Variations of jugular veins: phylogenic correlation and clinical implications.

To the Editor: Anatomic anomalies are supported by an underlying embryological basis and manifest their clinical impact. The external jugular vein is used as venous manometer, while both the external and internal jugular veins are used for IV catheterization to conduct diagnostic procedures or IV therapies. The variations are important for interventional radiologists who perform transjugular procedures, such as port implantations and the transjugular intrahepatic portosystemic shunt or selective venous blood samplings in patients with hyperparathyroidism of unknown origin. (1)

During routine dissection, variations of major veins were observed on the right side of the head and neck of a middle-aged male cadaver. These variations were found only in 1 of 15 cadavers studied. The external jugular vein began at the angle of the mandible as the continuation of posterior division of retromandibular and passed at first superficial to the sternocleidomastoid muscle, then deep to the muscle and drained into the internal jugular vein above the midpoint of the line joining the angle of the mandible to the middle of the clavicle. The anterior jugular vein was not found at its usual position, but it was passing horizontally superficially to the submandibular gland and joined the common facial vein. The posterior auricular vein was draining into the retromandibular vein before it divided into anterior and posterior divisions. The transverse cervical vein and the supra-scapular vein opened into the internal jugular vein.

Hollinshead (2) described variations of the external jugular vein (1): It runs vertically downwards across the superficial surface of the sternocleidomastoid muscle (very rarely deep into it). (2) In one third of cases, it ends in the internal jugular vein in its lower part. Yadav et al (3) reported a case where the external jugular vein crossed superficially to the sternocleidomastoid muscle and ended in the internal jugular vein, above the level of the superior belly of omohyoid muscle (incidence, 1 of 10 cadavers). In contrast to the above-mentioned literature, in the present report, the external jugular passed obliquely downwards and lateral, at first superficial to the sternocleidomastoid and then obliquely downwards and medial deep to it and drained into the internal jugular vein high up at level of junction of upper 2/5 and lower 3/5 of the line joining the angle of the mandible to middle of the clavicle (incidence, 1 of 15 cadavers). Hollinshead (2) also described variable communications of the anterior jugular vein with the internal jugular or facial vein. He reported absence of 1 anterior jugular vein in 13% cases. Present observations report the anterior jugular vein draining and terminating into internal jugular after joining the common facial vein, while the paramedian portion of the anterior jugular vein was found missing on the right side. Hollinshead (2) further reported that external jugular vein usually receives the transverse cervical vein and suprascapular vein. In the present case, these veins were draining into the internal jugular vein. In its usual course, the posterior division of the retromandibular vein unites with the posterior auricular vein to form the external jugular vein. While in the present report, the posterior auricular vein drained into the undivided retromandibular vein, whose posterior division continued as the external jugular vein. This unilateral spectrum of anatomic variation makes it a rare special case.

Each precardinal vein (also called anterior cardinal) consists of two parts: (1) the primary head vein and (2) the true precardinal. The precardinals continue as internal jugular veins. The external jugular and subclavian veins are both extraneous vessels that develop independently and attach secondarily. (4) In the course of normal development, the deep parts of cephalic venous ring along the medial end of the clavicle forms the subclavian vein and receives the external jugular vein as a tributary. The primary head vein also joins the cephalic venous ring and forms the internal jugular vein. (3) In the present case, the external jugular vein drains that portion of the cephalic venous ring which was incorporated into internal jugular veins. Subsequently, with elongation of the neck, the terminal portion of the external jugular vein moved higher up. Hence, the anterior jugular vein, transverse cervical vein, and suprascapular vein, all of which usually open into the external jugular vein, in the present case opened into the internal jugular vein. Gupta et al reported the drainage pattern found in horse, ox, and dog, where the vein from the face drained into the external jugular vein, the internal jugular vein being either absent or a small vessel accompanying the carotid artery. (5) On the basis of the aforesaid observations, the anatomic variations of the present case can be said to be more evolved.

R. Prakash

L. V. Prabhu

J. Kumar

V. Nayak

Kasturba Medical College 

Benjai, Mangalore, India

G. Singh

I.M.S., Banaras Hindu University 

Varanasi, U.P., India

References

1. Sugg SL, Fraker DL, Alexander R, et al. Prospective evaluation of selective venous sampling for parathyroid hormone concentration in patients undergoing reoperations for primary hyperparathyroidism. Surgery 1993;114:1004-1010.

2. Hollinshead WH. Anatomy for Surgeons: The Head and Neck, 3rd ed. New York, Harper and Row Publishers, 1982, pp 467-469.

3. Yadav S, Ghosh SK, Anand C. Variations of superficial veins of head and neck. Anat Soc India 2000;49:61-62.

4. Arey LB. Developmental Anatomy. 7th ed. Philadelphia, WB Saunders Company, 1974, pp 364-365.

5. Gupta V, Tuli A, Choudhry R et al. Facial vein draining into external jugular vein in humans: its variations, phylogenetic retention and clinical relevance. Surg Radiol Anat 2003;25:36-41.