr. 72Kr is the heaviest N=Z nucleus for which this quantity has been measured and provides a benchmark in a region of the nuclear chart dominated by rapidly changing deformations and shapes mediated by the interplay of strongly oblate and prolate-driving orbitals. The deduced quadrupole deformation strength is in agreement with a variety of self-consistent models that predict an oblate shape for the ground state of 72Kr. Large-scale shell-model Monte Carlo calculations reproduce the experimental B(E2) value and link the result to the occupation of the deformation-driving g9/2 orbit.

Reduced occupancy of the deeply bound 0d(5/2) neutron state in 32Ar.

The 9Be(32Ar, 31Ar)X reaction, leading to the 5/2+ ground state of a nucleus at the proton drip line, has a cross section of 10.4(13) mb at a beam energy of 65.1 MeV/nucleon. This translates into a spectroscopic factor that is only 24(3)% of that predicted by the many-body shell-model theory. We introduce refinements to the eikonal reaction theory used to extract the spectroscopic factor to clarify that this very strong reduction represents an effect of nuclear structure. We suggest that it reflects correlation effects linked to the high neutron separation energy (22.0 MeV) for this state.

New direct reaction: two-proton knockout from neutron-rich nuclei.

The reaction 9Be(28Mg,26Ne+gamma)X has been studied at 82 MeV/nucleon together with two similar cases, 30Mg and 34Si. Strong evidence that the reactions are direct is offered by the parallel-momentum distributions of the reaction residues and by the inclusive cross sections. The pattern of the partial cross sections for 28Mg suggests the presence of correlations. A preliminary theoretical discussion based on eikonal reaction theory and the many-body shell model is presented. The reaction holds great promise for the study of neutron-rich nuclei.