Hippocampus and its involvement in Alzheimer's disease: a review.

Hippocampus is the significant component of the limbic lobe, which is further subdivided into the dentate gyrus and parts of Cornu Ammonis. It is the crucial region for learning and memory; its sub-regions aid in the generation of episodic memory. However, the hippocampus is one of the brain areas affected by Alzheimer's (AD). In the early stages of AD, the hippocampus shows rapid loss of its tissue, which is associated with the functional disconnection with other parts of the brain. In the progression of AD, atrophy of medial temporal and hippocampal regions are the structural markers in magnetic resonance imaging (MRI). Lack of sirtuin (SIRT) expression in the hippocampal neurons will impair cognitive function, including recent memory and spatial learning. Proliferation, differentiation, and migrations are the steps involved in adult neurogenesis. The microglia in the hippocampal region are more immunologically active than the other regions of the brain. Intrinsic factors like hormones, glia, and vascular nourishment are instrumental in the neural stem cell (NSC) functions by maintaining the brain's microenvironment. Along with the intrinsic factors, many extrinsic factors like dietary intake and physical activity may also influence the NSCs. Hence, pro-neurogenic lifestyle could delay neurodegeneration.

Extensor carpi radialis brevis origin, nerve supply and its role in lateral epicondylitis.

Lateral epicondylitis (LE) or tennis elbow has been the subject of concern during the last 60 years, but the pathogenesis of the LE remains unclear. The LE can be due to the tendinogenic, articular or neurogenic reasons. Numerous theories have been put fourth in the recent past, out of which one of the most popular theories is that the condition results from repeated contraction of the wrist extensor muscles, especially the extensor carpi radialis brevis (ECRB) which may compress the posterior branch of the radial nerve (PBRN) at the elbow during pronation. We studied 72 upper limbs (36 formalin-fixed cadaver) for the origin, nerve supply and the course of PBRN in relation to the ECRB as one of the goal for the present study. The possible presence of an arch of the ECRB around the PBRN was also observed and recorded. The nerve to ECRB was a branch from the radial nerve in 11 cases (15.2%); from the PBRN in 36 cases (50%) and from the superficial branch of the radial nerve in 25 cases (34.7%), respectively. The ECRB had a tendinous arch in 21 cases (29.1%); a muscular arch in 8 (11.1%) cases and the arch was absent in 43 cases (59.7%). When the ECRB had a tendinous or muscular arch around the PBRN, it may compress the same and this condition may worsen during the repeated supination and pronation as observed in tennis and cricket players. The presence of such tendinous or muscular arch should be considered by orthopedicians and neurosurgeons, while releasing the PBRN during LE surgery.

Morphology of the lacrimal sac and nasolacrimal duct in adult human cadaver.

The lacrimal sac (LS) is a dilated structure that lies in the lacrimal fossa, and the nasolacrimal duct (NLD) is the continuation of LS from its neck up to the inferior meatus of the nose. A study of 50 specimens of formalin-fixed adult cadavers of both sexes of Indian origin was conducted. The morphological features like length and breadth of LS and NLD, along with the histology of LS has been observed. The mean length of LS and NLD on the right side was 10.5 mm (1.04) and 16 mm (2.6) respectively, whereas the mean breadth of the above structures, on the right side was 6 mm (0.63) and 5.66 mm (0.81) respectively. The mean length of LS and NLD on the left side was 10.57 mm (1.13) and 16.42 mm (2.29), whereas, the mean breadth of the same structure on the left side was 6.71 mm (0.95) and 5 mm (0.81) respectively. The sides did not show any significant statistical difference but when the correlation between the length and breadth of LS is considered, significance was observed in the lacrimal sac of the left side. No variations were observed in the gross structure of LS and NLD. Microscopic study showed the presence of elastic fibers in LS. The importance of LS and NLD is that the blockage of this lacrimal passage is the most common cause of epiphora (watering of the eye). The presence of elastic fibers in this study confirms the hypothesis that the sac elasticity may perform a dynamic role, in forceful evacuation of lacrimal fluid in reverse direction (Tab. 2, Fig. 3, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

Four-headed biceps and triceps brachii muscles, with neurovascular variation.

Anatomical variations of the biceps brachii and triceps brachii have been described by various authors, but the occurrence of four-headed biceps brachii and triceps brachii in an ipsilateral arm is rare and has not been reported before in the literature. During routine cadaveric dissection in the department of anatomy, Kasturba Medical College, Mangalore, India, various unusual variants were noted in the left arm of a cadaver of a 67-year-old man. The variants include a four-headed biceps, a four-headed triceps, communication between the musculocutaneous and median nerves, and a high origin of deep brachial artery from the axillary artery. The occurrence of these anomalies and the clinical and morphological significance are discussed.

The accessory heads of flexor pollicis longus and flexor digitorum profundus: Incidence and morphology.

Kiloh-Nevin syndrome caused by compressive neuropathy of the anterior interosseous nerve in the forearm is believed to occur because of its compression by the accessory head of flexor pollicis longus (FPLah). Gantzer described two accessory muscles, the more frequent is the FPLah and the less frequently observed is the flexor digitorum profundus accessory head (FDPah). Many studies have reported the prevalence, origin, insertion, nerve supply, and relations of these accessory muscles, most of them focusing on the FPLah. This study was designed to investigate the prevalence, morphology, relation to median and anterior interosseous nerve, and also the coexistence of both the accessory heads. A total of 126 upper limbs of the embalmed cadavers were examined in this study. Fifty-eight limbs (46.03%) showed the presence of the FPLah and 18 limbs (14.28%) had the FDPah. The most common origin of both the accessory muscle bellies was from the under surface of the flexor digitorum superficialis. The FPLah inserted into the FPL muscle at varying levels with 80% inserting into the proximal third of FPL, whereas the FDPah in all cases ended near the level of the wrist joining with one or more tendons of the FDP. Clinical implication of the variation is discussed.

A study of anatomical variability of the omohyoid muscle and its clinical relevance.

OBJECTIVE: The omohyoid muscle is a long, thin muscle consisting of superior and inferior bellies and an intermediate tendon, which runs obliquely in the lateral cervical region. The omohyoid is important in neck dissections because it is the surgical landmark for level III and IV lymph node metastases. METHODS: In the present study, the anterior and posterior triangle of the neck was dissected in 35 male cadavers and observed for variations in the omohyoid bilaterally. Observations were focused on variations in number, attachments, and position of omohyoid. RESULTS: Among the 35 cadavers studied, double omohyoid was present in one cadaver, inferior belly originated from the clavicle in three cadavers, superior belly merged with the sternohyoid in two cadavers, and the omohyoid received additional slips from the sternum in one cadaver. Standard attachment and position of the omohyoid was observed in the remaining cadavers. CONCLUSION: Variations of this muscle are important because of its close relation to the large vessels and brachial plexus. Because of the direct adhesion of the intermediate tendon to the anterior wall of the internal jugular vein and its connection with it through a thin lamina of the pretracheal layer of the cervical fascia, the contraction of the omohyoid muscle has a direct effect on the lumen of this vessel.

Anatomical variation of radial wrist extensor muscles: a study in cadavers.

OBJECTIVE: The tendons of the extensor carpi radialis longus and brevis muscles are quite useful in tendon transfer, such as in correction of finger clawing and restoration of thumb opposition. Knowledge of additional radial wrist extensor muscle bellies with independent tendons is useful in the above-mentioned surgical procedures. METHODS: The skin, subcutaneous tissue, and antebrachial fascia of 48 (24 on the right side and 24 on left side) male upper limb forearms were dissected. The following aspects were then analyzed: (a) the presence of additional muscle bellies of radial wrist extensors, (b) the origin and insertion of the additional muscle, and (c) measurements of the muscle bellies and their tendons. RESULTS: Five out of 48 upper limbs (10.41%) had additional radial wrist extensors; this occurred in 3 out of 24 left upper limbs (12.5%) and 2 out of 24 right upper limbs (8.3%). In one of the right upper limbs, two additional muscles were found. The length and width of each additional muscle belly and its tendon ranged between 2 - 15 cm by 0.35 - 6.4 cm and 2.8 - 20.8 cm by 0.2 0.5 cm, respectively. The additional radial wrist extensor tendons in our study basically originated either from the extensor carpi radialis longus or brevis muscles and were inserted at the base of the 2nd or 3rd metacarpal bone. CONCLUSION: The present study will inform surgeons about the different varieties of additional radial wrist extensors and the frequency of their occurrence.

Incidence of accessory phrenic nerve and its clinical significance: a cadaveric study.

UNLABELLED: The description of accessory phrenic nerve (APN) in the standard textbooks and available literature is vague and sometimes limited to few lines. The incidence of APN varies a great deal from 17.6 % to 80.9 % in the available literature. The aim of the present study was to calculate the incidence and variation of APN in Indian population. MATERIAL AND METHODS: Forty five adult formalin-fixed cadavers (35 male, 10 female; 90 sides) used for gross anatomy dissection for undergraduates; during the 2 year period 2006-2007 were considered. Findings were recorded at different stages of the dissection. RESULTS: Out of 90 body sides studied, the APN was present in 48 sides (53.3 %). In 17 of the above sides the APN was confined to the cervical region (Cervical type) and in 31 sides the APN entered the thorax (Thoracic type), all anterior to the subclavian vein (SV). In eleven specimens the APN was found bilaterally. CONCLUSION: The incidence of APN, with its course and relation to the various structures in cervical and thoracic region will help the surgeons while performing internal thoracic artery (ITA) grafting and other radical neck surgery.

The morphology of meningo-orbital foramen in south Indian population.

When present, the meningo-orbital foramen forms an additional link between the orbit and the middle cranial fossa. It contains an arterial anastomose between the middle menigeal artery--the meningo-lacrimal branch and the lacrimal artery--the meningeal branch. The incidence of this foramen is known to vary between 28-82.9%. In the present study of 138 dry adult skulls of South Indian origin, the meningo-orbital foramen was present in 80.4% of population. The mean distance of the meningo-orbital foramen from the supra-orbital notch was 34.14 mm (29-38 mm) and from the fronto-zygomatic suture it was 26.10 mm (28-35 mm). The incidence and location of the meningo-orbital foramen may be of surgical significance to ophthalmologists (Tab. 1, Fig. 3, Ref. 7).

An unusual course and entrapment of the lingual nerve in the infratemporal fossa.

The infratemporal fossa is one of the most difficult regions of skull base to access surgically. The presence of the ossified pterygospinous and pterygoalar ligaments makes it more critical and difficult to access, with an occasional entrapment of structures like the mandibular nerve (MN) and its branches. During a routine dissection of an adult male cadaver, an unusual course of the lingual nerve (LN) was found with an entrapment of the nerve between the ossified pterygospinous ligament and the medial pterygoid muscle. Furthermore, all the three branches of the posterior division of the mandibular nerve communicated with each other by two anastomosing branches. The clinical significance of the present variations has been discussed (Fig. 1, Ref. 23).

Multiple supernumerary muscles of the arm and its clinical significance.

During routine cadaveric dissection of the flexor compartment of the right arm, multiple supernumerary muscles were observed in a 56-year-old male cadaver. There were three supernumerary muscles took taking origin independently from the humerus distally to the insertion of coracobrachialis muscle. The upper two supernumerary muscles were attached to the common tendon of the biceps brachii muscle and considered as its additional heads. The third supernumerary muscle passed between the biceps brachii and brachialis muscles, then crossed obliquely the brachial artery and median nerve nearing cubital fossa to get inserted in to the radial side of the humeral head of the pronator teres. The clinical significance of the above variations is discussed (Fig. 1, Ref. 16).

An additional radial wrist extensor and its clinical significance.

The knowledge of anatomical variations in the antebrachial and dorsal regions of the arm and hand are useful in hand surgery. The extensor carpi radialis intermedius and extensor carpi radialis accessorius are two classic variants described for the radial wrist extensors, in the antebrachial region. We report an additional extensor carpi radialis muscle taking origin from the common extensor origin, between the extensor carpi radialis longus and extensor digitorum communis. The tendon of the variant muscle divides below the abductor pollicis longus and becomes attached to the base of the second and third metacarpal bone. Due to its considerable size and independent origin from the lateral epicondyle, we suggest the present variation should be named extensor carpi radialis tertius. The clinical significance of the present variation is discussed.

Unusual origin of dorsal nerve of penis and abnormal formation of pudendal nerve--clinical significance.

The nerve roots of the sacral plexus are fascinating and critical in the functions of defecation, micturition, parturition, and even participate in the mechanism of male sexual functions of erection and ejaculation. During our routine cadaveric dissection of the right gluteal region of a 45-year-old male cadaver, we came across an unusual origin of the dorsal nerve of the penis (DNP) and abnormal formation of the pudendal nerve. The clinical aspects of the particular variations are discussed.

The Paracondylar Skull Base: Anatomical Variants and Their Clinical Implications.

AIM: The knowledge of the vasculature around the paracondylar region is important in neurosurgical procedures such as the paracondylar and lateral supracondylar approaches. The objectives of the present study were to determine the prevalence of paracondylar emissary foramina in the adult skull bases and to study the morphology of condylar canals and hypoglossal canals. MATERIAL AND METHODS: The present study included 48 adult human skulls that were obtained from the gross anatomy laboratory of our institution. The paracondylar region was macroscopically observed for the variant foramina, canals and grooves. RESULTS: It was observed that the paracondylar emissary foramen was present in 16 skulls (33.3%). The foramen was found bilaterally in 7 skulls (14.6%) and unilaterally in 9 skulls (18.7%). The hypoglossal canal was single in 35 (72.9%) skulls, double in 11 skulls (22.9%), and triple in 2 skulls (4.2%). The paracondylar process (2.1%) and the paracondylar groove (2.1%) were seen in 1 skull each. The posterior condylar canal was found to be patent in 19 (39.6%) skulls. CONCLUSION: The present study observed that, the paracondylar emissary vein is not rare in occurrence as it is observed in 33.3% of cases. The identification of the paracondylar emissary veins and accessory vessels is important to avoid dangerous bleeding during the surgery. The morphological knowledge of the foramina around the paracondylar region is enlightening to the chiropractors, neurosurgeons and radiologists.

Morphology and topography of the parietal emissary foramina in South Indians: an anatomical study.

The objectives of the present study were to study the prevalence of the parietal emissary vein in adult South Indian population and to study the distance of foramen from the sagittal suture. There were 58 adult human skulls in the present study which were available at the anatomy department of our institution. The study included 116 parietal bones which have been observed macroscopically for the number, prevalence and topography of the emissary foramen. The emissary foramen was present in 83 parietal bones (71.5%) of the present study. It was present at the junction between the middle 1/3 and posterior 1/3 region of the parietal bone. The foramen was observed solitary in 73 parietal bones (62.9%), double in 8 bones (6.9%), and triple in 2 parietal bones (1.7%). The foramen was not observed in 33 parietal bones (28.4%). The bilateral absence of parietal emissary foramen was seen in 7 skulls (12.1%). It was absent unilaterally in 19 skulls (32.7%). The accessory foramina were seen in only 8 skulls (13.8%). The mean distance of the foramen from the sagittal suture was 6.7±2.9 mm and 6.8±2.8 mm on the right and left sides respectively. The prevalence of parietal emissary vein in the present study was 71.5%. The present study has observed important data about the morphology and morphometry of the parietal emissary vein in South Indian population. The identification of parietal emissary veins and accessory veins is important in the operation room to prevent the blood loss.

Effect of sildenafil-induced nitric oxide on the histomorphology of cardiomyocytes in male rats.

INTRODUCTION: Although sildenafil citrate, one of the selective phosphodiesterase-5 (PDE5) inhibitors, is considered the best treatment for erectile dysfunction, studies have shown that it has also a beneficial effect on a variety of cardiovascular conditions. In spite of reports of a significant protective effect of sildenafil against necrosis in intact hearts, there are also contradictory reports regarding its beneficial effect on the heart. Since there are not enough reports regarding the histomorphological changes in the cardiomyocytes after exposure to sildenafil citrate, the present study was conducted to observe the same along with other biochemical parameters. MATERIALS AND METHODS: Adult male albino rats of Wistar strain were used in the present study. The animals were divided into a control group and two experimental groups containing six rats each. The animals were treated with a solution of sildenafil citrate dissolved in distilled water. Histomorphological changes were observed by light microscopy and the levels of nitric oxide (NO) and PDE in the heart were measured by spectrophotometry. RESULTS: It was observed that animals treated with sildenafil citrate showed a highly significant increase in NO and a decrease in PDE level, but the histological architecture of the cardiomyocytes did not show much change other than a slightly elongated and swollen nucleus. CONCLUSIONS: This study shows that sildenafil citrate at low dosage is well tolerated by cardiac muscle cells, but as dosage increases, it may become detrimental through its NO and PDE activity.

Morphological analysis and morphometry of the foramen magnum: an anatomical investigation.

AIM: The objectives were to study the morphology of the foramen magnum in dry skulls and to evaluate its antero-posterior diameter, transverse diameter and the foramen magnum index. MATERIAL AND METHODS: The foramen magna of 53 dry human cadaver skulls that were obtained from the neuroanatomy laboratory were examined. Different shapes of the foramen magnum were macroscopically noted and classified. The antero-posterior and transverse diameters were measured and the average foraminal index was calculated. RESULTS: The foramen magnum shapes were determined as a round shape in 22.6% of cases, egg shape in 18.9%, tetragonal in 18.9%, oval in 15.1%, irregular in 15.1%, hexagonal in 5.6% and pentagonal in 3.8% of the cases. In 20.7% of skulls, the occipital condyle was observed to protrude into the foramen. The mean antero-posterior and transverse diameter of the foramen magnum was determined as 31 ± 2.4 mm and 25.2 ± 2.4 mm respectively. The average foramen magnum index was 1.2 ± 0.1. CONCLUSION: The present study has determined the various shapes of foramen magnum and its morphometry. The data obtained may be of useful to the neurosurgeon in analyzing the morphological anatomy of craniovertebral junction. The findings are also enlightening for the anthropologists, morphologists and clinical anatomists.

A morphometric study of foramen ovale.

AIM: To note the morphological variations and morphometric details of foramina ovale in dry adult skulls of Indian origin. MATERIAL AND METHODS: 82 dry adult human skulls of unknown sex and of Indian origin were obtained and variations in appearance and number of foramen ovale were noted. The length and width of the foramina ovale of both sides were determined using digital Vernier calipers and area (A) was also calculated and analyzed. RESULTS: Out of 82 adult skulls, the values for the right side was 7.64 ± 1.194 mm, 5.128 ± 0.827 mm and 30.808 ± 7.545 mm2 and for the left side the values was 7.561 ± 1.123 mm, 5.244 ± 0.950 mm and 31.310 ± 8.262 mm2 respectively, for the mean length, width and area of the foramen ovale. The shape of foramen was typically ovale in most of the skulls (56.70%) with some bony variations such as spine, tubercles etc. CONCLUSION: There was no statistically significant difference between the two sides in length, width and area of foramen ovale and there was a positive correlation between lengths and areas of both sides.