Human Anatomy and Physiology - I. V. Gayvoronsky 2011

Cardiovascular System
Arterial System

The Arteries of the systemic Circulation deliver Blood to the hemo-microcirculatory bed and subsequently to the Tissues. The arterial system consists of arteries, the largest of which share a similar angioarchitecture and topography in most individuals (Fig. 12.8).

The largest artery in The Human Body is the aorta, aorta. Its average diameter is approximately 2 cm. The aorta is classified as an elastic-type artery. It originates from the left ventricle and comprises three parts: the ascending aorta, the aortic arch, and the descending aorta. The descending aorta is further subdivided into the thoracic and abdominal parts. At the level of the fifth lumbar vertebra, the Abdominal Aorta bifurcates into the right and left common iliac arteries (Fig. 12.9).

The ascending aorta, pars ascendens aortae. In its initial segment, it lies posterior to the pulmonary trunk. It gives rise to the aforementioned right and left coronary arteries, which supply The Heart wall. Ascending superiorly and to the right, the ascending aorta continues as the aortic arch.

The aortic arch, arcus aortae. It is named after its characteristic curvature. Three major arteries originate from its superior surface: the brachiocephalic trunk, the left common carotid artery, and the left Subclavian Artery. The brachiocephalic trunk branches off the aortic arch, extends superiorly and to the right, and then divides into the right common carotid and right subclavian arteries.

The right common carotid artery arises from the brachiocephalic trunk, whereas the left arises directly from the aortic arch. Consequently, the left common carotid artery is longer than the right. Along its course, this vessel gives off no branches.

The common carotid artery lies adjacent to the anterior tubercles of the transverse processes of the V–VI cervical vertebrae, against which it can be compressed in the event of trauma. The common carotid artery is situated lateral to the Esophagus and Trachea. At the level of the upper border of the thyroid Cartilage, it terminates by dividing into its terminal branches: the external and internal carotid arteries (Fig. 12.10). In the region of this bifurcation, the arterial pulse can be palpated beneath the Skin. Located here as well is the carotid sinus—a cluster of chemoreceptors that monitor The chemical composition of the blood.

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Fig. 12.8. Arterial system (schematic diagram):

1 — facial artery; 2 — left common carotid artery; 3 — left subclavian artery; 4 — axillary artery; 5 — left brachial artery; 6 — radial artery; 7 — ulnar artery; 8 — deep palmar arch; 9 — superficial palmar arch; 10 — abdominal aorta; 11 — left common iliac artery; 12 — external iliac artery; 13 — femoral artery; 14 — internal iliac artery; 15 — popliteal artery; 16 — posterior tibial artery; 17 — anterior tibial artery; 18 — dorsalis pedis artery; 19 — deep artery of the thigh; 20 — renal artery; 21 — right brachial artery; 22 — right subclavian artery; 23 — brachiocephalic trunk; 24 — occipital artery; 25 — superficial temporal artery

The External Carotid Artery, a. carotis externa, ascends superiorly to the level of the external acoustic meatus. Its branches can be classified into four groups: anterior, posterior, medial, and terminal.

Fig. 12.9. Segments and Branches of the aorta:

1 — vertebral artery; 2 — thyrocervical trunk; 3 — left common carotid artery; 4 — left subclavian artery; 5 — axillary artery; 6 — aortic arch; 7 — bronchial branches; 8 — Thoracic Aorta; 9 — intercostal arteries; 10 — celiac trunk; 11 — superior mesenteric artery; 12 — abdominal aorta; 13 — left testicular (ovarian) artery; 14 — inferior mesenteric artery; 15 — external iliac artery; 16 — median sacral artery; 17 — Ureter; 18 — lumbar artery; 19 — right testicular (ovarian) artery; 20 — Kidney; 21 — renal artery; 22 — suprarenal gland; 23 — inferior phrenic artery; 24 — ascending aorta; 25 — brachial artery; 26 — brachiocephalic trunk; 27 — right subclavian artery; 28 — right common carotid artery

Fig. 12.10. Arteries of the HEAD and Neck:

1 — frontal artery; 2 — angular artery; 3 — maxillary artery; 4 — inferior alveolar artery; 5 — facial artery; 6 — lingual artery; 7 — superior thyroid artery; 8 — right common carotid artery; 9 — ascending cervical artery; 10 — inferior thyroid artery; 11 — thyrocervical trunk; 12 — internal thoracic artery; 13 — subclavian artery; 14 — superficial cervical artery; 15 — transverse cervical artery; 16 — suprascapular artery; 17 — deep cervical artery; 18 — vertebral artery; 19 — external carotid artery; 20 — Internal Carotid Artery; 21 — occipital artery; 22 — superficial temporal artery

1. The Anterior Group of branches comprises: the superior thyroid artery, which supplies blood to the Larynx, Thyroid Gland, and Neck Muscles; the lingual artery, supplying the Tongue, sublingual salivary gland, and oral mucosa; and the facial artery, which supplies the submandibular gland, palatine tonsil, Lips, and Muscles of facial expression, continuing to the medial angle of the eye as the angular artery.

2. The posterior group includes: the occipital artery, supplying the corresponding scalp region; the posterior auricular artery, which supplies the auricle, external acoustic meatus, and Middle ear; and the sternocleidomastoid artery, supplying the Muscle of the same name.

3. The medial branch is the ascending pharyngeal artery, which supplies blood to the Pharynx, Tonsils, pharyngotympanic tube, soft palate, and middle ear.

4. The terminal branches are the superficial temporal and maxillary arteries. The superficial temporal artery runs anterior to the external acoustic meatus and participates in the Blood supply to the soft Tissues of the face, as well as the frontal, temporal, and parietal regions. The maxillary artery passes medial to the neck of the Mandible, supplying the deep facial tissues, Teeth, and dura mater. In addition, the maxillary artery supplies the Muscles of Mastication and contributes to the blood supply of the Nasal cavity, infraorbital region, and soft palate.

The internal carotid artery, a. carotis interna, gives off no branches in the neck. It passes through the carotid canal of the Temporal bone into the cranial cavity, where it continues as the anterior and middle cerebral arteries. The anterior cerebral artery participates in supplying the Medial surface of the cerebral hemispheres. The middle cerebral artery runs within the lateral sulcus of the corresponding hemisphere, supplying the frontal, temporal, and parietal lobes.

The subclavian artery, a. subclavia, is longer on the left side than on the right. It arches over the first rib and passes between the scalene muscles alongside the Brachial Plexus. This artery gives off several branches:

1) the internal thoracic artery descends posterior to the costal cartilages, supplying the Thymus, Pericardium, anterior chest wall, mammary gland, Diaphragm, and anterior abdominal wall;

2) the vertebral artery courses through the transverse foramina of the upper six cervical vertebrae, enters the cranial cavity through the foramen magnum, and unites with the contralateral vertebral artery to form the unpaired Basilar artery. The latter gives off branches to the Medulla Oblongata, Pons, Cerebellum, and Midbrain, and subsequently bifurcates into the two posterior cerebral arteries, which supply the occipital lobe and part of the temporal lobe;

3) the thyrocervical trunk, the branches of which supply blood to The Thyroid Gland, neck muscles, the first intercostal space, and certain back muscles.

Thus, the branches of the subclavian artery supply blood to the Brain and partially to the Spinal Cord, chest, muscles and skin of the anterior abdominal wall, diaphragm, and several Internal Organs, including the larynx, trachea, esophagus, thyroid gland, and thymus.

The circle of Willis is an arterial ring located on the ventral surface of the cerebrum, representing a prominent anastomosis between the right and left internal carotid arteries and the basilar artery. The latter is formed by the confluence of the two vertebral arteries.

The right and left anterior cerebral arteries anastomose with each other via the anterior communicating artery. The internal carotid artery communicates with the posterior cerebral artery (a branch of the basilar artery) through the posterior communicating artery. As a result, the cerebral arterial circle (circle of Willis) is formed. It comprises the anterior cerebral, anterior communicating, internal carotid, posterior communicating, and posterior cerebral arteries (Fig. 12.11). The presence of the circle of Willis makes it possible to compensate for a decrease or cessation of BLOOD FLOW IN one of the cerebral feeding arteries at the expense of other vessels.

Fig. 12.11. Arteries of the brain:

1, 11 — middle cerebral artery; 2 — internal carotid artery; 3 — posterior communicating artery; 4 — cerebellar arteries; 5 — anterior spinal artery; 6 — vertebral artery; 7 — posterior spinal artery; 8 — medulla oblongata; 9 — basilar artery; 10 — posterior cerebral artery; 12 — anterior cerebral artery; 13 — anterior communicating artery

Fig. 12.12. Arteries of the upper limb:

1 — vertebral artery; 2 — thyrocervical trunk; 3 — subclavian artery; 4 — internal thoracic artery; 5 — subscapular artery; 6 — lateral thoracic artery; 7 — deep artery of the arm; 8 — arterial network of the elbow joint; 9 — ulnar artery; 10 — deep palmar arch; 11 — superficial palmar arch; 12 — radial artery; 13 — common interosseous artery; 14 — brachial artery; 15 — posterior circumflex humeral artery; 16 — anterior circumflex humeral artery; 17 — axillary artery

The axillary artery, a. axillaris, is the direct continuation of the subclavian artery (Fig. 12.12).

Its major branches include: the thoracic arteries, supplying the pectoralis Major and minor muscles; the thoracoacromial artery, supplying the skin and Muscles of the chest and shoulder joint region; the lateral thoracic artery, supplying the skin and muscles of the lateral chest wall; the subscapular artery, supplying the muscles of the shoulder girdle and back; and the anterior and posterior humeral circumflex arteries, which supply the skin and muscles of the upper third of the arm.

Emerging from beneath the lower border of the pectoralis major muscle, the axillary artery continues as the brachial artery.

The brachial artery, a. brachialis, lies medial to the biceps brachii muscle. Its pulsation is easily palpable in the middle third of the arm, within the sulcus between the biceps and triceps muscles. Blood pressure is typically measured over the brachial artery. Along its course, this vessel gives off branches that supply the muscles of the arm, the elbow joint, and the humerus. The largest of these is the deep artery of the arm (profunda brachii), which runs through the humeromuscular canal. In the cubital fossa, the brachial artery divides into its terminal branches — the radial and ulnar arteries.

The radial artery, a. radialis, runs along the anterior aspect of the radius and is readily palpable in the radial sulcus, particularly in its lower third between the flexor carpi radialis and brachioradialis muscles. In its lower third, the radial artery lies most superficially and can be compressed against the bone; this is the standard site for taking the pulse. Passing onto the hand, the artery winds around the lateral aspect of the wrist, courses anteriorly between the First and Second Metacarpal bones, and continues into the deep palmar arch, which gives off branches to the muscles and skin of the hand.

The ulnar artery, a. ulnaris, runs along the ulnar side of the anterior forearm, giving off branches to the elbow joint and forearm muscles. One of its branches is the common interosseous artery, whose branches course adjacent to the interosseous membrane of the forearm. Entering the hand, the ulnar artery continues as the superficial palmar arch. Both the superficial and deep palmar arches give off branches to the muscles and skin of the hand. The digital arteries arise from the palmar arches and run along the sides of the digits within the subcutaneous tissue. The digits feature a well-developed network of anastomoses, with the greatest concentration found in the region of the distal Phalanges.

The descending aorta, pars descendens aortae. The aortic arch continues as the descending aorta, which runs through the thoracic cavity and is referred to as the thoracic aorta. Below the diaphragm, the thoracic aorta becomes the abdominal aorta. The latter terminates at the level of the fourth lumbar vertebra by dividing into its terminal branches — the right and left common iliac arteries.

The thoracic aorta is located in the posterior Mediastinum to the left of THE Vertebral Column (see Fig. 12.9). It gives off visceral and parietal branches. The visceral branches include: the tracheal and bronchial branches, which supply the trachea, Bronchi, and lung parenchyma; and the esophageal and pericardial branches, supplying the corresponding organs. The parietal branches include the superior phrenic arteries, which supply the diaphragm, and the posterior intercostal arteries, which participate in the blood supply to the chest wall, Mammary Glands, muscles and skin of the back, and the spinal cord.

The abdominal aorta descends anterior to the lumbar vertebral bodies, lying slightly to the left of the median plane. As it courses inferiorly, it gives off parietal and visceral branches. The parietal branches are paired: the inferior phrenic arteries and four pairs of lumbar arteries, which supply the diaphragm, lumbar region, and spinal cord, respectively. The visceral branches are subdivided into paired and unpaired groups. The paired branches include the middle suprarenal, renal, and ovarian (testicular) arteries, which supply the corresponding organs.

The unpaired branches are the celiac trunk, the superior mesenteric artery, and the inferior mesenteric artery.

The celiac trunk arises from the abdominal aorta at the level of the first lumbar vertebra and divides into three major branches heading toward The Stomach (left gastric artery), Liver (common hepatic artery), and Spleen (splenic artery). These branches contribute to the blood supply of these organs, as well as the duodenum, Pancreas, and Gallbladder. Along the lesser and greater curvatures of the stomach, branches of the celiac trunk form prominent anastomoses.

The superior and inferior mesenteric arteries participate in the blood supply to the intestines. The superior mesenteric artery supplies the entire Small Intestine, cecum and Appendix, ascending colon, and the right half of the transverse colon. The inferior mesenteric artery supplies the left half of the transverse colon, descending and sigmoid colons, as well as the upper rectum. Numerous anastomoses exist between these two vessels.

At the level of the fourth lumbar vertebra, the abdominal aorta divides into the right and left common iliac arteries. Each of these, in turn, gives rise to the internal and external iliac arteries.

The internal iliac artery, a. iliaca interna, descends into the lesser pelvis, where it divides into anterior and posterior trunks that supply the pelvic organs and walls. Its principal visceral branches include: the umbilical artery, which supplies the lower ureter and Urinary Bladder; the uterine (prostatic) artery, which supplies the Uterus and its appendages and the Vagina in females, and the prostate, Seminal Vesicles, and ampullae of the Ductus Deferentes in males; and the internal pudendal artery, which supplies the Scrotum (or Labia Majora), Penis (or Clitoris), Urethra, rectum, and perineal muscles.

The Parietal branches of the internal iliac artery include: the iliolumbar artery, supplying the back and Abdominal muscles; the lateral sacral arteries, supplying the sacrum and spinal cord; the superior and inferior gluteal arteries, supplying the skin and muscles of the gluteal region and the hip joint; and the obturator artery, supplying the pelvic and thigh muscles.

The external iliac artery, a. iliaca externa, is the continuation of the common iliac artery. It passes beneath the inguinal ligament into the thigh through the vascular compartment and continues as the femoral artery (Fig. 12.13). Its branches supply the iliacus muscle and the anterior abdominal wall.

Fig. 12.13. Arteries of the lower limb:

1 — right common iliac artery; 2 — abdominal part of the aorta; 3 — left common iliac artery; 4 — median sacral artery; 5 — internal iliac artery; 6 — femoral artery; 7 — popliteal artery; 8 — posterior tibial artery; 9 — fibular (peroneal) artery; 10 — digital arteries; 11 — dorsal arterial arch; 12 — dorsal artery of the FOOT; 13 — anterior tibial artery; 14 — genicular articular network; 15 — deep artery of the thigh; 16 — external iliac artery

The femoral artery, a. femoralis, upon emerging from beneath the inguinal ligament, passes between the anterior and medial muscle groups of the thigh and further into the popliteal fossa. Along its course, this artery gives off branches that supply the muscles of the thigh, external genitalia, as well as PARTS OF THE abdominal wall and skin. The most significant branch of the femoral artery is the deep artery of the thigh (profunda femoris artery), which plays a vital role in supplying blood to the Posterior muscle group.

The continuation of the femoral artery is the popliteal artery, a. poplitea.

It runs along the posterior surface of the knee joint deep within the popliteal fossa and supplies the knee joint. Upon entering the leg, it divides into the posterior and anterior tibial arteries.

The posterior tibial artery, a. tibialis posterior, descends along the deep musculature and primarily supplies the posterior muscle group of the leg. The fibular (peroneal) artery, branching off from it, supplies the Lateral Muscle Group of the leg. Having passed beneath the medial malleolus, the posterior tibial artery reaches the plantar surface of the foot and divides into its terminal branches—the lateral and medial plantar arteries—which supply the foot from its plantar side.

The anterior tibial artery, a. tibialis anterior, courses anterior to the interosseous membrane of the leg, supplying the anterior muscle group. Descending downward, it continues onto the dorsum of The Foot as the dorsal artery of the foot, the branches of which participate in the blood supply of the dorsal region and anastomose with each other and with the Vessels of the sole.

The digital arteries of the foot (plantar and dorsal) run close to their lateral surfaces. The plantar vessels are considerably more developed than the dorsal ones, forming capillary networks near the fingertips (toes).

Arterial anastomoses. Branches of adjacent arteries, originating from the same or different parent trunks, interconnect to form closed arterial loops. The site where arteries connect with one another is called an anastomosis. Anastomoses occur in virtually every region of the vascular bed. As a rule, vessels of approximately the same diameter anastomose with each other. Inter-system and intra-system anastomoses are distinguished. Inter-system anastomoses are vessels connecting the branches of major (trunk) arteries: the aorta, subclavian arteries, external and internal carotid arteries, and external and internal iliac arteries. Inter-system anastomoses also include connections between vessels of opposite sides of the body. An example is the Circle of Willis (anastomoses between the right and left internal carotid systems, and the right and left subclavian systems). Intra-system anastomoses represent connections between branches of a single major arterial trunk. They are much more common than inter-system anastomoses.

Collateral circulation. In the event of damage or occlusion of a major arterial vessel, Blood flow through it ceases or slows down significantly. As is well known, if blood fails to reach a specific tissue area, the latter undergoes necrosis—it dies off. However, in most cases, this does not happen due to The Development of collateral circulation and blood delivery via anastomoses. Collateral circulation is The process of supplying blood via alternative pathways circumventing local obstructions in the patency of main vessels. In some organs, where anastomoses between intra-organ vessels are poorly developed, collateral circulation may be insufficient. For instance, occlusion of the coronary arteries can lead to myocardial necrosis (myocardial infarction).

Sites for digital compression of major arteries. Several major arteries can be palpated on the human body where they lie superficially. When arteries are injured, their lumen remains open (gapes). Consequently, blood spurts from these vessels in a forceful, pulsating stream. To temporarily stop bleeding, it is recommended to press the damaged vessel against bony structures (Fig. 12.14). Thus, the abdominal aorta can be compressed against the vertebral column in the umbilical region, which halts bleeding from downstream vessels. The common carotid artery is compressed against the sixth cervical vertebra. The superficial temporal artery is easily palpated in the temporal region anterior to the external acoustic meatus. To stop bleeding from the axillary artery or the upper parts of the brachial artery, the subclavian artery can be compressed against the first rib. Within the axilla, the axillary artery is pressed against the head of the humerus. In the middle third of the arm, the brachial artery is compressed along its medial border. The external iliac artery can be pressed against the pubic bone ramus, the femoral and popliteal arteries against the Femur, and the dorsal artery of the foot against the Tarsal Bones.

Fig. 12.14. Sites for digital compression of major arteries:

1 — radial; 2 — ulnar; 3 — brachial; 4 — axillary; 5 — posterior tibial; 6 — dorsal artery of the foot; 7 — popliteal; 8 — femoral; 9 — subclavian; 10 — common carotid; 11 — facial; 12 — superficial temporal