The effect of morphological variability of Dorello's canal on surgical procedures - a review.

Dorello's canal is an arched structure of bone-fibrous character located in the petroclival venous confluence atop the petrosal bone in the petroclival region. It is bordered by the petrosphenoidal ligament, the petrous part of the temporal bone and the lateral border of the upper part of clivus. Its content in the vast majority of variants comprises the abducens nerve, the inferior petrosal sinus, the venous drainage and the dorsal meningeal artery or its medial branch. With the development of microsurgical techniques, this area has gained huge clinical importance, mainly concerning the order in which the above-mentioned elements (especially the position of the abducens nerve) are arranged in relation to each other. These structures appear in different variant forms and necessitate an individual clinical approach. The main purpose of this review is to present condensed information about possible intercorrelations among them and to indicate, on the basis of the available literature and research, possible surgical approaches and the need to consider the variability when treatments in this region are planned.

The clinical anatomy of variations of the pectoralis minor.

Shoulder pathology is a very common medical presentation and can be due to anatomical variations. Therefore, knowledge of variants is important for the clinician treating patients with such complaints so that misdiagnosis is minimized and iatrogenic injury prevented. A review of the literature was performed of the variant anatomy of the pectoralis minor muscle. The aim of this review is to better inform clinicians who might treat patients with shoulder pathology so that if identified, variants of the pectoralis minor muscle are better appreciated.

Risk Factors of Intervertebral Disc Pathology-A Point of View Formerly and Today-A Review.

Intervertebral disc pathology is a common disorder that can be caused by genetic, mechanical, and behavioral factors; however, it is possible to slow its progression. Although environmental and behavioral factors were previously considered to be the sole causes of intervertebral disc pathologies such as disc herniation, recent studies have shown that genetic factors also play an important role. This review compares the perception of major risk factors from the last and present centuries. It also examines individual genetic and non-genetic factors acting as risk factors, as well as some approaches for preventing intervertebral disc pathologies, and compares available statistics regarding disc herniation.

The proximal humeral attachment of the lateral head of the triceps brachii: a cadaveric study and potential site for radial nerve compression.

BACKGROUND: Knowledge of potential compression sites of peripheral nerves is important to the clinician and surgeon alike. One anatomical location for potential compression of the radial nerve, which is rarely mentioned in the literature, is at the proximal humeral attachment of the lateral head of the triceps brachii at the level of the proximal spiral groove. As no anatomical studies have been devoted to this band, the present study was conducted. METHODS: Ten adult fresh-frozen cadavers were dissected and the lateral head's attachment onto the posterior humerus evaluated for a band. This anatomy and its relation to the radial nerve during range of motion of the elbow and forearm were evaluated. RESULTS: A band was found on 15 of 20 arms. On five sides, the band was comprised of grossly muscle fibers of the lateral head of the triceps brachii and was not tendinous. The bands were crescent-shaped, straight, and duplicated on nine, five, and one arm, respectively. The length of the bands ranged from 1.1 to 2.2 cm (mean 1.54 cm). The width of the bands ranged from 0.5 to 1.1 cm (mean 0.8 cm). With elbow extension and the forearm in neutral, all bands were lax. With elbow extension and the forearm supinated, the bands became tauter less the muscular bands. In elbow extension and with the forearm in supination, the bands became most taut less the muscular bands. CONCLUSIONS: The presence of a fibrous band extending from the lateral head of the triceps brachii is common and should be among the differential diagnoses of anatomical sites for potential proximal radial nerve compression when other more common locations are ruled out.

A proposal for a new classification of soleus muscle morphology.

INTRODUCTION: The soleus muscle (SM) is located in the superficial posterior compartment of the leg, together with the gastrocnemius muscle (GM) and plantaris muscle. There is little information on the morphological variability (pennation) of the SM. The aim of the study is to characterize the variations in the morphology of the pennation of the SM and to create the first accurate classification. MATERIAL AND METHODS: Eighty lower limbs (40 left, and 40 right) fixed in 10% formalin solution were examined. The morphology of the central tendon, medial and lateral aponeuroses was evaluated, together with the pennation angle. RESULTS: In all cases, the soleus muscle was present. Four types could be distinguished based on muscle fibre morphology. In order of frequency: Type 1 - bipennate (43.75%); Type 4 - non-pennate (36.25%); Type 2 - unipennate (15%); Type 3 - multipennate (5%). No significant difference in type distribution was observed with regard to body side (p=0.9018) or gender (p=0.0844). CONCLUSION: The soleus muscle is characterized by high morphological variability. Based on the pennation angle, four types (1-4) of soleus muscle are distinguishable.

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.

Anatomical variations and innervation patterns of the superior oblique muscle.

GOAL: The location and anatomical relationships of the superior oblique muscle make surgical intervention difficult. The aim of the present paper was therefore to supplement existing anatomical descriptions of this muscle. Its anatomical variability is particularly emphasized, including variations in muscle and tendon size and details of the innervation pattern. MATERIALS AND METHODS: The study was conducted on 78 orbits from 39 adult human cadavers of both sexes (18 males and 21 females). The roof and upper part of the medial and lateral walls of the orbit were carefully removed, which allowed the superior oblique muscle and trochlear nerve to be exposed along their entire course. Sihler's stain was applied to visualize the intramuscular distribution of the trochlear nerve. RESULTS: The length of the muscle between the origin and trochlea ranged from 37.8 to 56.5mm, the length of the tendinous expansion ranged from 16.3 to 22.8mm, and the width of the scleral insertion of the muscle's tendon ranged from 5.4 to 9.6mm. In two cadavers, accessory muscular slips connecting the levator palpebrae superioris muscle to the trochlea of the superior oblique muscle were present unilaterally. The distance from the level of the trochlea attachment to the anteriormost endings of the intramuscular branches varied from 17.2 to 21.5mm. CONCLUSIONS: The intramuscular nervous branches of the trochlear nerve form a tree-like pattern. Unexpected anatomical variations such as accessory muscular bands could be relevant during orbital imaging or surgeries.

Gross anatomy of coronary veins of the European bison (Bison bonasus).

BACKGROUND: Although significant efforts have been put into restituting the European bison (Bison bonasus) and increasing its population, it remains a globally endangered species and requires conservation. Protection programs of bison indicate the need for morphological studies of their individual systems, in order to enhance restitution programs and enable appropriate veterinary care. The aim of this study was to investigate the morphology of the coronary veins of the European bison (Bison bonasus). RESULTS: The study was carried out on 78 hearts of European bison of both sexes, aged 5 to 21 years. The subepicardial veins were clearly visible after being filled with dyed synthetic latex (LBS 3060), Plastogen G and Batson's No. 17. In all the studied animals, the great cardiac vein drains into the coronary sinus. The interventricular paraconal branch and the circumflex branch of the great cardiac vein were distinguished. The left marginal vein, which originated in the apical area or halfway along the length of the left ventricular margin, was easily identified in 65 animals (83%). In most animals (51 bison, 65%), the middle cardiac vein drained into the coronary sinus, while in some animals it drained into the right atrium (27 animals, 35%). CONCLUSIONS: Blood from the cardiac walls is drained into the great cardiac vein, the middle cardiac vein, the right coronary veins and numerous small cardiac veins.

Anatomy, physiology, and updates on the clinical management of constipation.

Clinical management of constipation has evolved from the prescription of dietary supplements, to potent stimulant laxatives, to corrective surgeries for organic blockage. Yet constipation does not respond to a one-size-fits-all treatment. In recent decades, the Bristol Stool Form Scale and Rome III diagnostic criteria have allowed for algorithmic diagnosis, yet these criteria could benefit from further extension and meaningful discussion. This review incorporates pertinent clinical updates and uses the anatomy and physiology of constipation as helpful signposts for the practicing clinician.

Comparison of lateral and medial rectus muscle in human: an anatomical study with particular emphasis on morphology, intramuscular innervation pattern variations and discussion on clinical significance.

This paper aims to present various aspects of the anatomy of horizontal (i.e., lateral and medial) rectus muscles. It mainly compares morphology and detailed patterns of intramuscular innervation of those muscles. It is also one of the first reports that uses the Sihler's stain to examine human extraocular muscles. The study was conducted on 80 isolated cadaveric hemi-heads. Sihler technique of nerves staining served to expose the course of intramuscular branches of the oculomotor and abducens nerves. The lateral rectus was longer (48 mm versus 46.5 mm) and more distant from the limbus (6.8 mm versus 5.7 mm) than the medial rectus muscle. Three variants of the abducens nerve primary division were observed in the lateral rectus muscle. In the medial rectus muscle, the motor branch from the oculomotor nerve was more evenly divided into sub-branches. In both examined horizontal rectus muscles, primary muscular branches split into secondary sub-branches, which undergo numerous further divisions. The most numerous terminal sub-branches formed the terminal plexus. The distance between the insertion and the anterior-most end of the terminal plexus referenced to the total length of the muscle ranged from 35.4 to 48.5% for the lateral rectus muscle and from 36.3 to 50.5% for medial rectus muscle. Both horizontal rectus muscles share similar general pattern of distribution of intramuscular nerves, with characteristic root-like arborizations of sub-branches. The terminal nerve plexus was observed near half of both muscles' length. Knowledge of variations and innervation pattern of the extraocular muscles may be relevant during ophthalmology surgeries.

Intramuscular innervation of the lateral rectus muscle evaluated using sihler's staining technique: Potential application to strabismus surgery.

The latest research suggests that the abducens nerve may be divided into subbranches that reach functionally distinct zones of the lateral rectus muscle. The goal of the study was to examine this muscle's innervation, including the detailed distribution of the intramuscular subbranches of the abducens nerve. Twenty-five lateral rectus muscle specimens were harvested (with the orbital segment of the abducens nerve), fixed in 10% formalin solution, and stained with Sihler's whole mount nerve staining technique. Subbranches running to the lateral rectus divided into two main groups: superior and inferior. Both groups of subbranches are distributed in a fan-shaped manner, show a characteristic "tree-like" branching pattern and form terminal plexus near the proximal half of the lateral rectus muscle. However, some smaller subbranches run as far as the muscle's insertion, and recurrent subbranches also reach its origin. With respect to their course to the muscle's origin or insertion, the smallest subbranches running within the muscle may be associated with innervation of the tendon. In the majority of cases (88%), superior and inferior subbranches of the abducens nerve overlapped in the central one-third of the lateral rectus muscle's width so that any clearly distinct anatomical segments of the muscle could be observed based on Sihler's technique. In the remaining 12% of specimens, superior and inferior groups of subbranches innervated two distinct compartments of the lateral rectus muscle with no overlapping. Dense, fan-shaped distribution of abducens nerve intramuscular subbranches can be observed within the lateral rectus muscle. Clin. Anat. 33:585-591, 2020. © 2019 Wiley Periodicals, Inc.

Anatomical variations of the dentate gyrus in normal adult brain.

Recent scientific papers indicate the clinical significance of the dentate gyrus. However, a detailed knowledge of the anatomical variations of this structure in normal adult brain is still lacking. An understanding of the variable morphology of the dentate gyrus may be important for diagnostic neuroimaging. Thus, the purpose of this macroscopic cadaveric study was to describe the anatomical variations of the dentate gyrus. Forty formalin-fixed human cerebral hemispheres, obtained from bodies of donors without the history of neuropathological diseases, were included in the study. The dentate gyrus was classified as well-developed, when it protruded completely from under the fimbria of the hippocampus. The gyrus was classified as underdeveloped, when it was covered by the fimbria of the hippocampus (but clearly visible at the coronal section of the hippocampal formation), while the hypoplastic gyrus was not visible macroscopically under the fimbria of the hippocampus. The well-developed type was observed in 27 cases (67.5%). The thickness of well-developed type of the dentate gyrus, measured between the fimbriodentate sulcus and hippocampal sulcus, varied from 2.74 to 5.21 mm (mean = 3.67 mm, median = 5.54 mm, SD 0.65 mm). In the next nine cases (22.5%), the dentate gyrus was underdeveloped. The thickness of underdeveloped type of the dentate gyrus varied from 1.75 to 2.37 mm (mean = 2.02 mm, median = 2.16 mm, SD 0.33 mm). In the remaining four cases (10%), the dentate gyrus was hypoplastic and could not be distinguished macroscopically. In all injected hemispheres, arterial supply of the dentate gyrus was provided by the branches of the posterior cerebral artery. Awareness of normal variations of the dentate gyrus may allow for better correlation of anatomical knowledge with radiological data and for use this knowledge to describe abnormal conditions.

Anatomical variations of the ciliary ganglion with an emphasis on the location in the orbit.

The ciliary ganglion is of outmost physiological importance, due to its involvement in pupillary light reflex circuits. The ciliary ganglion may be damaged during surgical procedures. Therefore, the aim of the study was to examine the anatomical variations of the ganglion with an emphasis in location in the orbit. Anatomical variations of the parasympathetic root of the ganglion were also examined and classified. 40 orbits were dissected. The orbital content was removed en bloc. The lateral rectus muscle was detached from its insertion and reflected. After the removal of the orbital fat, the ciliary ganglion was visualized. Then, the morphology, roots and location of the ganglion were assessed. The location of the ciliary ganglion varied from 17 to 83.7% (mean = 51.4%, median = 53%, SD 14.8%) of the distance between the point of the optic nerve emerging from the eyeball and the common tendinous ring (counting from the front). In most cases (55%) it was found between 50.1 and 75% of the distance between the back of the eye and the common tendinous ring, while in 37.5% of cases it was found between 25 and 50% of this distance. The parasympathetic root of the ciliary ganglion was variable. Its origin was from the nerve to the inferior oblique muscle in most of cases. In four cases (10%), the parasympathetic root of the ciliary ganglion was duplicated. The ciliary ganglion occupies a variable position with regards to the optic nerve. The parasympathetic root of the ganglion may be unusually short or doubled.

Posterior Sacrococcygeal Plexus: Application to Spine Surgery and Better Understanding Low-Back Pain.

OBJECTIVE: The sacral dorsal rami form the posterior sacrococcygeal plexus (PSCP), which has been scantly studied. This study's goal was to clarify the PSCP s detailed anatomy and discuss its clinical relevance. METHODS: Ten sides of 5 fresh-frozen cadavers were dissected for this research. After the muscles covering the sacrum were removed, the PSCP was identified and traced under the operating microscope until the entire plexus was exposed. The contributions to this plexus and its relations to surrounding anatomic structures were recorded. RESULTS: The PSCP was found on all sides and was composed of a medial trunk (MT), communicating branches, and a lateral trunk. Each sacral dorsal ramus's MT formed a series of loops created by adjacent sacral dorsal rami placed between the transverse tubercles and the posterior sacral foramina. The MT, communicating branches, and lateral trunk demonstrated potential entrapment sites. CONCLUSIONS: To our knowledge, this is the first anatomic study that provides detailed images that indicate 3 potential sites where surrounding structures could entrap the PSCP. Knowledge of its detailed anatomy might help in better understanding low-back pain, targeting pain sources and guide spine surgeons for avoiding injury to these nerves.

Anatomical variations of the levator palpebrae superioris, including observations on its innervation and intramuscular nerves' distribution pattern.

BACKGROUND: The levator palpebrae superioris muscle (LPS) acts as the upper eyelid's major elevator and retractor and is innervated by the oculomotor nerve. The muscle's paralysis is manifested by ptosis. MATERIAL AND METHODS: 70 orbits were dissected. After removing the orbital roof, the LPS' shape and anatomical variations (i.e., the presence of accessory muscular bands or atypical formation of the muscle) were assessed. To visualize the distribution of the oculomotor nerve's intramuscular sub-branches, the isolated levator palpebrae superioris muscles were stained using Sihler's staining technique. RESULTS: Several LPS anatomical variations were observed in the specimens examined, in seven of which (7/70; 10%) additional delicate muscular slips arose from the LPS' lateral border and reached the lacrimal gland. Histological examination confirmed the presence of striated skeletal muscle fibers in all those cases. In three other specimens (3/70; 4.28%), supernumerary muscular bands ("tensor trochleae") were found that linked the levator with the superior oblique muscle's trochlea. In the next case, the LPS' origin was double and the muscle was bipartite on its proximal half. In most cases (55/70; 78.6%), muscular branches formed a single bundle that wrapped around the superior rectus muscle's medial border to reach the levator's inferior surface. Intramuscular sub-branches were distributed largely within the proximal two-thirds of the LPS and formed an irregular, tree-like pattern. However, thin sub-branches and small retrograde sub-branches extended as far as the muscle's insertion. CONCLUSIONS: Plastic surgeons and ophthalmologists should be aware of the levator palpebrae superioris muscle's anatomic variations both in planning and conducting surgeries on the upper eyelid.

The Superficial Venous System of the Forelimb of the Anubis Baboon (Papio anubis): The Distribution of Perforating Veins and Venous Valves.

The superficial veins of the forelimb show high variability, both in man and in other primates, regarding the number of main venous trunks, their course, as well as the origin and location of openings. The distinction between two venous systems-the superficial and deep was made based on the relation of specific venous channels to the deep fascia; both groups of veins anastomose to each other through perforators piercing the deep fascia. In our work, we paid special attention to the organization of the venous system within the forelimb of the Anubis baboon (Papio anubis), as well as communications between the superficial and deep venous system. The main aim of the study was a detailed examination of the location of venous valves and perforating veins in forelimb of Anubis baboon. In the Anubis baboon, we observed the absence of the basilic vein. The main vessel within the forelimb, in the superficial venous system, was a well-developed cephalic vein. In all the cases, the cephalic vein opened into the external jugular vein. Also, in all of the examined specimens, there was an additional anastomosis connecting the cephalic and external jugular vein, i.e., persistent jugulocephalic vein located anterior to the clavicle. The venous vessels in the Anubis baboon were arranged in two main layers: superficial and deep, with both systems being connected by perforators located at the level of the carpus and cubital fossa. The number of venous valves within the cephalic vein was greater on the forearm the same as the mean intervalvular distance.

Anatomical Variations of the Supraorbital and Supratrochlear Nerves: Their Intraorbital Course and Relation to the Supraorbital Margin.

BACKGROUND This study aimed to describe the topographical anatomy of the supraorbital and supratrochlear nerves. Anatomical variations of both the intraorbital course of the 2 nerves and their relation to the supraorbital margin were analyzed. MATERIAL AND METHODS The research material involved 50 isolated adult cadaveric hemi-heads and 25 macerated adult skulls. All studied specimens were of Caucasian origin. RESULTS Taking into account the location of the frontal nerve division, 2 main variants of the intraorbital course of the supraorbital and supratrochlear nerves were distinguished. The first variant (variant I, 42%) involved cases in which the supraorbital and supratrochlear nerves branched off from the frontal nerve in the distal half of the length of the orbit. In the second variant (variant II, 58%), the frontal nerve branched into the supraorbital and supratrochlear nerves in the proximal half of the orbit. Variant II was characterized by the presence of a thick supraorbital nerve and a long, tiny supratrochlear nerve. For variant I, 27.8% of the supraorbital nerves were divided into the medial and lateral branch within the orbit, whereas, for variant II, 75% of nerves were divided into the medial and lateral branch within the orbit (before crossing the supraorbital margin). Single passage was observed on the supraorbital margin in 80% of wet specimens and in 78% of orbits examined on the macerated skulls. CONCLUSIONS Both the intraorbital and extraorbital course of the branches of the supraorbital and supratrochlear nerves were highly diverse. These variations should be taken into account during medical procedures performed within the orbital and frontal regions.

Anatomical Variations of the Pectoralis Major Muscle: Notes on Their Impact on Pectoral Nerve Innervation Patterns and Discussion on Their Clinical Relevance.

BACKGROUND: The presented study attempts to classify individual anatomical variants of the pectoralis major muscle (PM), including rare and unusual findings. Rare cases of muscular anomalies involving the PM or its tendon have been presented. An attempt has also been made to determine whether anatomical variations of the PM may affect the innervation pattern of the lateral and medial pectoral nerves. MATERIAL AND METHODS: The research was carried out on 40 cadavers of both sexes (22 males, 18 females), owing to which 80 PM specimens were examined. RESULTS: Typical PM structure was observed in 63.75% of specimens. The most frequently observed variation was a separate clavicular portion of the PM. In one female cadaver (2.5% of specimens) the hypotrophy of the clavicular portion of the PM was noticed. In two male cadavers (5% of specimens) the fusion between the clavicular portion of the PM and the deltoid muscle was observed. In one of those cadavers, small sub-branches of the lateral pectoral nerve bilaterally joined the clavicular portion of the deltoid muscle. The detailed intramuscular distribution of certain nerve sub-branches was visualized by Sihler's stain. PM is mainly innervated by the lateral pectoral nerve. In all specimens stained by Sihler's technique, the contribution of the intercostal nerves in PM innervation was confirmed. CONCLUSIONS: Surgeons should be aware of anatomic variations of the PM both in planning and in conducting surgeries of the pectoral region.

Persistent Median Artery as an Unusual Finding in the Carpal Tunnel: Its Contribution to the Blood Supply of the Hand and Clinical Significance.

BACKGROUND Knowledge of the variable relation of the persistent median artery (PMA) to the median nerve and its contribution to the formation of the superficial palmar arch is of great clinical significance. This study presents a proposal of specific variables which might be introduced to characterize the PMA in the wrist region. MATERIAL AND METHODS One hundred and twenty-five randomly selected, isolated upper limbs fixed in 10% formalin solution were subjected to anatomical dissection. RESULTS Of the 125 upper limbs, PMA was found in 5 specimens (4% of the total number of limbs). In the carpal tunnel, the artery occupied the anterolateral position (2 cases), the anterior position (2 cases) or the anteromedial position (1 case) in relation to the median nerve. Two types of superficial palmar arches with significant contributions from the PMA were observed in the studied material: complete medio-ulnar arch and an incomplete arch without a connection between the territories of the ulnar and median arteries. The mean ratio of the diameter of the PMA to the diameter of ulnar artery at the level of the wrist was 0.59 (min.=0.38, max=0.83, SD=0.19). CONCLUSIONS Orthopedic and hand surgeons should be aware of the probability of occurrence of the PMA in both planning and conducting surgeries within the wrist region and within the carpal tunnel, as this anomalous vessel might present significant contributions to the arterial blood supply of the hand and might potentially play an important role in the presence of notable clinical symptoms and presentations.

Hypoplastic superficial brachioradial artery coexisting with atypical formation of the median and musculocutaneous nerves: a rare combination of unusual topographical relationships.

The use of the term "brachioradial artery" was introduced for the high origin of the radial artery. Although the prevalence of the brachioradial artery reported by different authors varies from 4.67 to 15.6%, the presence of the hypoplastic brachial segment of the brachioradial artery is rare with an occurrence rate of 0.83%. Moreover, in just 0.6% of cases the loop of the median nerve may be placed near half of the length of the brachial artery, as in the case described in our report. A comprehensive understanding of anatomical variations of neurovascular structures in the upper limb is of great clinical significance. The presented case report illustrates a rare manifestation of persistent primitive developmental relationships in the arterial pattern of the upper limb (persistent, hypoplastic brachial segment of the superficial brachioradial artery), coexisting with atypical formation of the median and musculocutaneous nerves. Anatomical variations of vessels and nerves may coexist which should be taken into account when performing vascular, reconstructive or orthopedic surgery.