Internal jugular vein
The internal jugular vein receives eight tributaries along its course. Its function is to drain the venous blood from the majority of the skull, brain, and superficial structures of the head and neck.
This article will discuss the anatomy and function of the internal jugular vein.
|Drains from||Sigmoid sinus|
|Tributaries||Inferior petrosal sinus, vein of cochlear duct, meningeal veins, pharyngeal venous plexus, lingual vein, common facial vein, sternocleidomastoid vein, superior and middle thyroid vein|
|Drains to||Brachiocephalic vein|
|Drainage area||Brain, skull, oral cavity, superficial structures of face and neck|
Origin and course
The internal jugular vein originates within the posterior part of the jugular foramen, under the posterior part of the floor of the tympanic cavity. The IJV is continuous with the sigmoid sinus; however, its origin is demarcated by a dilation called the superior bulb of internal jugular vein.
The internal jugular vein passes through the jugular foramen together with the internal carotid artery. It lies posterior to the artery, with the glossopharyngeal (CN IX), vagus (CN X), accessory (CN XI) and hypoglossal (CN XII) nerves passing between their adjoining surfaces. The internal jugular vein then traverses the carotid sheath, descending in a nearly vertical fashion down the neck. Within the sheath, the IJV lies lateral to the common carotid artery and the vagus nerve.
The IJV ends posteriorly to the sternal end of the clavicle by merging with the ipsilateral subclavian vein and forming the brachiocephalic (innominate) vein. Prior to its termination, the IJV usually features a terminal dilation called the inferior bulb of internal jugular vein.
The tributaries of the internal jugular vein are the inferior petrosal sinus, vein of cochlear duct, meningeal veins, pharyngeal venous plexus, lingual vein, common facial vein, sternocleidomastoid vein, superior and middle thyroid vein.
Along its course, the internal jugular vein is related to several structures of the neck. Going from the skull to the clavicle, the relations of the IJV are as follows;
- The posterior aspect of the vein is related to the rectus capitis lateralis, transverse process of atlas, scalenus anterior, cervical plexus, phrenic nerve, thyrocervical trunk, vertebral vein and subclavian artery.
- The whole anterior aspect of the vein, except for a short superior portion, lies deep to the sternocleidomastoid muscle. Below the sternocleidomastoid, the anterior surface of the vein is crossed by the posterior belly of digastric and superior belly of omohyoid muscles, which divide the vein into three areas;
- The area of the vein above the posterior belly of digastric muscle is crossed by the parotid gland, styloid process, accessory nerve (CN XI), posterior auricular and occipital arteries.
- The area between the bellies of digastric and omohyoid muscles is crossed by the ansa cervicalis and the muscular branches of superior thyroid artery that supply the sternocleidomastoid muscle.
- The area below the omohyoid muscle is related to the sternocleidomastoid directly, as well as the infrahyoid muscles and the anterior jugular vein.
Jugular venous pressure (JVP)
The jugular venous pressure and jugular venous pulse are used as indirect measures of cardiac function. More specifically, since the jugular veins are the most accessible connection to the right side of the heart, the JVP is used to examine the function of the right atrium.
The JVP is usually assessed on the right side of the patient’s neck. The examiner palpates the internal jugular vein in order to determine the location and quality of the jugular venous pulse. The mean jugular venous pressure is defined as a distance between the midpoint of the right atrium and the palpable jugular venous pulsation. The normal mean jugular venous pressure is 6-8 cm H2O (4.4-5.8 mmHg). A value below the normal range usually indicates hypovolemia, while a value higher than normal is a classic sign of venous hypertension due to impaired cardiac filling.