Lecture 4- Venous drainage of the head and neck Flashcards
Majority of veins follow a similar route to
the arteries and share the same names. Plexus of veins that covers the whole scalp that drain into larger veins.
Anatomically, the venous drainage can be divided into three parts:
- Venous drainage of the brain and meninges: Supplied by the dural venous sinuses.
- Venous drainage of the scalp and face: Drained by veins synonymous with the arteries of the face and scalp. These empty into the internal and external jugular veins.
- Venous drainage of the neck: Carried out by the anterior jugular veins.
There are three main jugular veins –
external, internal and anterior. They are ultimately responsible for the venous drainage of the whole head and neck.
The external jugular vein and its tributaries supply
the majority of the external face.
Posterior auricular vein
– drains the area of scalp superior and posterior to the outer ear.
Retromandibular vein (posterior branch)
– itself formed by the maxillary and superficial temporal veins, which drain the face.
posterior auricular vein and retromandibular vein
combine immediatley posteror to the angle of the mandivle and inferior to the outer ear, forming the external jugular vein
after formation, the external jugular vein
descends down the neck within the superifical fascia. runs anteriorly to the sternocleidomastoid muscel
In the root of the neck, the external jugular vein passes
underneath the clavicle, and terminates by draining into the subclavian vein
anterior jugular veins
vary from person to person. They are paired veins, which drain the anterior aspect of the neck. Often they will communicate via a jugular venous arch. The anterior jugular veins descend down the midline of the neck, emptying into the subclavian vein.
Front of scalp supplied by:
- *
- Supra-orbital vein
- Supratrochlear vein
- Both drain into the facial vein
drainage of the scalp
Drainage of the scalp
- Most blood drains away superficially
- Some blood from the scalp can drain into areas containing venous blood called Dural venous sinus
- Drains via emissary veins through the skull into dural venous sinuses
- Risk of infection- meningitis
internal jugular vein veigns in the
cranial cavity as a continuation of the sigmoid sinus
The initial part of the internal jugular vein is dilated and is known as the superior bulb. It exits the skull via the jugular foramen.
pathways of the internal jugular vein out of the skull
In the neck, the internal jugular vein descends within the carotid sheath, deep to the sternocleidomastoid muscle and lateral to the common carotid artery. At the base of the neck, posteriorly to the sternal end of the clavicle, the IJV combines with the subclavian vein to form the brachiocephalic vein. Immediately prior to this, the inferior end of internal jugular vein dilates to form the inferior bulb. It has a valve that stops back-flow of blood.
During its descent down the neck, the internal jugular vein receives blood from
the facial, lingual, occipital, superior and middle thyroid veins. These veins drain blood from the anterior face, trachea, thyroid, oesophagus, larynx, and muscles of the neck.
Dural Venous Sinuses
The dural venous sinuses are spaces between the periosteal and meningeallayers of dura mater, which are lined by endothelial cells. They collect venous blood from the veins that drain the brain and bony skull, and ultimately drain into the internal jugular vein.
The cavernous sinuses are a clinically important pair of dural sinuses. They are located next to
the lateral aspect of the body of the sphenoid bone. This sinus receives blood from the superior and inferior ophthalmic veins, the middle superficial cerebral veins, and from another dural venous sinus; the sphenoparietal sinus.
Located within the cavernous sinus is the internal carotid artery, which crosses the sinus. This allows for cooling of the arterial blood before it reaches the brain.
If the cavernous sinus becomes infected, nerves that pass through the sinus are
at risk of damage.
The facial vein is connected to cavernous sinus via the superior ophthalmic vein. The facial vein is valveless – blood can reverse direction and flow from the facial vein to the cavernous sinus. This provides a potential pathway by which infection of the face can spread to the venous sinuses.
Venous drainage of the face
Superficial veins
- Supra-orbital vein and supratrochlear vein form the angular vein which drains into the facial vein
- Facial vein joins other veins to form the common facial vein
- Common facial vein drains into the internal jugular vein
Danger triangle of the face
- Region where the facial vein can drain backwards into the cavernous sinus
- Infections in that area can spread via the facial vein and end up in the dural venous sinuses.
describe the pathway of the dural venous sinuses
Dural venous sinuses
Channels formed in the layer of the dura
- Not found all over the head
- Tiny veins drain the cerebral structures into the sagittal sinus (inferior or superior)
- Superior and inferior sagittal sinus will meet at the confluence of the sinuses
- Sweeps round in an s shape pattern exiting through the jugular foramen
- When the sinuses drain through the jugular foramen the blood vessel becomes the internal jugular vein
- Internal jugular vein joins the subclavian vein to form the brachiocephalic vein which forms the superior vena cava joining to the right side of the heart
Jugular veins and Jugular Venous Pressure
As its directly connected to the right atrium, we use the right internal jugular vein to measure venous pressure
- Patient at 45 degrees
- Head slightly tilted to the left
- IJV mostly hidden by SCM
- Look for pulsations through the muscles
- Measure the hight of the sternal angle and add 5cm, gives an estimate of the right atria pressure in cmH2O
