Anatomical variations in the superficial venous system of the neck: an image-based study using contrast-enhanced computed tomography.

PURPOSE: The superficial venous system (SVS) of the neck receives blood from the face and oral cavity. The SVS comprises the anterior jugular vein (AJV), external jugular vein (EJV), and facial vein (FV). Comprehensive knowledge of the normal anatomy and potential variations in the venous system is valuable in surgical and radiological procedures. This study aimed to update the anatomic knowledge of the SVS using a radiographic approach, which is a beneficial data source in clinical practice. METHODS: Contrast-enhanced computed tomography images of the neck of patients with head and neck cancer treated between 2017 and 2020 were retrospectively evaluated. Each side of the neck was counted separately. A total of 302 necks of 151 patients were enrolled in this study. RESULTS: The medial AJV was absent in 49.7% (75/151) of the patients on the left side, which was significantly greater than the 19.2% (29/151) on the right (p < 0.001). The left AJV drained into the right venous system in 6.6% (10/151) of the necks. In 48.3% (146/302) of the necks, the FV did not flow into the internal jugular vein but rather into the EJV or AJV; these findings were significantly more frequent than those reported in previous studies. The diameters of the veins were significantly larger when they received blood from the FV than when they were not connected to the FV. CONCLUSION: These findings indicate that the AJV has a rightward preference during its course. The course of the FV is diverse and affects the diameter of connected veins.

Anatomical variations in the course of spinal accessory nerve in the neck triangles: A descriptive study.

BACKGROUND: Spinal Accessory Nerve (SAN), which innervates the sternocleidomastoid (SCM) and trapezius muscles, is closely related to the internal jugular vein (IJV) in the anterior triangle of the neck and passes superficially in the posterior triangle. Injury to SAN is a major complication of level II neck dissection, leading to shoulder syndrome. The present study aims to assess the course and its relation to the SCM muscle and IJV in the Tamil ethnolinguistic groups in South India. METHODS AND MATERIALS: The anterior and posterior triangles of the neck were dissected in 28 formalin-fixed adult cadavers. The course of the SAN and the entry and exit points of SAN along the SCM muscle were assessed using the mastoid process as the reference. Recorded data was analyzed using SPSS software. RESULTS: The SAN was anteriorly related to the IJV in 58.73%, posteriorly in 37.5%, and pierced through the IJV in 3.57% of the specimens. The entry and exit points of SAN from the mastoid process were 37.86±7.26mm and 48.55±8.22mm, respectively. In 86.67% of the cases, the SAN traversed through the SCM muscle, and in 13.33%, it was deep to the SCM. CONCLUSION: The present study reports that the SAN is variable in its course, and relation to SCM and IJV. Knowledge about the variant anatomy of the SAN in the triangles of the neck is important and it aids surgeons to prevent iatrogenic injuries to SAN or IJV and enhance surgical safety in neck procedures.

Drainage Pattern of Craniofacial Veins With Emphasis on its Influence on Facial Reconstruction Procedures.

As the facial transplantation procedures are becoming more popular and frequent in recent years, for repairing facial trauma, variations in the veins of head and neck needs to be reported time and again. This study was undertaken to examine the course and drainage pattern of the facial vein and external jugular vein on this context and emphasize its surgical implications. The authors studied the head and neck region of 50 embalmed cadavers of both sexes to document normal and variant anatomy of facial, retromandibular, and external jugular veins. In 30% of the head and neck regions, different draining pattern of the above-mentioned veins were observed. One of the rare variation discovered was the splitting of the retromandibular vein to embrace the external carotid artery within the parotid gland. The data about variations in the termination of facial vein, retromandibular vein, and external jugular vein, as observed in the present study might be useful in avoiding accidental injury to these vessels during any surgical intervention in the face as well as neck. Level of Evidence: IV.

Detailed Anatomy of Bridging Veins Around the Foramen Magnum: a Multicenter Study Using Three-dimensional Angiography.

BACKGROUND AND PURPOSE: There has been limited literature regarding the bridging veins (BVs) of the medulla oblongata around the foramen magnum (FM). The present study aims to analyze the normal angioarchitecture of the BVs around the FM using slab MIP images of three-dimensional (3D) angiography. METHODS: We collected 3D angiography data of posterior fossa veins and analyzed the BVs around the FM using slab MIP images. We analyzed the course, outlet, and number of BVs around the FM. We also examined the detection rate and mean diameter of each BV. RESULTS: Of 57 patients, 55 patients (96%) had any BV. The median number of BVs was two (range: 0-5). The BVs originate from the perimedullary veins and run anterolaterally to join the anterior condylar vein (ACV), inferior petrosal sinus, sigmoid sinus, or jugular bulb, inferolaterally to join the suboccipital cavernous sinus (SCS), laterally or posterolaterally to join the marginal sinus (MS), and posteriorly to join the MS or occipital sinus. We classified BVs into five subtypes according to the draining location: ACV, jugular foramen (JF), MS, SCS, and cerebellomedullary cistern (CMC). ACV, JF, MS, SCS, and CMC BVs were detected in 11 (19%), 18 (32%), 32 (56%), 20 (35%), and 16 (28%) patients, respectively. The mean diameter of the BVs other than CMC was 0.6 mm, and that of CMC BV was 0.8 mm. CONCLUSION: Using venous data from 3D angiography, we detected FM BVs in most cases, and the BVs were connected in various directions.

Central venous pressure line insertion for the primary health care physician.

Central venous access is an important procedure to understand and perform not only in the emergency unit but also for prolonged reliable venous access. All clinicians must be familiar and confident with this procedure. This paper will focus on applied anatomy in respect of common anatomical sites for venous access, the indications, the contraindications, the technique and complications that may arise following the procedure. This article is part of a series on vascular access. We have previously written on the intra osseous procedure and an article on umbilical vein catheterisation will follow.

Anatomical Variations of the External Jugular Vein: A Pictorial and Critical Review.

(1) Background: The external jugular vein (EJV) descends on the sternocleidomastoid muscle to drain deep into the subclavian vein. Anatomical variations of the EJV are relevant for identification of the greater auricular nerve, flap design and preparation, or EJV cannulation. (2) Methods: Different publications were comprehensively reviewed. Dissections and three-dimensional volume renderings of peculiar cases were used to sample the review. (3) Results: Different anatomical possibilities of the EJV were critically reviewed and documented: fenestrations and double fenestrations, true or false duplications, triplication, absence, aberrant origin or course, or bifurcation. Tributaries of the EJV, such as the facial and posterior external jugular veins, are discussed. The internal jugular vein termination of the EJV is also presented. (4) Conclusions: Care should be taken when different morphological features of the EJV are encountered or reported.

Normal reference values for magnetic resonance imaging measurements of the fetal internal jugular veins in middle and late pregnancy.

BACKGROUND: At present, there is a lack of normal magnetic resonance imaging (MRI) morphometric reference values for fetal internal jugular veins during middle and late pregnancy. OBJECTIVE: We used MRI to assess the morphology and cross-sectional area of the internal jugular veins of fetuses during middle and late pregnancy and to explore the clinical value of these parameters. MATERIALS AND METHODS: The MRI images of 126 fetuses in middle and late pregnancy were retrospectively analysed to determine the optimal sequence for imaging the internal jugular veins. Morphological observation of the fetal internal jugular veins in each gestational week was carried out, lumen cross-sectional area was measured and the relationship between these data and gestational age was analysed. RESULTS: The balanced steady-state free precession sequence was superior to other MRI sequences used for fetal imaging. The cross section of fetal internal jugular veins was predominantly circular in both the middle and late stages of pregnancy, however the prevalence of an oval cross section was significantly higher in the late gestational age group. The cross-sectional area of the lumen of the fetal internal jugular veins increased with increasing gestational age. Fetal jugular vein asymmetry was common, with the right jugular vein being dominant in the high gestational age group. CONCLUSION: We provide normal reference values for fetal internal jugular veins measured by MRI. These values may form the basis for clinical assessment of abnormal dilation or stenosis.

Assessment of jugular bulb variability based on 3D surface models: quantitative measurements and surgical implications.

PURPOSE: High-riding jugular bulbs (JBs) among other anatomical variations can limit surgical access during lateral skull base surgery or middle ear surgery and must be carefully assessed preoperatively. We reconstruct 3D surface models to evaluate recent JB classification systems and assess the variability in the JB and surrounding structures. METHODS: 3D surface models were reconstructed from 46 temporal bones from computed tomography scans. Two independent raters visually assessed the height of the JB in the 3D models. Distances between the round window and the JB dome were measured to evaluate the spacing of this area. Additional distances between landmarks on surrounding structures were measured and statistically analyzed to describe the anatomical variability between and within subjects. RESULTS: The visual classification revealed that 30% of the specimens had no JB, 63% a low JB, and 7% a high-riding JB. The measured mean distance from the round window to the jugular bulb ranges between 3.22 ± 0.97 mm and 10.34 ± 1.41 mm. The distance measurement (error rate 5%) was more accurate than the visual classification (error rate 15%). The variability of the JB was higher than for the surrounding structures. No systematic laterality was found for any structure. CONCLUSION: Qualitative analysis in 3D models can contribute to a better spatial orientation in the lateral skull base and, thereby, have important implications during planning of middle ear and lateral skull base surgery.

Should Sedillot's triangle be used for central venous cannulation? A cadaveric study.

Central venous access remains an integral part of perioperative and intensive care, and several methods have been described to locate the internal jugular vein (IJV) prior to cannulation. The apex of Sedillot's triangle between the manubrial and clavicular heads of the sternocleidomastoid (SCM) muscle is a commonly used anatomical landmark for a central percutaneous approach to the IJV, but the literature highlights failures and complications when adopting this method. This cadaveric study was designed to investigate the usefulness of Sedillot's triangle to locate the IJV. Sixty-one cadavers were used for investigation at the University of Cambridge Human Anatomy Centre. Sedillot's triangle was dissected and a pin was inserted in a sagittal plane at the apex of the triangle. The location of the pin in relation to the IJV was recorded. The distance between the sternal and clavicular heads of SCM was also measured. In total, the pin inserted at the apex of Sedillot's triangle pierced the IJV in 72/117 (61.5%) of dissections, with 71.4% on the right and 52.5% on the left. There was important variation in SCM anatomy, and there was no gap between its two heads in 12% of the neck dissections. We demonstrate an overall poor success rate of the central percutaneous approach using Sedillot's triangle, although our findings are limited being a simulated cadaveric study. We support education and use of ultrasound in addition to landmark techniques to aid the safe insertion of central venous catheters.

Clinical applications of the mastoid emissary vein.

PURPOSE: During retrosigmoid craniotomy, the mastoid emissary vein (MEV) can be a source of considerable bleeding during the operation, especially when the larger diameter MEV or sigmoid sinus is torn. In this study, we evaluated the relevant structure of the MEV for their anatomy and applied the data in surgery to summarize their clinical significance. METHODS: The posterior craniocervical regions of 15 silicon-injected Chinese human cadaver specimens were dissected to expose the MEV and adjacent structures. Fifty-one patients who were scheduled to undergo retrosigmoid craniotomy were selected. All patients underwent preoperative routine CT of the head. The relevant data were collected on cadaveric anatomy and CT. Eventually, all patients underwent retrosigmoid craniotomy and the MEV was observed during the operation. RESULTS: In cadaver specimens, the prevalence of the MEV was 90.0%. It originated from the middle and lower parts of the posterior wall of the sigmoid sinus and extended in the posterior direction in the mastoid process, usually having 1-2 external openings (86.7%) and only 1 internal opening. The intraosseous courses of the MEV were classified as straight and curved. The straight type accounted for 57.9%, and the curved type for 42.1%. The mean diameter of the MEV was 1.84 ± 0.85 mm, and the straight length of the MEV inside the mastoid process was 11.93 ± 3.58 mm. In 16.7% and 6.7% of all cadaver specimens, the MEV diameter was greater than 2.5 and 4 mm, respectively. In 51 patients (bilateral), routine head CT scan showed the MEV in 49.0% of the patients, and the MEV diameter was greater than 2.5 and 4 mm, respectively, in 17.6% (18/102) and 3.9% (4/102) of the cases. During surgery (unilateral) in the 51 patients, 48 had the MEV and 3 had no MEV. None of the patients had sigmoid sinus tears or massive bleeding. CONCLUSION: In the process of retrosigmoid craniotomy, detailed anatomical knowledge of the MEV, well-planned CT scan, and meticulous microsurgical techniques are key for successful operation, which can reduce the occurrence of complications.

Anatomical Characteristics of the Anterior Jugular Vein and Its Clinical Relevance.

INTRODUCTION: The anterior jugular vein (AJV) is part of the superficial venous drainage system of the head and neck. Recently, interest in AJV is increasing as various surgical procedures have been developed. The authors conducted a cadaveric study to determine characteristics of AJV in Koreans. METHODS: A total of 44 cadavers were dissected. Anatomical characteristics were analyzed for 34 cadavers in which AJV was well observed. RESULTS: In this study, 21 were males and 13 were females. There were 8 cadavers with only 1 AJV from both sides. There was no significant difference in anatomical characteristics according to gender or AJV variation except for a difference in the length of the neck according to gender. However, it was possible to find a safety zone at the main landmark of the neck that could avoid AJV damage. CONCLUSIONS: By using this safety zone, it is possible to prevent damage to the AJV and reduce complications during various surgical procedures on the head and neck.

The Wandering Nerve: Positional Variations of the Cervical Vagus Nerve and Neurosurgical Implications.

BACKGROUND: The vagus ("wandering") nerve is the longest cranial nerve with the largest territory of innervation in the human body. Injury during various operative procedures involving the anterior or lateral neck may lead to serious complications. Per "textbook" descriptions, the cervical vagus nerve (CVN) commonly locates within the carotid sheath, in between the common carotid artery (CCA) and internal jugular vein (IJV). However, anatomic variations in its positioning may occur more often than expected and intraoperative identification may anticipate potential surgical pitfalls. METHODS: A literature review was conducted per PRISMA guidelines for all studies describing positional variations of the CVN within the carotid sheath. A rare and potentially dangerous variation, occurring in only 0.7% of all reported cases, is illustrated with a cadaveric case. RESULTS: Overall, 10 anatomic CVN variations have been described across 971 specimens. The non-textbook variations (26.5%) consist of: lateral (4.7%), anterolateral (8.7%), posteromedial (0.2%), posterior (5.8%), anterior (3.1%), medial (0.7%), and anteromedial (0.4%) to the CCA, as well as posterolateral (0.3%) and posterior (2.6%) to IJV. The "textbook" anatomic location is posterolateral to CCA (73.5%). Moreover, an increase in variability is reported on the left side (17.1%) compared with the right (11.3%). Our cadaveric dissection revealed a right-sided CVN directly medial to the CCA. CONCLUSIONS: Positional variations of the CVN occur in over 26% of patients and may add difficulty to an array of surgical procedures. Knowledge of these variations and their prevalence may aid the surgeon in conducting a more precise dissection possibly preventing significant potential adverse sequelae.

Ultrasound Probe Positions for Internal Jugular Vein Cannulation: A Prospective Study of Different Techniques.

OBJECTIVE: We compared sonoanatomy of the internal jugular vein (IJV) the high (HA), conventional (CA) and the medial oblique approach (MA) to identify the best approach and head position for IJV cannulation. MATERIALS & METHODS: Total of 45 volunteers aged 18-65 years were included in this study. The degree of overlap in percentage, depth of IJV from skin, antero-posterior (AP) and transverse diameters (TD) of IJV were measured in real time with ultrasound (US). Measurements were taken in the HA, CA and MA in neutral and 30° head rotation on both the right and left side of the neck. RESULTS: The HA had lower percentage of overlap when compared to CA and MA in neutral and 30° head rotation (p= 0.002 to ≤0.001). The IJV was more shallow in the CA and MA. The AP and TD of the IJV were larger in the MA when compared to HA (p=<0.001) and CA (p =0.026 to < 0.001) and the right IJV has a larger AP and TD in all approaches. DISCUSSION: The HA had the least percentage of overlap compared to CA and MA, therefore the risk of accidental ICA puncture can be reduced. The apparent overlap seen in MA may not reflect the actual scenario because of the way the US beam cuts the vessel. The AP and TD of IJV were significantly increased in the MA, which would ease CVC. CONCLUSION: We conclude and recommend the medial oblique probe position with 30° head rotation provides optimal real time sonographic parameters for US guided IJV cannulation.

Duplication of the external jugular vein: a language barrier of database search in classic anatomical studies.

OBJECTIVE: Many anatomical variations of the superficial veins of the head and neck have been reported throughout the literature. Accordingly, anatomists and surgeons must have a comprehensive understanding of these variations to avoid confusion. Duplication of the external jugular vein (EJV) is occasionally observed during routine cadaveric dissections; however, this variation seems to be reported less often than actual experience suggests. Therefore, to gain a better understanding of its anatomical and clinical implications, an analysis of the available data should be available. Thus, in this article, we reviewed the current available literature for studies reporting duplication of the EJV. METHODS: We conducted a search using PubMed and Google Scholar with the following keywords: "duplication of the external jugular vein," "division of the external jugular vein," and "fenestration of the external jugular vein," "double external jugular vein," and "doubled external jugular vein." As a case illustration, we also describe a case of a duplicated EJV found during a right neck dissection of a female cadaver. RESULTS: Twenty sides across sixteen different studies were analyzed including the present case. All studies were published between 2009 and 2020. EJV division patterns were classified as either duplication, fenestration, fenestration followed by duplication, or double fenestrations. CONCLUSIONS: We have reviewed the literature regarding cases documenting duplication/fenestration of the EJV. As it is often difficult to find recent studies that report on classic anatomical variations, therefore, revisiting older articles and textbooks is necessary for achieving a "comprehensive" review, especially across different languages.

Surgical and embryological perspective of a big loop of internal carotid artery extending laterally beyond internal jugular vein.

Knowledge of variations of the internal carotid artery is significant to surgeons and radiologists. The internal carotid artery normally runs a straight course in the neck. Its anomalies can lead to its iatrogenic injuries. We report a case of a large loop of the internal carotid artery in a male cadaver aged about 75 years. The common carotid artery terminated by dividing it into the external carotid artery and internal carotid arteries at the level of the upper border of the thyroid cartilage. From the level of origin, the internal carotid artery coursed upwards, backwards and laterally, and formed a large loop behind the internal jugular vein. The variation was found on the left side of the neck and was unilateral. The uncommon looping of the internal carotid artery might result in altered blood flow to the brain and may lead to misperceptions in surgical, imaging, and invasive procedures.

The position of the common facial vein in neonates: An alternate route for central venous catheter placement.

INTRODUCTION: We determine the location of the common facial vein (CFV) in a sample of neonates and assess the safety of this vein as an alternative access route for a central venous catheter (CVC). MATERIALS AND METHODS: We dissected both the left and right sides of the neck region in 24 neonatal, formalin-fixed cadavers, exposing the underlying soft tissues and neurovascular structures. We identified the CFV, which we then pinned together with the internal jugular vein, cervical branch of facial nerve, marginal mandibular branch of the facial nerve, the cricoid cartilage, brachiocephalic vein, and the mastoid and sternal attachments of the sternocleidomastoid muscle. We measured the CFV and the related pinned structures. RESULTS: In neonates, the CFV intersected the anterior border of sternocleidomastoid on average 19.53 mm (left) and 21.73 mm (right) from its sternal attachment. CONCLUSION: We found the CFV inferior to the upper one third and just superior to half of the length of the sternocleidomastoid muscle, indicating a possible "safe-zone" where a skin incision could be made over the anteromedial border of sternocleidomastoid. The CFV is easily identified from surrounding landmarks. It could be used as a safe, alternative route for inserting a CVC if its average length (8.72 mm) and diameter (1.50 mm) are taken into account.