Anatomy of the Vessels and Nerves of the Head and Neck (Angioneurotomy) - Chornokulskyi S.T. 2009

Development of blood vessels

Development of Arteries

The transition from the branchial type of Blood Circulation to the pulmonary type during phylogeny is accompanied by the reduction of the branchial apparatus and transformations of the associated arterial bed.

In human ontogenesis, as in all terrestrial vertebrates, the initial stage of circulation is of the branchial type. In a three-week human embryo, the truncus arteriosus of The Heart divides into two ventral aortas, which form the first pair of aortic arches and continue into the descending dorsal aortas. Below the aortic arches, the two dorsal aortas fuse to form a single dorsal aorta. In total, six pairs of aortic arches (I–VI) are formed — arcus aortae primus, secundus, tertius, quartus, quintus, sextus (Fig. 6A). The I, II, and V pairs of aortic arches soon regress, whereas the III, IV, and VI pairs, along with separate segments of the ventral and dorsal aortas, play a major role in The formation of the Arteries of the HEAD, neck, trunk, and limbs (Fig. 6B).

✵ The sixth pair of aortic arches, following the division of the truncus arteriosus into the ascending aorta and pulmonary trunk (at 6 weeks), forms the pulmonary arteries. In addition, the left VI aortic arch forms an anastomosis with the left dorsal aorta, known as the ductus arteriosus (Botallo) ductus arteriosus Botalli [Fig. 6B (10)]. The roots of the pulmonary arteries fuse with the pulmonary trunk, with the right pulmonary artery losing its connection to the right dorsal aorta.

✵ The fourth pair of aortic arches: the left transforms into the aortic arch, which connects the ascending aorta with the left dorsal aorta. The latter turns into the descending part of the definitive aorta, while the right dorsal aorta posterior to the IV right aortic arch regresses.

— The IV right aortic arch forms the proximal segment of the right Subclavian Artery. The left subclavian artery develops from the ventral branch of the dorsal intersegmental artery — a branch of the left dorsal aorta. The segment of the right ventral aorta between its origin and the IV right aortic arch turns into the brachiocephalic trunk, and the segments of both ventral aortas between the IV and III aortic arches become the right and left common carotid arteries. Their direct continuation distally from the III aortic arches are the external carotid arteries.

✵ The third pair of aortic arches:

the right and left III aortic arches and corresponding dorsal aortas, via their segments between the III and I aortic arches, transform into the internal carotid arteries.

The initial sections of the I–II pairs of aortic arches do not obliterate completely and give rise to:

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Fig. 6. Development of major arteries based on the aortic arches (after W. Broman)

A — Ventral and dorsal aortas and aortic arches of the human embryo:

1 - VI — first (I) to sixth (VI) aortic arches;

2 - right and left ventral aortas;

3 - right and left dorsal aortas (Fig. 6A);

4 - pulmonary branches;

5 - right dorsal aorta; 6 - dorsal intersegmental arteries (I).

B — Derivatives of the aortic arches:

2 - External Carotid Artery (a. carotis externa);

3 - Internal Carotid Artery (a. carotis interna);

4 - right and left pulmonary arteries (aa. pulmonales dextra et sinistra);

7 - brachiocephalic trunk (truncus brachiocephalicus);

8 - aortic arch (arcus aortae);

9 - descending aorta (aorta descendens);

10 - ductus arteriosus (Botallo) (ductus arteriosus Botalli);

11 - left subclavian artery (a. subclavia sinistra)

II aortic arch — lingual and ascending pharyngeal arteries;

I aortic arch — maxillary, facial, and superficial temporal arteries.

Branches of the dorsal aorta — dorsal intersegmental arteries divide into dorsal and ventral branches. Within the Head and Neck, the dorsal branches give rise to the vertebral and basilar arteries, while in the trunk, they form the posterior intercostal and lumbar arteries. From the ventral branches of the III–VII dorsal intersegmental arteries, the left subclavian artery and the distal segment of the right subclavian artery are formed. The subclavian arteries grow into the upper limb buds (axial artery of the upper limb) at the level of the III and VIII dorsal intersegmental arteries, forming capillary networks along the nerve trunks.

The segmentation of certain dorsal arteries within the trunk is lost during Embryogenesis, giving rise to lateral and ventral visceral arteries. The lateral visceral arteries develop into the paired phrenic, renal, suprarenal, and testicular (ovarian) arteries; the ventral visceral arteries develop into the vitelline arteries, which form the celiac trunk, superior mesenteric artery, and inferior mesenteric artery. The caudally located ventral visceral arteries give rise to the right and left umbilical arteries, each of which forms the axial artery of the lower limb. The latter regress as the fetus develops, and vascularization of the lower limb is subsequently provided by the external iliac artery, whereas the umbilical artery persists merely as a branch of the internal iliac artery.

Development of Veins (Fig. 7, 8)

The venous sinus of the heart in a four-week embryo receives symmetrical right and left common cardinal veins (ducts of Cuvier), formed by the fusion of the anterior and posterior cardinal veins, as well as the unpaired, slender primary r. cava inferior, and paired vitelline and umbilical veins.

This was the stage of paired symmetrical veins.

The growth and relocation of the heart from the cervical region to the thoracic cavity, along with the Separation of its arterial and venous components, create more favorable hemodynamic conditions in the right anterior cardinal vein. Thus begins the stage of transverse anastomoses:

1st anastomosis — between the anterior cardinal veins, which enlarges and transforms into the left brachiocephalic vein. Consequently, all blood from the upper part of the embryo's body is channeled into the right common cardinal vein, which subsequently transforms into the SUPERIOR VENA CAVA.

The left anterior cardinal vein below the anastomosis ceases to function and obliterates, whereas the left common cardinal vein persists only in its terminal segment and transforms into the coronary sinus of the heart.

The portion of the right anterior cardinal vein superior to the anastomosis develops into the right brachiocephalic vein, while the inferior portion — together with the right common cardinal vein — forms the superior vena cava.

Fig. 7. Arteries and VEINS OF THE yolk sac of a three-week embryo and their connections with intraembryonic vessels (according to M. A. Tsyhomirov):

1 - heart;

2 - II, III, and IV aortic arches;

3 - dorsal aorta;

4 - common cardinal vein;

5 - left vitelline artery and vein;

6 - right vitelline artery and vein;

7 - venous sinus of the heart

II. Anastomoses between the posterior cardinal veins.

✵ In the iliac region, a transverse anastomosis shunts blood from the left posterior cardinal vein into the right. As a result, the segment of the left posterior cardinal vein located above the anastomosis regresses, and the anastomosis itself transforms into the left common iliac vein. The right posterior cardinal vein proximal to the anastomosis forms the right common iliac vein, and distal to it (up to The entry of the renal veins) forms the secondary INFERIOR VENA CAVA. The proximal segment of the v. cava inferior develops from the unpaired primary vena cava, which connects with the secondary inferior vena cava at the site of entry of the left renal vein (acting as the third transverse anastomosis), ultimately forming the definitive inferior vena cava.

Fig. 8. Venous system of a 4-week human embryo

1 - anterior cardinal vein;

2 - common cardinal vein;

3 - umbilical vein;

4 - vitelline vein;

5 - subcardinal vein (left);

6 - posterior cardinal vein;

7 - subcardinal vein (right);

8 - Liver (hepar)

With the enhancement of the drainage function of the v. cava inferior and the regression of the mesonephros, The Role of the posterior cardinal veins diminishes, while subcardinal veins develop in parallel with them, forming the azygos venous system. The right one transforms into the v. azygos, and the left one into the v. hemiazygos accessoria. The v. hemiazygos empties into the v. azygos via the fourth transverse anastomosis formed in the thoracic region between the former posterior cardinal veins.

Development of the HEPATIC PORTAL VEIN

The Formation of the hepatic portal vein is influenced by the venous blood outflow from the primitive gut via the vitelline veins. The vitelline veins empty into the venous sinus of the heart, and as the liver develops, they branch off into afferent veins supplying it. The latter arborize within the liver primordium, forming sinusoids from which blood is drained by efferent veins emptying into the inferior vena cava. The segment of the vitelline veins proximal to the Water/144.html">Origin of the afferent veins regresses, facilitated by the growth of The Liver and intestines, as well as the Atrophy of the yolk sac. Consequently, the hepatic portal vein is formed from the section of the vitelline veins extending from the entry point of the mesenteric veins (visceral veins) to the afferent veins of the liver.

Anatomical variants in The Development of Blood Vessels (Figs. 9, 10)

The most frequent developmental anomalies occur among the derivatives of the aortic arches, although the arteries and veins of the trunk and limbs also exhibit numerous variations. This issue is thoroughly covered in the peerless monograph by the Kyiv anatomist Professor M.A. Tikhomirov, "Variants of Arteries and Veins of The Human Body" (Kyiv, 1899, p. 374, fig. 68). M.A. Tikhomirov notes that the variations of the aortic arch branches are numerous and diverse, describing in detail six main variants—ranging from a single-branched to a six-branched aortic arch. Most of these variations, the author points out, are associated with significant Variability in the development of the subclavian artery as a double-rooted vessel. The normal pattern (77%) is considered to be three Branches of the aortic arch from right to left: the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery (Fig. 11).

Malformations of the arterial vessels (Figs. 8a, 9 A, B)

— Persistence of both fourth aortic arches and the roots of the dorsal aortae forms an aortic ring that encircles and subsequently compresses the Esophagus and Trachea (Fig. 9 B, b).

— Double aortic arch (as a normal condition in reptiles) (Fig. 9 A, b). — Right-sided aortic arch (in situs viscerus inversus).

— Coarctation (localized narrowing) of the aorta.

— Patent ductus arteriosus.

— Coarctation of the pulmonary artery.

— Variants of the aortic arch branches and its trajectory (according to H. Lippert, 1969) are demonstrated in Fig. 10. Malformations of the venous vessels (Fig. 10 a).

— Pulmonary veins, which may empty into:

— the superior vena cava;

— the left brachiocephalic vein;

— the azygos vein instead of the left atrium.

— Duplication of the superior vena cava:

— duplication of the lower segment of the inferior vena cava (below the entry of the renal veins);

— left-sided inferior vena cava;

— interrenal venous ring.

Fig. 8a. Double aortic arch:

1 — trachea;

2 — oesophagus;

3 — а. carotis communis sinister;

4 — а. subclavia sinistra;

5 — n. vagus siniser;

6 — n. recurrens;

7 — arcus aortae sinister;

8 — а. thyroidea ima;

9 — arcus aortae dexter;

10 — a. subclavia dextra;

11 — n. vagus dexter;

12 — a. carotis communis dextra

Fig. 9. Developmental anomalies of the aortic arch branches.

A — 4-branched aortic arch (according to M. A. Tikhomirov):

1 — ascending aorta (aorta ascendens);

2 — descending aorta (aorta descendens);

3 — left common carotid artery (а. carotis communis sinistra);

4 — right common carotid artery (а. carotis communis dextra);

5 — left subclavian artery (а. subclavia sinistra);

6 — right subclavian artery (a. subclavia dextra);

7 — pulmonary trunk (truncus pulmonalis);

8 — trachea (trachea);

9 — esophagus (oesophagus).

a — double aortic arch and its origin:

1-6 — aortic arches;

2 — descending aorta;

5 — left subclavian artery;

6 — right subclavian artery;

10 — internal carotid artery;

11 — external carotid artery.

B — double aortic arch ("aortic ring"):

1 — ascending aorta;

2 — descending aorta;

3 — external carotid arteries (right, left);

4 — internal carotid arteries (right, left);

5 — subclavian arteries (right, left);

6 — pulmonary trunk.

b — 1, 2, 3, 4, 5, 6 correspond to B

Fig. 10. Variant branching patterns of the aortic arch in %% (according to H. Lippert, 1969)

Fig. 10 a. Normal branching of the aortic arch

(arrow indicates sinus transversus pericardii):

1 - aortic arch (arcus aortae);

2 - brachiocephalic trunk

(truncus brachiocephalicus);

3 - left common carotid artery

(a. carotis communis sinistra);

4 - left subclavian artery

(а. subclavia sinistra);

5 - arterial ligament (Botallo)

(lig. arteriosum Borallo);

6 - pulmonary trunk (truncus pulmonal is);

7 - inferior vena cava (vena cava inferior);

8 - superior vena cava (vena cava superior)

Fig. 10 a. Developmental Anomalies of the inferior vena cava:

A - interrenal "venous ring" resulting from embryonic anastomosis of the subcardinal veins;

B - left-sided lower segment (infrarenal) of the inferior vena cava and the "venous ring";

1 - hepatic veins (vv. heparicae);

2 - suprarenal part of the inferior vena cava;

3 - suprarenal veins (vv. suprarenales);

4 - renal veins (vv. renales);

5 - embryonic anastomosis between subcardinal veins and formation of the renal "venous ring";

6 - inferior vena cava based on the left subcardinal vein (B);

7 - gonadal veins;

8: A - inferior vena cava, B - right subcardinal vein;

9 - common iliac veins (vv. iliacae communes);

10 - median sacral vein (v. sacraHs mediana)

Fig. 10 b. Normal inferior vena cava (3):

1 - right renal vein (v. renalis dextra);

2 - hepatic veins (vv. hepaticae);

3 - inferior vena cava (v. cava inferior);

4 - left testicular (ovarian) vein [v. testicularis (ovarica) sinistra];

5 - right common iliac vein (v. iliaca communis dextra);

6 - right internal iliac vein (v. iliaca interna dextra);

7 - right external iliac vein (v. iliaca externa dextra);

8 - right testicular (ovarian) vein [v. testicularis (ovarica) dextra]