The membranous layer of superficial fascia: evidence for its widespread distribution in the body.

A discrete membranous layer, "stratum membranosum", in human subcutaneous tissue is classically described as confined to the lower anterior abdominal wall and perineum and referred to as Scarpa's and Colles' fasciae, respectively. Evidence for its existence elsewhere in the body is scanty and therefore the present study was undertaken. Dissection of six embalmed adult cadavers, along with ultrasound imaging on four living subjects, were carried out to determine the existence, topography, and thickness of the membranous layer of superficial fascia in different regions of the body. In all six cadavers, a continuous layer of fibrous membrane in the superficial fascia was found consistently in all the dissected regions of the body and was also confirmed by ultrasonography. The arrangement and thickness of this membranous layer varied according to body region, body surface, and gender. It was thicker in the lower than in the upper extremity, on the posterior than anterior aspect of the body, and in females than in males. The mean thickness of the membranous layer ranged from 39 to 189 mum, being thickest in the leg and thinnest over the dorsum of the hand. The membranous layer was observed to have two or even three components in regions such as the breast, back, thigh, and arm and was seen to split, forming special compartments around subcutaneous major veins of upper and lower extremities, with fibrous septa extending to attach to the vessel wall. Functionally, the membranous superficial fascia may play a role in the integrity of the skin and support for subcutaneous structures particularly veins, by ensuring their patency. Understanding the topographic anatomy of this fascial layer may help explain body-contour deformities and provide the anatomic basis for surgical correction.

Early age of disease onset in African American type 1 diabetes patients is associated with DQB1*0201 allele.

The goal of this study is to assess the association of HLA-DQ alleles with the age of onset of type 1 diabetes in African American patients. Using PCR oligonucleotide typing, HLA-DQA1 and DQB1 alleles were determined. DQA1*0301, DQB1*0201, and DQB1*0302 were significantly increased in African American patients. However, the DQB1*0602 allele was decreased in these patients. In addition, DQA1*0401 and DQB1*0402, were associated with protection in African Americans. When stratified by age of onset, prepubertal patients showed an absence of the protective allele DQB1*0602 and a significant increase in DQB1*0201 compared to postpubertal patients. The high frequency of the HLA-DQ susceptibility allele in pre-pubertal patients suggest that the biology of disease in this group may differ from type 1 diabetes with a later age of onset.

Attitudes and reactions of Arab medical students to the dissecting room.

A questionnaire on the emotional and psychological reactions of Arab medical students to the dissecting room (DR) was distributed to 272 students in four successive pre-clinical and clinical years in the same academic year (1993-1994) at Sultan Qaboos University (SQU) Medical College; 205 students responded. Varying degrees of fear on first entering the DR was reported by 46%. The most frequent reactions were recurring visual images of cadavers (total 38%) and temporary loss of appetite (total 22.5%). Students' reactions were most commonly elicited by the smell of the DR (total 91%) and by fear of infection (total 62%). The most frequent method of coping with such fears was by rationalization (total 65%). Significant gender differences (P < 0.05) were found concerning all aspects of the DR experience. Female students showed higher levels of fear, reported stronger physical and behavioral reactions, were more disturbed by certain stimuli in the DR, and used certain coping methods more frequently than their male peers. The need for appropriate psychological preparation of students before studying human cadaveric anatomy is discussed.

Brachial plexus palsy and spinal subarachnoid pneumatosis following trauma.

The case of a 33-year-old male involved in a road traffic accident, resulting in brachial plexus palsy associated with subarachnoid pneumatosis, is described. A knowledge of the regional anatomy at the root of the neck is used to explain the patient's neurological signs and the mechanism of entry of air into the subarachnoid space.

Teaching of human anatomy: a role for computer animation.

Computer-assisted learning fulfils an important need for pictorial representation of the functions of organs and systems. The various computer techniques of animation and morphing provide promising horizons for medical educational technology. Image acquisition is one of the most resource-intensive components of animation sequence development. Images can be drawn as originals or can be copied/scanned from various sources. By standardizing the initial (starting) image to the particular/basic need of the teacher and projecting the end-point image by using a vector animation package, 'films' can be created to demonstrate any form of movement. In the Anatomy Department, Sultan Qaboos University in Muscat, computer-animated tutorials are being introduced to illustrate normal and abnormal functional anatomy. The heart and its valve mechanisms have been selected as a pilot study. The student response is very positive and the technique has great potential. Embryology animations showing the formation and growth of organs such as the brain and spinal cord are also being developed.

Cytogenetic analysis of children suspected of chromosomal abnormalities.

Karyotypes were examined in 122 Omani children suspected of having chromosomal abnormalities. A total of 50 (41 per cent) had an abnormal karyotype: 38 (31 per cent) were Down's syndrome whilst a further 12 (10 per cent) had other types of chromosomal abnormalities. These findings suggest that cytogenetic analysis is useful in the investigations of children with congenital anomalies of unknown origin; to confirm clinical diagnosis in children with known cytogenetic syndromes and for genetic counselling.

Assessment of basic medical sciences in an integrated systems-based curriculum.

Basic medical sciences at Sultan Qaboos University (SQU) are taught in a systems-based curriculum. During the development of the courses different formats have been used for the written examinations and also different types of questions. This paper compares students' performance in relation to examination format and to types of questions used. The formats were non-coordinated (NCAs), each discipline having a separate paper; coordinated (CAs), questions from various disciplines being given in the same paper but with separate sections for each discipline; and integrated assessments (IAs), questions being grouped under structure, function, and problem-based integrated long essays. The types of questions used were multiple choice (MCQs), short essays (SEQs), and structured integrated long essays (SILEQs). Students performed better in SEQs than in MCQs. Our analyses also show that SILEQs measure skills similar to those of MCQs and SEQs combined. Students performed best in NCAs. In CAs, students concentrated on those disciplines carrying most weight in the final grade. Currently we use IAs consisting of two parts: part I, comprising MCQs and SEQs, and part II, comprising SILEQs. To date, students are performing better in part II than in part I. We suggest that it is prudent to use different types of questions to measure students' knowledge and skills when IAs are used for systems-based courses.

Diagnosis and management of paragangliomas of the skull base.

In appropriately selected patients, glomus tumors of the head and neck are best treated surgically. Unresectability is not a factor in therapeutic planning for local disease control. Existing techniques and exposures for tumor removal can be reliably applied to these paragangliomas, with acceptable morbidity and mortality. A team approach to this problem is mandatory.

Pharyngocutaneous fistulas in advanced cancer: closure with musculocutaneous or muscle flaps.

Two hundred cases of head and neck cancer were reviewed and 16 pharyngocutaneous fistulas identified, for an incidence of 6 percent. The fistulas were closed with pectoralis major muscle flaps in four patients, pectoralis musculocutaneous flaps in seven patients, sternocleidomastoid muscle flaps in four patients, and latissimus dorsi flaps in two patients. Four types of fistulas were identified, and flap selection was determined by fistula location. Successful closure was obtained in 15 patients (88 percent), although one patient died from recurrence with a persistent fistula.

Quantitative histological changes in the small intestine of rats artificially reared on different milk substitutes.

Growth of the small intestine was studied in rats reared normally by their mothers (MR) or artificially reared (AR) by intragastric infusion of milk substitutes from postnatal day 5. Two milk substitutes were used: one high in carbohydrate and low in protein as compared with rats' milk (Messer) and the other closely resembling rats' milk in its composition (Auestad). Pups reared on these formulae are termed ARM and ARA, respectively. Pups were killed at 7, 12, and 20 days for quantitative histological measurements on transverse sections of duodenum and ileum. They included cross-sectional areas of muscle and of mucosa and submucosa combined (other tissue), internal and external perimeters, and length of longest villus profile. Artificial rearing affected mucosal and submucosal measures, but did not affect muscle. The effects depended on age, type of milk substitute, and site within the small intestine. There was a tendency for deficient growth of small intestine in the early stages of artificial rearing, especially in the ileum of ARA pups. Enhancement of growth as shown by cross-sectional area of mucosa and submucosa and by longest villus profile occurred later--by 12 days in the duodenum and by 20 days in the ileum of ARM pups. Enhanced growth was less evident in ARA rats, being apparent only in the duodenum, and not until 20 days were the cross-sectional area of mucosa and submucosa and the longest villus profile increased.

Skull-base surgery: operative refinements.

Advances in microsurgical techniques, with the use of the laser and the ultrasonic suction aspirator, have paved the way for even more aggressive surgical approaches to large skull-base lesions, such as glomus tumors, adenocarcinomas of the temporal bone, and cranial nerve neuromas. Postoperative morbidity of multiple cranial nerve dysfunction has been aggravated in the past by cerebrospinal fluid leakage and/or gastro-intestinal dysfunction. At the Otology Group, P.C., in the course of dealing with more than 86 skull-base tumors, we have developed a standardized, multispecialty approach to such extensive skull-base lesions, including tracheotomy, gastrostomy, "ventriculoatrial" shunt placement, and rotated temporalis muscle flap closure. This article presents cases that illustrate the evolution of the current, "standard skull-base" operative procedure and the rationale for incorporation of the shunt and the muscle flap closure as operative refinements. Their beneficial effects upon postoperative morbidity are detailed.

Comparison of the structure of human intervertebral discs in the cervical, thoracic and lumbar regions of the spine.

Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.

A radiographic study of variations of the human fetal spine.

Variations of the vertebral column were considered to be those deviations from the norm which were still compatible with normal life and not pathological. The incidence of these variations is described as seen radiographically in a group of normal human fetuses. Ossification centers for the costal processes of cervical vertebra 7 were found to be common (19%), being present in approximately one-fifth of the total number of fetuses studied. They were mostly present as bilateral centers (15%), but because of the cross-sectional nature of the study, it could not be determined whether these centers would have developed into actual cervical ribs. Far less common were the presence of lumbar ribs (1%). Ossification of the vertebral centra was found to be confusing with no clearly defined pattern being evident. In particular, there was a suggestion that some of the vertebral centra might well develop at least initially from bilateral centers. There was also evidence that the vertebral body was the product of four centers and this was supported by other literature. No variations were found which suggested that the vertebra develops from two somite levels, and this appears to be in conflict with the commonly accepted resegmentation theory.

Disruption of passive avoidance memory by REM sleep deprivation: methodological and pharmacological considerations.

The present experiments were designed to examine more closely the variables responsible for the disruption of passive avoidance memory produced by REM sleep deprivation. In the pharmacological study it was found that imipramine could reverse the memory disruption exhibited by rats maintained on large platforms (presumably not REM-deprived) while both imipramine and physostigmine were required to reverse the memory disruption exhibited by rats maintained on small platforms. In the methodological study it was found that those animals maintained on the smallest platforms and therefore having the largest weight to area ratio exhibited the greatest degree of memory disruption. It is concluded that further modification and verification of the platform techniques of REM deprivation is required before firm conclusions about its neurochemical basis and behavioural functions can be made.

A radiographic study of the growth in width of the human fetal vertebral column.

Only a few studies have concerned themselves with the development of the fetal vertebral column, and this paper attempts to extend the literature. Standards are presented for the growth in width of the human vertebral column between 10 and 26 weeks of conceptual age. The growth patterns show that cervical and lumbar enlargements are not present at 8 weeks but develop slowly and become clearly present at 26 weeks. The growth equations also show that groups of vertebrae have their own growth patterns, indicating that the vertebral column could be separated into five groups: C1-C5, C6-C7, T1-T12, L1-S1, and S2-S5. Furthermore, comparisons with growth patterns available for growth in length from other studies reveal that some vertebrae appear to develop in one dimension independently of another.

Glomus Tumors. Diagnosis, classification, and management of large lesions.

Glomus tumors of the temporal region and skull base can range in size from small microscopic lesions confined to the promontory to large destructive and neurologically aggressive agents of substantive incapacitation. Contemporary diagnostic and surgical technology has made definitive management of these historically dreaded management of these historically dreaded lesions confidently practical. Prompted by these advances, a new classification of glomus tumors is disclosed. The specific problem of the large chemodectoma at the skull base is addressed and a series of such cases reviewed. Surgical therapy is viewed as definitive, and the technique employed by the members of The Otology Group, PC, is described.

A radiographic study of the longitudinal growth of primary ossification centers in limb long bones of the human fetus.

This paper describes an extensive study of the growth of ossification centers in limb long bones of the human fetus from 8 to 26 weeks of conceptual age. Longitudinal measurements were made of the femur, tibia, fibula, humerus, radius, and ulna. Comparisons were made between bones on the left and right sides of the body and between the sexes. Standards are presented for the growth of these centers. They compare well with previous studies, any differences being accounted for by different methods of aging and measurement. A complicated picture of growth of the two sides of the fetal body is presented. Growth of the humerus, tibia, and fibula appears to be dominant on the left side of the body while growth in the femur is dominant on the right. At present, no explanation is available, but it is possible that factors such as manual dominance may be related. Evidence also is presented which suggests that the female fetus is in advance of the male in terms of ossification but only ater 21 weeks gestation.

A morphological and histological study of the postnatal development of intervertebral discs in the lumbar spine of the rabbit.

Some basic features in the development of the structure of the annulus fibrosus and nucleus pulposus in the rabbit, as described by previous workers, have been confirmed in the present study. However, the greater thickness of the anterior part of the disc, as compared with the posterior region, and the distinctive arrangement of lamellae in the posterior part of the disc, cannot be attributed, as conventionally claimed from studies of the human spine, to a secondary curvature in the lumbar spine associated with an upright posture: for these features are present in the lumbar spine of the quadrupedal rabbit with its primary curvature. Secondary ossification produces a plate-like epiphysis separating the growth cartilage from the intervertebral disc. A distinct cartilaginous plate, limiting the nucleus pulposus in the rabbit intervertebral disc, only becomes apparent when collagen fibres cease to traverse the area above and below the nucleus pulposus.