34. The superior and inferior vena cava. Portal vein – position and main tributaries. Anastomoses between the two caval veins. Anastomoses between the portal and systematic circulation.

SVC

• Is a
• valveless
• thin walled
• low pressure tube
• Short vein
• Diameter 2-3 cm.
• Function: drains deoxygenated blood from the upper part of the body into the right atrium.
• Location: located in the anterior right part of the superior mediastinum.

Azygos v. L. Brachiocephalic trunk R. Brachiocephalic trunk jugular v. and subclavian v. join into the L. brachiocephalic trunk; drains into SVC

• Begines: behind the lower border of 1st right costal cartilage (by union of both brachiocephalic veins).
• Ends behind the 3rd right costal cartilage (by opening into the right atrium)

HEAD & NECK VEINS

• Veins of the cranial Cavity: Cerebral veins drain into dural venous sinuses:

These sinuses are either single or paired:

• Single:

1. Superior sagittal sinus.
2. Inferior sagittal sinus.
3. Straight sinus.
4. Occipital sinus.

• Paired:

1. Cavernous sinuses.
2. Transverse.
3. Sigmoid sinuses: which form the internal jugular veins.

• Veins of the face and neck:

1. Facial vein
2. Temporal v.
3. Maxillary v.
4. Occipital.

• Cerebral veins
• drains
• dural venous sinuses
• drain into
• Sigmoid sinuses
• drain into
• Internal jugular
• Face + Neck veins: Facial drains into Internal jugular
• Maxillary v., Temporal v., Occipital v. drain into External jugular vein
• External jugular vein drains into Subclavian vein.
• Internal jugular + Subclavian vein drain into Brachiocephalic vein.