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Background: In recent years, the fasciae of the human body have received significant attention because of their crucial role in the transmission of muscle force. However, studies on the development of the fasciae, particularly the cervical fascia, remain scarce., Purpose: This study was performed to examine the development of the fascia of the infrahyoid strap muscles, also known as the middle layer of the deep cervical fascia (MDCF), in 17 human embryos aged 6-8 weeks and 20 human foetuses aged 9-14 weeks., Methods: Histological examination of serial sections was performed using conventional light microscopy., Results: Three stages in the development of the MDCF were identified: the initial, formation, and maturation stages. In the initial stage (week 6 of development, Carnegie stages 18-19), the mesenchymal primordium of the epimysium of the infrahyoid muscles was observed and found to be continuous with the mesenchymal primordium of the MDCF. The infrahyoid muscles already exhibited intramuscular fibres, the primordium of the perimysium, and the endomysium. In the formation stage (weeks 7-8 of development, Carnegie stages 20-23), fibroblast-like cells and collagen fibres appeared in the primordium of the muscle epimysium and in the MDCF. Intramuscular fibres had become very evident. In the maturation stage (from week 9 of development onward), further development and organisation of the fascial structures occurred., Conclusion: Our results suggest that the MDCF of the neck develops in parallel with the mechanical activity of this region. The relationship between the MDCF and the lymphatic and venous structures of this region suggests that the MDCF may facilitate venous and lymphatic circulation., Competing Interests: Declaration of Competing Interest No potential conflict of interest was reported by the author(s)., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: The objectives of this ultrasound and anatomical study were: (1) To evaluate the reliability of ultrasound identification of the enthesis of the central slip of the extensor digitorum tendon (CSET) using cadaver specimens; (2) To assess the concordance of the measurement of the CSET thickness by ultrasound and gross anatomy; (3) To evaluate the variation in ultrasound identification of the CSET enthesis in a cadaveric experimental model of PIP synovitis., Methods: Four rheumatologist ultrasonographers blindly and independently measured by ultrasound the CSET enthesis thickness in the second to fifth fingers of 8 hands from fresh-frozen human cadavers in two rounds. These fingers were dissected and the thickness of the CSET measured by the anatomist. In addition, an artificial synovitis was created in the proximal interphalangeal (PIP) joints of a different cadaveric hand. The ultrasonographic CSET enthesis thickness was measured by the four investigators before and after intra-articular ultrasound guided injection of material., Results: Intra- and inter-observer reliability of CSET enthesis thickness measurement were good to excellent (ICC 0.93 for intra-observer agreement and 0.89-0.92 for inter-observer agreement). Ultrasound measurements were consistent and only slightly smaller than the anatomical ones (µ = -0.039 mm). The differences between the measurements of CSET enthesis thickness before and after the synovitis model were not statistically significant., Conclusion: Ultrasound demonstrated high multiobserver reliability and agreement with gross anatomy in identifying the CSET enthesis and discriminated it from the capsular tissue of the PIP. Furthermore, an experimental model of PIP synovitis did not interfere with its identification., Competing Interests: Conflict of interest None., (Copyright © 2024 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Purpose: Depending on its axis, pronation varies from the radius rotation around the steady ulna to the reciprocal adduction of the radius and abduction of the ulna. While there is no question that pronator teres is a central pronation agonist, anconeus's role is not settled. The current investigation comparing palpation and ultrasonography in these two muscles during pronation along the axis capitulum-second digit evolved from a serendipitous finding in a clinical anatomy seminar., Methods: Single-hand palpation and two-transducer ultrasonography over anconeus and pronator teres were used on ten normal subjects to investigate their contraction during pronation around the capitulum-second digit axis. These studies were done independently and blind to the results of the other. The statistical analysis between palpation and ultrasonography was performed with Cohen's kappa coefficient and the χ2 test., Results: On palpation, on resisted full pronation, anconeus contracted in 8/10 subjects and pronator teres in 10/10 subjects. Without resistance, the corresponding ratios were 5/10 and 9/10. On two-transducer ultrasonography, the comparable ratios were 7/10 and 10/10, and 3/10 and 10/10. A fair concordance (Cohen's kappa = 0.21) between palpation and ultrasonography in detecting the simultaneous status of anconeus and pronator teres during resisted full pronation. Anatomic dissection illustrated the elements involved., Conclusions: Plain palpation confirmed by ultrasonography showed the simultaneous contraction of anconeus and pronator teres during resisted pronation in most of the studied subjects. The study suggests that palpation can be helpful in directly studying muscle activity during movement., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Introduction: To date, there have been no studies conducted on the development of interosseous muscles (IO) in the human hand. This study aimed to investigate the development of these muscles in order to clarify their terminal insertions and their relationship with the metacarpophalangeal joints., Methods: Serial sections of 25 human specimens (9 embryos and 16 fetuses) between the 7th and 14th weeks of development, sourced from the Collection of the Department of Anatomy and Embryology at UCM Faculty of Medicine, were analyzed bilaterally using a conventional optical microscope., Results: Our findings revealed that, during the 7th week of development, the metacarpophalangeal interzone mesenchyme extended into the extensor apparatus of the fingers. Furthermore, we observed that the joint capsule and the tendon of the IO derive from the articular interzone mesenchyme. By the end of the 7th week, corresponding to Carnegie stage 21, the myotendinous junction appeared, initiating cavitation of the metacarpophalangeal joint. During the fetal period, the terminal insertions of the IO were identified: both the dorsal interosseous (DI) and palmar interosseous (PI) muscles insert into the metacarpophalangeal joint capsule and establish a connection with the volar plate located at the base of the proximal phalanx and the extensor apparatus. Some muscle fibers also attach to the joint capsule at the level of the proximal synovial cul-de-sac. The functional implications of these findings are discussed within this work., Conclusion: This study provides the first detailed description of the development of the interosseous muscles in the human hand., (© 2024 S. Karger AG, Basel.)

Background: Forearm intersection syndrome causes pain, swelling, and a rub at the dorsal distal forearm where the first extensor compartment muscles intersect with the second compartment tendons. Although primary care settings tend to treat mild cases, high-performance athletes may suffer from severe symptoms that require surgery. This proof-of-concept study aims to help detect the anatomical substrate of forearm intersection syndrome using palpation and ultrasonography when available., Methods: Five individuals were studied using independent palpation and ultrasonography to identify the first dorsal compartment muscles and the second dorsal compartment tendons. The distances between the dorsal (Lister's) tubercle of the radius and the ulnar and radial edges of the first dorsal compartment muscles were measured to determine the location and extent of the muscle-tendon intersection. The palpatory and ultrasonographic measurements were compared using descriptive statistics and the paired t -test., Results: The mean distances from the dorsal tubercle of the radius to the ulnar and radial borders of the first dorsal compartment muscles were 4.0 cm (SE 0.42) and 7.7 cm (SE 0.56), respectively, based on palpation. By ultrasonography, the corresponding distances were 3.5 cm (SD 1.05, SE 0.47) and 7.0 cm (SD 1.41, SE 0.63). Both methods showed a similar overlap length. However, ultrasonography revealed a shorter distance between the dorsal tubercle of the radius and the ulnar border of the first compartment than palpation ( p = 0.0249)., Conclusions: Our findings indicate that a basic knowledge of anatomy should help health professionals diagnose forearm intersection syndrome through palpation and, if available, ultrasonography.

Background: Palpation, a traditional haptic ability, is used daily by practitioners of all medical and surgical specialties to assess patients. In the current study, one of the authors, in a routine clinical setting, was able to deduce the dynamic features of the putative inferior belly of omohyoid. This led to a proof-of-concept study that yielded results consistent with the clinical findings., Methods: The first part of the study involved a survey of 300 rheumatic disease patients in whom the greater supraclavicular fossa was explored by palpation. While the patient kept the head straight, the clinician placed his middle three fingers 2.5-3 cm dorsal to the clavicle in the window between the sternocleidomastoid and trapezius clavicular insertions, explored the supraclavicular fossa, and palpated the paired contractile inferior belly of the assumed omohyoid during flexion in the three orthogonal planes. In the second part of the study, five normal subjects were examined in a similar manner by the same clinician and had independent ultrasonography performed on the dominant side. Descriptive statistics were used, and Yates' corrected chi-squared test was applied to certain nominal variables. Additionally, a comparative anterolateral bilateral neck dissection was performed in a cadaveric specimen., Results: Both studies showed that the contractile structure was the inferior belly of omohyoid and that its contraction occurred during anterior neck flexion and was opposite to the side of neck rotation, resembling the sternocleidomastoid., Conclusions: Palpation uncovered a previously unknown function of the inferior belly of omohyoid, suggesting that physical examination of the musculoskeletal system based on palpation may lead to hypotheses worthy of exploration.

Aim: Tenosynovitis is one of the most frequently described inflammatory lesions in psoriatic dactylitis. The aim of the study was to assess by ultrasound the distribution of content within the synovial sheath of the finger flexor tendons in a cadaveric experimental model of tenosynovitis and to describe anatomically the elements of the space between the flexor tendons and the palmar aspect of the proximal phalanx of the fingers., Material and Method: Silicone was injected under ultrasound guidance into the digital flexor sheath of the index finger of a hand specimen. Ultrasound images of the distribution of the filling of the flexor synovial space with the injected material were obtained. These images were compared with images from patients with psoriatic dactylitis. The palmar regions of the hand and fingers were dissected to check the distribution of the injected silicone in the synovial cavity. Additionally, we dissected the 2nd to 5th fingers of five cadaveric hands, including the one used for the experiment., Results: During the injection of the substance, we observed an increasing homogeneous hypoechoic band around the flexor tendons that differed from the images of patients. Dissection of the specimen showed the injected silicone distributed throughout the digital flexor sheath to the distal interphalangeal joint. In addition, we provided an illustrated anatomical description of the elements located between the flexor tendons and the palmar aspect of the proximal phalanx, the inflammation of which could simulate flexor tenosynovitis., Conclusion: The observations of this study may contribute to a better understanding of the anatomical structures involved in PsA dactylitis.

Background: The buccinator muscle derives from the mesenchyme of the second pharyngeal arch. In adults, it has a quadrilateral shape, occupying the deepest part of the cheek region. Its function is complex, being active during swallowing, chewing, and sucking. To our knowledge, there are no studies that have specifically analyzed the relationship of the buccinator muscle fibers and neighboring connective tissue of the cheek in humans, neither during development nor in adults. Such relationships are fundamental to understand its function. Thus, in this study the relations of the buccinator muscle with associated connective tissue were investigated., Methods: The buccinator muscle region was investigated bilaterally in 41 human specimens of 8-17 weeks of development. Moreover, four complete adult tissue blocks from human cadavers (including mucosa and skin) were obtained from the cheek region (between the anterior border of the masseter muscle and the nasolabial fold). All samples were processed with standard histological techniques. In addition, subsets of sections were stained with picrosirius red (PSR). Furthermore, immunoreactivity against type I and III collagen was also studied in adult tissues., Results: The buccinator muscle showed direct relationships with its connective tissue from 8 to 17 weeks of development. Collagen fibers were arranged in septa from the submucosa to the skin through the muscle. These septa were positive for type I collagen and presented elastic fibers. Fibrous septa that were positive for type III collagen were arranged from the lateral side of the muscle to the skin., Conclusions: The intimate relationship between buccinator muscle fibers and cheek connective tissue may explain the complex functions of this muscle., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

This study aimed to determine by ultrasonography, and cadaveric dissection, whether the firm cords felt by palpation at the sides of the proximal phalanx (PP), actively flexing, and extending the proximal interphalangeal (PIP) joint while keeping the metacarpophalangeal (MCP) joint extended are the lateral bands (LBs) of the extensor apparatus. If so, palpation of the LBs could help evaluate hand conditions that impact the digits' intrinsic muscles. To this end, the PP of the middle and ring fingers of the dominant hand of seven subjects were studied by palpation on both sides. Ultrasonography (US) was performed with a hockey-stick transducer placed on the ulnar side. Five cadaveric hands were dissected, exposing the dorsal extensor apparatus. On palpation, a firm cord was consistently felt at the PP's sides in all subjects. These cords moved widely forward on PIP flexion and backward with PIP extension. By US scanning, the cords corresponded to the LBs. However, the forward movement had only a median of 1.8 mm (range 0.7-3 mm) in the middle finger and a median of 1.1 mm (range 0.3-2.7 mm) in the ring finger compared with an estimated 5-10 mm upon palpation. Cadaveric dissection confirmed the forward movement of the LBs in PIP flexion. We concluded that the firm cords felt at the PP sides are the LBs of the extensor apparatus. We confirmed their movement with the active flexion/extension of the PIP joint. Comparing the wide palpatory and the meager US motion, a haptic illusion of motion may be present., (© 2021 Anatomical Society.)

Pillar pain represents one of the most common complications of classic open carpal tunnel release (CTR). This complication causes a sense of discomfort worse than the compression syndrome itself. We, herein, introduce a new treatment method for CTR through a mini-incision, which allows subcutaneously cutting the transverse carpal ligament (TCL) and releasing the median nerve without neurovascular complications. This mini-incision approach can allow the direct visualization and preservation of the thenar motor branch in those rare cases where it has an aberrant origin. For the past 10 years, we have consecutively performed this technique in the surgical treatment of 318 patients with the diagnosis of primary CTS, without developing any neurovascular and tendon injuries as well as pillar pain.

Background: The Chievitz's organ or juxta-oral organ is a mysterious bilateral structure, phylogenetically preserved, which develops from the mouth epithelium as an invagination that loses connection to it in the prenatal period. It is located laterally to the walls of the oral cavity in an imprecise anatomical location and receives abundant innervation from the buccal nerve. Structurally it consists of non-keratinizing squamous-like neuroepithelial cells surrounded by two layers of connective tissue with nerve fibers and different morphotypes of sensory corpuscles. Its function is completely unknown although based on its rich innervation it is assumed that works as a mechanoreceptor., Methods: We have performed immunohistochemistry for axonal and Schwann cells, and the putative mechanoproteins ASIC2, TRPV4 and Piezo2 in sections of fetal juxta-oral organ., Results: Intraparenchymatous nerve fibers and sensory corpuscles were observed as well as immunoreactivity for Piezo2 in both nerve fibers and epithelial parenchymatous cells., Conclusions: We add indirect evidence that the juxtaoral organ is a mechanoreceptor because in addition to its dense innervation, the epithelial cells and sensory nerve fibers display immunoreactivity for the mechanogated ion channel Piezo2. Based on current knowledge, the functional and clinical importance of the juxta-oral organ should be further investigated., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Background: A knowledge of the anthropometric characteristics of the coracoid graft (CG) that can be obtained by the open and arthroscopic Latarjet techniques may be beneficial in the preoperative planning and intraoperative decision making for coracoid osteotomy and transfer. We have not found any study that compared the morphology of the CG that can be obtained from open and arthroscopic Latarjet techniques. The purpose of this study was to verify if the basic anthropometric characteristics of CGs are equivalent., Hypothesis: We hypothesize that the basic anthropometric characteristics of the CGs are similar., Methods: Twenty fresh-frozen human paired cadaveric shoulder specimens that had been randomly distributed in two groups of 10 specimens each were used. Two surgeons, each with experience in performing the open and arthroscopic Latarjet technique, performed these procedures in each of the respective groups (OG, open group; AG, arthroscopic group). A CT scan was performed. Using the volume rendering technique, a metric analysis of the volume, area and length of the CG were performed, evaluated and statistically analysed., Results: There were no significant differences in length (p=0.162) (mean length, 22.6mm for OG and 23.6mm for AG). There were significant differences in the volume (p=0.031) and area (p=0.007) of the CG, being lower in the OG (mean volume, 2.8 cm 3 for OG and 3.6 cm 3 for AG; mean area, 9.9 cm 2 for OG and 12.8 cm 2 for AG). No significant differences were observed by sex or laterality., Conclusion: The mean lengths of the CGs that were obtained by each technique are equivalent. However, the areas and volumes of the grafts are different, being lower in the open surgery. These differences have not been an impediment to perform the technique. Our results corroborates that consolidation is more related to the preparation and placement than to the anthropometric characteristics of the CG. No significant differences were observed by sex or laterality., Level of Evidence: Basic Science., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Background: Since the description of the arthroscopic Latarjet technique, discussion about the superiority of the open or arthroscopic procedure has arisen. The appropriate placement of the coracoid graft (CG) on the anterior glenoid neck is reported to be the most important step of the Latarjet procedure., Purpose: To verify if there are differences in the parameters that may affect the final position and fixation of CG obtained from the open and arthroscopic Latarjet techniques., Study Design: Controlled laboratory study., Methods: Twenty fresh-frozen human paired cadaveric shoulder specimens were randomly distributed in 2 surgery groups (open group [OG] and arthroscopic group [AG]) with 10 specimens in each. Two surgeons, each with experience performing open and arthroscopic Latarjet techniques, executed these procedures: one surgeon performed all open techniques, and the other performed all arthroscopic techniques, respectively. After surgery, a computerized tomography scan was performed. The surgical time, the position of each CG, a series of variables that might affect the CG fixation, and the level of the subscapularis muscle split were evaluated., Results: The mean surgical time was significantly longer in the AG (mean, 26 minutes for OG and 57 minutes for AG). Three intraoperative complications (30%) were identified in the AG, consisting of graft fractures. The CG was determined to be in an optimal cranial-caudal position in 90% of specimens of the OG and 44% of the AG (Fisher, P = .057). In both groups, the CG was placed in an optimal medial-lateral position in all specimens. In the OG, the degree of parallelism between the major axes of the glenoid surface and CG was significantly greater than in the AG (mean, 3.8º for OG and 15.1º for AG). No significant differences were observed in superior and inferior screw orientation between the groups. In the longitudinal and transverse directions, significant differences were found in the centering of the superior screw, being closer to the ideal point in the OG than in the AG. The location where the longitudinal subscapularis muscle split was performed was significantly higher in the AG., Conclusion: The open Latarjet technique required less surgical time; presented a lower number of intraoperative complications; and allowed more adequate placement of the CG, better centering of the screws, and a subscapularis muscle split closer to the ideal position., Clinical Relevance: The reported benefits of the arthroscopic Latarjet technique seem less clear if we take into account the added surgery time and complications.

In recent years, there has been much discussion concerning the cervical fasciae. The aim of this study is to confirm and to describe the development of the alar fascia as well as its relationship with nearby structures. Histological preparations of 25 human embryos (6-8 weeks of development) and 25 human fetuses (9-12 weeks of development) were studied bilaterally using a conventional optical microscope. Our study confirms the existence of the alar fascia and permits three stages to be established during its development. The initial stage (1st), corresponding to the 6th week of development (Carnegie stages 18-19), is characterized by the beginning of the alar fascia primordium in the retroesophageal space at the level of C7-T1. In the formation stage (2nd), corresponding to the 7th and 8th weeks of development (Carnegie stages 20-23), the alar fascia primordium grows upwards and reaches the level of C2-C3. In the maturation stage (3rd), beginning in the 9th week of development, the visceral, alar and prevertebral fasciae can be identified. The alar fascia divides the retrovisceral space (retropharyngeal and retroesophageal) into two spaces: one anterior (between the alar fascia and the visceral fascia and extending from C1 to T1, named retropharyngeal or retroesophageal space according to the level) and the other posterior (between the alar fascia and the prevertebral fascia, named danger space). We suggest that this latter space be named the retroalar space. This study suggests that alar fascia development is related to mechanical factors and that the alar fascia permits the sliding of the pharynx and the oesophagus during swallowing., (© 2019 Anatomical Society.)

Interosseous tendon inflammation (ITI) has been described in rheumatoid arthritis (RA). Whether ITI occurs in at-risk individuals before the onset of clinical synovitis is unknown., Objectives: To investigate, by MRI, ITI in anti-cyclic citrullinated peptide (CCP)-positive at-risk individuals (CCP +at risk) and to describe the anatomy, prevalence and clinical associations across the RA continuum., Methods: Hand MRI was performed in 93 CCP + at risk, 47 early RA (ERA), 28 established 'late' RA (LRA) and 20 healthy controls (HC) and scored for ITI, flexor tenosynovitis (TSV) and RA MRI scoring at the metacarpophalangeal joints (MCPJs). Cadaveric and histological studies were performed to explore the anatomical basis for MRI ITI., Results: The proportion of subjects with ITI and the number of inflamed interosseous tendons (ITs) increased along the disease continuum (p<0.001): 19% of CCP +at risk, 49% of ERA and 57% of LRA had ≥1 IT inflamed . ITI was not found in any HC. ITI was more frequently identified in tender MCPJs compared with nontender MCPJs (28% vs 12%, respectively). No IT tenosynovial sheath was identified in cadavers on dissection or histological studies suggesting MRI findings represent peritendonitis. Dye studies indicated no communication between the IT and the joint., Conclusions: ITI occurs in CCP + at-risk individuals and can precede the onset of clinical synovitis. The ITs may be important nonsynovial extracapsular targets in the development and progression of RA., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

The aim of this study was to determine the main stages of submandibular salivary gland development during the embryonic period in humans. In addition, we studied submandibular salivary gland development in rats on embryonic days 14-16 and expression in the submandibular salivary gland region with the monoclonal antibody HNK-1. Serial sections from 25 human embryos with a greatest length ranging from 10 to 31 mm (Carnegie stages 16-23; weeks 5.5-8 of development) and Wistar rats of embryonic days (E) 14-16 were analysed with light microscopy. Five stages of submandibular salivary gland development were identified. The prospective stage (1), between weeks 5.5 and early week 6, is characterized by a thickening of the epithelium of the medial paralingual groove in the floor of the mouth corresponding to the primordium of the submandibular salivary gland parenchyma. At this stage, the primordium of the parasympathetic ganglion lies below the lingual nerve. The primordium of the submandibular salivary gland parenchyma is observed in rats on E14 in the medial paralingual groove with mesenchymal cells, underlying the lingual nerve. These cells are HNK-1-positive, corresponding to the primordium of the parasympathetic ganglion. The bud stage (2), at the end of week 6 in humans and on E15 in rats, is characterized by the proliferation and invagination of the epithelial condensation, surrounded by an important condensation of the mesenchyme. The pseudoglandular stage (3) at week 6.5 is characterized by the beginning of the formation of lobes in the condensed mesenchyme. The canalicular stage (4), between week 7 and 7.5, is characterized by the appearance of a lumen in the proximal part of the submandibular duct. The innervation stage (5) occurs during week 8, with the innervation of the submandibular and interlobular ducts. Nervous branches arriving from the parasympathetic ganglion innervate the glandular parenchyma. Numerous blood vessels are observed nearby. Our results suggest that submandibular salivary gland development requires interactions among epithelium, mesenchyme, parasympathetic ganglion and blood vessels., (© 2019 Anatomical Society.)

The anatomical variations of the proximal portion of the long head of the biceps brachii tendon (LHBT) are rarely observed in clinical practice. However, an increase in the rate of shoulder arthroscopic surgery has led to an increase in the observation of anatomical variations of this region. The aim of this work was to analyze the development of the LHBT in 23 human embryos ranging from the 6th to 8th weeks of development. The LHBT develops from the glenohumeral interzonal mesenchyme in the 6th week. By week 7, the myotendinous junction of the LHBT develops. The anlage of the LHBT is separated from that of the glenohumeral capsule during week 8. Our results suggest that the most important period for the LHBT development occurs between the 6th and 8th weeks of embryonic development. Alterations during this critical period may cause anatomical variations of the LHBT. An additional case report from our own experience is provided as Supplementary material., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

The goal of this study is to clarify the development of the long head of the biceps brachii tendon (LHBT) and to verify the existence and development of the coracoglenoid ligament. Histological preparations of 22 human embryos (7-8 weeks of development) and 43 human fetuses (9-12 weeks of development) were studied bilaterally using a conventional optical microscope. The articular interzone gives rise to the LHBT, glenoid labrum, and articular capsule. During the fetal period, it was observed that in 50 cases (58%), the LHBT originated from both the glenoid labrum and the scapula, while in 36 cases (42%), it originated only from the glenoid labrum. The coracoglenoid ligament, first described by Sappey in 1867, is a constant structure that originates at the base of the coracoid process and projects toward the glenoid labrum zone, which is related to the origin of the LHBT. The coracoglenoid ligament was more easily identifiable in the 36 cases in which the LHBT originated only from the glenoid labrum. We suggest that the coracoglenoid ligament is a constant anatomical structure, is not derived from the articular interzone unlike the LHBT, and contributes to the fixation of the glenoid labrum in the scapula in cases in which the LHBT originated only from the glenoid labrum. We postulate that, when the LHBT is fixed only at the glenoid labrum, alterations in the coracoglenoid ligament could lead to a less sufficient attachment of the glenoid labrum to the scapula which could predispose to a superior labral lesion., (© 2017 S. Karger AG, Basel.)

The development of the synovial membrane was analyzed in serial sections of 21 temporomandibular joints of human fetuses at 9 to 13 weeks of gestation. Sections of two fetuses at 12 weeks of development were used to perform immunohistochemical expression of the markers CD68 and Hsp27 on the synovial lining. Macrophage-like type A and fibroblast-like type B cells, which express CD68 and Hsp27, respectively, were observed at the twelfth week of development. Our results suggest that the development of the synovial membrane is related to the vascularization of the joint and the formation of the articular cavities.

Objective. To characterize morphologically and ultrastructurally using light microscopy, the scanning electron microscopy and transmission electron microscopy the intima synovial of the temporomandibular joint (TMJ) of human fetuses between the 10th and the 38th week of development. Materials and Methods. The TMJ was dissected bilaterally in 37 human fetuses belonging to the Institute of Embryology of the University Complutense of Madrid and of the Federal University of São Paulo. Results. The outcome by light microscopy showed the morphology of the TMJ and that the formation of inferior joint cavity precedes the superior joint cavity and the presence of blood vessels in the synovial. Conclusion. By scanning and transmission electron microscopy we observed the presence of two well-defined cell types in the intima layer of synovial of the TMJ of human fetuses, macrophage-like type A cell and fibroblast-like type B cell, and the presence of the a third cell type, defined by the name of intermediate lining cell in the intima layer of the synovial.

There is controversy regarding the description of the different regions of the face of the superficial musculoaponeurotic system (SMAS) and its relationship with the superficial mimetic muscles. The purpose of this study is to analyze the development of the platysma muscle and the SMAS in human specimens at 8-17 weeks of development using an optical microscope. Furthermore, we propose to study the relationship of the anlage of the SMAS and the neighbouring superficial mimetic muscles. The facial musculature derives from the mesenchyme of the second arch and migrates towards the different regions of the face while forming premuscular laminae. During the 8th week of development, the cervical, infraorbital, mandibular, and temporal laminae are observed to be on the same plane. The platysma muscle derives from the cervical lamina and its mandibular extension enclosing the lower part of the parotid region and the cheek, while the SMAS derives from the upper region. During the period of development analyzed in this study, we have observed no continuity between the anlage of the SMAS and that of the superficial layer of the temporal fascia and the zygomaticus major muscle. Nor have we observed any structure similar to the SMAS in the labial region.

This study seeks to determine the main events that occur in the development of the ciliary body (CB) in the 5-14th week of development. The CB develops from the distal portion of the optic cup (OC) and the neighboring mesenchyme. During the 5th week of development, 4 zones were observed in the distal portion of the OC: in zone 1, the epithelia of the outer and inner layers of the OC came into contact. This contact coincided with the appearance of mainly apical granule pigments. This zone corresponded to the anlage of the epithelial layers of the CB. In zone 2, the cells surrounded the marginal sinus and contained scarce pigment granules and nuclei in the basal position. This zone corresponded to the anlage of the iris. Zone 3 was triangular in shape and its vertex ran towards the marginal sinus and corresponded to common cell progenitors. Zone 4 corresponded to the retinal pigment epithelium anlage and the neural retina anlage. We determined the onset of the stroma and the ciliary muscle anlage at the end of the 7th week. In the 13-14th week, we observed the anlage of the orbicularis ciliaris (pars plana of the CB) and corona ciliaris (pars plicata of the CB), in addition to the anlage of the ciliary muscle. Our study, therefore, establishes a precise timetable of the development of the CB., (© 2013 S. Karger AG, Basel.)

The present study seeks to determine the main events that occur in the development of the tensor veli palatini (TVP). A light microscope was used on serial sections of 60 human specimens from weeks 6 to 16 of development. The TVP becomes visible in an embryo of 14.5 mm greatest length (GL; week 6) from a common blastema with the medial pterygoid muscle. In embryos of Carnegie stage 20 (week 7), the TVP is differentiated and relates to the anlage of the pterygoid hamulus. At week 8 of development, when the palatal shelves become horizontal, the presence of the anlage of the palatine aponeurosisis distinguished and is reached by the TPV. In an embryo of 30 mm GL, the chondrification nucleus of the pterygoid hamulus and the synovial bursa of the TVP are identifiable. At week 9, the TVP is continuous with the palatine aponeurosis. At week 13, a connective tissue lamina appears between the TVP and the intramembranous ossification center for the anterior process of the malleus, which we know as the goniale and interpret as an attachment of the muscle to the primary vertebrate jaw or incudomalleal joint. The TVP from its origin, innervation and relation to the goniale appears to be a muscle of mastication that, at the end of the embryonic period, reaches the palatine aponeurosis anlage and the mesenchyme of the auditory tube and specializes in the movements of the soft palate and the auditory tube., (Copyright © 2011 S. Karger AG, Basel.)

This study was carried out on histological aspects of the extratympanic portion of the discomallear ligament (DL) in adult humans. The temporomandibular joint (TMJ) was dissected bilaterally in 20 cadavers; in 15 cases the articular disc (AD) and the retroarticular tissue were extirpated. The extratympanic portion of the DL had the shape of a base-down triangle, in relation to the AD, and an upper vertex, in relation to the petrotympanic fissure. In five cases, the base, measured bilaterally, had an average length of 6.4 mm, while the distance from the base to the upper vertex averaged 9.3 mm in length. The extratypanic portion of the DL is an intrinsic ligament of the TMJ, composed of collagen fibres and abundant elastic fibres. We propose that this ligament could act as a tensor of the synovial membrane in movements of the TMJ., (© 2011 The Authors. Journal of Anatomy © 2011 Anatomical Society of Great Britain and Ireland.)

The supracochlear cartilage is known as an accessory cartilage of the chondrocranium situated between the otic capsule and the trigeminal ganglion. Although claimed to appear regularly during human development, its incidence and development have been reported only scarcely in the literature. The aim of this study was to describe the position and relationships of the supracochlear cartilage during its development. This study was made in 96 human specimens of 7-17 weeks of development, belonging to a collection of the Embryology Institute of Complutense University of Madrid. In addition, three-dimensional reconstruction of the supracochlear cartilage was made from 1 specimen. This cartilage, spherical in shape, appeared bilaterally in 23 specimens and unilaterally (left side) in 5. In our results, the supracochlear cartilage was found in 26.5% of the cases and was related to the trigeminal ganglion, the dura mater of the trigeminal cavity and the otic capsule. In 4 specimens, bilaterally, the supracochlear cartilage was continuous with the otic capsule. This work suggests that, based on the structures to which the supracochlear cartilage is related, it could be derived from the cranial neural crest., (Copyright © 2010 S. Karger AG, Basel.)

The objective was to study the morphology of the articular disc and analyse the immunohistochemical expression of types I and III collagen markers in the temporomandibular joint (TMJ) disc of human foetuses of different gestational ages. Twenty TMJ from human foetuses supplied by Universidade Federal de Uberaba with gestational ages from 17 to 24 weeks were studied. The gestational age of the foetuses was determined by measuring the crown-rump (CR) length. Macroscopically, the foetuses were fixed in 10% formalin solution and dissected by removing the skin and subcutaneous tissue and exposing the deep structures. Immunohistochemical markers of type I and III were used to characterize the existence of collagen fibres. Analysis of the immunohistochemical markers of types I and III collagen revealed the presence of heterotypical fibril networks.

The objective was to analyze the development of the stapedius muscle to understand an isolated unilateral absence of the tendon of the stapedius muscle in a human fetus. The study was made on 50 human embryos and fetuses aged 38 days to 17 weeks post-conception. The stapedius muscle was formed by two anlagen, one for the tendon, which derives from the internal segment of the interhyale and another for the belly, located in the second pharyngeal arch, medially to the facial nerve and near the interhyale. In the interhyale, two segments were observed forming an angle and delimited by the attachment of the belly of the stapedius muscle. The internal segment will form the tendon. The lateral segment of the interhyale was attached to the cranial end of the Reichert's cartilage (laterohyale), and normally it disappears at the beginning of the fetal period. The right unilateral agenesia of the tendon of the stapedius muscle, observed for the first time in a human fetus of 14 weeks post-conception development (PCd), was brought about by the lack of formation or the regression of the internal segment of the interhyale. It presented a belly of the stapedius muscle with an anomalous arrangement, and with a pseudo tendon originated by the persistence of the external segment of the interhyale., ((c) 2009 Wiley-Liss, Inc.)

This article presents two cases of anastomosis of hypoglossal nerves in the suprahyoid region in human embryos of CR length 10.75 and 17.5 mm. This variation was studied in two human specimens at this stage of development and compared with the normal arrangement of the hypoglossal nerves in embryos at the same stage. The anastomotic branches were of similar caliber to the main trunks. In both cases the anastomosis was located dorsal to the origin of the geniohyoid muscles and caudal to the genioglossus muscles, lying transversally over the cranial face of the body of the hyoid bone anlage. The anastomosis formed a suprahyoid nerve chiasm on the midline in the embryo of 10.75 mm CR length.

An unusual muscular variation, the cleidoatlanticus muscle, was observed on the right-hand side of the lateral cervical region. The upper third of the muscle was concealed by the sternocleidomastoid muscle. There was a loop of nerves surrounding the muscle, formed by an anastomosis between the transverse cervical nerve and the greater auricular nerve. A fine vascular-nervous pedicle (formed by a small branch from the transverse cervical artery and by a branch from the medial supraclavicular nerve) entered the deep surface of the muscle at the junction of its middle and lower thirds. Taking into account the relationships that presented with the superficial branches of the cervical plexus, we consider that the cleidoatlanticus muscle is derived from the sternocleidomastoid muscle.

This study analyses some morphological and histological aspects that could have a role in the development of the condylar cartilage (CC). The specimens used were serial sections from 49 human fetuses aged 10-15 weeks. In addition, 3D reconstructions of the mandibular ramus and the CC were made from four specimens. During weeks 10-11 of development, the vascular canals (VC) appear in the CC and the intramembranous ossification process begins. At the same time, in the medial region of the CC, chondroclasts appear adjacent to the vascular invasion and to the cartilage destruction. During weeks 12-13 of development, the deepest portion of the posterolateral vascular canal is completely surrounded by the hypertrophic chondrocytes. The latter emerge with an irregular layout. During week 15 of development, the endochondral ossification of the CC begins. Our results suggest that the situation of the chondroclasts, the posterolateral vascular canal and the irregular arrangement of the hypertrophic chondrocytes may play a notable role in the development of the CC.

The temporomandibular joint (TMJ) is a complex joint due its development and filogeny. This complexity explains the lack of descriptions of the posterior joint capsule. Nowadays it is necessary to establish the limits of this joint part owing to a correct arthroscopic access. Dissecting human cadavers it will determine this joint segment and describe its anatomic relations.

Purpose: The aim of this work was to clarify the arrangement of the posterior segment of the temporomandibular joint capsule and its pertinent relationships., Materials and Methods: The temporomandibular region was dissected bilaterally in 20 adult cadavers. Natural stained latex was injected into 16 cadavers through the external carotid artery to facilitate the dissection of the arterial vessels., Results: The posterior segment of the joint capsule is made up of the so-called "bilaminar zone" of the articular disc. The upper internal portion of the posterior segment of the capsule was reinforced by the discomalleolar ligament. The retroarticular space was filled with loose connective tissue and the anterior branches of the anterior tympanic artery were distributed throughout the posterior segment of the joint capsule., Conclusion: The posterior segment of the temporomandibular joint capsule corresponds to the bilaminar zone of the articular disc. The structures of the retroarticular space are extracapsular.

The aim of this study was to determine the principal developmental stages in the formation of the excretory lacrimal system in humans and to establish its morphogenetic period. The study was performed using light microscopy on serial sections of 51 human specimens: 33 embryos and 18 fetuses ranging from 8 to 137 mm crown-rump length (CR; 5-16 weeks of development). Three stages were identified in the morphogenesis of the excretory lacrimal system: (1) the formative stage of the lacrimal lamina (Carnegie stages 16-18); (2) the formative stage of the lacrimal cord (Carnegie stages 19-23); and (3) the maturative stage of the excretory lacrimal system, from the 9th week of development onward. A three-dimensional reconstruction of the excretory lacrimal system was performed from serial sections of an embryo at the end of the embryonic period (27 mm CR).

The origin of the styloglossus muscle was histologically studied bilaterally in nine human fetuses (18 sides). In all cases, the muscle originated in Reichert's cartilage, which gives rise to the temporal styloid process. We identified three types of variation: type A, an accessory muscle fascicle originating from the mandibular angle, found in 7 cases (12 sides); type B, where the styloglossus muscle was attached to the mandibular angle by fibrous tracts, found in three cases (4 sides); and type C, where an accessory muscle fascicle arose from the fibrous tract connecting Reichert's cartilage to the mandibular angle; found in one case. In all cases (2 sides), the styloglossus muscle was innervated by the hypoglossal nerve. Relationships between the styloglossus muscle and vasculonervous elements of the prestyloid and retrostyloid spaces were analysed.

This study was performed on 50 human embryos and fetuses between 7 and 17 weeks of development. Reichert's cartilage is formed in the second pharyngeal arch in two segments. The longer cranial or styloid segment is continuous with the otic capsule; its inferior end is angulated and is situated very close to the oropharynx. The smaller caudal segment is in contact with the body and greater horn of the hyoid cartilaginous structure. No cartilage forms between these segments. The persistent angulation of the inferior end of the cranial or styloid segment of Reichert's cartilage and its important neurovascular relationships may help explain the symptomatology of Eagle's syndrome.

The immunocytochemical development of the thoracolumbar sympathetic ganglion and its adrenal counterpart was studied in the chick from days 3.5 to 12 of incubation, using antibodies to 17 separate antigens, including antibodies to pan-neuroendocrine markers, catecholamine-synthesizing and proprotein-processing enzymes, and neuropeptides. Some of the antigens studied (Go protein-alpha subunit, thyrosine hydroxylase, and galanin) were strongly expressed from the first days of development, whereas others (chromogranin-A, chromogranin-B, 7B2 protein, and somatostatin) showed a diverse immunoreactive expression at different stages. Three different patterns were found in the development of both adrenal medulla and thoracolumbar sympathetic ganglion. In the first (chromogranin-A and B, Go protein-alpha subunit, tyrosine hydroxylase, HNK-1, and galanin), virtually all medullary and thoracolumbar sympathetic ganglion cells were strongly immunostained from day 4 onward. Except for HNK-1, chromogranin-A and B, there was a steady increase in immunoreactive cells for all the remaining antigens up to day 12. In the second (7B2 protein, proprotein convertase 2, and secretogranin II), full antigenic expression was reached in medullary and thoracolumbar sympathetic ganglion cells by day 10. In the third pattern (proprotein convertase 3, somatostatin, dopamine-beta-hydroxylase, neuron-specific enolase, vasoactive intestinal polypeptide, and met-enkephalin), differences in immunoreactivity were observed between the medullary and thoracolumbar sympathetic ganglion cells.

The juxtaoral organ was studied using light microscopy in 55 human embryos and 90 fetuses at different stages of development. The juxtaoral organ arises from the epithelium at the bottom of the transverse opening of the primitive mouth during O'Rahilly stage 16 and becomes detached from the epithelium after O'Rahilly stage 18. The juxtaoral organ is innervated by the buccal nerve from O'Rahilly stage 20 onward, and its connective tissue capsule is clearly visible after week 11 of development. This study enabled us to describe three main periods of juxtaoral organ development: (1) the period of epithelial condensation and invagination, at O'Rahilly stages 16-17; (2) the period during which the juxtaoral organ becomes detached from the oral epithelium and is innervated, at O'Rahilly stages 18-23; and (3) the period during which the connective tissue capsule is formed, after week 11 of development. We also analysed the juxtaoral organ of five additional fetuses by immunohistochemistry with anti-NF-200 to verify their innervation. The results show that the juxtaoral organ may have a function in the mechanical activity of the region.

During routine bilateral dissection of 64 upper limbs in 32 adult human cadavers, four cases of an axillary arch, a muscular anomaly, were found. In one case, the axillary arch presented on both sides and in two cases it presented unilaterally on the right side. The innervation and relationships of the axillary arches are reported and the surgical significance of the anomaly is discussed., (Copyright 2003 Wiley-Liss, Inc.)

The aim of this study was to determine the main stages of the lacrimal gland's developmental process in humans and to establish its precise morphogenetic timetable. Its onset is generally assumed to take place at O'Rahilly's stage 21, arising from an epithelial thickening of the superior extreme of the temporary conjunctival fornix. However, the present study points to a prior stage in the process: the presence of epithelial-mesenchymal changes in embryos at O'Rahilly's stage 19. The study was performed using light microscopy on serial sections of 37 human specimens: 23 embryos and 14 fetuses ranging from 15 to 137 mm crown-rump length (7-116 weeks of development). Three stages in lacrimal gland morphogenesis were identified: (1) the presumptive glandular stage, O'Rahilly's stages 19-20, characterized by a thickening of the superior fornix epithelium together with surrounding mesenchymal condensation; (2) the bud stage, generally assumed to be the first manifestation of glandular origin, characterized initially by the appearance of nodular formations in the region of the superior conjunctival fornix and concluding with the appearance of lumina within the epithelial buds; and (3) the glandular maturity stage, weeks 9-16, the period in which the gland begins to take on the morphology of adulthood.

The vascular or cartilage canals of the mandibular condyle were studied in human fetuses, whose ages extended from the 9th to the 13th week of development. The vascular canals are firstly constituted by an invagination of mesenchimal cells which is in connection with the mesenchimal layer of the condyle envelope. During the 11th week of development a vessel penetrates in the invaginations. In the 12th and 13th weeks, the canals show a clearly defined pattern: some of them are located in the anterointernal region of the condyle, being those associated with the insertion of the lateral pterygoid muscle; two or three can be seen in the posterointernal region, whereas only one vascular canal, but th-e biggest one, is located in the posteroexternal region. This well defined disposition is related with the direction of the condylar growth during this period of the development.

The aim of this study was to describe the course of the buccal nerve and its relationships with the temporalis muscle during the prenatal period. Serial sections of 90 human fetal specimens ranging from 9 to 17 wk development were studied by light microscopy. Each fetal specimen was studied on both right and left sides, making a total of 180 cases for study. A 3-D reconstruction of the region analysed in one of the specimens was made. In 89 cases the buccal nerve was located medial to the temporalis muscle; in 73 cases it penetrated the muscle; in 15 cases it lay in a canal formed by the muscle fibres and was covered by fascia, and finally, in 3 cases it was a branch of the inferior alveolar nerve. The study has revealed that in a large number of cases the buccal nerve maintains an intimate association with the temporalis muscle.

Many studies have been published on the development of the human elbow joint, but authors disagree on its morphogenetic timetable. Most discrepancies center on the cavitation of the elbow joint (including the humeroradial, humeroulnar, and superior radioulnar joints), and the organization of the tunnel of the ulnar nerve. We summarize our observations on the development of the elbow joint in 49 serially sectioned human embryonic (n = 28) and fetal (n = 21) upper limbs. During week 12, ossification begins in the epiphyses of the elements comprising the elbow joint. At the end of the embryonic period, the shallow groove between the posterior aspect of the medial epicondyle and the olecranon process, begins to be visible. The elbow joint cavity appears in O'Rahilly stage 21 (51 days) at the level of the humeroulnar and humeroradial interzones. Formation of the cavity begins at the medialmost portion of the humeroradial interzone and the lateralmost portion of the humeroulnar interzone. The annular ligament begins to develop in O'Rahilly stage 21 (51 days), and the superior radioulnar joint cavity appears between this ligament and the lateral aspect of the head of the radius during O'Rahilly stage 23 (56 days). We established the morphogenetic timetable of the human elbow joint., (Copyright 2000 Wiley-Liss, Inc.)

A human cadaver was studied which presented a biceps brachii with three heads of origin in the left arm. The third or humeral head presented an unique area of insertion into the bicipital aponeurosis (lacertus fibrosus).

A great deal of research has been published on the development of the human temporomandibularjoint (TMJ). However, there is some discordance about its morphological timing. The most controversial aspects concern the moment of the initial organization of the condyle and the squamous part of the temporal bone, the articular disc and capsule and also the cavitation and onset of condylar chondrogenesis. Serial sections of 70 human specimens between weeks 7 and 17 of development were studied by optical microscopy (25 embryos and 45 fetuses). All specimens were obtained from collections of the Institute of Embryology of the Complutense University of Madrid and the Department of Morphological Sciences of the University of Granada. Three phases in the development of the TMJ were identified. The first is the blastematic stage (weeks 7-8 of development), which corresponds with the onset of the organization of the condyle and the articular disc and capsule. During week 8 intramembranous ossification of the temporal squamous bone begins. The second stage is the cavitation stage (weeks 9-11 of development), corresponding to the initial formation of the inferior joint cavity (week 9) and the start condylar chondrogenesis. Week 11 marks the initiation of organization of the superior joint cavity. And the third stage is the maturation stage (after week 12 of development). This work establishes three phases in TMJ development: 1) the blastematic stage (weeks 7-8 of development); 2) the cavitation stage (weeks 9-11 of development); and 3) the maturation stage (after week 12 of development). This study identifies the critical period of TMJ morphogenesis as occurring between weeks 7 and 11 of development.

Purpose: The aim of this work was to clarify the vascular relationships between the middle ear and the temporomandibular joint region during human fetal development., Materials and Methods: Light microscopic studies were done on 40 human fetuses from 72 mm crown-rump length (C-R) to 150 mm C-R, which were stained by various methods. Five human fetuses were dissected. Natural latex with industrial coloring was injected through the external carotid artery. All specimens were dissected bilaterally., Results: The limits of the retroarticular region and the fetal tympanosquamosal fissure are shown. The anterior tympanic artery has a variable origin. In most cases, it originates from the maxillary artery; in other cases it originates from the superficial temporal artery or the bifurcation of the external carotid artery. On its way through the retroarticular region, it gives branches to the posterior part of the temporomandibular joint. It progresses along the most lateral part of the tympanosquamosal fissure, dividing into three branches that extend throughout the middle ear. A number of venous spaces in the retroarticular region that constitute the retrodiscal venous plexus. Small venous vessels along the fetal tympanosquamosal fissure accompany the anterior tympanic artery and drain into the retrodiscal venous plexus., Conclusions: During human fetal development, there is a wide connection across the tympanosquamosal fissure between the middle ear and the temporomandibular joint region. The anterior tympanic artery and its branches, as well as small venous vessels that are connected with the retrodiscal venous plexus, extend along the most lateral part of the fissure.