Elastic and collagenous fibers in the temporomandibular joint capsule of the rabbit and their functional relevance

This study deals with the form and function of the temporomandibular joint capsule and compares the histological structure of the capsule and kinetics of condylar and disc movement in rabbit and man. The morphology of the capsule of the jaw joint of the rabbit was studied by means of histological sections of isolated capsules, celloidin sections of decalcified heads, and cryostat sections containing the joint, fixed in jaw open and closed positions. General staining methods and selective methods for elastin and collagen were used. The volume density of the elastic fibers was determined morphometrically. The capsule consists of a portion connecting disc and skull and a portion connecting disc and mandible. The former portion has a fibrous outer layer of dense connective tissue. It contains numerous bundles of specifically oriented collagen but hardly any elastic fibers. Few irregularly arranged elastic fibers are present in the lateral and medial areas of the capsule. In contrast, the portion connecting disc and condylar process contains not only oriented collagen but also large amounts of elastic fibers. Anteriorly, there is a thin elastic band that is stretched greatly at jaw opening. Posteriorly, the capsule takes the appearance of a large fibro-elastic pad that covers the posterior extension of the condyle. This part is somewhat stretched when the jaw is closed. The findings correlate well with the results of jaw movement studies, showing a remarkable capability for condylar protrusion and retrusion. In contrast to the situation in humans, this movement occurs mainly between condyle and disc. It is made possible by the rather tight connections between skull and disc and flexible ones between disc and condyle.     

Innervation and functional characteristics of connective tissues,especially elastic fibers,in human fetal thoracic intervertebral articular capsule and its surroundings

The articular capsules between the thoracic vertebrae, which have physiologically different functions from those of other levels of the vertebrae, have yet to be subjected to neuro-anatomical and fine structural analysis. In the present study, we analyzed serial frozen sections of decalcified thoracic vertebrae in human fetuses, and identified the articular capsule tissue with its unique distribution of elastic fibers. The fine structure of the elastic fibers was studied by transmission electron microscopy. In the early-stage fetus, the fibrous membrane forming the lateral intervertebral articular capsule contained abundant thin elastic fibers consisting of microfibrils. In the late-stage fetus, the lateral capsule of fibrous membrane was occupied by thick elastic fibers. A medial articular capsule, namely the ligamenta flava, contained numerous thick elastic fibers in both early and late-stage fetuses. The distributional differences in nerve fibers between early and late-stage fetuses were determined by immunostaining, using antibodies raised against protein gene product 9.5 (PGP 9.5; ubiquitin carboxyl-terminal hydrolase). Innervation by PGP 9.5 immunoreactive fibers was limited to the areas of the articular capsules near the blood vessels, which may indicate their functional relation with blood flow. No PGP 9.5 immunoreactive fibers were found in the ligamenta flava of the late-stage fetus. Innervation might be directly involved in the development of the intervertebral articular capsules in normal human fetuses.     

Normal variations of the lumbar facet joint capsules

The anatomy and variations of the lumbar facet joint capsules have not been described in detail. Fifty lumbar cadaver facet joints were studied with cryomicrotomy. The axial sections were analyzed to describe the normal appearance of the facet joint capsule. In the majority of cases the facet joint capsule extended beyond the confines of the borders of the facet joint proper. The most common patterns were extensions along the inferior articular process near the dorsal or along the inferior or superior articular process in the ventral aspect of the joint. The study extends previous anatomic studies on the facet joint capsule.     

Distribution of sensory receptors in joints of the upper cervical column in the laboratory marsupial monodelphis domestica.

In order to investigate the sensory innervation, the upper cervical spine of a small laboratory marsupial (monodelphis domestica) was examined with serial section light microscopy and re-embedding of selected sections for electron microscopy. Large numbers of free nerve endings supplied by A delta- and C-fibres were found in the longitudinal ligaments and facet joint capsules. Electron microscopically, areas of direct contact between axon and collagen fibres of the surrounding connective tissue separated only by the basal lamina were observed. Such structural adaptations suggest mechanoreceptive or polymodal nociceptive functions. In addition, about 100 small lamellated corpuscles were found in the longitudinal ligaments mainly concentrated around the first intervertebral disk. Electron microscopy shows finger-like processes extending from the axon terminal into the inner core lamellae. These are the likely sites of the mechanoelectric transduction process. Smaller numbers of lamellated corpuscles were seen in the lower intervertebral disks and facet joint capsules. Lamellated corpuscles are known to function as rapidly adapting mechanoreceptors supplementing information supplied by muscle spindles to the CNS about position and movement of the cervical spine.     

大鼠颈脊神经节中降钙素基因相关肽免疫阳性神经元分支至颈椎关节突关节囊和前肢

目的探讨颈椎关节突关节疼痛综合征并发上臂痛的神经解剖学机制。方法以抗降钙素基因相关肽（CGRP）抗体对SD大鼠C4-T1关节突关节囊作免疫组织化学染色。将荧光标记物快蓝（FB）和核黄（NY）分别注射到SD大鼠右侧桡神经和C1～T1颈椎关节突关节囊。显微镜下观察颈脊神经背根节（DRG）内被逆行荧光标记的神经元，再用抗CGRP抗体行免疫组织化学染色，观察DRG内的CGRP免疫阳性神经元。最后比较荧光照片和免疫组织化学照片上的神经元。结果C4～T1关节突关节囊上分布着丰富的CGRP免疫阳性神经纤维，它们或独立走行或交织成网。在C5～T1各节段的DRG中均可观测到被FB单标（76％）、NY单标（16％）和FB／NY双标（8％）的神经元。约40％的荧光逆行标记神经元在免疫组织化学染色的切片上呈CGRP免疫反应阳性。结论大鼠颈部DRG内一部分含GRP的感觉神经元的周围突分两支，一支支配颈椎关节突关节囊，另一支随桡神经分布到前（上）肢。提示，颈椎关节突关节疼痛综合征并发上臂牵涉痛的神经形态学基础之一可能发生在DRG水平。     

Response and receptive-field properties of spinomesencephalic tract cells in the cat

Recordings were made from 90 identified spinomesencephalic tract (SMT) cells in the lumbosacral spinal cord of cats anesthetized with alpha-chloralose and pentobarbital sodium. Recording sites were located in laminae I-VIII. Antidromic stimulation sites were located in different regions of the rostral and caudal midbrain including the periaqueductal gray, midbrain reticular formation, and the deep layers of the superior colliculus. Twelve SMT cells were antidromically activated from more than one midbrain level or from sites in the medial thalamus. The mean conduction velocity for the population of cells sampled was 45.2 +/- 21.4 m/s. Cells were categorized based on their responses to graded intensities of mechanical stimuli and the location of excitatory and/or inhibitory receptive fields. Four major categories of cells were encountered: wide dynamic range (WDR); high threshold (HT); deep/tap; and nonresponsive. WDR and HT cells had excitatory and/or inhibitory receptive fields restricted to the ipsilateral hindlimb or extending to other parts of the body including the tail, forelimbs, and face. Some cells had long afterdischarges following noxious stimulation, whereas others had high rates of background activity that was depressed by nonnoxious and noxious stimuli. Deep/tap cells received convergent input from muscle, joint, or visceral primary afferent fibers. The placement of mechanical lesions at different rostrocaudal levels of the cervical spinal cord provided information related to the spinal trajectory of SMT axons. Six axons were located contralateral to the recording electrode in the ventrolateral/medial or lateral funiculi while two were located in the ventrolateral funiculus of the ipsilateral spinal cord. Stimulation at sites used to antidromically activate SMT cells resulted in the inhibition of background and evoked responses for 22 of 25 cells tested. Inhibitory effects were observed on responses evoked by low/high intensity cutaneous stimuli and by the activation of joint or muscle primary afferent fibers. Based on the response and receptive-field properties of SMT cells it is suggested that the SMT may have an important role in somatosensory mechanisms, particularly those related to nociception.     

Development and distribution of elastic fibers in the mandibular joint of the mouse. A comparison of fetal,suckling, juvenile and adult stages

Development and distribution of elastic fibers were studied in mandibular joints of white Swiss mice which ranged from 15 days insemination age to three months postnatal. Paraffin sections were stained with Weigert's resorcin-fuchsin and Verhoeff's elastic tissue stain. Elastogenesis does not begin until the major elements of the mandibular joint are present. The first distinct elastic elements appear as granules at the nineteenth to twentieth day insemination age. Early sites of elastogenesis occur in the peripheral portions of the articular disk, at the transition and continuation of fibrous disk tissue with the periarticular tissues, and with the periosteum around the neck of the mandible. The concentration, length and caliber of fibers is increased markedly during the suckling stage, especially in the walls of the medial and lateral recesses of the synovial cavities, and in the posterior continuation of the disk to form a fibroelastic band of attachment to the squamosal bone. Prominent bands of long elastic fibers appear in the epimysium of the lateral pterygoid and masseter muscles in the young adult. The central portion of the disk and the articular surfaces of the mandibular condyle and fossa contain no elastic fibers, confirming the contention that these surfaces are not particularly stress-bearing. Stretch and shearing stresses are created, however, which require extensive elastic fiber development in other joint tissues.     

The periaqueductal gray in the cat projects to lamina VIII and the medial part of lamina VII throughout the length of the spinal cord

The periaqueductal gray (PAG) plays an important role in analgesia as well as in motor activities, such as vocalization, cardiovascular changes, and movements of the neck, back, and hind limbs. Although the anatomical pathways for vocalization and cardiovascular control are rather well understood, this is not the case for the pathways controlling the neck, back, and hind limb movements. This led us to study the direct projections from the PAG to the spinal cord in the cat. In a retrograde tracing study horseradish peroxidase (HRP) was injected into different spinal levels, which resulted in large HRP-labeled neurons in the lateral and ventrolateral PAG and the adjacent mesencephalic tegmentum. Even after an injection in the S2 spinal segment a few of these large neurons were found in the PAG. Wheat germ agglutinin-conjugated HRP injections in the ventrolateral and lateral PAG resulted in anterogradely labeled fibers descending through the ventromedial, ventral, and lateral funiculi. These fibers terminated in lamina VIII and the medial part of lamina VII of the caudal cervical, thoracic, lumbar, and sacral spinal cord. Interneurons in these laminae have been demonstrated to project to axial and proximal muscle motoneurons. The strongest PAG-spinal projections were to the upper cervical cord, where the fibers terminated in the lateral parts of the intermediate zone (laminae V, VII, and the dorsal part of lamina VIII). These laminae contain the premotor interneurons of the neck muscles. This distribution pattern suggests that the PAG-spinal pathway is involved in the control of neck and back movements. Comparing the location of the PAG-spinal neurons with the results of stimulation experiments leads to the supposition that the PAG-spinal neurons play a role in the control of the axial musculature during threat display.     

Physiological and morphological identification of ventrolateral fibers relaying cerebellar information to the cat motor cortex

In the cat motor cortex, recordings were obtained from thalamocortical fibers and then these fibers were intra-axonally injected with horseradish peroxidase. Each fiber was identified by both orthodromic activation from the ventrolateral nucleus of the thalamus and by monosynaptic activation from the brachium conjunctivum. In anesthetized cats, all ventrolateral thalamic fibers tested had bursts of spikes with an intraburst frequency of about 400 Hz. The bursts occurred spontaneously and in response to thalamic or brachium stimulation. Fast pyramidal tract cells had clusters of excitatory postsynaptic potentials with the same internal frequency as the bursting afferents, strongly suggesting that they arise from the ventrolateral afferents. The horseradish peroxidase-injected ventrolateral afferents were distributed to many zones within the motor area and had loose arborizations within cortical layers. Terminals were generally located in layer III and in the upper part of layer VI. None was observed in the more superficial layers.The ventrolateral thalamic afferents in the motor cortex establish a point to zones connectivity. This may provide a morphological basis for the central organization of certain movements that necessitate simultaneous contraction of many muscles.     

Anatomical characteristics of the iliopubic tract: Implications for repair of inguinal hernias

The high recurrence rate of inguinal hernias following primary repair has prompted us to re-examine the anatomy of the inguinal region with particular emphasis on the iliopubic tract (IPT). The IPT is described as an aponeurotic band forming the inferior margin of the transversus abdominis lamina. We documented the presence and degree of development of the IPT in dissections of 151 embalmed inguinal regions and in serial sagittal sections of four body halves. The iliopubic tract was identified in all specimens. It stretched between the anterior superior iliac spine laterally and the pubic tubercle and the pubic tubercle and pectineal line medially. The intervening arch formed a discrete structure of variable thickness and was substantial in 63 specimens. Histological sections demonstrated that the IPT is connected to the inguinal ligament, fascia lata, and anterior femoral sheath and is composed primarily of collagenous fibers with a minor elastic component. These data indicate that the iliopubic tract is a consistent and easily identified structure in the inguinal regions. These results suggest that dissection of the iliopubic tract, like the inguinal ligament, should become an integral part of the assessment of groin anatomy during hernia repair. © 1992 Wiley-Liss, Inc.     

The termination of spinomesencephalic fibers in cat

Summary The projections to the midbrain from the spinal cord have been investigated in the cat with the degeneration technique and by using horseradish peroxidase (HRP) as an anterograde tracer. Two types of spinal cord lesions were performed: 1) Cordotomies at cervical or thoracic levels transecting the ventral and lateral funiculi. 2) Transections of the ventral, ventrolateral, dorsolateral or dorsal funiculus, respectively, at cervical levels. In the anterograde tracing experiments HRP was injected into the spinal cord at cervical, lumbar or sacral levels.The results show large projections to the lateral and ventrolateral parts of the periaqueductal gray (PAG1), the posterior pretectal nucleus (PP) and the nucleus of Darkschewitsch (D). More moderate projections go to the medial division of the periaqueductal gray (PAGm), the cuneiform nucleus (CF), the mesencephalic reticular formation (MRF), lateral part of the deep layer of the superio colliculus (SP) and magnocellular medial geniculate nucleus (GMmc), while scattered spinal fibers are present in the dorsal part of the periaqueductal gray (PAGd), the external inferior collicular nucleus (IX), the intermediate layer of the superior colliculus (SI), the lateral part of the red nucleus (NR) and in the Edinger-Westphal portion of the oculomotor nucleus (3). In addition a few fibers are present in the interstitial nucleus of Cajal (CA) and anterior pretectal nucleus (PAc).The results indicate that at midcervical levels most of the spinomesencephalic fibers ascend in the ventral funiculus, with only a moderate fraction ascending in the ventral half of the lateral funiculus. Almost no fibers ascend in the dorso-lateral funiculus and none appear to pass in the dorsal funiculus.No distinct somatotopic pattern was found in the spinomesencephalic projections, but more fibers from cervicobrachial segments terminate in the rostral than in the caudal parts of the terminal fields in PAG, CF, SP and IX, while the lumbar fibers were more numberous in the caudal parts. PP seems to receive spinal fibers mainly from the caudal half of the cord.     

Histotopographical study of human periocular elastic fibers using aldehyde-fuchsin staining with special reference to the sleeve and pulley system for extraocular rectus muscles

The aim of this study was to investigate the detailed configuration of periocular elastic fibers. Semiserial paraffin sections were made using 40 whole orbital contents from 27 elderly cadavers and stained by the aldehyde-fuchsin method. Periocular tissues were classified into three types according to directions of the elastic fibers, i.e., tissues containing anteroposteriorly running elastic fibers, those with mediolateral fibers, and those with meshwork of fibers. Anteroposterior elastic fiber-dominant tissue was seen in the upper eyelid and newly defined pulley plate for the medial and lateral recti (MR, LR). Mediolateral fibers were predominant in the central part of the inferior rectus pulley. In the pulley plates for the MR and LR, anteroposteriorly running fibers encased the striated muscle. Tenon’s capsule and the epimysium of the recti were mediolateral fiber-dominant. However, at the entrance of the muscle terminal where Tenon’s capsule reflects and continues to the epimysium, composite elastic fibers provided a meshwork-like skeleton. The elastic mesh was also seen around the lacrimal canaliculi. The pulley for the recti seemed to be composed of two parts—a connective tissue plate encasing the recti and specialized Tenon’s capsule at an entrance or porta of the muscle. For both parts, elastic fibers were major functional components. The anteroposterior elastic fibers in the MR and LR pulley plates, especially, seemed to receive anteroposteriorly directed stress and tension from these striated muscles. The elastic interfaces seemed to prevent any concentration of stress that would interfere with periocular striated muscle functions, including hypothetical active pulleys.     

Dorsal column nuclei afferents in the lateral funiculus of the cat: Distribution pattern and absence of sprouting after chronic deafferentation

Summary In adult cats the successive degeneration technique has been used to demonstrate the existence and distribution pattern of lateral funicular fibers to the dorsal column nuclei (DCN) originating from the brachial and thoracic cord. In a first operation, interruption of the dorsal columns at appropriate cervical levels and of the lateral funiculus at low thoractic levels was performed. Thirteen months later, a lesion was made in the lateral funiculus at upper brachial or uppermost thoracic levels. Fiber degeneration in the DCN consequent to this second operation is not contaminated by damage to dorsal roots or by interruption of lateral funicular afferents from lumbo-sacro-coccygeal segments. All animals were sacrified 7 days after the second operation. Serial sections through the medulla oblongata, impregnated with the Fink-Heimer technique, show that fibers ascending from brachial levels in the dorsal part of the lateral funiculus reach the cuneate nucleus either by a dorsomedial route through the tegmentum or by ascending in the restiform body. Degenerated fibers distribute selectively to the rostral part, and to a lesser extent to the base, of the cuneate nucleus. Only very few fibers ascending from thoracic levels in the lateral funiculus distribute to the DCN.Abbreviation List CUN cuneate nucleus - DV dorsal motor nucleus of vagus nerve - EC external cuneate nucleus - GR gracile nucleus - HYP hypoglossal nucleus - int nucleus intercalatus - PH nucleus praepositus hypoglossi - PM paramedian nucleus - SOL solitary nucleus and tract - VEST vestibular complex - X nucleus X of Brodal and Pompeiano (1957) - Z nucleus Z of Brodal and Pompeiano (1957) - V spin spinal trigeminal nucleus     

脑矢状断层解剖学研究

目的 为脑解剖学教学及临床MRI诊断提供形态学基础资料。方法 采用成人尸体脑部4例，用火锦胶包埋技术，并利用大脑切片机从矢状位做连续切片，片厚1.0mm。结果 选取典型层面观察。分析了脑内有关结构的位置，毗邻及形态特点，内囊膝层面是显示整脑子连续性及内囊内走行纤维束的最佳层面；纹状体层面最易显示纹状体结构及内囊后肢；壳层面显示整体海马结构较好。结论 本研究对于脑解剖学教学及MRI诊断具有重要的应用价值。     

Functional anatomy of the major cardiac nerves in cats

In recognition of the extensive use of the cat as an experimental model of cardiac innervation, the effects of electrical stimulation of stellate ganglia, thoracic vagosympathetic complexes, and individual feline cardiopulmonary nerves on heart rate, blood pressure, and contractility in all four cardiac chambers were analysed and correlated with the anatomy of the thoracic autonomic nervous system. The right and left stellate ganglia in cats are relatively large and globular. Distinct dorsal and ventral ansae subclavia arise from these ganglia, connecting with the relatively small, spindle-shaped middle cervical ganglia situated in the apices of the thoracic cage bilaterally. A cranial pole nerve arises from each of the middle cervical ganglia and courses cranially to unite with the ipsilateral superior cervical ganglia. On each side, the major cardiopulmonary nerves arise from the middle cervical ganglion, the relatively large vagosympathetic trunk, and the stellate ganglion. On the right side these nerves consist of a very small right stellate cardiac nerve, a recurrent cardiac nerve, a group of craniovagal nerves and a group of caudovagal cardiopulmonary nerves. On the left side are the left stellate cardiac, ventrolateral, ventromedial, and innominate cardiopulmonary nerves. All of these nerves contain efferent parasympathetic and/or sympathetic fibers which modify cardiac chronotropism and/or inotropism. Some contain afferent fibers. These results indicate that specific cardiopulmonary nerves exist in cats, which when stimulated, modify the cardiovascular system in specific fashions.     

Optimised robot-based system for the exploration of elastic joint properties

Numerous publications provide measured biomechanical data relating to synovial joints. However, in general, they do not reflect the non-linear elastic joint properties in detail or do not consider all degrees of freedom (DOF), or the quantity of data is sparse. To perform more comprehensive, extended measurements of elastic joint properties, an optimised robot-based approach was developed. The basis was an industrial, high-precision robot that was capable of applying loads to the joint and measuring the joint displacement in 6 DOF. The system was equipped with novel, custom-made control hardware. In contrast to the commonly used sampling rates that are below 100 Hz, a rate of 4 kHz was realised for each DOF. This made it possible to implement advanced, highly dynamic, quasi-continuous closed-loop controllers. Thus oscillations of the robot were avoided, and measurements were speeded up. The stiffness of the entire system was greater than 44 kNm⁻¹ and 22 Nm deg⁻¹, and the maximum difference between two successive measurements was less than 0.5 deg. A sophisticated CT-based referencing routine facilitated the matching of kinematic data with the individual anatomy of the tested joint. The detailed detection of the elastic varus-valgus properties of a human knee joint is described, and the need for high spatial resolution is demonstrated.     

Projection of cervical dorsal root fibers to the medulla oblongata in the brush-tailed possum,Trichosurus vulpecula

This study describes the projection of cervical spinal afferent nerve fibers to the medulla in the brush-tailed possum, a marsupial mammal. After single dorsal roots (between C₂ and T₁) were cut in a series of animals, the Fink-Heimer method was used to demonstrate the projection fields of fibers entering the CNS via specific dorsal roots. In the high cervical spinal cord, afferent fibers from each dorsal root form a discrete layer in the dorsal funiculus. The flattened laminae from upper cervical levels are lateral and those from lower cervical levels are medial within the dorsal columns. All afferent fibers at this level are separated from gray matter by the corticospinal fibers in the dorsal funiculus. All cervical roots project throughout most of the length of the well-developed main cuneate nucleus in a loosely segmentotopic fashion. Fibers from rostral roots enter more lateral parts of the nucleus, and fibers from lower levels pass to more medial areas; but terminal projection fields are typically large and overlap extensively. At more rostral medullary levels, fibers from all cervical dorsal roots also reach the external cuneate nucleus. The spatial arrangement here is more complex and more extensively overlapped than in the cuneate nucleus. Rostral cervical root fibers reach ventral and ventrolateral areas of the external cuneate nucleus and continue to its rostral pole; more caudal root fibers project to more dorsal and medial regions within the nucleus. These results demonstrate that projection patterns of spinal afferents in this marsupial are similar to those seen in the few placental species for which detailed data concerning this system are available.     

Light and electron microscopy of the human hepato-duodenal ligament: A morpho functional study

The morpho-functional relationships between the hepato-duodenal ligament and the superior part of the duodenum are analysed. Twenty-four specimens were removed during necropsies of adults and prepared according to various mesoscopic, microscopic, and ultramicroscopical methods, i. e., whole-mounts, membrane preparations, thick and thin histological sections, and polarized light, scanning, and transmission electron microscopy were employed. The hepato-duodenal ligament is formed by longitudinally elongated, type I collagen fiber bundles which are interlinked by more delicate bundles of type III collagen fibers. Longitudinally disposed elastic fibers are the principal component of the elastic fiber system of the ligament. These are in continuity with the elaunin and oxytalan fibers which are intermingled with the muscle cells of the vessels and duodenal wall, and fat cells of the ligament. Part of the muscle bundles of the external, longitudinal, muscle layer of the Cluodenum is anchored in the adventitial and subserosal collagen and elastic fiber framework of the organ while part inserts directly into the fibrous framework of the ligament. The fibrous system of the ligament is continuous with that of the subserosa and adventitia of the duodenum. © 1995 WiIey-Liss, Inc.     

Clinical importance of ligamentous and osseous structures in the cervical uncovertebral foraminal region

The vertebral artery, cervical spinal nerves, spinal nerve roots, and the bony and ligamentous tissue related to the cervical vertebrae are structures whose anatomy determines the path of a surgical approach. Defining the anatomy and, in particular, determining the precise location of vulnerable structures at the intervertebral foramen and the uncovertebral foraminal region (UVFR), a region defined by the uncinate process anteriorly, the facet joint posteriorly and the foramen transversarium laterally, has critical significance when selecting the safest surgical approach. We studied the anatomy of the vertebral artery, cervical spinal nerves, and spinal nerve roots within the UVFR in six cadaver specimens. We also obtained measurements of bony structures in 35 dry cervical vertebral columns, from C3-C7. The uncinate process (UP) projects superiorly from the posterolateral aspect of each cervical vertebral body, except for the first and second vertebrae. Because the posterior part of the UP lies adjacent to the vertebral artery, spinal nerve, and spinal nerve roots, its resection creates sufficient space to decompress these structures directly. The posterolateral surface of the UP is covered by ligamentous tissue that originates from the posterior longitudinal ligament and protects the neural and vascular structures during their decompression in the UVFR.