For foreign first-year students for autumn term Module Methodical elaboration for practice class on human anatomy for foreign first-year students for autumn term

The internal pudendal artery (a. pudenda interna; internal pudic artery) is the smaller of the two terminal branches of the anterior trunk of the hypogastric, and supplies the external organs of generation. Though the course of the artery is the same in the two sexes, the vessel is smaller in the female than in the male, and the distribution of its branches somewhat different. The description of its arrangement in the male will first be given, and subsequently the differences which it presents in the female will be mentioned.

The internal pudendal artery in the male passes downward and outward to the lower border of the greater sciatic foramen, and emerges from the pelvis between the Piriformis and Coccygeus; it then crosses the ischial spine, and enters the perineum through the lesser sciatic foramen. The artery now crosses the Obturator internus, along the lateral wall of the ischiorectal fossa, being situated about 4 cm. above the lower margin of the ischial tuberosity. It gradually approaches the margin of the inferior ramus of the ischium and passes forward between the two layers of the fascia of the urogenital diaphragm; it then runs forward along the medial margin of the inferior ramus of the pubis, and about 1.25 cm. behind the pubic arcuate ligament it pierces the inferior fascia of the urogenital diaphragm and divides into the dorsal and deep arteries of the penis.

Relations.—Within the pelvis, it lies in front of the Piriformis muscle, the sacral plexus of nerves, and the inferior gluteal artery. As it crosses the ischial spine, it is covered by the Glutæus maximus and overlapped by the sacrotuberous ligament. Here the pudendal nerve lies to the medial side and the nerve to the Obturator internus to the lateral side of the vessel. In the perineum it lies on the lateral wall of the ischiorectal fossa, in a canal (Alcock’s canal) formed by the splitting of the obturator fascia. It is accompanied by a pair of venæ comitantes and the pudendal nerve.

Peculiarities.—The internal pudendal artery is sometimes smaller than usual, or fails to give off one or two of its usual branches; in such cases the deficiency is supplied by branches derived from an additional vessel, the accessory pudendal, which generally arises from the internal pudendal artery before its exit from the greater sciatic foramen. It passes forward along the lower part of the bladder and across the side of the prostate to the root of the penis, where it perforates the urogenital diaphragm, and gives off the branches usually derived from the internal pudendal artery. The deficiency most frequently met with is that in which the internal pudendal ends as the artery of the urethral bulb, the dorsal and deep arteries of the penis being derived from the accessory pudendal. The internal pudendal artery may also end as the perineal, the artery of the urethral bulb being derived, with the other two branches, from the accessory vessel. Occasionally the accessory pudendal artery is derived from one of the other branches of the hypogastric artery, most frequently the inferior vesical or the obturator.

Branches.—The branches of the internal pudendal artery are:

Muscular.

Artery of the Urethral Bulb.

Inferior Hemorrhoidal.

Urethral.

Perineal.

Deep Artery of the Penis.

Dorsal Artery of the Penis.

The Muscular Branches consist of two sets: one given off in the pelvis; the other, as the vessel crosses the ischial spine. The former consists of several small offsets which supply the Levator ani, the Obturator internus, the Piriformis, and the Coccygeus. The branches given off outside the pelvis are distributed to the adjacent parts of the Glutæus maximus and external rotator muscles. They anastomose with branches of the inferior gluteal artery.

The Inferior Hemorrhoidal Artery (a. hæmorrhoidalis inferior) arises from the internal pudendal as it passes above the ischial tuberosity. Piercing the wall of Alcock’s canal it divides into two or three branches which cross the ischiorectal fossa, and are distributed to the muscles and integument of the anal region, and send offshoots around the lower edge of the Glutæus maximus to the skin of the buttock. They anastomose with the corresponding vessels of the opposite side, with the superior and middle hemorrhoidal, and with the perineal artery.

The Perineal Artery (a. perinei; superficial perineal artery) arises from the internal pudendal, in front of the preceding branches, and turns upward, crossing either over or under the Transversus perinæi superficialis, and runs forward, parallel to the pubic arch, in the interspace between the Bulbocavernosus and Ischiocavernosus, both of which it supplies, and finally divides into several posterior scrotal branches which are distributed to the skin and dartos tunic of the scrotum. As it crosses the Transversus perinæi superficialis it gives off the transverse perineal artery which runs transversely on the cutaneous surface of the muscle, and anastomoses with the corresponding vessel of the opposite side and with the perineal and inferior hemorrhoidal arteries. It supplies the Transversus perinæi superficialis and the structures between the anus and the urethral bulb

The Artery of the Urethral Bulb (a. bulbi urethræ) is a short vessel of large caliber which arises from the internal pudendal between the two layers of fascia of the urogenital diaphragm; it passes medialward, pierces the inferior fascia of the urogenital diaphragm, and gives off branches which ramify in the bulb of the urethra and in the posterior part of the corpus cavernosum urethræ. It gives off a small branch to the bulbo-urethral gland.

The Urethral Artery (a. urethralis) arises a short distance in front of the artery of the urethral bulb. It runs forward and medialward, pierces the inferior fascia of the urogenital diaphragm and enters the corpus cavernosum urethræ, in which it is continued forward to the glans penis.

The Deep Artery of the Penis (a. profunda penis; artery to the corpus cavernosum), one of the terminal branches of the internal pudendal, arises from that vessel while it is situated between the two fasciæ of the urogenital diaphragm; it pierces the inferior fascia, and, entering the crus penis obliquely, runs forward in the center of the corpus cavernosum penis, to which its branches are distributed.

The Dorsal Artery of the Penis (a. dorsalis penis) ascends between the crus penis and the pubic symphysis, and, piercing the inferior fascia of the urogenital diaphragm, passes between the two layers of the suspensory ligament of the penis, and runs forward on the dorsum of the penis to the glans, where it divides into two branches, which supply the glans and prepuce. On the penis, it lies between the dorsal nerve and deep dorsal vein, the former being on its lateral side. It supplies the integument and fibrous sheath of the corpus cavernosum penis, sending branches through the sheath to anastomose with the preceding vessel.

The internal pudendal artery in the female is smaller than in the male. Its origin and course are similar, and there is considerable analogy in the distribution of its branches. The perineal artery supplies the labia pudendi; the artery of the bulb supplies the bulbus vestibuli and the erectile tissue of the vagina; the deep artery of the clitoris supplies the corpus cavernosum clitoridis; and the dorsal artery of the clitoris supplies the dorsum of that organ, and ends in the glans and prepuce of the clitoris.

The inferior gluteal artery (a. glutæa inferior; sciatic artery), the larger of the two terminal branches of the anterior trunk of the hypogastric, is distributed chiefly to the buttock and back of the thigh. It passes down on the sacral plexus of nerves and the Piriformis, behind the internal pudendal artery, to the lower part of the greater sciatic foramen, through which it escapes from the pelvis between the Piriformis and Coccygeus. It then descends in the interval between the greater trochanter of the femur and tuberosity of the ischium, accompanied by the sciatic and posterior femoral cutaneous nerves, and covered by the Glutæus maximus, and is continued down the back of the thigh, supplying the skin, and anastomosing with branches of the perforating arteries.

Inside the pelvis it distributes branches to the Piriformis, Coccygeus, and Levator ani; some branches which supply the fat around the rectum, and occasionally take the place of the middle hemorrhoidal artery; and vesical branches to the fundus of the bladder, vesiculæ seminales, and prostate. Outside the pelvis it gives off the following branches:

Muscular.

Anastomotic.

Coccygeal.

Articular.

Comitans Nervi Ischiadici.

Cutaneous.

The Muscular Branches supply the Glutæus maximus, anastomosing with the superior gluteal artery in the substance of the muscle; the external rotators, anastomosing with the internal pudendal artery; and the muscles attached to the tuberosity of the ischium, anastomosing with the posterior branch of the obturator and the medial femoral circumflex arteries.

The Coccygeal Branches run medialward, pierce the sacrotuberous ligament, and supply the Glutæus maximus, the integument, and other structures on the back of the coccyx.

The Arteria Comitans Nervi Ischiadici is a long, slender vessel, which accompanies the sciatic nerve for a short distance; it then penetrates it, and runs in its substance to the lower part of the thigh.

The Anastomotic is directed downward across the external rotators, and assists in forming the so-called crucial anastomosis by joining with the first perforating and medial and lateral femoral circumflex arteries.

The Articular Branch, generally derived from the anastomotic, is distributed to the capsule of the hip-joint.

The Cutaneous Branches are distributed to the skin of the buttock and back of the thigh.

The iliolumbar artery (a. iliolumbalis) a branch of the posterior trunk of the hypogastric, turns upward behind the obturator nerve and the external iliac vessels, to the medial border of the Psoas major, behind which it divides into a lumbar and an iliac branch.

The Lumbar Branch (ramus lumbalis) supplies the Psoas major and Quadratus lumborum, anastomoses with the last lumbar artery, and sends a small spinal branch through the intervertebral foramen between the last lumbar vertebra and the sacrum, into the vertebral canal, to supply the cauda equina.

The Iliac Branch (ramus iliacus) descends to supply the Iliacus; some offsets, running between the muscle and the bone, anastomose with the iliac branches of the obturator; one of these enters an oblique canal to supply the bone, while others run along the crest of the ilium, distributing branches to the gluteal and abdominal muscles, and anastomosing in their course with the superior gluteal, iliac circumflex, and lateral femoral circumflex arteries.

The lateral sacral arteries (aa. sacrales laterales) arise from the posterior division of the hypogastric; there are usually two, a superior and an inferior.

The superior, of large size, passes medialward, and, after anastomosing with branches from the middle sacral, enters the first or second anterior sacral foramen, supplies branches to the contents of the sacral canal, and, escaping by the corresponding posterior sacral foramen, is distributed to the skin and muscles on the dorsum of the sacrum, anastomosing with the superior gluteal.

The inferior runs obliquely across the front of the Piriformis and the sacral nerves to the medial side of the anterior sacral foramina, descends on the front of the sacrum, and anastomoses over the coccyx with the middle sacral and opposite lateral sacral artery. In its course it gives off branches, which enter the anterior sacral foramina; these, after supplying the contents of the sacral canal, escapes by the posterior sacral foramina, and are distributed to the muscles and skin on the dorsal surface of the sacrum, anastomosing with the gluteal arteries.

The superior gluteal artery (a. glutæa superior; gluteal artery) is the largest branch of the hypogastric, and appears to be the continuation of the posterior division of that vessel. It is a short artery which runs backward between the lumbosacral trunk and the first sacral nerve, and, passing out of the pelvis above the upper border of the Piriformis, immediately divides into a superficial and a deep branch. Within the pelvis it gives off a few branches to the Iliacus, Piriformis, and Obturator internus, and just previous to quitting that cavity, a nutrient artery which enters the ilium.

The superficial branch enters the deep surface of the Glutæus maximus, and divides into numerous branches, some of which supply the muscle and anastomose with the inferior gluteal, while others perforate its tendinous origin, and supply the integument covering the posterior surface of the sacrum, anastomosing with the posterior branches of the lateral sacral arteries.

The deep branch lies under the Glutæus medius and almost immediately subdivides into two. Of these, the superior division, continuing the original course of the vessel, passes along the upper border of the Glutæus minimus to the anterior superior spine of the ilium, anastomosing with the deep iliac circumflex artery and the ascending branch of the lateral femoral circumflex artery. The inferior division crosses the Glutæus minimus obliquely to the greater trochanter, distributing branches to the Glutæi and anastomoses with the lateral femoral circumflex artery. Some branches pierce the Glutæus minimus and supply the hip-joint.

The external iliac artery is larger than the hypogastric, and passes obliquely downward and lateralward along the medial border of the Psoas major, from the bifurcation of the common iliac to a point beneath the inguinal ligament, midway between the anterior superior spine of the ilium and the symphysis pubis, where it enters the thigh and becomes the femoral artery.

Inferior Epigastric.

Deep Iliac Circumflex.

The inferior epigastric artery (a. epigastrica inferior; deep epigastric artery) arises from the external iliac, immediately above the inguinal ligament. It curves forward in the subperitoneal tissue, and then ascends obliquely along the medial margin of the abdominal inguinal ring; continuing its course upward, it pierces the transversalis fascia, and, passing in front of the linea semicircularis, ascends between the Rectus abdominis and the posterior lamella of its sheath. It finally divides into numerous branches, which anastomose, above the umbilicus, with the superior epigastric branch of the internal mammary and with the lower intercostal arteries. As the inferior epigastric artery passes obliquely upward from its origin it lies along the lower and medial margins of the abdominal inguinal ring, and behind the commencement of the spermatic cord. The ductus deferens, as it leaves the spermatic cord in the male, and the round ligament of the uterus in the female, winds around the lateral and posterior aspects of the artery.

The deep iliac circumflex artery (a. circumflexa ilium profunda) arises from the lateral aspect of the external iliac nearly opposite the inferior epigastric artery. It ascends obliquely lateralward behind the inguinal ligament, contained in a fibrous sheath formed by the junction of the transversalis fascia and iliac fascia, to the anterior superior iliac spine, where it anastomoses with the ascending branch of the lateral femoral circumflex artery. It then pierces the transversalis fascia and passes along the inner lip of the crest of the ilium to about its middle, where it perforates the Transversus, and runs backward between that muscle and the Obliquus internus, to anastomose with the iliolumbar and superior gluteal arteries. Opposite the anterior superior spine of the ilium it gives off a large branch, which ascends between the Obliquus internus and Transversus muscles, supplying them, and anastomosing with the lumbar and inferior epigastric arteries.

The anterior tibial artery commences at the bifurcation of the popliteal, at the lower border of the Popliteus, passes forward between the two heads of the Tibialis posterior, and through the aperture above the upper border of the interosseous membrane, to the deep part of the front of the leg: it here lies close to the medial side of the neck of the fibula. It then descends on the anterior surface of the interosseous membrane, gradually approaching the tibia; at the lower part of the leg it lies on this bone, and then on the front of the ankle-joint, where it is more superficial, and becomes the dorsalis pedis.

The anterior tibial artery is accompanied by a pair of venæ comitantes which lie one on either side of the artery; the deep peroneal nerve, coursing around the lateral side of the neck of the fibula, comes into relation with the lateral side of the artery shortly after it has reached the front of the leg; about the middle of the leg the nerve is in front of the artery; at the lower part it is generally again on the lateral side.

Posterior Tibial Recurrent.

Muscular.

Fibular.

Anterior Tibial Recurrent.

Anterior Lateral Malleolar.

The posterior tibial recurrent artery (a. recurrens tibialis posterior) an inconstant branch, is given off from the anterior tibial before that vessel passes through the interosseous space. It ascends in front of the Popliteus, which it supplies, and anastomoses with the inferior genicular branches of the popliteal artery, giving an offset to the tibiofibular joint.

The fibular artery is sometimes derived from the anterior tibial, sometimes from the posterior tibial. It passes lateralward, around the neck of the fibula, through the Soleus, which it supplies, and ends in the substance of the Peroneus longus.

The anterior tibial recurrent artery (a. recurrens tibialis anterior) arises from the anterior tibial, as soon as that vessel has passed through the interosseous space; it ascends in the Tibialis anterior, ramifies on the front and sides of the knee-joint, and assists in the formation of the patellar plexus by anastomosing with the genicular branches of the popliteal, and with the highest genicular artery.

The muscular branches (rami musculares) are numerous; they are distributed to the muscles which lie on either side of the vessel, some piercing the deep fascia to supply the integument, others passing through the interosseous membrane, and anastomosing with branches of the posterior tibial and peroneal arteries.

The anterior medial malleolar artery (a. malleolaris anterior medialis; internal malleolar artery) arises about 5 cm. above the ankle-joint and passes behind the tendons of the Extensor hallucis longus and Tibialis anterior, to the medial side of the ankle, upon which it ramifies, anastomosing with branches of the posterior tibial and medial plantar arteries and with the medial calcaneal from the posterior tibial.

The anterior lateral malleolar artery (a. malleolaris anterior lateralis; external malleolar artery) passes beneath the tendons of the Extensor digitorum longus and Peronæus tertius and supplies the lateral side of the ankle, anastomosing with the perforating branch of the peroneal artery, and with ascending twigs from the lateral tarsal artery.

The arteries around the ankle-joint anastomose freely with one another and form net-works below the corresponding malleoli. The medial malleolar net-work is formed by the anterior medial malleolar branch of the anterior tibial, the medial tarsal branches of the dorsalis pedis, the posterior medial malleolar and medial calcaneal branches of the posterior tibial and branches from the medial plantar artery. The lateral malleolar net-work is formed by the anterior lateral malleolar branch of the anterior tibial, the lateral tarsal branch of the dorsalis pedis, the perforating and the lateral calcaneal branches of the peroneal, and twigs from the lateral plantar artery.