|Year : 2015 | Volume
| Issue : 3 | Page : 196-198
Possible entrapment of external jugular vein in the supraclavicular triangle by the presence of accessory cleido-occipitalis muscle
Naveen Kumar, Jyothsna Patil, S Swamy Ravindra, Ashwini Aithal, Anitha Guru, Surekha D Shetty
Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal, Karnataka, India
|Date of Web Publication||9-Dec-2015|
Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal - 576 104, Karnataka
Source of Support: None, Conflict of Interest: None
Accessory cleido-occipitalis muscle is an additional muscle fascicle derived from occipital portion of trapezius muscle inserted into the clavicle. Since its location is confined to neck region, it is also known as cleido-occipitalis cervicis. In the present case, we report a unique case of accessory cleido-occipitalis muscle derived from trapezius muscle. It was more tendinous than muscular and its tendon was extending medially, crossing the supraclavicular triangle of the neck horizontally in close approximation of clavicle. A narrow gap between them was a passage for the external jugular vein with its possible entrapment. The external jugular vein is a clinically important superficial venous channel required for many therapeutic interventions. The possible entrapment of it could hinder these approaches and also could lead to several complications.
Keywords: Accessory cleido-occipitalis, cleido-occipitalis cervicalis, entrapment, external jugular vein
|How to cite this article:|
Kumar N, Patil J, Ravindra S S, Aithal A, Guru A, Shetty SD. Possible entrapment of external jugular vein in the supraclavicular triangle by the presence of accessory cleido-occipitalis muscle. Saudi J Health Sci 2015;4:196-8
|How to cite this URL:|
Kumar N, Patil J, Ravindra S S, Aithal A, Guru A, Shetty SD. Possible entrapment of external jugular vein in the supraclavicular triangle by the presence of accessory cleido-occipitalis muscle. Saudi J Health Sci [serial online] 2015 [cited 2019 Jul 20];4:196-8. Available from: http://www.saudijhealthsci.org/text.asp?2015/4/3/196/165491
| Introduction|| |
The trapezius muscle presents three parts of its fibres namely; upper or occipital fibres, that slopes downwards and laterally; middle fibres that extend horizontally and lower fibres that pass upwards and laterally. Since the upper or cervical fibres are attached to clavicle, they are also known as cleido-occipital portion of the trapezius muscle.
On the other hand, there is a variant muscle named as cleido-occipital muscle which represents detached segment of sternocleidomastoid (SCM) and constitute the posterior fibres of clavicular head of the SCM inserted into the occipital bone.
External jugular vein (EJV) is the vein of superficial jugular system formed in the substance of parotid gland. In its course, it descends down in the roof of posterior triangle of the neck, superficial to SCM and drains into subclavian vein. Its superficial course in the neck has made it advantageous for several therapeutic interventions. EJV is preferred as a grafting vessel into the carotid artery during endaterectomy and also in microvascular anastomosis in oral reconstruction procedures.
Sufficient reports on anatomical variations of EJV could be found in the literature. But, the possible entrapment of it in the neck either by the neighbouring structures or by the presence of anomalous structures is quite less common. We report here a case wherein the possible entrapment of EJV in a narrow gap between the tendon of accessory cleido-occipital muscle and the clavicle with its probable consequences.
| Case Report|| |
During routine cadaveric dissection for undergraduate medical students, we noticed an anomalous musculo-tendinous structure; an accessory cleido occipitalis muscle traversing the supraclavicular triangle of the neck. This accessory muscle was fleshy in its origin from the lower part of anterior border of occipital fibres of trapezius muscle and extended horizontally towards the sternal end of the clavicle and inserted into supero-posterior aspect of medial third of shaft of the clavicle [Figure 1] and [Figure 2]. This variant muscle was tendinous in its greater extent and it lied in close approximation with the medial aspect of the clavicle. The point of distal attachment was very close to the origin of clavicular head of SCM. The EJV was noted to be normal in formation, course and termination. However, just before its termination in to sublcavian vein it was found to be entrapped in a narrow gap created between the clavicle and the tendinous part of the accessory cleido-occipitalis muscle [Figure 1] and [Figure 2]. No nervous entrapment was noted otherwise. This anomalous feature was seen on the right side of the neck of a male cadaver aged about 60 years.
|Figure 1: Presence of accessory celido-occipitalis muscle (ACOM) arising from trapezius muscle (TM). EJV—external jugular vein, SCM—sternocleidomastoid, IHM—infrahyoid muscle, SSG—submandibular salivary gland, LON—lesser occipital nerve, GAN—Great auricular nerve, PEJV—posterior external jugular vein SSV—suprascapular vein|
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|Figure 2: (a and b) Closer view showing possible entrapment of external jugular vein (EJV) between the clavicle and tendon of accessory cleido-occipitalis muscle. SCM—sternocleidomastoid, TM—trapezius muscle|
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| Discussion|| |
Occurrence of detached bundles of trapezius muscle is rare and is differentially termed by the authors. An accessory muscular fascicle constituting both from occipital and cervical portions of the trapezius muscle, inserting into the clavicle at the junction of its middle and medial part, termed as anomalous cleido-occipitalis muscle by Rahaman and Yamadori. Although its features are similar to the accessory cleido-occipitalis muscle as we seen in the present case, no features of entrapment of vessels or nerves were mentioned in the report. However, in our case the external jugular vein had all possible chances of entrapment due to presence of variant muscle and its close relation to the clavicle.
Slip of the occipital portion of the trapezius muscle, with the partial fusion of it and inserting into mid portion of clavicle has been termed as cleido-occipitalis cervicalis muscle by Kwak et al., Suitability of this nomenclature has been justified by Paraskevas et al., as its location confined in the cervical region with cleido-occipital extent.
Paraskevas et al., reported accessory cleido-occipitalis muscle that forming a fibrous arch above the supraclavicular nerves. In the present case, supraclavicular nerves were not affected by the presence of accessory cleido-occipitalis muscle. Instead, the EJV had a possible entrapment in the narrow space between the tendon and the clavicle.
Swamy et al., reported a similar case of variant muscle in the neck with the passage of EJV through the triangular space created between the tendon of celeido-occipitalis cervicalis, trapezius muscle and the clavicle. In their case, the tendon of the muscle was in somewhat obliquely placed and therefore the resulting passage was quite spacious. Hence a chance of entrapment of EJV was unlikely. However, in the present case, the tendon of the accessory muscle was horizontally placed and it was almost parallel to the clavicle. Therefore created space was very narrow. As the EJV found to be passing through it, a high possibility of its compression was evident.
EJV is the preferred choice of vein for cannulation for intravenous therapy, haemodialysis etc., Due to its superficial and favourable course in the neck, it is mostly used for many interventional therapeutic approaches. It is also used in the estimation of central venous pressure.
During normal movements of scapula by the contraction of trapezius muscle along with the persistent variant muscle accessory cleido-occipitalis, might aggravate the compressing effect on the EJV resulting in venostasis. In addition to this, entrapped EJV might pose several clinical complications particularly during passage of catheter or cannula or manometer and could result in complication of perforation of the vessel and haemorrhage. Therefore, rare existence of such abnormal muscles adjacent to EJV must be confirmed before performing any therapeutic interventions. Presence of accessory muscles in the neck region erroneously interpreted as lymph node enlargement, cyst or venous thrombosis.
| Conclusion|| |
Variant morphology of the EJV and its possible entrapment in the neck might hinder several surgical approaches associated with it and thus could result in severe complications. Compression of the EJV by the anomalous muscles in the neck may lead to decreased venous return, venous engorgement and oedema of the face. Entrapment of EJV also could endanger the venous catheterisation.
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[Figure 1], [Figure 2]