Generality
The jugular veins are the venous blood vessels that connect the veins of the head with the succlavic veins. The succlavic veins are the veins that precede the brachycephalic veins, which end their course in the superior vena cava; the superior vena cava is the large venous blood vessel that collects all the blood coming from the supradiaphragmatic portion of the human body and places it in the heart.
Inside the jugular veins, the blood that has recently oxygenated the brain and the other tissues of the head flows.
There are two sets of jugular veins: the set of the two external jugulars and the set of the two internal jugulars.
The external jugular veins collect the blood that has sprayed the external part of the skull and the deeper tissues of the face; the internal jugulars, on the other hand, collect the blood that is sprayed on the brain, the meninges, the superficial tissues of the face and neck.
What are jugulars?
The jugulars, or jugular veins, are the venous blood vessels that connect the veins of the head and neck to the succlavic veins . The succlavic veins are the vessels that precede the brachycephalic veins (or innominate veins ), which end their path in the superior vena cava .
The superior vena cava is the large venous blood vessel that collects oxygen-free blood from the organs and tissues of the upper portion of the human body (supradiaphragmatic portion) and places it in the heart .
Thus, in the jugular veins flows oxygen-poor blood, blood that has recently oxygenated the brain and other structures of the head and must return to the heart (right atrium), for its re-oxygenation.
Anatomy
There are two sets of jugulars: the set of the two external jugular veins and the set of the two internal jugular veins.
EXTERIOR JUG HEADS
Located one on the right and one on the left of the neck, the external jugular veins drain the blood in the subclavian veins, with which they are in communication. Clearly, the right external jugular drains blood into the right subclavian vein, while the left external jugular drains blood into the left subclavian vein.
The external jugular veins gather much of the blood that has oxygenated the outer part of the skull and the deeper tissues of the face .
Each external jugular arises from the conjunction between the posterior division of the retromandibular vein and the posterior auricular vein .
The external jugular veins each possess two tributary veins (NB: tributaries mean tributaries). In fact, for each external jugular vein, there is a posterior external jugular vein and an anterior jugular vein . The posterior external jugular vein collects the blood that has oxygenated the back of the neck; the anterior jugular vein, on the other hand, collects the blood that has oxygenated the larynx and all the tissues of the lower portion of the jaw.
As far as the course of the external jugular veins is concerned, these originate where the parotid gland resides, around the height of the so-called angle of the jaw. From here, they descend perpendicularly along the neck, towards the collarbone. In the first part of this path, they settle on the posterior edge of the sternocleidomastoid muscle; subsequently, they cross the latter obliquely, reaching up to the subclavian muscle. At the level of the subclavian muscle, they join the succubic veins.
Each external jugular vein has two pairs of valves: a lower pair and an upper pair.
The lower pair of valves resides at the point where an external jugular vein joins a subclavian vein; the upper pair of valves is usually 4 centimeters higher than the clavicle. The jugular section between the two pairs of valves is called the sine.
The aforementioned valves are used to facilitate the transport of blood in the direction of the heart, but, contrary to what one might think, they do not prevent blood reflux; in other words, they do not prevent the blood from returning back.
INTERNAL JUGS
Like the external jugulars, the two internal jugulars are also one on the right and one on the left, on the neck. Combined with the corresponding subcutaneous veins in a more internal section, compared to what happens with the external jugular veins, their task is to collect the blood that has oxygenated the brain, the meninges, the superficial tissues of the face and neck .
The confluence of the internal jugular veins in the succlavic veins occurs very close to where the latter become brachycephalic veins.
The left internal jugular vein is slightly smaller than the right internal jugular vein.
As regards the course of the internal jugular veins, these originate at the base of the skull, at the point where the so-called inferior petrosal sinus and the so-called sigmoid sinus occur . According to some texts of human anatomy, the starting point of the internal jugular veins would be at the level of the posterior compartment of the jugular hole (or foramen).
From the point of origin, the internal jugular veins proceed along the neck in a vertical direction, occupying a lateral position, first of all, with respect to the internal carotid artery and, subsequently, to the common carotid artery.
In their vertical path along the neck, the internal jugulars are also close to the vagus nerve .
Curiously, both shortly after their origin and shortly before their joining with the succlavic veins, the internal jugular veins have a swelling: the swelling present at the origin is called the upper bulb, while the swelling present almost at the level of the subclavian vein takes the lower bulb name.
Each internal jugular vein contains a pair of valves. Located about 2.5 centimeters higher than where the internal jugular veins end, these valves facilitate the transport of blood, but do not prevent blood reflux.
The jugular veins, the carotid arteries and the vagus nerve are included within the so-called carotid sheath . The carotid sheath is a thickening of the deep cervical fascia.
Function
The jugulars contribute to the return to the heart of the blood which has recently oxygenated the various organs and tissues of the head.
This deoxygenated blood re-enters the right atrium of the heart, through the superior vena cava; once in the right atrium, the cardiac organ, thanks to its contractile capacity, places it first in the right ventricle and then in the lungs . The lungs are the site where oxygen-poor blood is oxygenated.
Thus, from the lungs, blood returns to the heart, precisely in the left atrium; from the left atrium it passes to the left ventricle, which, finally, provides to pump it in the circle in the arterial system.
clinic
The jugular veins lack a bone or cartilage protection, so they are extremely susceptible to damage and injury, which can result, for example, from a cut on the neck.
The injuries to the jugular veins are responsible for a conspicuous loss of blood, as the volume of blood that passes through them is considerable.
JUNE VENOUS WRIST
The pressure of the circulating blood inside the jugular vein is a useful parameter, in the diagnostic field, to identify heart diseases such as heart failure, tricuspid valve stenosis, tricuspid regurgitation or cardiac tamponade.
The measurement of the blood pressure circulating in the jugulars is called the jugular venous pulse .
