A morphological study of the vertebral venous plexus and its connections in the Cape dune mole‐rat,Bathyergus suillus (Bathyergidae)

Bathyergus suillus are subterranean rodents found in the Western Cape of South Africa, where they inhabit sandy, humid burrows. Vertebral venous plexuses around the vertebral column have been implicated in aiding the maintenance of a constant central nervous system temperature via its connections with muscles and interscapular brown adipose tissue. The morphology of the vertebral venous plexuses and its connections in B.suillus were investigated. Frozen (n = 10) animals were defrosted; the venous system injected with latex and the vertebral venous plexuses, azygos‐ and intercostal veins dissected along the dorsal and ventral aspects of the vertebral column. Specimens (n = 4) were used for histological serial cross sections of the thoracic vertebrae. Veins drained from the interscapular brown adipose tissue to the external vertebral venous plexus, via a dorsal vein at the spinous process of T2 which might represent the “vein of Sulzer” described in rats. The intercostal veins cranial to the level of T8 drained directly into the ventral external vertebral venous plexus instead of into the azygos vein as seen in rats. The azygos vein was situated ventrally on the thoracic vertebral bodies in the median plane as opposed to most rodents that have a left sided azygos vein. The internal vertebral venous plexus consisted of two ventrolateraly placed longitudinal veins in the spinal epidural space. Veins from the forelimbs entered the internal vertebral venous plexus directly at the levels of C7 and T1 and have not been described in other rodents. Serial histological sections, revealed no regulatory valves in vessels leading toward the internal vertebral venous plexus, allowing blood to presumably move in both directions within the vertebral venous plexus. The vertebral venous plexus of B. suillus shows similarities to that of the rat but the vessels from the forelimbs draining directly into to the internal vertebral venous plexus and the position of the azygos vein and the intercostal veins draining into the external vertebral venous plexus are notable exceptions. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Anatomy of the veins of the head in the domestic fowl

The anatomy of the cephalic venous system in the fowl was studied in 19 specimens by means of latex-injected preparations and by dissection. The brain sinuses converge dorsally upon the large cervical sinus and vertebral veins. Dorso-ventral communication is provided by the occipital veins posteriorly, while the ophthalmic system unites both dorsal and ventral sinuses and the temporal rete with the extracranial veins anteriorly. The jugular veins are formed from the superficial branches of the facial veins and serve mainly as outlets for extracranial blood. They are united at the base of the head by a prominent transverse anastomosis which slopes caudally towards the larger, right jugular. As in mammals, the carotid veins envelop the internal carotid arteries and anteriorly form a bulbous sinus cavernosus around the inter-carotid anastomosis.     

The vascularization of the human tela choroidea of the lateral ventricle

The human tela choroidea of the lateral ventricle is vascularized by arteries arising from the two systems which form the arterial circle of the base, i.e. the internal carotid system and the vertebral basilar system. This blood supply is given by one anterior choroidal artery and by several posterior choroidal arteries. These arteries anastomose to form multiple indirect and remote links between the carotid and vertebral basilar systems. The capillary networks of the tela choroidea of the lateral ventricle consists of a velar network and of a choroidal network. This duality is constantly observed in the choroid formations of the human brain. The venous vascularization of the tela is tributary of the venous circle of the base of the brain through choroidal veins that drain either into the internal cerebral veins or into the basal veins.     

Angiology of the brain of the baboon Papio ursinus, the vervet monkey Cercopithecus pygerithrus, and the bushbaby Galago senegalensis

The investigation was undertaken to compare the blood supply and venous drainage of the brain of the baboon P. ursinus, the vervet monkey C. pygerithrus, and the bushbaby G. senegalensis with that of man, because these animals are extensively used as research models. The blood supply of the three primates was found to be similar in each case. Like man they have a complete circulus arteriosus; but they have a single anterior cerebral artery, whereas man has paired anterior cerebral arteries. The arterial supply to the cerebellum in the primates is similar to that in man, the main difference being a "common inferior cerebellar artery" which bifurcates to form the anterior inferior cerebellar and posterior inferior cerebellar arteries. In man, these arteries arise separately from the basilar artery and vertebral arteries, respectively. The dural venous drainage was also found to be similar in these primates but was far more extensive than in man. The primates have additional sinuses--the more important of these being the "basisphenoid sinus" and the petrosquamous sinus. The former drains the basilar sinus and is itself drained via the vertebral venous plexus and internal jugular vein. The latter drains via the petrosquamous foramen into the retromandibular vein. The petrosquamous sinus has a rostral extension which drains through the foramen ovale and two lateral and medial connecting sinuses which drain the cavernous and basilar sinuses, respectively. These sinuses are not found in man.     

The study of cerebral venous blood flow disturbance peculiarity in the norm and under the extravasal compression of brachiocephalic veins with the use of magnetic resonance venography and ultrasound duplex scanning

The MR-venography of the veins and brain venous sinuses, brachiocephalic veins an internal jugular veins duplex scanning have been performed in order to study the distinctions of cerebral venous hemodynamics of healthy people and the patients with venous encephalopathy caused by the extravasal compression of the brachiocephalic veins at the neck level and the superior sections of mediastinum. It has been revealed that the blood flow reducing in transverse brain sinuses occurs not only in the case of outflow disorder in the distal sections of the venous system, but also in norm. This reducing depends on anatomic constitution of confluens sinuum and the venous angle type of brachiocephalic veins. The three venous angle types of brachiocephalic veins have been distinguished: y-type, mu-type and Y-type. It has been registered that in case of the mu-type angle the blood flow can be reduced in norm due to peripheral resistance increase at the physiological bends of nearly a right angle type. The distinctions of hemodynamics in case of venous obstruction in contrast to arterial obstruction have been described. It has been registered that in case of outflow trouble in one of the internal jugular veins the speed and the volume of the blood flow in it are progressively reduced depending on the duration and the manifestation of compression. All this results in narrowing of the vein diameter from the affected side, and in compensatory distention of the diameter and increase of blood flow volume in the contralateral internal jugular vein, vertebral and external jugular veins, in succession.     

Enhanced global mathematical model for studying cerebral venous blood flow

Here we extend the global, closed-loop, mathematical model for the cardiovascular system in Müller and Toro (2014) to account for fundamental mechanisms affecting cerebral venous haemodynamics: the interaction between intracranial pressure and cerebral vasculature and the Starling-resistor like behaviour of intracranial veins. Computational results are compared with flow measurements obtained from Magnetic Resonance Imaging (MRI), showing overall satisfactory agreement. The role played by each model component in shaping cerebral venous flow waveforms is investigated. Our results are discussed in light of current physiological concepts and model-driven considerations, indicating that the Starling-resistor like behaviour of intracranial veins at the point where they join dural sinuses is the leading mechanism. Moreover, we present preliminary results on the impact of neck vein strictures on cerebral venous hemodynamics. These results show that such anomalies cause a pressure increment in intracranial cerebral veins, even if the shielding effect of the Starling-resistor like behaviour of cerebral veins is taken into account.     

Homology and evolution of the orbitotemporal venous sinuses of humans.

The orbitotemporal venous sinuses accompany the intracranial branches of the stapedial artery. These sinuses are large in primitive primates and drain the extensive territories supplied by the stapedial artery as well as the brain. The orbit is drained by a wide cranio-orbital sinus which empties into the postglenoid emissary vein. Also emptying into the postglenoid vein is the petrosquamous sinus. The latter diverts cerebral blood from the transverse sinus and also drains the temporalis muscle. Emptying into both the cranio-orbital and petrosquamous sinuses are meningeal tributaries, which drain the cranial side wall and the dura mater. The relatively small sinus communicans runs in the angle between the petrosal bone and the cranial side wall. It commences at the postglenoid vein and connects the distal end of the petrosquamous sinus to the pterygoid venous plexus. In humans, the orbitotemporal sinus system is greatly modified. Its remnants persist for the most part as "middle meningeal veins." The system no longer drains the orbit, the temporal fossa, or the brain. The petrosquamous sinus becomes attenuated or obliterated along part or all of its length. The postglenoid vein vanishes. The cranio-orbital sinus is reduced in diameter and its connection to the orbit is feeble or absent. During development, the posterior end of the cranio-orbital sinus migrates inferiorly along the sinus communicans. In most individuals, this migration ceases at the foramen spinosum, site of the emissary vein of the sinus communicans. Meningeal tributaries are relatively large in humans, and drain principally into the cranio-orbital sinus or sphenoparietal sinus. The sphenoparietal sinus is an evolutionary novelty restricted to hominoids and is frequently developed in only Homo and Pongo.     

Intraosseous veins of the maxilla in the newborn]

The intraosseous veins of the maxilla in newborns grow larger with enlargement of the bone and become disposed in three mutually perpendicular planes. The venous plexus of the alveolar process is large. V. v. vallares are thin and interlace forming a network. The veins of interdental septum are well pronounced. The thick venous network of the periosteum and the mucous membrane of the nasal surface of the palatine process includes the vessels transversal and longitudinal to the nasal septum. The venous loops of the incisor part are of triangular, pentagonal and polygonal shape. The veins of the palatine process are connected with 3-4 large vessels falling into the vessels of the tear duct. The transversal and oblique veins of the oral surface of the palatine process are connected with large vessels disposed in parallel to the medial structure of the hard palate. The venous network of the incisor part of the bone is restricted by densified small arc-shaped plexuses. Two-three largest veins lie sagittally and, connected by arc-shaped anastomoses, are tributaries of the vessels of the palate bone, soft palate and pharynx.     

Head and Neck Veins of the Mouse. A Magnetic Resonance,Micro Computed Tomography and High Frequency Color Doppler Ultrasound Study

To characterize the anatomy of the venous outflow of the mouse brain using different imaging techniques. Ten C57/black male mice (age range: 7-8 weeks) were imaged with high-frequency Ultrasound, Magnetic Resonance Angiography and ex-vivo Microcomputed tomography of the head and neck. Under general anesthesia, Ultrasound of neck veins was performed with a 20MHz transducer; head and neck Magnetic Resonance Angiography data were collected on 9.4T or 7T scanners, and ex-vivo Microcomputed tomography angiography was obtained by filling the vessels with a radiopaque inert silicone rubber compound. All procedures were approved by the local ethical committee. The dorsal intracranial venous system is quite similar in mice and humans. Instead, the mouse Internal Jugular Veins are tiny vessels receiving the sigmoid sinuses and tributaries from cerebellum, occipital lobe and midbrain, while the majority of the cerebral blood, i.e. from the olfactory bulbs and fronto-parietal lobes, is apparently drained through skull base connections into the External Jugular Vein. Three main intra-extracranial anastomoses, absent in humans, are: 1) the petrosquamous sinus, draining into the posterior facial vein, 2) the veins of the olfactory bulb, draining into the superficial temporal vein through a foramen of the frontal bone 3) the cavernous sinus, draining in the External Jugular Vein through a foramen of the sphenoid bone. The anatomical structure of the mouse cranial venous outflow as depicted by Ultrasound, Microcomputed tomography and Magnetic Resonance Angiography is different from humans, with multiple connections between intra- and extra- cranial veins.     

Venous haemodynamics response to hypercapnia

The authors' aim was to evaluate the response of the intracranial venous system to application of functional tests. In 46 healthy volunteers, the basal veins were examined using venous transcranial color-coded duplex sonography. We evaluated angle-corrected venous peak-systolic flow velocities (V(vb)) in response to hypercapnia (I group: 29 subjects) and the orthostatic test (II group: 17 subjects). We have found that hypercapnia inducesa significant increase of the flow velocities in the basal veins, on average 60 +/- 22.7% (p < 0.00001). The reaction prevents venous hyperaemia, i. e., significant increase of the cerebral blood flow volume and the drainage of the brain. In contrast to hypercapnia, the orthostatic test led to decrease in the flow velocities in the basal veins. The percentage of velocity decrease ranged from 16to 32% (p < 0.001). Posturally induced reduction of the venous flow volume prevents excessive drainage from the brain. Thus, we have shown that both tests can be used for evaluation of reactivity of the intracranial venous system and they can complement each other.     

Venous stagnation induced by 7 dyas in HDT, in the cerebral, ophtalmic, renal and splancnhic territories

The scientific objectives was to quantify the vascular changes in the brain, eye fundus, renal parenchyma, and splanchnic network. Heart, Portal, Jugular, femoral veins were investigate by Echography. The cerebral mesenteric, renal and ophthalmic arteries were investigated by Doppler. Eye fundus vein an papilla were investigated by optical video eye fundus. The Left ventricle volume decreased as usual in HDT. The cerebral and ophthalmic vascular resistances did'nt change whereas the eye fundus papilla and vein, and the Jugular vein increased. These arterial and venous data confirm the existence of cephalic venous blood stasis without sign of intracranial hypertension. On the other hand the kidney volume increased which is in agreement with blood flow stagnation at this level. At last the Mesenteric vascular resistance decreased and the Portal vein section increased in HDT which is in favor of an increase in flow and flow volume through the splanchnic area.     

Does thoracic pump influence the cerebral venous return?

We assessed the hemodynamic effects induced by the thoracic pump in the intra- and extracranial veins of the cerebral venous system on healthy volunteers. Activation of the thoracic pump was standardized among subjects by setting the deep inspiration at 70% of individual vital capacity. Peak velocity (PV), time average velocity (TAV), vein area (VA), and flow quantification (Q) were assessed by means of echo color Doppler in supine posture. Deep respiration significantly increases PV, TAV, and Q, but it is limited to the extracranial veins. To the contrary, no significant hemodynamic changes were recorded at the level of the intracranial venous network. Moreover, at rest TAV in the jugular veins was significantly correlated with Q of the intracranial veins. We conclude that the modulation of the atmospheric pressure operated by the thoracic pump significantly modifies the hemodynamics of the jugular veins and of the reservoir of the neck and facial veins, with no effect on the vein network of the intracranial compartment.     

Some aspects concerning the peculiarities of the pterygoid venous plexus in man related to age

The pterygoid venous plexus (pt.v.pl.) was studied in 54 human heads (adults, children, fetuses) halved in the middle sagital plan, using microdissections and injections with PVC, coloured gelatin and roentgenopaque masses. In adults, the pt.v.pl. was closely related to the external pterygoid muscle. The superficial variant (more frequent) maintained connections with the facial vein through a venous network named by us "plexus pterygo-temporo-buccalis". The deep variant (less frequent) could be included in the system of venous plexuses placed at the basis cranii. Its tributaries, accompanying the lingual nerve, established connections with the veins of the sublingual compartment (a fact not yet mentioned in the literature). In children and old humans the pt.v.pl. was formed only by some large veins giving a radiate structure ("starfish-shaped" plexus) corresponding to the first and second portion of the maxillary artery. These results revealed that the pt.v.pl. is a unique formation which could be more developed laterally or medially in comparison with the external pterygoid muscle, in relation with the superficial or deep position of the maxillary artery. The practical importance of the pt.v.pl. is emphasized.     

An angiographic study of the carotid arterial and jugular venous systems in the cat.

Standard techniques for performing carotid angiography in dogs and in man were adapted to the cat in order to study the vascularization of both intracranial and extracranial structures. Venous drainage was examined by venography of selected vessels. The carotid-cerebral and the vertebral-basilar arterial systems of the cat were studied, although no attempt was made to define the territory supplied by each system. In serial angiograms, vascularization of the rete mirabile conjugatum was visualized and distinct arterial and venous retia were delineated. Large facial veins were seen approximately one second after the intra-arterial injection of radio-contrast material. The early filling of the large facial veins appeared to be the result of an artery-to-venous shunt. Contrast material flowed posteriorly in these veins and drained into the venous rete. When contrast material was injected either into the sagittal sinus or retrograde in the external jugular vein, the internal jugular vein was visible in four of ten cats. This vessel drained blood directly from intracranial contents before anastomosis with the vertebral and external jugular veins.     

Arterialization of the venous system of the brain

The possibility of reverse perfusion of the brain (in which arterial blood flows to brain tissues through venous vessels, and venous blood is drained by the arteries) was studied in acute and chronic experiments on dogs. Blood pressure in cerebral veins could reach 90--120 mm Hg, in Willisii arteries it was 5--35 mm Hg. Liquor pressure reached 20--35 mmHg. After temporary arterialization of the brain venous system (10, 30 and 60 min) the animals survived without impairment of the brain function and behaviour. In the future reverse perfusion of the brain (in which blood pressure in the arteries falls to the level of venous pressure) could be used as a means of urgent surgical intervention in cases of threatened or beginning intracranial arterial hemorrhage.     

The intrarenal and pericapsular venous systems of kidneys of the ringed seal, Phoca hispida

The kidneys of Phoca hispida are comprised of many closely adherent renculi, each of which is a small kidney, functionally independent of its neighbours except with respect to venous drainage. Venous blood from the rencular parenchyma drains to the periphery through interlobular veins. These interlobular veins empty into a perirencular plexus comprised of subcapsular veins on the free surface of the renculus, interrencular veins on adjoined surfaces, and marginal subcapsular veins lying in the furrows between adjoined renculi. A pericapsular plexus of large veins overlies the marginal subcapsular veins and has frequent connections with them. Blood drains from the pericapsular plexus into large superficial collecting veins that converge over the surface of the kidney toward the divided hilum and connect directly to the paired trunks of the posterior vena cava. There are also connections to other major venous systems of the region. There is no arcuate venous system, no major vein at the rencular hilum, and no vein of consequence emerging from the renal hilum. Venous outflow is virtually entirely directed to the peripheral plexuses. The venous pattern differs from that of most mammals in which blood drains from the renal parenchyma to arcuate veins and leaves the kidney through a renal vein, or veins, emerging from the hilum. The walls of veins in the kidney are remarkably thin in comparison to their size. Subcapsular veins up to 0.5 mm wide have walls on the parenchymal side that in places consist only of a thin, fenestrated endothelium and a basal lamina.     

Veins of the human cerebellum

(1) The veins of the human cerebellum, which may be classified into internal and external venous channels, correspond, in this respect, to the veins of the cerebral hemispheres. (2) The external cerebellar veins are arranged in three groups which, in turn, correspond to the three cerebellar surfaces and which communicate extensively. Accordingly, the terminal segments of the cerebellar veins overlap, which implies that no one-to-one relationship exists between the mouths of the individual veins and their respective distributions. (3) The terminal segments of the cerebellar veins are the superior petrosal sinus, the tentorial venous sinuses, the great vein of Galen and the internal vertebral plexus. (4) The tentorial venous channels may form a collateral venous arrangement. (5) The internal cerebellar veins consist of the nuclear veins and the medullary veins. (6) The medullary veins form a cortex-perforating group and a group located in the basal medullary region. The latter form a venous arborization of blood vessels not described thus far. This group of veins opens chiefly into the vein of the lateral recess of the fourth ventricle.(7) Attention is called to a 'venous watershed' corresponding to the one that exists in the cerebral hemispheres. (8) The veins of the dentate nucleus are composed of several venous channels draining its external surface and one single vein draining its internal surface. The latter has not been described thus far. The external veins of the dentate nucleus open into the venous star and the cortex-perforating veins. The internal nuclear vein, on the other hand, emerging from the hilum of the dentate nucleus, runs along the superior cerebellar peduncle. Thus, the term 'vena centralis nuclei dentati' appears to be appropriate to designate this vessel. It ultimately opens into the precentral cerebellar vein. (9) In certain places, various-colored substances used for injection form mixed pools.     

Observations on the venous system of three species of Polypterus (Pisces)

The venous system of Polypterus exhibits general asymmetry. The features that characterize the venous system of this peculiarly African fish are the possession of many blood sinuses, the segmental drainage of blood, the continuation of the posterior cardinal veins as separated vessels and the occurrence of several anastomozes between the latter.
In the absence of any recent comprehensive work on the blood system of this fish, it was thought that investigation of the circulatory system of Polypterus would be valuable. In this paper attention is drawn to Budgettapos;s (1902) original work on a larva of Polypterus senegalus. Contrary to Budgettapos;s findings it is concluded that what he called the "interrenal" vein is in fact the right posterior cardinal vein. It is also found that paired posterior cardinal veins exist in all adults.     

Blood vessels and the occurrence of arteriovenous anastomoses in cephalic heat loss areas of mallards,Anas platyrhynchos (Aves)

Summary 1. The blood supply to cephalic heat loss areas (nasal and oropharyngeal mucosa, bill, eyelids) was studied in mallards by using plastic corrosion casts. The structure and organization of the blood vessels, as well as the occurrence of arteriovenous anastomoses (AVAs), were examined by scanning electron microscopy of vascular casts and by paraffin sections.2. Submucosal venous plexuses (cavernous tissue) are present in the nasal cavity, tongue, and lateral margins of the palate. These plexuses receive blood from post-capillary venules, but may also receive a non-nutritive component via numerous AVAs.3. High densities of AVAs were found in the eyelids and in the tip of the bill. In the tongue and nasal mucosa, the AVAs decreased in number caudally. The reason for regional differences in the density of AVAs is discussed in relation to variation in mechanical and thermal stimulation of the tissues.4. The connection of the different heat loss areas with the Rete ophthalmicum, which is a countercurrent heat exchanger important for brain cooling, is pointed out. The vascular pattern of the head suggests that sphincteric veins are involved in regulating the venous return from the evaporative surfaces of the nasal cavity and palate. One of these veins had, in addition to the normal circular smooth muscle fibres, a conspicuous component of longitudinally arranged, subendothelial, smooth muscle fibres.