Circulatory System II and Great Vessels

Circulatory System II

• Venules have the lowest pressure.
• Capillaries are sites for gas exchange.

Great Vessels

• The aorta emerges from the left ventricle.
• At first, the aorta moves upwards, then curves downwards.
• Parts of the aorta:
  • Ascending aorta
  • Aortic arch
  • Descending aorta (divided into thoracic and abdominal aorta)
  • Location varies according to its region (imb and neck)

Aortic Arch

• Curves to the left, like an inverted U.
• Superior to the heart.
• Gives off three major arteries: brachiocephalic trunk, left common carotid artery, and left subclavian artery.

Arteries of the Upper Limb

• Subclavian artery is the artery of the upper extremity.
• Branches into axillary and then brachial arteries.
• Brachial artery terminates into ulnar and radial arteries.
• Changing angle for brachial pulse (radial and ulnar).

Common Carotid Artery

• Divides into internal and external carotid arteries.
• Internal carotid artery goes into skull cavity, nourishing the brain.
• External carotid artery nourishes head and neck structures except the brain.
• Foramen magnum separation.

Aorta Termination

• Aorta terminates at the level of L4 vertebra.
• Bifurcation is where aorta divides into two terminal branches.
• Right and left common iliac arteries.
• Each common iliac artery gives off internal and external iliac branches.
  • Internal carotid artery supplies organs in the pelvis.
  • External iliac artery continues as femoral artery, supplying lower extremity.

Femoral Artery

• Reaches the back of the knee, becoming the popliteal artery.
• Popliteal artery splits into anterior and posterior arteries.

Lower Limb Veins

• Superficial veins: Arcus venosus dorsalis, great saphenous, and small saphenous veins.
  • Great saphenous vein opens into femoral vein.
  • Small saphenous vein empties into popliteal vein.

Deep Veins of the Lower Limb

• Anterior and posterior tibial veins and fibular veins drain into popliteal veins.
• Popliteal vein continues as femoral vein in the thigh region.

Intravenous Injection

• Tourniquet is used for intravenous injection.
• Puncture site covered.
• Specimen retrieved.
• Angle of injection determined by the vein's location.