The costotransverse ligaments in human: a detailed anatomical study

Exploring the uncharted: Missing anatomical names in the Terminologia Anatomica

Effective communication and precise navigation within the intricacies of the human body rely on robust anatomical terminology. Since its creation by the Federative Committee on Anatomical Terminology (FCAT), the Terminologia Anatomica (TA 1998) has consistently served as the benchmark in the field. However, the constant advancement of anatomical knowledge requires regular revisions, updates, and enhancements of anatomical nomenclature to accommodate the latest scientific discoveries. The recent adoption of the second edition of Terminologia Anatomica (TA 2019) by the International Federation of Associations of Anatomists (IFAA) has drawn attention to certain notable omissions. Despite over a century of dedicated work establishing standard anatomical terminology, specific widely recognized gross anatomical structures are still absent from the official listing in the Terminologia Anatomica. There is, however, a consensus that the inclusion of names for trivial or variably present structures should be avoided. Accordingly, this article focuses on a thoughtfully selected group of anatomical structures, which are so important that they are routinely discussed during anatomy courses, despite their exclusion from the official lists of anatomical terms. These basic structures hold fundamental importance for both anatomy education and clinical practice. Consequently, their appropriate nomenclature warrants consideration for inclusion in future editions of TA.

Costovertebral and costotransverse joint involvement in spondyloarthritis

OBJECTIVES

Costovertebral (CV), costotransverse (CTr), sternoclavicular (SC), and manubriosternal (MS) joints are impacted in spondyloarthritis (SpA) patients; however, clinical aspects of these involvements require additional evaluation.

METHODS

A total of 281 SpA patients who had undergone chest computed tomography (CT) for any reason between 2010 and 2020 were included in the study. SpA patients were divided into three groups, ankylosing spondylitis (AS), non-radiographic axial SpA, and psoriatic arthritis. Thirty age- and sex-matched rheumatoid arthritis (RA) patients and 30 non-rheumatic disease individuals were selected for comparison. An experienced radiologist reviewed 24 CV, 20 CTr, 2 SC, and 1 MS joints from a thorax CT for each patient. All joints were classified as: normal (0); suspicious (1), mild (2), moderate (3), or severe (4).

RESULTS

Total CV and CTr joint scores differed between diseases (p < .001). Male AS patients had higher CV and CTr scores than female AS patients (male CV score: 52 [range 0-96] and CTr score: 22 [range 0-80]; female CV score: 20 [range 0-96] and CTr score: 12 [range 0-79]). Strong negative correlations were detected in AS patients between chest expansion and CV (r = -0.703 p = .007) and CTr (r = -0.763 p = .002) joint involvement; positive correlations between CV and CTr joints, and modified Stoke Ankylosing Spondylitis Spinal Score (p < .05); and no significant association for MS and SC joints.

CONCLUSIONS

CV and CTr joint involvement on thorax CT was more severe in AS and negatively affected chest expansion. The use of thorax CT scans performed for other indications in the examination of these joints may be advantageous for the early beginning of rehabilitation programs targeted at maintaining chest mobility.

Anatomical classification and clinical application of thoracic paraspinal blocks

Various techniques for regional anesthesia and analgesia of the thorax are currently being used in clinical practice. A recent international consensus has anatomically classified paraspinal blocks in the thoracic spinal region into the following four types: paravertebral, retrolaminar, erector spinae plane, and intertransverse process blocks. These blocks have different anatomical targets; thus, the spreading patterns of the injectates differ and can consequently exhibit different neural blockade characteristics. The paravertebral block directly targets the paravertebral space just outside the neuraxial region and has an analgesic efficacy comparable to that of the epidural block; however, there are multiple potential risks associated with this technique. Retrolaminar and erector spinae plane blocks target the erector spinae plane on the vertebral lamina and transverse process, respectively. In anatomical studies, these two blocks showed different injectate spreading patterns to the back muscles and the fascial plane. In cadaveric studies, paravertebral spread was identified, but variable. However, numerous clinical reports have shown paravertebral spread with erector spinae plane blocks. Both techniques have been found to reduce postoperative pain compared to controls; however, the results have been more inconsistent than with the paravertebral block. Finally, the intertransverse process block targets the tissue complex posterior to the superior costotransverse ligament. Anatomical studies have revealed that this block has pathways that are more direct and closer to the paravertebral space than the retrolaminar and erector spinae plane blocks. Cadaveric evaluations have consistently shown promising results; however, further clinical studies using this technique are needed to confirm these anatomical findings.

Anatomical method for rib disconnection during posterior costotransversectomy for paravertebral access to the ventral thoracic spine

Posterior surgical approaches to the thoracic spine are commonly used for degenerative diseases, tumors, trauma, and other operative indications. A posterior approach for access to the paravertebral space is advantageous because it allows for resection of the vertebral body without violating the pleural cavity. Posterior costotransversectomy (PCT) is widely used for this purpose. It involves resection of the rib head after the ligamentous complexes have been disconnected from the transverse process and lateral vertebral body. The current literature provides only vague descriptions of the steps involved in rib disconnection with respect to PCT. A comprehensive knowledge of the anatomical relationships of the ligamentous and soft tissue complexes connecting the rib to the vertebral body is paramount for completing an efficient and safe surgery. This manuscript describes an anatomically directed method for rib disconnection during costotransvrersectomy.

Comparison of the analgesic effect of ultrasound-guided paravertebral block and ultrasound-guided retrolaminar block in Uniportal video-assisted Thoracoscopic surgery: a prospective, randomized study

Background

The optimal modality for postoperative analgesia after uniportal video-assisted thoracoscopic surgery (UVATS) for the treatment of lung cancer has not yet been determined. Both ultrasound-guided paravertebral block (PVB) and retrolaminar block (RLB) have been reported to be successful in providing analgesia after UVATS. However, which block technique provides superior analgesia after UVATS is still unclear. This randomized study was designed to compare the postoperative analgesic effects and adverse events associated with ultrasound-guided PVB and RLB after UVATS.

Methods

Sixty patients with lung cancer were randomized to undergo ultrasound-guided PVB (group P) or ultrasound-guided RLB (group R). In group P, 30 mL of 0.5% ropivacaine was injected at the T3 and T5 levels via ultrasound-guided PVB (15 mL at each level on the operative side). In group R, 30 mL of 0.5% ropivacaine was injected at the T3 and T5 levels via ultrasound-guided RLB (15 mL at each level on the operative side). The primary outcome was the numerical rating scale (NRS) score within 48 h after surgery. The secondary outcomes were total postoperative sufentanil consumption, time to first analgesic request and adverse events.

Results

At 3, 6, 12, 24, 36 and 48 h postoperatively, the NRS score at rest in group P was lower than that in group R (p < 0.05). At 3, 6, 12, 24 and 36 h postoperatively, the NRS score while coughing in group P was lower than that in group R (p < 0.05). The total postoperative sufentanil consumption in group P was significantly lower than that in group R (p < 0.001). Additionally, the time to first analgesic request was longer in group R than in group P (p < 0.0001). The incidence of nausea in group R was higher than that in group P (p < 0.05).

Conclusions

In patients with lung cancer undergoing UVATS, ultrasound-guided PVB with 0.5% ropivacaine provides better analgesia and results in less nausea than ultrasound-guided RLB. Compared with ultrasound-guided RLB, ultrasound-guided PVB seems to be a better technique for analgesia in UVATS.

Trial registration

The name of this study is the Effect And Mechanism Of Ultrasound-guided Multimodal Regional Nerve Block On Acute And Chronic Pain After Thoracic Surgery. This study was registered in the Chinese Clinical Trial Registry (ChiCTR2100044060). The date of registration was March 9, 2021.

Randomized trial comparing the spread of erector spinae block with the combination of erector spinae block and retrolaminar block in soft embalmed Thiel cadavers

BACKGROUND

Erector spinae plane (ESP) and retrolaminar (RL) blocks show unreliable spread. We hypothesize that the combination of ESP and RL blocks provides more extensive and reliable spread of dye than single ESP blocks. Our primary objective was to compare the spread of dye to the paravertebral spaces after the combination block and ESP block in Thiel embalmed cadavers. Spread, the primary end point, was defined as the number of paravertebral spaces colored with dye per injection.

MATERIALS AND METHODS

A single anesthetist performed ultrasound-guided ESP (20 mL) and combination of ESP and RL (10 mL each) blocks at the third thoracic vertebra of eight soft embalmed Thiel cadavers. Tissue displacement was visualized on an adjacent strain elastography image. Cadavers were dissected 24 hours later and anatomical structures were inspected for the presence of dye.

FINDINGS

Dye was visualized in more paravertebral spaces with the combination block (median 3 (IQR 3-5 (range 0-8)) vs 1.5 (IQR 0.25-2.75 (range 0-3) and difference (1.5 (0-4), p=0.04). Six out of seven (86%) combined erector spinae and RL blocks spread to at least three paravertebral spaces compared with two out of eight (25%) ESP blocks (RR 3.4, 95% CI 1.0 to 11.8; p=0.04). Contralateral spread occurred in three combination blocks and in one ESP block (OR 9.0, 95% CI 4.0 to 21.1; p<0.001).

CONCLUSIONS

In conclusion, the combination of ESP and RL blocks was more extensive and reliable than ESP block alone.

Comparison of analgesic efficacy of the conventional approach and mid-transverse process to pleura approach of the paravertebral block in video-assisted thoracoscopy surgeries: A randomised controlled trial

Background and Aims

The paravertebral block (PVB) is an effective alternative to thoracic epidural analgesia for post-operative analgesia in thoracic surgeries. Despite the use of ultrasound in PVB, the search for a safer approach continues. This study was conducted to compare the analgesic efficacy of conventional and mid-transverse process to the pleura (MTP) approach of the PVB.

Methods

Forty patients aged between 18-60 years, posted for video-assisted thoracoscopic surgery, were enroled for this study. Patients were randomised into two groups using a random number table, and group allocation was done by the sealed opaque envelope method. One group received PVB by conventional approach (group CP). In contrast, patients in the other group (group MP) received PVB by the mid-transverse process to pleura (MTP) approach before induction of general anaesthesia under ultrasound guidance. The study's primary aim was to compare analgesic consumption in the first 24 hours. Secondary aims were comparing the Visual Analogue Scale (VAS) score, block performance time, dermatomal spread, haemodynamic parameters such as heart rate (HR), oxygen saturation (SpO₂), and non-invasive blood pressure (NIBP), patient satisfaction scores, and complications observed. Data were analysed using Statistical Package for the Social Sciences version 23.

Results

Demographic parameters, block performance time, and dermatomal distribution were comparable in both groups. We did not find any statistical difference in the analgesic consumption in the first 24 hours (P = 0.38), VAS at rest or on movement, complication rates, and patient satisfaction scores between the groups.

Conclusion

The MTP approach of the PVB is as effective as the conventional thoracic paravertebral approach for post-operative analgesia in video-assisted thoracoscopic surgeries.

Inflammatory disease of the costotransverse joints: US evaluation in 15 symptomatic patients

The costotransverse joints (CTJs) are small arthrodial joints which articulate with the costal tuberosity on the transverse process of the thoracic vertebrae. CTJs are composed of oval-shaped facets with a major axis, vertical at the upper vertebrae and almost horizontal at the lower vertebrae. This position explains the different movements of the ribs: the cranial ribs move on the sagittal plane and the caudal ribs on the transverse plane. Movements in directions other than these usual CTJ spatial planes can cause inflammation resulting in a stinging pain in the space between the scapula and thoracic spine. We studied 15 subjects with paravertebral pain compatible with CTJ pathology. Mean age was 29 years, 11 females/4 males. In 12 patients, the non-dominant limb was affected. US imaging was carried out using linear 12 MHz and 9 MHz probes. Scanning was performed following the long axis of the rib (transverse plane) and the short axis (sagittal plane). Sagittal scanning is the method of choice for detection of possible joint effusion and comparison with undamaged joints above and below. US identified joint effusion correlating with the site of pain in all patients. Thickening of the posterior costotransverse capsular ligament was detected in six patients mainly affecting the first thoracic vertebrae. Power Doppler showed intraarticular hypervascularization in four patients. US imaging should be performed as a first-line examination in the evaluation of patients with stinging pain in the paravertebral region. US evidence of effusion within the joints is a sure sign of involvement of these structures.

Anatomical basis of erector spinae plane block: a dissection and histotopographic pilot study

Purpose

Erector spinae plane (ESP) block is an interfascial blockade used in different clinical scenarios. This study investigated the ventral extent of dye diffusion in ESP block.

Methods

The ultrasound-guided ESP block was bilaterally performed with an injection at the T5 vertebral level (21-Gauge, 50 mm needle), using diluted black tissue marking dye (20 mL; 1:4 ratio with standard saline solution) instead of local anesthetic on two fresh-frozen corpses within the body donation program of the University of Padova. Subsequently, the gross anatomical dissection was performed by a combined posterior plus anterior approach, and the histotopographic examination completed.

Results

Macroscopically by gross anatomical dissection, the dye spreading ranged on the dorsal side of the chest from T2/3 to T10/11 with an extension up to 10 cm laterally, and on the ventral side of the chest from T2/3–T9/10. Microscopically by histotopographic examination, the dye diffused ventrally to the intercostal spaces (2–3 and 5–6 spaces on the right and left, respectively) by following the blood vessels coupled to the dorsal nerve passing through the costotransverse foramen.

Conclusions

The anterior pathway of dye diffusion from the site of injection within the erector spinae muscle group during an ESP block seems to follow the blood vessels and dorsal rami of spinal nerves, suggesting the passing through the costotransverse foramen to reach the anterior paravertebral space and the intercostal nerves. These findings display an anterior histotopographic diffusion of dye resembling a paravertebral block.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00540-020-02881-w.

Erector spinae plane block: A narrative review with systematic analysis of the evidence pertaining to clinical indications and alternative truncal blocks

STUDY OBJECTIVE

This narrative review discusses the anatomy, mechanism of action, techniques, pharmacology, indications, complications and substitutes for erector spinae plane (ESP) blocks.

INTERVENTIONS

The Medline, Embase and Google Scholar databases (inception-last week of April 2020) were searched. For indications and alternative blocks, a systematic analysis of the available evidence was carried out. In order to highlight the best evidence available, only randomized trials with prospective registration, blinded assessment and sample size justification were retained for analysis.

MAIN RESULTS

The collective body of anatomical studies suggests that ESP block may work through a combination of different mechanisms (e.g., local anesthetic spread to the thoracic paravertebral space, epidural space, and dorsal ramus). Compared to control, the available evidence suggests that ESP block results in decreased postoperative pain and opioid requirement for a wide array of thoracic and abdominal surgical interventions. Erector spinae plane blocks and thoracic paravertebral blocks seem to provide comparable benefits for thoracoscopic and breast cancer surgery when performed with a similar number of injections. Currently, ESP blocks should be favored over intercostal blocks since, at best, the latter provide similar analgesia to ESP blocks despite requiring multiple-level injections.

CONCLUSIONS

In recent years, ESP blocks have become the topic of considerable clinical interest. Future trials are required to investigate their optimal technique, dose of local anesthetic and perineural adjuvants. Moreover, additional investigation should compare ESP blocks with robust multimodal analgesic regimens as well as truncal blocks such as thoracic epidural block, midpoint transverse process to pleura block, PECS block, quadratus lumborum block, and transversus abdominis plane block.

Are single-injection erector spinae plane block and multiple-injection costotransverse block equivalent to thoracic paravertebral block?

BACKGROUND

Thoracic paravertebral block (TPVB) is considered the gold standard for hemithoracic regional anaesthesia. Erector spinae plane block (ESPB) is a new posterior thoracic wall block. Multiple-injection costotransverse block (MICB) mimics TPVB but with injection points within the thoracic intertransverse tissue complex and posterior to the superior costotransverse ligament. We aimed to compare the spread of injectate into the thoracic paravertebral space (TPVS) resulting from single-injection ESPB and MICB, respectively, with TPVB.

METHODS

Ten soft-embalmed cadavers were utilised. In five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided single-injection ESPB or single-injection TPVB; vice versa on the other side. In another five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided MICB or multiple-injection TPVB. About 20 mL of dye was injected in each hemithorax with all techniques.

RESULTS

With TPVB, the dye was consistently present in the TPVS with concomitant epidural spread in the majority of cases. The injectate spread into the TPVS with ESPB (60%) and MICB (100%). MICB consistently stained the ventral rami (T1-7), communicating rami and thoracic sympathetic trunk without epidural spread. Dissection after MICB revealed dye spread into the TPVS via the costotransverse foramina and along the dorsal branches of the posterior intercostal veins.

CONCLUSIONS

Consistent spread of dye into the TPVS colouring the ventral rami, the communicating rami, and the sympathetic trunk was observed with MICB; in this respect equivalent to TPVB. ESPB exhibited only partial success and was not equivalent to TPVB. No epidural spread was found with neither MICB nor ESPB.

The Morphology and Clinical Significance of the Extraforaminal Ligaments at the T1-T12 Levels

STUDY DESIGN

A dissection-based study of 10 embalmed human cadavers.

OBJECTIVE

The purpose of this study was to describe the extraforaminal ligaments in the exit regions of the T1-T12 intervertebral foramina and to discuss their possible clinical significance.

SUMMARY OF BACKGROUND DATA

The ligaments at the lumbar intervertebral foramina have been well studied. However, detailed descriptions of the extraforaminal ligaments at the T1-T12 levels are lacking.

METHODS

Two hundred forty T1-T12 intervertebral foramina from 10 embalmed cadavers were studied. The presence of the ligament was noted. The quantity, morphology, distributions, proximal attachments, distal attachments, and spatial orientations of the extraforaminal ligaments in the exit regions of the T1-T12 intervertebral foramina were examined. The length, width, diameter, and thickness of the ligaments were measured with digital calipers by three independent investigators.

RESULTS

A total of 564 extraforaminal ligaments were identified in the 229 intervertebral foramina; no ligaments were found in the other 11 intervertebral foramina, resulting in an occurrence rate of extraforaminal ligaments of 95.42%. One hundred thirty-six (24.11%) of the extraforaminal ligaments were radiating ligaments, and 428 (75.89%) were transforaminal ligaments. Radiating ligaments had a tendency to be abundant at T1 and T9-T12 and sparse at T2-T8. There were 245 (43.44%) ligaments at the anterior aspect of the exit regions of the intervertebral foramina, 225 (39.89%) ligaments at the posterior aspect, 64 (11.35%) ligaments at the inferior aspect, and 30 (5.32%) ligaments at the superior aspect.

CONCLUSION

In the exit region of thoracic intervertebral foramina, there are two types of extraforaminal ligaments. They may serve as a protective mechanism against traction and play a role in the positioning of the nerves in the intervertebral foramen. Transforaminal ligaments may be an underlying cause of rib or chest pain after thoracic fracture and may be of clinical importance to surgeons.

LEVEL OF EVIDENCE

N/A.

Comparison of injectate spread and nerve involvement between retrolaminar and erector spinae plane blocks in the thoracic region: a cadaveric study

Although different injection locations for retrolaminar and erector spinae plane blocks have been described, the two procedures have a similar anatomical basis. In this cadaveric study we compared anatomical spread of dye in the thoracic region following these two procedures. Following randomisation, 10 retrolaminar blocks and 10 erector spinae plane blocks were performed on the left or right sides of 10 unembalmed cadavers. For each block, 20 ml of dye solution was injected at the T5 level. The back regions were dissected and the involvement of the thoracic spinal nerve was also investigated. Twenty blocks were successfully completed. A consistent vertical spread, with deep staining between the posterior surface of the vertebral laminae and the overlaying transversospinalis muscle was observed in all retrolaminar blocks. Moreover, most retrolaminar blocks were predominantly associated with fascial spreading in the intrinsic back muscles. With an erector spinae plane block, dye spread in a more lateral pattern than with retrolaminar block, and fascial spreading in the back muscles was also observed. The number of stained thoracic spinal nerves was greater with erector spinae plane blocks than with retrolaminar blocks; median 2.0 and 3.5, respectively. Regardless of technique, the main route of dye spread was through the superior costotransverse ligament to the ipsilateral paravertebral space. Although erector spinae plane blocks were associated with a slightly larger number of stained thoracic spinal nerves than retrolaminar blocks, both techniques were consistently associated with posterior spread of dye and with limited spread to the paravertebral space.

Ligaments of the Costovertebral Joints including Biomechanics, Innervations, and Clinical Applications: A Comprehensive Review with Application to Approaches to the Thoracic Spine

Few studies have examined the costovertebral joint and its ligaments in detail. Therefore, the following review was performed to better elucidate their anatomy, function and involvement in pathology. Standard search engines were used to find studies concerning the costovertebral joints and ligaments. These often-overlooked ligaments of the body serve important functions in maintaining appropriate alignment between the ribs and spine. With an increasing interest in minimally invasive approaches to the thoracic spine and an improved understanding of the function and innervation of these ligaments, surgeons and clinicians should have a good working knowledge of these structures.

Different Approaches to Ultrasound-guided Thoracic Paravertebral Block: An Illustrated Review

Given the fast development and increasing clinical relevance of ultrasound guidance for thoracic paravertebral blockade, this review article strives (1) to provide comprehensive information on thoracic paravertebral space anatomy, tailored to the needs of a regional anesthesia practitioner, (2) to interpret ultrasound images of the thoracic paravertebral space using cross-sectional anatomical images that are matched in location and plane, and (3) to briefly describe and discuss different ultrasound-guided approaches to thoracic paravertebral blockade. To illustrate the pertinent anatomy, high-resolution photographs of anatomical cross-sections are used. By using voxel anatomy, it is possible to visualize the needle pathway of different approaches in the same human specimen. This offers a unique presentation of this complex anatomical region and is inherently more realistic than anatomical drawings.

Immunohistochemical study of human costotransverse joints: A preliminary investigation

The human costotransverse joint (CTJ) is the articulation between the posterior tubercle of the ribs with the first through tenth costal facet of the thoracic transverse processes. While the CTJ is well defined anatomically and considered a synovial joint, the human CTJ as a pain generating structure is controversial and not supported from a histological perspective. The objective of the present study was to investigate the histological pain producing properties of CTJ capsule tissue. Ten micron cross-sections at each level (1-10) were stained with H & E or immunostained with antisera against Substance P (SP), calcitonin-gene-related peptide (CGRP), and neuropeptide Y (NPY). Immunoreactivity was confirmed for SP, CGRP, and NPY within the CTJ tissue samples of two unembalmed male cadavers. The presence of previously mentioned neuropeptides suggests that human CTJ is capable of producing pain through somatic and autonomic nervous systems. Therefore, clinicians should consider the CTJ as a differential diagnostic possibility when examining and treating painful thoracic conditions.

Age estimation from stages of union of the vertebral epiphyses of the ribs

This study attempts to fill a persistent gap in the literature by documenting the timing of epiphyseal union at the vertebral end of the ribs in a sample of modern Portuguese skeletons. The skeletal remains of 53 females and 45 males, between the ages of 11 and 30, were taken from the Lisbon documented skeletal collection. Individuals in the sample have been previously described as being representative of a middle-to-low socioeconomic segment of the early 20th century Lisbon population. Three anatomical locations were examined for epiphyseal union: the head, the articular tubercle and the nonarticular tubercle. The first epiphysis to show partial union is that of the nonarticular tubercle (females, 11-19 years; males, 11-19 years), followed by the epiphysis of the articular tubercle (females, 11-20 years; males, 16-20 years), and finally by the head epiphysis (females, 15-24 years; males, 16-22 years), which can still show incomplete epiphyseal closure at 25 and 24 years for females and males, respectively. A trend for earlier female maturation was observed, but the statistical tests only confirmed this result for some ribs and age groups. No directional asymmetry was found, but a significant fluctuating asymmetry was observed in all three epiphyses. A preliminary analysis showed that the asymmetric group of individuals in the study sample includes all the rural-to-urban migrants, relative to the symmetric group.

Extraforaminal ligament attachments of the thoracic spinal nerves in humans

An anatomical study of the extraforaminal attachments of the thoracic spinal nerves was performed using human spinal columns. The objectives of the study are to identify and describe the existence of ligamentous structures at each thoracic level that attach spinal nerves to structures at the extraforaminal region. During the last 120 years, several mechanisms have been described to protect the spinal nerve against traction. All the described structures were located inside the spinal canal proximal to the intervertebral foramen. Ligaments with a comparable function just outside the intervertebral foramen are mentioned ephemerally. No studies are available about ligamentous attachments of thoracic spinal nerves to the spine. Five embalmed human thoracic spines (Th2–Th11) were dissected. Bilaterally, the extraforaminal region was dissected to describe and measure anatomical structures and their relationships with the thoracic spinal nerves. Histology was done at the sites of attachment of the ligaments to the nerves and along the ligaments. The thoracic spinal nerves are attached to the transverse process of the vertebrae cranial and caudal to the intervertebral foramen. The ligaments consist mainly of collagenous fibers. In conclusion, at the thoracic level, direct ligamentous connections exist between extraforaminal thoracic spinal nerves and nearby structures. They may serve as a protective mechanism against traction and compression of the nerves by positioning the nerve in the intervertebral foramen.