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See video at UNSWTV Anatomy of the Peripheral Vasculature
Arteries of the head, neck and upper limbs
- The head, neck and upper limbs receive their blood supply from branches of the arch of the aorta
- Recall that the Rt subclavian a arises as a branch of the brachiocephalic trunk
- On the Lt hand side, the Lt subclavian a arises directly from the aorta, it ascends just behind the common carotid artery, until it reaches the sternoclavicular joint, when it deviates laterally. From this point on, the two subclavian arteries have the same course and distribution in each of the two limbs.
- The two common carotid arteries supply most of the blood to the head and neck. They pass up, into the neck, and run on the lateral sides of the viscera of the neck (e.g. trachea, larynx and thyroid).
- Subclavian artery has a number of branches arising from it. One important one is the first branch: the vertebral artery. This artery passes deeply through the neck and enters the cranial cavity. It supplies the posterior part of the brain and the spinal cord
- After giving off the vertebral artery, the subclavian artery passes over the top of the first rib. Once it reaches the outer edge of the first rib, it is called the axillary artery.
- Note the sternomastoid muscle, passing obliquely across the neck towards the midline. The common carotid artery runs deep to the sternomastoid muscle (lateral to the larynx). Once it reaches the upper border of the thyroid cartilage (C4), it divides into its two terminal branches: the external carotid artery, which supplies most of the structures outside of the cranial cavity (we can see branches for the thyroid gland, larynx, and tongue). Note one of its important branches, the facial artery, which travels up onto the surface of the face.
- The other main branch of the common carotid is the internal carotid artery, which passes deeply to the neck, and gives no branches to the neck before it enters the cranial cavity, where it supplies the brain and other structures inside the cavity.
- Note the subclavian/axillary artery as it passes out towards the upper limb. As the axillary artery passes through the axilla, it is surrounded by the branches of the brachial plexus (which forms the nerves that supply the upper limb). It sends branches to the muscles of the surrounding region. One of these branches is the circumflex artery, which is often a pair of arteries, that surround the neck of the humerus, providing a collateral supply for the shoulder joint.
- The next branch of note is the profunda brachii artery (deep brachial artery). This artery passes deep into the arm and runs with the radial nerve posterior to the humerus
- Note the teres major muscle. The axillary artery, at the lower border of the teres major, changes its name to the brachial artery. The brachial artery continues down the arm along the medial border of the biceps muscle. The artery and the vein together enter the cubital fossa (triangular region anterior to the elbow joint). It's not possible to see the brachial artery and vein in a superficial dissection, because they're under the cover of the bicipital aponeurosis, and they lie medial to the biceps tendon at this point.
- It is as this point, just above the elbow, that you feel/listen for for the brachial artery when taking a brachial pulse/blood pressure
- In the cubital fossa, the brachial artery divides into a radial and ulnar artery. The radial artery passes laterally, and runs down the lateral side of the arm, along the border of the brachioradialis muscle. At the wrist, the artery becomes superficial. At this point, we can push down on the artery to find a radial pulse.
- The ulnar artery is the second branch coming off the brachial artery in the cubital fossa. It passes deep to the pronator teres and some of the flexors of the forearm, and comes to lie on the medial side of the arm, where it runs beneath the flexor carpi ulnaris tendon.
- Radial artery can be palpated on lateral side of the wrist (radial pulse), where it lies lateral to the flexor carpi radialis muscle
- Ulnar artery is located laterally, next to the flexi carpi ulnaris muscle. It lies medial to the pisiform bone. It then enters the palm and lies beneath the palmar aponeurosis. If we lift the palmar aponeurosis, we see the ulnar artery turns across the hand, forming the superficial palmar arch. Arising from this arch we see branches that pass toward the webbed space between each of the fingers. Once these arteries reach the webbed space, they branch into digital arteries, which run down the sides of the adjacent fingers. The arteries run with the digital nerves as they head towards the tips of the fingers. Bleeding in the fingers can be stopped by pressing the sides of the fingers (hence stopping the bloodflow).
- Radial artery passes from the front of the wrist, around the lateral side of the wrist, beneath the long extensor tendons for the thumb, coming to lie in the anatomical snuff box. From here, the artery pierces a muscle between the index finger and thumb, and then emerges on the palmar surface on the hand (very deep). Here, it is referred to as the deep palmar arch. The deep palmar arch has little branches that unite with the branches of the digital branches of the superficial arch. It also has communicating branches at each end that connect it with the superficial arch. This provides a collateral circulation for the hand.
Veins of the head, neck, and upper limbs
- Two major veins drain blood from the head and neck. The first (and largest) is the internal jugular vein, which runs laterally to the common carotid arteries. Running in between these two structures is the vagus nerve. Together, the internal jugular vein, the vagus nerve, and the carotid artery, run down within a sheath of connective tissue called the carotid sheath.
- The internal jugular vein unites on each side with the subclavian vein carrying blood from the upper limb, to form the left and right brachiocephalic veins. These two veins unite to form the superior vena cava which drains into the right atrium of the heart. The internal jugular vein drains the brain and cranial cavity, and the deep structures of the head and neck.
- More superficial structures drain into another vein that crosses the surface of the sternomastoid muscle: the external jugular vein. This vein will empty into the junction of the internal jugular and the subclavian veins on each side.
- Venous blood from the upper and lower limbs drains via two sets of veins:
- the deep veins (accompanying each of the arteries, and named in the same way. The smaller arteries are each accompanied by a pair of deep veins (e.g. radial artery has paired radial veins). These veins are called the venae comitantes (accompanying veins). The venae comitantes are very small because the bulk of the blood from the upper limb is actually drained through the superficial veins.
- the superficial veins are extremely variable between individuals, but everyone has two common superficial veins. These arise from a plexus of veins on the dorsal surface of the hand, known as the dorsal venous network
- on the lateral side, a vein forms known as the cephalic vein. This vein runs up the lateral side of the forearm, past the elbow, and continues across the biceps muscle and enters the deltopectoral groove (between the pectoralis major and deltoid muscles) to join with the axillary vein
- the second major superficial vein arises on the medial side of the dorsal venous arch: the basilic vein. The basilic vein passes up, along the medial side of the arm, and passes around the flexor group of muscles onto the front of the elbow. It then empties into the axillary vein in the arm. The cephalic and basilic veins are generally joined by a communicating vein that passes across the front of the cubital fossa: the median cubital vein. This is where samples of blood are commonly taken
Arteries of the lower limbs
- On a deep dissection of the posterior abdominal wall, we can see the descending aorta (a continuation of the arch of aorta). The descending aorta passes along the vertebral column, just to the left of the midline. When it reaches the fourth lumbar vertebra, it bifurcates into the two common iliac arteries. These pass laterally until they reach the sacroiliac joint, where they bifurcate to form the external iliac artery (which will supply most of the blood to the lower limb) and the internal iliac (which supplies blood to the pelvic organs and muscles of the gluteal region).
- The lower border of the anterior abdominal wall is the inguinal ligament, extending from the ASIS laterally to the pubic tubercle medially. The external iliac artery passes beneath the midpoint of the inguinal ligament. At this point, it changes its name to the femoral artery. The pulse of the femoral artery can be felt by putting your finger just beneath the midpoint of the inguinal ligament.
- The femoral artery is now located in a space on the front of the thigh which is known as the femoral triangle (bounded superiorly by the inguinal ligament, medially by the medial border of the adductor longus muscle, and laterally by the medial border of the sartorius muscle). Within the femoral triangle, we can see it is located laterally to the femoral vein, and medially to the femoral nerve.
- Remember: Dick VAN Dyke.
- Approximately 5cm below the inguinal ligament, the femoral artery gives off a large deep branch called the profunda femoris artery (deep femoral artery). The femoral artery proper passes down the front of the thigh towards the apex of the femoral triangle, where it enters a muscular canal called the adductor canal. At the lower end of this canal, it pierces the adductor magnus muscle at the adductor hiatus (hole in the adductor magnus at the distal termination of the adductor canal), and emerges in the popliteal fossa on the posterior surface of the knee.
- If we look at a superficial dissection of the posterior part of the thigh, we can separate the hamstrings to see the perforating branches of the profunda femoris artery that have come through to supply the hamstrings in the posterior compartment of the thigh.
- Popliteal fossa is a diamond-shaped region in the posterior of the knee, whose bounds are:
|Superior|| superior and medial:
the semitendinosus muscle and semimembranosus muscle
| superior and lateral:|
the biceps femoris muscle
|Inferior|| inferior and medial:
the medial head of the gastrocnemius muscle
| inferior and lateral:|
the lateral head of the gastrocnemius muscle and plantaris muscle
- The femoral artery pierced the adductor magnus muscle and emerged in this fossa. Once it reached the popliteal fossa, its name changed to the popliteal artery (the deepest structure in the popliteal fossa).
- Lying superficially to it is the popliteal vein. The artery is on the deep surface of that vein. Running superficially to both those structures is the tibial nerve.
- At the bottom of the popliteal fossa, the popliteal artery ends by dividing into an anterior and posterior tibial artery.
- The anterior tibial artery pierces the interosseous membrane and passes forward into the anterior compartment of the leg.
- An anterior view of the anterior compartment of the leg shows the anterior tibial artery running through the anterior compartment, deep to all the muscles of this compartment, which it supplies. It emerges from the anterior compartment of the leg and crosses the ankle at the midpoint of the lateral and medial malleoli, and it is at this point that a pulse of this artery can be felt.
- The remainder of the artery continues down onto the dorsum of the foot, where it gives off an arch that are similar to those of the dorsum of the hand.
- Looking at a deep dissection of the leg where the superficial muscles are removed. We can see where the anterior tibial artery forms. The remaining blood vessel is the posterior tibial artery, which can be seen running down the back of the leg, beneath the superficial muscles, and winding around below the medial malleolus at the ankle. This is where we take a pulse for the posterior tibial artery.
- It then passes down onto the sole of the foot, and forms an arch that is similar to the deep arch of the hand.
Veins of the lower limbs
- Like the upper limb, venous blood from the lower limb drains by two sets of veins: deep and superficial. The deep veins accompany the corresponding arteries. The superficial veins lie in the subcutaneous tissue and send connecting branches through to the deep veins along their course. The reason blood travels in the deep veins of the lower limb is that it's travelling against gravity. And because the deep veins are interspersed amongst the muscles, flow in these veins is assisted by contraction of the leg muscles.
- Like the upper limb, we have a dorsal venous network on the dorsum of the foot. Again like the upper limb, two important veins arise from this venous network, one from each side of the dorsal venous network. On the lateral side, a vein called the small saphenous vein forms. This vein passes below the lateral malleolus of the ankle, runs up the midline of the leg to reach the popliteal fossa, where it drains into the popliteal vein. The short saphenous vein is important because it is a site in the lower limb where varicosities occur in the superficial veins. These varicosities occur as a result of faulty valves in the connecting veins between the deep and superficial veins.
- The second major vein in the leg (and the largest vein in the body) is the great saphenous vein. It arises from the medial side of the venous network of the foot, passes in front of the medial malleolus, and travels along the medial side of the leg.
- At the knee, it is found one hand's breadth behind the patella. It then ascends obliquely across the front of the thigh to reach the femoral triangle, where it drains into the femoral vein.
- The great saphenous vein can also become varicose in some individuals, and is also occasionally used for bypass surgery on the heart (to replace the blocked coronary artery).