Anatomical study on branching pattern and variations of orbital segment of the oculomotor nerve

Background: This study aims to revisit the anatomy of orbital segment of the third cranial nerve (CN III). The study also involved morphometric measurements of CN III muscular branches. Detailed description of observed anatomical variations and their incidence was also included. The study supplements earlier findings with detailed observations of the neuromuscular relations. Materials and methods: The study was conducted on 52 orbits taken from 26 cadaveric heads (10 males and 16 females; Central European population). Results: Anatomical variations of the orbital segment of the CN III observed on the examined material involved both the superior and inferior branch of this nerve. The muscular branch innervating the levator palpebrae superioris muscle occasionally pierces the superior rectus muscle. The nerve to the inferior oblique muscle may pierce and innervate the inferior rectus muscle. In rare instances, duplication of the parasympathetic root of the ciliary ganglion may also occur. Among the muscular branches, the smallest diameter reached the branch to the levator palpebrae superioris muscle. Among the three muscular branches derived from the inferior branch of the CN III, the nerve to the inferior oblique was the longest one. Its length varied from 28.9 mm to 37.4 mm. The shortest was the muscular branch to the inferior rectus muscle. Its length varied from 0 mm (when muscular sub-branches arose directly from the nerve to the inferior oblique muscle) to 7.58 mm. Conclusions: This study presented the characteristic of orbital segment of the CN III, including anatomical variations and morphometric measurements relevant to intraorbital procedures

Circumaortic left renal vein (circumaortic renal collar) associated with the presence of vascular anomalies: a case series and review of literature

Renal vessels exhibit a high degree of anatomical variations in terms of their number, level of origin, diameter and topographical relationships. In particular, it applies to the left renal vein which can take retroaortic or even circumaortic placement. Anatomical variations of the left renal vein may be of great clinical significance, particularly in the case of renal transplantation, retroperitoneal surgery as well as vascular or diagnostic procedures. Thus, the aim of this report was to present a complete anatomical description of two cases of the circumaortic left renal vein (CLRV; circumaortic renal collar) co-existing with the presence of various vascular anomalies. In the first case, the circumaortic renal collar was connected via a large anastomosis with the hemiazygos vein and was associated with the presence of the supernumerary left renal artery located below the main left renal artery. In the second case, the circumaortic renal collar was accompanied by the renal artery dividing close to its origin. Moreover, in the latter case, the fusiform aneurysm of the abdominal aorta was observed. In both cases, the CLRV began as a single and short trunk. On its further course, the initial segment of the CLRV was divided into two limbs — anterior (anterior left renal vein) and posterior (posterior left renal vein). Both anterior and posterior limb of the CLRV opened into the inferior vena cava.

Klingler’s method of brain dissection: review of the technique including its usefulness in practical neuroanatomy teaching, neurosurgery and neuroimaging

Klingler’s technique was discovered in the 1930s. It is a modified method of brain fixation and dissection, based on freezing and thawing of the brain tissue, subsequent peeling away of white matter fibres and the gradual exposure of white matter tracts. The added value of this technique is that it is carried out in a stratigraphic manner. This fact makes it an invaluable tool for an in-depth understanding of the complex anatomical organisation of the cerebral hemispheres. The purpose of this paper is to provide a review of Klingler’s method while taking into account the original description of the technique and its value for medical training. The historical background, the concise outline of white matter organisation, as well as our own experience in using this procedure for research and teaching activities were also included. The fibre dissection technique may still be considered an excellent complementary research tool for neuroanatomical studies. Numerous detailed observations about the white matter topography and spatial organisation have been recently made by applying this method. Using this technique may also improve understanding of the three-dimensional intrinsic structure of the brain, which is particularly important both in under- and postgraduate training in the field of neuroanatomy

Types of inferior phrenic arteries: a new point of view based on a cadaveric study

Background: The diaphragm is supplied by the superior and inferior phrenic arteries. This present study focusses on the latter. The inferior phrenic arteries (IPA) usually originate from the abdominal aorta. The two arteries have different origins, and knowledge of these is important when performing related surgical interventions and interventional radiological procedures. The aim of this study was to identify variations in the origin of the IPA and conduct relevant morphometric analyses.Materials and methods: The anatomical variations in the origins of the left inferior phrenic artery (LIPA) and the right inferior phrenic artery (RIPA) were examined in 48 cadavers fixed in 10% formalin solution. A dissection of the abdominal region of the cadavers was performed according to a pre-established protocol using traditional techniques. Morphometric measurements were then taken twice by two of the researchers.Results: In the cadavers, six types of origin were observed. In type 1, the most common type, the RIPA and LIPA originate from the abdominal aorta (AA) (14 = 29.12%). In type 2, the RIPA and the LIPA originate from the coeliac trunk (CT) (12 = 24.96%). In type 3, the RIPA and the LIPA originate from the left gastric artery, with no CT observed (3 = 6.24%). Type 4 has two subtypes: 4A, in which the LIPA originates from the AA and the RIPA originates from the CT (9 = 18.72%) and 4B, in which the RIPA originates from the AA and the LIPA originates from the CT (6 = 12.48%). In type 5, the LIPA originates from the AA and the RIPA originates from the AA (1 = 2.08%). Type 6 is characterised by the RIPA and LIPA forming a common trunk originating from the CT (3 = 6.24%). Conclusions: Our findings suggest the presence of six different types of LIPA and RIPA origin. The most common form is type 1, characterised by an IPA originating from the abdominal aorta, while the second most common is type 2, in which the IPA originates from the AA by a common trunk. The diversity of other types of origin is associated with the occurrence of coeliac trunk variation (type 3). No significant differences in RIPA diameter could be found, whereas LIPA diameter could vary significantly. No significant differences in RIPA and the LIPA diameter could be found according to sex

Unusual formation of the musculocutaneous and median nerves: a case report refined by intraneural dissection and literature review

This report presents a detailed anatomical investigation of an upper limb specimen showing an atypical formation of the musculocutaneous nerve (MCN) and median nerve (MN). The study was refined by intraneural dissection, which supplements earlier descriptions of similar anatomical variations and allows for revision of the accepted classification.The case described in this report was an incidental finding during routine dissection of a fixed isolated upper limb. Intraneural dissection revealed partial fusion between the MCN and aberrant bundles of the MN. Those aberrant bundles joined the main steam of the MN at the level at which the MCN branched off as an independent nerve. The procedure allowed the aberrant fibres of the MN to be differentiated from the MCN. The presence of separate bundles in a territory corresponding to the MCN was confirmed, although those bundles and the aberrant MN bundles were covered by a common epineurium. The aberrant MN bundles running within the MCN did not contribute to innervation of the forearm muscles. They rejoined the main nerve trunk in the arm.A comprehensive understanding of the diverse anatomical variations of the upper limb nerves could be crucial for the safety and success of surgical procedures, especially procedures for reconstructing the brachial plexus or its branches

Comparison of the Superior and Inferior Rectus Muscles in Humans: An Anatomical Study with Notes on Morphology, Anatomical Variations, and Intramuscular Innervation Patterns

A comparison of the superior and inferior rectus muscles was performed to determine whether they have similar structures and innervation attributable to their participation in the same type of, although antagonistic, eye movements. The study was conducted on 70 cadaveric hemiheads, and the anatomical variations in the superior and inferior rectus muscles were assessed. Sihler’s whole mount nerve staining technique was used on 20 isolated superior and 20 isolated inferior rectus muscle specimens to visualize the intramuscular distribution of the oculomotor nerve subbranches. In two cases (~2.8%), variant muscular slips were found that connected the superior and inferior rectus muscles. In 80% of cases, muscular branches arising directly from the inferior branch of the oculomotor nerve innervated the inferior rectus muscle, while in 20% of cases, the nerve to the inferior oblique muscle pierced the inferior rectus muscle and provided its innervation. In 15 of 70 specimens (21.4%), a branch to the levator palpebrae superioris muscle pierced the superior rectus muscle. The distance between the specific rectus muscle’s insertion and the anterior-most terminations of the nerves’ subbranches with reference to the muscle’s total length ranged from 26.9% to 47.2% for the inferior rectus and from 34.8% to 46.6% for the superior rectus, respectively. The superior rectus muscle is slightly longer and its insertion is farther from the limbus of the cornea than is the inferior rectus muscle. Both muscles share a common general pattern of intramuscular nerve subbranches’ arborization, with characteristic Y-shaped ramifications that form the terminal nerve plexus located near half of the muscles’ length. Unexpected anatomical variations of the extraocular muscles may be relevant during orbital imaging or surgical procedures