Part 27

_a._ =A. umbilicalis= (Fig. 126, _n_).--This small artery arises from the hypogastric about one centimeter from the beginning of the latter, and passes ventrad to the bladder. Here it divides into two branches--the =superior vesical= to the sides of the bladder, the =inferior vesical= to the neck of the bladder and the urethra.

_b._ =A. glutea superior= (Fig. 126, _p_).--This passes dorsolaterad from the hypogastric and reaches the pelvic wall against the medial surface of the ilium. Here it divides into two branches. One passes between the iliopsoas muscle and the ventral border of the ilium to the medial surface of the gluteus maximus; it gives branches to the gluteus muscles, the pyriformis, and the rectus femoris. The other branch passes dorsad of the ilium, sending a branch to the medial surface of the gluteus medius, and a small branch which joins the lateral sacral artery and enters thus the sacral canal.

_c._ =A. hemorrhoidalis media= (Fig. 126, _r_).--The middle hemorrhoidal passes ventrad from the hypogastric, onto the lateral surface of the rectum. It passes caudad near the ventral side of the rectum as far as the anus. A short distance from the origin it gives off a branch which passes almost directly ventrad toward the beginning of the urethra. In the male this branch is small, sending twigs to the urethra and the prostate. In the female it is much larger, forming =A. uterina= (Fig. 112, 3, page 265). The uterine artery turns craniad onto the uterus, which it supplies, passing to the cranial end of the uterine cornu and anastomosing with the ovarian artery.

The middle hemorrhoidal gives off in the female branches to the vagina (Fig. 112, _m_) and neck of the bladder (_k_), and a large branch to the urogenital sinus (_n_); it then supplies the anal glands and other structures about the anus, and anastomoses with the terminal branches of the hemorrhoidalis superior. In the male branchlets are given to the urethra, to the bulbourethral (or Cowper’s) gland, and to the penis. The =A. dorsalis penis= is a small branch which passes along the median dorsal groove of the penis to the glans. The middle hemorrhoidal then supplies the structures about the anus and anastomoses with the superior hemorrhoidal, as in the female.

_d._ =A. glutea inferior= (Fig. 126, _q_).--This is the terminal portion of the hypogastric. It passes along with the great sciatic nerve to the great sciatic notch, and reaches the medial surface of M. pyriformis. It divides into branches which supply the gluteus and pyriformis muscles, while a small branch accompanies the great sciatic nerve. A small branch also passes onto the lateral surface of the tail, extending caudad along its side.

11. =A. sacralis media= (Fig. 126, _o_).--This is the continuation of the aorta into the sacral and caudal regions. It extends to near the end of the tail, lying in the ventral middle line against the sacral and caudal vertebræ. In the caudal region it passes through the hæmal arches, covered by the chevron bones. Between the vertebræ it gives off side branches comparable to the intercostal and lumbar arteries of the aorta.

Branches of the sacralis media:

_a._ =A. sacralis lateralis.=--Behind the first sacral vertebra a large branch, the lateral sacral, is given off on each side. This enters the first anterior sacral foramen, gives a branch to the structures in the sacral canal, and sends a dorsal branch out through the posterior sacral foramen to the muscles on the dorsal side of the sacrum.

Similar but smaller branches are given off between the succeeding vertebræ, sacral and caudal.

_The External Iliac and its Branches._--The origin of the external iliac (Fig. 126, _k_) is described above (page 307). It gives off the following branches:

1. =A. profunda femoris= (Fig. 126, _y_).--This is given off just before the external iliac leaves the abdominal cavity. It passes caudad, and about one centimeter from its origin it gives off three branches, sometimes all separately, sometimes two in common. One of these passes mediad in the lateral ligament of the bladder and ramifies on the lateral surface of that organ. A second passes through the abdominal wall and into the fat on the medial surface of the thigh; it sends a branch caudad toward the external genital organs, while its main trunk passes distad in the subcutaneous fat almost to the knee. From one of these two a small branchlet passes in the male to the spermatic cord and accompanies this to the testis; it represents thus the =external spermatic artery=. The third branch, =A. epigastrica inferior=, passes directly to the ventral surface of the rectus abdominis muscle, on which it passes craniad, sending branches to the muscles of the abdominal walls. It anastomoses with terminal branches of the internal mammary artery.

The profunda femoris itself passes between the iliopsoas and the pectineus muscles, then to the medial surface of the adductor femoris. It divides into branches which supply the pectineus, adductor longus, adductor femoris, caudofemoralis, quadratus femoris, semimembranosus, and semitendinosus.

[Illustration: FIG. 127.--SUPERFICIAL ARTERIES, VEINS, AND NERVES ON THE MEDIAL SIDE OF THE LEG.

_a_, A. and V. femoralis; _b_, N. femoralis; _c_, A. profunda femoris; _d_, A. and V. circumflexa femoris lateralis; _e_, ramus muscularis; _f_, A. saphena and V. saphena magna; _g_, N. saphenus; _h_, A. and V. articularis genu suprema; _i_, N. tibialis; _j_, plantar branch of A. saphena; _k_, dorsal branch of A. saphena. 1, M. sartorius; 2, M. tensor fasciæ latæ; 3, M. rectus femoris; 4, M. iliopsoas; 5, M. pectineus; 6, M. adductor longus; 7, M. adductor femoris; 8, M. semimembranosus; 9, M. gracilis; 10, M. semitendinosus; 11, medial head of M. gastrocnemius; 12, M. plantaris; 13, M. flexor longus digitorum; 14, M. tibialis anterior; 15, tibia.]

2. =A. femoralis= (Fig. 127).--This is the continuation of the external iliac onto the medial surface of the thigh. The artery lies in a triangular depression between the borders of the sartorius (1) and gracilis (9) muscles. The floor of the depression is formed by the adductor longus (6), pectineus (5), vastus internus, and rectus femoris (3) muscles. This triangular depression is known as the =iliopectineal= fossa, or Scarpa’s triangle; it contains also the femoral vein (_a_) and saphenous nerve (_g_), which pass along with the artery. The artery extends distad, and at about the middle of the length of the thigh it passes, along with the vein and nerve, into a groove between the vastus medialis and the adductor femoris. This groove is converted into a canal by the overlying aponeurosis; it is known as =Hunter’s canal= or the =canalis adductorius=. At the distal end of the adductor femoris the femoral artery ceases to be superficial and passes between the vastus medialis and the semimembranosus to the popliteal space; it now receives the name =A. poplitea=.

Branches of the femoral artery:

_a._ =A. circumflexa femoris lateralis= (Fig. 127, _d_).--The lateral circumflex arises from the femoral about one centimeter from its emergence from the abdominal cavity. It passes craniad and laterad and divides into two main portions. One part passes between the rectus femoris and vastus medialis, gives branches to these muscles, and sends an ascending branch to the structures about the hip-joint, and a descending branch into the vastus medialis muscle. The remainder of the lateral circumflex passes along the inner (lateral) surface of the sartorius (1) to the cranial border of the leg, giving branches to the sartorius (1) and tensor fasciæ latæ (2).

_b._ A large =muscular= branch (_e_) passes caudad (or ventrad) and distad across the distal end of the adductor femoris (7) and between the gracilis (9) and semimembranosus, supplying these muscles. Other small muscular branches may be given off from both sides of the femoral.

_c._ =A. articularis genu suprema= (_h_).--The superior articular artery arises from the femoral, either in common with the saphenous artery or separately, a little proximad of the point where the femoral ceases to be superficial. It passes toward the knee, between the vastus medialis and semimembranosus, and covered by the sartorius (1), and ramifies over the medial surface of the knee-joint and in the structures just proximad of the joint.

_d._ =A. saphena= (_f_).--The saphenous artery frequently takes origin in common with the superior articular (_h_), but may arise separately at about the same level. It passes distad across the gracilis (9), accompanied by the saphenous nerve (_g_) and vein, sends several branches dorsad (toward the knee), and at about the middle of the lower leg it divides into two main branches, a =dorsal= branch (_k_), passing to the dorsum of the foot, and a =plantar= branch (_j_), to the sole of the foot. The dorsal branch is accompanied by the main saphenous nerve (_g_) and vein. It sends one or two branches to the medial side of the ankle-joint, passes then onto the dorsum of the foot, and divides into four main branches. The medial one passes along the medial side of the medial digit; the other three pass to the intervals between the digits. Each divides into two branches which supply the contiguous sides of the two digits between which the interval lies. The dorsal branch thus supplies arteries to the sides of all the digits except to the lateral side of the lateral digit. This is supplied by A. suralis.

The plantar branch (_j_) is larger than the dorsal. It passes distad on the medial surface of the flexor longus hallucis, accompanied by the tibial nerve, and across the space between the tendon of Achilles and the flexor. It gives superficial and deep branches to the structures about the ankle-joint, and sends inward a branch from the lateral side (Fig. 128, _d_) which joins the termination of A. tibialis anterior to form the plantar arch. It then passes distad along the plantar surface of the foot, nearer its medial border. Beneath the pad in the sole of the foot it divides into three branches which supply the interosseous spaces between the three digits.

_e._ =A. poplitea.=--The main trunk of the femoral artery passes between the vastus medialis and the semimembranosus and then through the distal portion of the adductor femoris to reach the popliteal space. This is the space ventrad (or caudad) of the knee, between the biceps femoris on one side and the semimembranosus on the other. Here the artery receives the name =A. poplitea=, or popliteal artery. The popliteal artery gives off a number of large branches as it passes through the popliteal space, passes between the condyles of the femur and underneath the popliteal muscle, and finally turns dorsolaterad between the tibia and fibula, just distad of the head of the fibula. It now receives the name =A. tibialis anterior= and passes distad along the dorsal (anterior) border of the fibula.

Branches of the popliteal artery:

1. =A. suralis.=--This is a large branch which passes distad from the caudal side of the popliteal artery. It sends branches to the biceps and to the fat in the popliteal space, and passes onto the ventral border of the lateral head of the gastrocnemius. It sends branches to both heads of the gastrocnemius and to the popliteus, passes distad onto the lateral surface of the tendon of Achilles, and may be traced to the proximal portion of the dorsolateral side of the foot, where it sends many branches to the integument about the ankle-joint. It then passes along the lateral side of the foot and supplies the artery on the lateral side of the fifth digit.

2. =Aa. genu posteriores.=--Several small arteries which pass to the knee-joint.

3. =Rami musculares.=--Numerous small branches to the muscles about the popliteal space.

4. =A. tibialis posterior.=--This is the largest branch of the popliteal artery, which it leaves just before the latter passes beneath the popliteal muscle. The tibialis posterior passes at first mediad, then turns distad, passes across the popliteus muscle onto the surface of the flexor longus hallucis, and ramifies in the substance of this muscle and its tendon. It gives branches also to the gastrocnemius and soleus. (It does not pass into the foot as does the corresponding artery in man.)

5. =A. tibialis anterior.=--The anterior tibial artery is the continuation of the popliteal after its passage through the interosseous membrane between tibia and fibula to the dorsal side of the lower leg. Here it passes distad, lying against the interosseous membrane, between the extensor longus digitorum and the tibialis anterior muscle, or

## partly imbedded in the substance of the latter. It passes, lying beneath

the tendons of these muscles, through the transverse ligament proximad of the malleoli, thus reaching the dorsum of the foot. It extends distad across the tarsus to the space between the second and third metatarsals, and through this space to the plantar side of the foot (Fig. 128). Here it receives one or two small branches (_a_ and _d_) from the plantar branch of A. saphena (forming with them the =plantar arch= (_c_)), and passing distad and slightly laterad, divides into three main portions (_e_). These (=Aa. digitales plantares=) pass to the three intervals between the digits. The medial one passes along the lateral side of the second digit; the next divides, sending a branch to the lateral side of the third digit and the medial side of the fourth; the lateral one passes along the medial border of the fifth digit. The Aa. digitales plantares send numerous branches to the interosseous muscles.

[Illustration: FIG. 128.--DEEP ARTERIES ON THE PLANTAR SURFACE OF THE FOOT.

_a_, medial twig from plantar branch of A. saphena; _b_, A. tibialis anterior (or plantaris profunda); _c_, plantar arch; _d_, lateral twig from plantar branch of A. saphena; _e_, terminal branches from A. tibialis anterior.]

Branches of the tibialis anterior:

_a._ =A. tibialis recurrens.=--Immediately after passing through the interosseous membrane the anterior tibial sends a small artery proximad to the knee-joint.

_b._ =Rami musculares.=--Numerous short branches throughout the course of the artery, to the muscles about it.

_c._ =Ramus superficialis.=--A larger branch leaves the lateral surface of the artery about one-third the distance from the knee to the ankle and passes along with the superficial peroneal nerve, at first beneath M. peroneus longus, then superficially. It passes onto the dorsal surface of the foot and becomes connected with terminal branches of =A. saphena=.

_d._ =A. tarsea medialis.=--This arises from the tibialis anterior just distad of the transverse ligament through which it passes at the ankle, passes over the medial surface of the astragalus, and is distributed to the ligaments about the ankle-joint. It anastomoses with the plantar branch of A. saphena.

_e._ =A. metatarsea.=--The metatarsal artery passes laterad from the tibialis anterior at the distal boundary of the tarsus, on the dorsal surface of the foot. It sends branches distad in the intervals between the third and fourth and the fourth and fifth metatarsals.

The distal branches (Fig. 128) of the tibialis anterior have been described in the general description of the artery.

THE VEINS. VENÆ.

=Venæ pulmonales. The Pulmonary Veins.=

The pulmonary veins follow in the lungs the course of the bronchi. They enter the left auricle in three groups (Fig. 116, page 276). The first of these (_i_) comes from the anterior and middle lobes of the right side, the second (_h_) from the corresponding lobes of the left side, and the third (_g_) from the terminal lobes of both sides. Each group is composed of two or three veins and opens into a sinus or extension of the auricle. The sinuses are from their position dextral (_i_), sinistral (_h_), and dorsal (_g_).

=The Veins of the Body.=

The veins of the body may be classified into three main groups: (1) the veins of the heart; (2) the superior vena cava and its branches; (3) the inferior vena cava and its branches. The portal system of veins will be considered with the inferior vena cava.

1. Veins of the Heart.

The veins of the heart consist of one large vein, the =vena cordis magna=, and a number of small veins.

=Vena cordis magna= (Fig. 118, 3).--This arises as a number of scattered branches on the surface of both ventricles. These unite to form two main trunks. One of these, on the ventral side of the heart, marks externally the septum between the two ventricles. It passes beneath the left auricular appendage, then turns to the left and passes along the sulcus coronarius to the dorsal side of the heart. Here it unites with the second main trunk which ramifies over the surface of the left ventricle. Arriving at the base of the right auricle it enters this by the coronary sinus, which lies just beneath the opening of the inferior vena cava.

In addition to the vena cordis magna and its branches there are a number of small veins, especially in the wall of the right ventricle. These enter the right auricle by a number of small separate openings along the sulcus coronarius.

2. =Vena cava superior= (Fig. 129, _b_).

The superior vena cava is the great vein returning the blood from the head, fore-limb, and cranial part of the trunk. It extends from the level of the first rib on the right side of the vertebral column to the right auricle. Its caudal end lies dorsad of the aortic arch. Opposite the right rib it is formed by the junction of the two innominate veins (_m_).

Branches of the superior vena cava:

1. =V. azygos= (_d_).--The first branch of the superior vena cava is the azygos vein, which enters the vena cava on the right side a centimeter or less craniad of the root of the right lung. It is formed in the abdominal cavity by the confluence of two or three small veins, which collect the blood from the muscles of the dorsal wall of the abdomen. The small median trunk thus formed enters the thoracic cavity between the crura of the diaphragm and lies on the ventral surface of the centra of the thoracic vertebræ, slightly to the right of the middle line. The azygos receives the =intercostal= veins (_n_), which correspond to the intercostal arteries and have the same course and distribution. In the caudal part of the thoracic cavity the intercostals enter the azygos separately, but the intercostals of the cranial intercostal spaces usually unite two or three together and enter the azygos by one or more common trunks. The azygos also receives =bronchial= and =œsophageal= veins, corresponding to the similarly named arteries.

[Illustration: FIG. 129.--THORACIC BLOOD-VESSELS, FROM THE RIGHT SIDE.

_a_, aorta; _b_, vena cava superior; _c_, vena cava inferior; _d_, V. azygos; _e_, A. subclavia dextra; _f_, A. mammaria interna; _g_, V. mammaria interna; _h_, costocervical axis; _i_, united trunk of vertebral and costocervical veins; _j_, A. and V. axillaris; _k_, V. jugularis externa; _l_, V. jugularis interna; _m_, the two innominate veins; _n_, intercostal arteries and veins; _o_, thyrocervical axis. 1, heart; 2, trachea; 3, œsophagus; _I_-_XI_, cut ends of the first eleven ribs.]

2. =V. mammaria interna= (_g_).--The internal mammary veins follow the corresponding arteries. The two veins unite to form a common trunk which, after receiving a branch from the cranial part of the sternum, enters the vena cava opposite the third rib.

3. =Vv. anonymæ= (Fig. 129, _m_; Fig. 115, _p_).--The innominate veins unite opposite the first intercostal space to form the vena cava superior. Each extends from the cranial end of the vena cava superior craniolaterad to a point a short distance craniad of the first rib and is there formed by the union of the =external jugular= (Fig. 129, _k_) and =subclavian= (_j_) veins. The innominate vein has the following branches:

A and B. =Vv. vertebralis= and =costocervicalis= (_i_).--The vertebral and costocervical veins unite to form a single trunk which enters the innominate about opposite the first rib. These two veins follow the corresponding arteries. (Sometimes the vertebral and costocervical veins enter the innominate separately, and in other cases one or more of the components of the costocervical veins (e.g., the transversa colli) may enter the axillary vein. In other cases the entire common trunk of the vertebralis and costocervicalis may enter the superior vena cava directly.)

C. =V. subclavia.=--The subclavian vein enters the innominate at about the level of the first rib. Outside of the thorax it is called the axillary vein (_j_); this comes from the arm.

[Illustration: FIG. 130.

SUPERFICIAL ARTERIES, VEINS, AND NERVES ON THE EXTENSOR SIDE OF THE ARM AND DORSUM OF THE HAND.

_a_, V. cephalica; _b_, V. mediana cubiti; _c_, V. cephalica antibrachii; _d_, A. collateralis radialis superior; _e_, Aa. and Vv. digitales dorsales; _f_, A. radialis; _g_, superficial radial nerve; _h_, N. musculocutaneus; _i_, N. cutaneus medialis.]

=Veins of the Arm.=--The blood is returned from the arm by two systems of veins,--a deep and a superficial system.

The deep system is composed of veins which correspond to the branches of the axillary artery, follow in general the same course, and receive the same names (Fig. 122). They unite to form the axillary vein. The brachial vein does not pass with the brachial artery through the supracondyloid foramen.

The superficial system comprises the vena cephalica and its branches.

=V. cephalica= (Fig. 130).--Several superficial branches lying in the palm of the hand unite to form a common trunk which curves about the radial side of the wrist and here unites with a similarly formed trunk from the dorsum of the hand. The vein formed by this union, vena cephalica (antibrachii) (_c_), passes to the elbow accompanying the radial nerve (_g_) and the collateral radial artery (_d_), and lying on the extensor carpi radialis longus muscle just beneath the integument. It receives small lateral superficial branches. At the elbow it divides into two: these are the vena cephalica (humeri) (_a_) and the =vena mediana cubiti= (_b_). The latter passes beneath the pectoantibrachialis muscle, across the biceps, and unites with the brachial vein in the concavity of the elbow.

The vena cephalica (humeri) passes at the elbow onto the upper arm, following the lateral border of the clavobrachial muscle. It thus reaches the acromiodeltoid muscle, where it divides into two branches. One passes inward beneath the acromiodeltoid, and joins the vena circumflexa posterior (a branch of the axillary). The second continues over the outer surface of the shoulder, and finally joins the vena transversa scapulæ (a branch of the external jugular).

D. =V. jugularis externa= (Fig. 131; Fig. 65, 5, page 109).--The external jugular vein comes from the head and face. It is formed by the junction of the anterior (Fig. 131, _c_) and posterior (_b_) facial veins near the ventral border of the sternomastoid muscle. It passes thence obliquely across the sternomastoid to the triangular interval between it and the clavotrapezius. In the interval it receives a small branch which accompanies the branch of the transversa scapulæ artery to the clavobrachialis muscle, receives next the common trunk of the vena cephalica and transversa scapulæ, and opposite the cranial end of the manubrium receives the internal jugular vein (Fig. 129, _l_). It then unites with the subclavian to form the innominate vein. Near the point where it receives the internal jugular the external jugular vein receives the =thoracic duct= (Fig. 118, 5).

Branches of the external jugular:

_a._ =V. transversa scapulæ.=--This follows the course of the artery of the same name. One of its branches receives one of the two terminal divisions of the vena cephalica (q. v.). In many cases veins which correspond to branches of the transversa scapulæ artery enter the external jugular separately (as shown in Fig. 118, _x_ and _y_).

_b._ =V. cervicalis ascendens.=--A small branch which follows the corresponding branch of the thyrocervical axis.