Mecanismo de Cobertura

Inferior phrenic arteries. The inferior phrenics emerge from the aorta at T12, just inferior to the diaphragm. They serve the inferior diaphragm surface.

Celiac trunk. This very large unpaired branch of the abdomi- nal aorta divides almost immediately into three branches: the common hepatic, splenic, and left gastric arteries (Fig- ure 19.24b). The common hepatic artery (he˘-pat⬘ik) gives off branches to the stomach, duodenum, and pancreas. Where the gastroduodenal artery branches off, it becomes the hepatic

artery proper, which splits into right and left branches that serve the liver. As the splenic artery (splen⬘ik) passes deep to the stomach, it sends branches to the pancreas and stomach and terminates in branches to the spleen. The left gastric artery (gaster stomach) supplies part of the stomach and the infe- rior esophagus. The right and left gastroepiploic arteries (gas tro-epı˘-plo⬘ik), branches of the gastroduodenal and splenic arteries, respectively, serve the greater curvature of the stomach. A right gastric artery, which supplies the stomach’s lesser cur- vature, may arise from the common hepatic artery or from the hepatic artery proper.

(continued) TABLE 19.7

Liver (cut) Diaphragm

Esophagus Left gastric artery

Superior mesenteric artery Left gastroepiploic artery Spleen Stomach Pancreas (major portion lies posterior to stomach)

Splenic artery Inferior vena cava

Celiac trunk

Hepatic artery proper Common hepatic artery Gastroduodenal artery Right gastric artery Gallbladder

Abdominal aorta

Right gastroepiploic artery

Duodenum

(b) The celiac trunk and its major branches. The left half of the liver has been removed. Figure 19.24 (continued)

19

Superior mesenteric artery(mes-en-ter⬘ik). This large, un- paired artery arises from the abdominal aorta at the L1level im- mediately below the celiac trunk (Figure 19.24d). It runs deep to the pancreas and then enters the mesentery, where its numer- ous anastomosing branches serve virtually all of the small intes- tine via the intestinal arteries, and most of the large intestine— the appendix, cecum, ascending colon (via the ileocolic and right colic arteries), and part of the transverse colon (via the middle colic artery).

Suprarenal arteries (sooprah-re⬘nal). The middle supra- renal arteries flank the origin of the superior mesenteric artery as they emerge from the abdominal aorta (Figure 19.24c). They supply blood to the adrenal (suprarenal) glands overlying the kidneys. The adrenal glands also receive two sets of branches not illustrated: superior suprarenal branches from the nearby in- ferior phrenic arteries, and inferior suprarenal branches from the nearby renal arteries.

Renal arteries. The short but wide renal arteries, right and left, issue from the lateral surfaces of the aorta slightly below the superior mesenteric artery (between L1and L2). Each serves the kidney on its side.

Gonadal arteries (go-na˘dul). The paired gonadal arteries are called the testicular arteries in males and the ovarian

arteries in females. The ovarian arteries extend into the pelvis to serve the ovaries and part of the uterine tubes. The much longer testicular arteries descend through the pelvis and in- guinal canals to enter the scrotum, where they serve the testes. Inferior mesenteric artery. This final major branch of the ab- dominal aorta is unpaired and arises from the anterior aortic surface at the L3 level. It serves the distal part of the large intestine—from the midpart of the transverse colon to the midrectum—via its left colic, sigmoidal, and superior rectal branches (Figure 19.24d). Looping anastomoses between the superior and inferior mesenteric arteries help ensure that blood will continue to reach the digestive viscera in cases of trauma to one of these abdominal arteries.

Lumbar arteries. Four pairs of lumbar arteries arise from the posterolateral surface of the aorta in the lumbar region. These segmental arteries supply the posterior abdominal wall. Median sacral artery. The unpaired median sacral artery is- sues from the posterior surface of the abdominal aorta at its ter- minus. This tiny artery supplies the sacrum and coccyx. Common iliac arteries. At the L4level, the aorta splits into the right and left common iliac arteries, which supply blood to the lower abdominal wall, pelvic organs, and lower limbs (Figure 19.24c).

Arteries of the Abdomen(continued) TABLE 19.7

C H E C K Y O U R U N D E R S TA N D I N G

15. Which paired artery supplies most of the tissues of the head

except for the brain and orbits?

16. Name the arterial anastomosis at the base of the brain. 17. Name the four unpaired arteries that emerge from the ab-

dominal aorta. For answers, see Appendix G.

19 (continued)

TABLE 19.7

(c) Major branches of the abdominal aorta.

Hiatus (opening) for inferior vena cava

Diaphragm

Inferior phrenic artery

Middle suprarenal artery Renal artery

Superior mesenteric artery

Inferior mesenteric artery Median sacral

artery _{Common iliac artery}

Ureter Gonadal (testicular or ovarian) artery Hiatus (opening) for esophagus Celiac trunk Adrenal (suprarenal) gland Kidney Abdominal aorta Lumbar arteries

(d) Distribution of the superior and inferior mesenteric arteries. The transverse colon has been pulled superiorly.

Celiac trunk Transverse colon Inferior mesenteric artery Aorta Descending colon Sigmoid colon Rectum Superior mesenteric artery Ascending colon Ileum

Right common iliac artery

Appendix Cecum

Branches of the inferior mesenteric artery

• Left colic artery • Sigmoidal arteries • Superior rectal artery

Branches of the superior mesenteric artery

• Middle colic artery • Intestinal arteries • Right colic artery • Ileocolic artery

19

At the level of the sacroiliac joints, the common iliac arteries di- vide into two major branches, the internal and external iliac ar- teries (Figure 19.25a). The internal iliacs distribute blood mainly to the pelvic region. The external iliacs primarily serve the lower limbs but also send some branches to the abdominal wall. Description and Distribution

Internal iliac arteries. These paired arteries run into the pelvis and distribute blood to the pelvic walls and viscera (bladder, rectum, uterus, and vagina in the female and prostate and duc- tus deferens in the male). Additionally they serve the gluteal muscles via the superior and inferior gluteal arteries, adduc- tor muscles of the medial thigh via the obturator artery, and external genitalia and perineum via the internal pudendal artery (not illustrated).

External iliac arteries. These arteries supply the lower limbs (Figure 19.25b). As they course through the pelvis, they give off branches to the anterior abdominal wall. After passing under the inguinal ligaments to enter the thigh, they become the femoral arteries.

Femoral arteries. As each of these arteries passes down the an- teromedial thigh, it gives off several branches to the thigh mus- cles. The largest of the deep branches is the deep artery of the thigh (also called the deep femoral artery), which is the main supply to the thigh muscles (hamstrings, quadriceps, and adduc- tors). Proximal branches of the deep femoral artery, the lateral and medial circumflex femoral arteries, encircle the neck of the femur. The medial circumflex artery is the major vessel to the head of the femur. If it is torn in a hip fracture, the bone tissue of the head of the femur dies. A long descending branch of the lat- eral circumflex artery supplies the vastus lateralis muscle. Near the knee the femoral artery passes posteriorly and through a gap in the adductor magnus muscle, the adductor hiatus, to enter the popliteal fossa, where its name changes to popliteal artery. Popliteal artery. This posterior vessel contributes to an arte- rial anastomosis that supplies the knee region and then splits into the anterior and posterior tibial arteries of the leg.

Anterior tibial artery. The anterior tibial artery runs through the anterior compartment of the leg, supplying the extensor muscles along the way. At the ankle, it becomes the dorsalis pedis artery, which supplies the ankle and dorsum of the foot, and gives off a branch, the arcuate artery, which issues the dorsal metatarsal arteries to the metatarsus of the foot. The su- perficial dorsalis pedis ends by penetrating into the sole where it forms the medial part of the plantar arch. The dorsalis pedis artery provides a clinically important pulse point, the pedal pulse. If the pedal pulse is easily felt, it is fairly certain that the blood supply to the leg is good.

Posterior tibial artery. This large artery courses through the posteromedial part of the leg and supplies the flexor muscles. Proximally, it gives off a large branch, the fibular (peroneal) artery, which supplies the lateral fibularis muscles of the leg. On Arteries of the Pelvis and Lower Limbs

TABLE 19.8