study on the sites of articulations between the two human hemimandibles

Thirty-two human mandibles, aging from nine weeks in utero [I.U.] till one year postnatally [P.N.] have been used in the present study. For gross anatomical structure, axial and coronal scan planes were taken, and a three- dimensional computerized tomography [C.T.] reconstruction was carried out. The bodies of the mandibles were separated from the two rami and fixed in 10% formalin. The specimens were processed for light microscopic study. At the ninth week I.U., the symphysis menti was only formed of mesenchymal tissue bounded on either side by labial bony trabeculae, Meckel's cartilage and oral bony trabeculae. Rostrally, the bilateral rods of Meckel's cartilage approached each other but were separated by a rim of mesenchymal tissue. The three-dimensional C.T. scan revealed a triangular defect between the two hemimandibles. By the twelfth week I.U., two secondary cartilaginous structures, completely separated from Meckel's cartilage, were observed in the caudal portion of the midline mesenchyme. By the twenty-eighth week I.U., signs of endochondral ossification appeared in the secondary cartilages and ended by the formation of a mental ossicle at the fortieth week I.U. The mental ossicle appeared conical in shape, and showed consistent gradual growth reaching its maximum by the age of first month P.N. Finally, complete fusion of the mental ossicle with the hemimandibles had occurred by the age of five months P.N., while the hemimandibles were still separated by a rim of mesenchymal tissue rostral to the mental ossicle. Fusion of the hemimandibles in that region proceeded from an inward to an outward direction. Thus, by the end of the first year P.N., the mandible became a single bone. The study revealed that the single mental ossicle is not an integral part of the symphyseal region, but is rather a contributor in the construction of the symphysis menti. Moreover, the study showed that the symphysis menti is not simply a midline one as thought long ago, and confirmed the existence of two different sites of articulations between the hemimandibles. The first one was located in the midline, between the rostral portions of the hemimandibles and simulated a fibrous joint. The second one was observed to lie on either side of the midline, between the mental ossicle and the caudal portion of each hemimandible, and simulated in structure a primary cartilaginous joint. Both articulations ended by synostosis, by the end of the first year P.N

Absence of musculocutaneous nerve associated with a third head of biceps brachii muscle and entrapment of ulnar nerve

Variations in the formation of the brachial plexus and in the course of its branches are not as uncommon as was once thought. A description of the abnormalities and complexities of the anatomy of the upper arm is very important with regard to surgical approaches. This case study reports a combined absence of musculocutaneous nerve associated with a third head of biceps brachii muscle in the left upper arm of an adult male cadaver. Moreover, the left ulnar nerve is entrapped within the substance of the medial head of the triceps muscle. The clinical implications, as well as the possible clinical symptoms resulting from these anomalies are discussed

effect of intraneural injection of 5% phenol, glycerol and 5% phenol in glycerol in the albino rat sciatic nerve: a comparative histological and immunocytochemical study

The aim of the present study was to perform a comparative histological study on the effects of neuroblocking agents, namely 5% phenol, glycerol and combined 5% phenol in glycerol, injected intraneurally in the rat sciatic nerve. Twenty adult male albino rats were divided into 4 groups, 5 animals each. The right sciatic nerve of each animal was exposed and an intraneural injection of 0.1 ml of normal saline for the first group, 5% phenol for the second, glycerol for the third and 5% phenol in glycerol for the fourth group. Animals were sacrificed after 2 weeks and a part of the sciatic nerve distal to the site of injection was excised. Paraffin sections were prepared and processed for hematoxylin and eosin and for immunocytochemical staining to demonstrate S-100 protein. The results showed that the effect of intraneural injection of 5% phenol was directed primarily towards endoneurial blood vessels that appeared dilated and congested. Intraneural oedemna together with mononuclear cellular infiltration resulted in degeneration and destruction of nerve fibers. In case of intraneural injection of glycerol, axonal damage was more severe due to a direct toxic effect resulting in a massive destruction of nerve fibers. Intraneural injection of 5% phenol in glycerol caused intraneural oedema with minimal axonal damage. The present study showed that intraneural injection of combined 5% phenol in glycerol caused less endoneurial damage than injection of each agent separately

Bilateral sternalis muscles

Bilateral sternalis muscles were observed during dissection of the thoraco-abdominal region of a male cadaver. A full description of the muscles, as well as their attachments and innervations were reported. A brief review of the existing literature, regarding the nomenclature, incidence, attachments, innervations and clinical relevance of the sternalis muscle, is also presented

human mandible: a detailed study on the prenatal and postnatal developmental changes in the sites of articulations between its two halves

Thirty-two human mandibles, aging from nine weeks in utero [I.U.] till one year postnatally [P.N.] have been used in the present study. For gross anatomical structure, axial and coronal scan planes were taken, and a three- dimensional computerized tomography [C.T.] reconstruction was carried out. The bodies of the mandibles were separated from the two rami and fixed in 10% formalin. The specimens were processed for light microscopic study. At the ninth week I.U., the symphysis menti was only formed of mesenchymal tissue bounded on either side by labial bony trabeculae, Meckells cartilage and oral bony trabeculae. Rostrally, the bilateral rods of Meckells cartilage approached each other but were separated by a rim of mesenchymal tissue. The three-dimensional C.T. scan revealed a triangular defect between the two hemimandibles. By the twelfth week LU., two secondary cartilaginous structures, completely separated from MeckelIs cartilage, were observed in the caudal portion of the midline mesenchyme. By the twenty- eighth week I.U., signs of endochondral ossification appeared in the secondary cartilages and ended by the formation of a mental ossicle at the fortieth week I.U. The mental ossicle appeared conical in shape, and showed consistent gradual growth reaching its maximum by the age of first month P.N. Finally, complete fusion of the mental ossicle with the hemimandibles had occurred by the age of five months P.N., while the hemimandibles were still separated by a rim of mesenchymal tissue rostral to the mental ossicle. Fusion of the hemimandibles in that region proceeded from an inward to an outward direction. Thus, by the end of the first year P.N., the mandible became a single bone. The study revealed that the single mental ossicle is not an integral part of the symphyseal region, but is rather a contributor in the construction of the symphysis menti. Moreover, the study showed that the symphysis menti is not simply a midline one as thought long ago, and confirmed the existence of two different sites of articulations between the hemimandibles. The first one was located in the midline, between the rostral portions of the hemimandibles and simulated a fibrous joint. The second one was observed to lie on either side of the midline, between the mental ossicle and the caudal portion of each hemimandible, and simulated in structure a primary cartilaginous joint. Both articulations ended by synostosis, by the end of the first year P.N

detailed study on the thoracic intertransverse musculature: description of newly discovered muscles

The thoracic intertransverse muscles were subjected to a detailed study. Twenty-five human cadavers, 15 males and 10 females with a mean age of 50 years and with normal spines, constituted the material of the study. The study was performed using both anterior and posterior approaches to the thoracic intertransverse spaces as well as to those in the cervico-thoracic and thoraco-lumbar junctions. In all spaces, two vertical muscular slips, medial and lateral, connecting successive transverse processes were identified. The two slips were clearly differentiated from each other and were separated by a branch of dorsal ramus of the corresponding spinal nerve. They were covered by the intertransverse ligament. In the space between the transverse processes of eleventh and twelfth thoracic vertebrae, a third muscular slip extended between the adjacent borders of the two transverse processes. In the thoraco-lumbar space, two additional slips were identified. The medial one extended between the bases of the two transverse processes. The most lateral was the largest and extended from the medial half of the lower border of the transverse process of twelfth thoracic to the whole length of the upper border of first lumbar vertebra. The latter slip was covered, anteriorly, by a thick ligament. In the cervico-thoracic junction and the following two thoracic intertransverse spaces, three triangular muscles, described and reported for the first time, extended from the transverse processes of seventh cervical, first and second thoracic vertebrae to the upper borders of necks of first, second and third ribs, respectively. The three muscles were suggested to be parts of the intertransverse musculature. All muscles were found to be supplied by dorsal rami of spinal nerves. The study demonstrated that the change in the morphology of the intertransverse system from one region to another is gradual. The homologies between cervical and thoracic intertransverse muscles were discussed. The study added a more relevant knowledge and corrected inaccurate information about the thoracic intertransverse musculature

Amelioration the effect of sciatic nerve transection in the dorsal root ganglia in albino rat by methylprednisolone acetate

The present study was performed to investigate the neuroprotective effect of methylprednisolone [MP] acetate on the cells of the dorsal root ganglia [DRG] following transection of the sciatic nerve in albino rats. Twenty adult male Sprague-Dawley albino rats were allocated into 4 groups. Animals of group II were injected with a single dose of normal saline. Animals of group II were injected with a single dose of MP acetate. Animals of both groups were subjected to surgical Sham's operation prior to the injection. Animals of both groups III and IV were subjected to transection of the right sciatic nerve. Those of group IV were injected with a single dose of MP acetate following transection. After 2 weeks, all animals were sacrificed and the fifth lumbar DRG were excised and processed for light microscopy. The results showed marked pathological lesions in the cells of DRG of animals of group III in the form of chromatolysis, eccentric position of nuclei, appearance of intracytoplasmic vacuoles, necrosis and disappearance of some DRG neurons. Inflammatory mononuclear cells were observed in the vicinity of degenerating and necrotic cells. The cells of DRG of animals of group IV showed a picture almost similar to that of the cells of DRG of animals of both control groups I and II. In conclusion, the present study has proved the neuroprotective effect of MP acetate in experimental model of peripheral nerve crush injury

Bohlerls and Gissane's angles of the Calcaneus in the Saudi population

The purpose of this study is to measure Bohler s angle [BA] and Gissane s angle [GA] in the Saudi population and compare their values to the published data. Lateral plain radiographs of 229 normal feet and ankles of 158 females and 71 males, with age range of 15-72 years, were studied retrospectively at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia between 2002 and 2003. Bohler's angle and GA were measured and the mean and standard deviation of each angle were calculated. The relationship between each angle and age, gender, and side of body was tested, and compared to international figures. The mean BA in the Saudi population was 31.21 degree with a range of 16-47 degree. The mean GA was 116.16 degree with a range of 96-152 degrees. Bohler's angle and GA are not significantly related to age, gender, or side of body. Moreover, the range of both angles was wider than that reported in the literature. The study shows the difference between the Saudi and various other populations in regard to BA and GA, and reinforces the need to establish the normal ranges of BA and GA in a given population

Ergonomic assessment of three computer keyboard in correlation with wrist and forearm kinesiology

The use of the standard [flat] keyboard design for long periods without sufficient recovery periods may result in cumulative trauma disorders [CTD]. Accordingly, many ergonomic [alternative] keyboards have been produced. So, the present study aimed to perform a sort of comparative ergonomic assessment among 3 commercially available keyboard in correlation with the kinesiology of the wrist and forearm; they are the standard, the natural and the split designs. Ten professional computer operators were subjected to video recording while typing on the 3 designs. Chosen snap shots were printed and the different angles were measured by a goniometery; namely, pronation/supination of forearm, extension/flexion, ulnar/radial deviation angles of the wrist. The present results showed statistically significant differences of the angles among the 3 designs tested. Both ergonomic keyboards placed the forearm and wrist closer to the neutral position than did the standard ones; while, the split keyboard markedly reduced pronation, the natural keyboard kept the forearm in moderate pronation. No significant difference in preference [questionnaire] was found between the standard and natural designs, both of which were preferred over the split. So, it could be concluded that of the 3 keyboard designs evaluated, the natural design incorporated moderate changes to the standard ones. These changes promoted a more natural hand position while typing, thereby reducing the potential for CTD

Morphometry of the coraco-acromial arch in correlation with chronic impingement syndrome

The coracoacromial arch [C-A] was examined in 100 human adult dry scapulae for the presence and shape of degenerative changes [enthesopathy]. Morphometric measures were applied on the parts constituting the C-A arch, then the results were statistically analyzed and tabulated. The correlation between the values of each measure and the incidence of acromial enthesopathy were tested. The latter was found in 22% of scapulae and showed a significant correlation with the increase in the acromial length, slope and angle of the acromion consequently. Coracoid enthesopathy [spur] was present in only 5% of the specimens and showed a correlation with the increased coracoid prominence and the narrow coracoglenoid space