Inferior Alveolar Artery

The inferior alveolar artery is the blood vessel which supplies the bone and tissues of the mandible (lower jaw). Among the arteries of the face, it has one of the longest courses, sending many secondary side branches. It is also known as the inferior dental artery in old anatomy books.

The inferior alveolar artery arises from the inferior side of first portion of the maxillary artery, which is the mandibular part. Then it stretches downwards and forwards, running through the mandibular foramen. Together with the inferior alveolar nerve and vein, it travels into the mandibular canal.

Branches

Before entering the mandibular canal, the inferior alveolar artery gives off the mylohyoid artery, which descends obliquely forwards to supply the mylohyoid and digastric muscles. As it runs through the mandibular canal, the inferior alveolar gives off the dental arteries, which are small side branches that bring oxygenated blood to the teeth, tooth sockets, gum, and the spongy substance of mandible.

Before anastomosing with the terminal portion of its contralateral artery, the inferior alveolar gives off the mental artery. This branch makes its way through the mental foramen, emerging superficially on the other side on the forward portion of mandible to supply the region of chin and lower lip, anastomosing with small branches of the inferior labial artery, which originates from the facial artery.

Below, a schematic picture of the external carotid and the maxillary in the right side of face, showing the point of origin and course of the inferior alveolar artery.

Greater Palatine Artery

The greater palatine artery is an important blood vessel which supplies the hard palate and the gum. It is one of the two branches into which the descending palatine artery divides; the other being the lesser palatine branch. You must remember that the descending palatine originates from the third portion of the maxillary artery, which in turn springs from the external carotid.

The greater palatine artery arises from the descending palatine in the greater palatine canal. Then it runs down together with the lesser palatine artery and nerve for about one cm. It emerges out onto the roof of the oral cavity through the greater palatine foramen, stretching in the palatine groove of the hard palate.

The greater palatine artery travels forwards in this groove, giving off several collateral branches as it goes. These secondary branches further ramify to bring oxygenated blood to the bone of the hard palate, the gum, and the mucous membrane.

Below, a picture of sagittal section of the nasal cavity and oral cavity, showing the right lateral wall of nose and roof of oral cavity. To the right of the nasal cavity, you can see the descending palatine divide into the lesser and the greater palatine artery.

Descending Palatine Artery

The descending palatine artery is one of the terminal branches of the maxillary artery, which in turn arises from the external carotid. It supplies the soft palate, the gums, and the mucous membrane and bone of the hard palate.

The descending palatine artery originates from the pterygopalatine part of the maxillary (third portion in some text). Right before it takes a downward course, it gives off its first branch, which is the artery of pterygoid canal. Then it descends into the greater palatine canal where it forks into two branches 1) the greater palatine artery and 2) the lesser palatine artery. The former supplies the hard palate, its mucous membrane and the gum, while the latter brings oxygenated blood to the soft palate and part of tonsil.

Below, schematic picture of nasal cavity and mouth, showing the descending palatine artery and its branches. The third portion of maxillary cannot be seen because it is hidden in the pterygopalatine fossa.

Ascending Palatine Artery

The ascending palatine artery is the first branch of the facial artery, which in turn arises from the external carotid. It supplies the soft palate, the walls of pharynx, the tonsils, as well as the styloglossus and the stylopharyngeous muscle with oxygenated blood.

The ascending palatine originates from the superior-posterior side of facial artery. Then it travels up on the lateral wall of the pharynx, between the styloglossus and the stylopharyngeous muscle, giving off collateral branches that supplies these muscles.

The ascending palatine artery keeps climbing up to reach the levator veli palatini muscle, where it divides into two secondary branches; one which brings oxygenated blood to the soft palate; the other pierces the superior constrictor muscle to supply the tonsil and Eustachian tube. These final branches anastomoses with terminal branches of the ascending pharyngeal artery.

Below, schematic picture of the face region, showing the external carotid, the facial, and the ascending palatine artery.

Facial Artery

The facial artery is a blood vessel which supplies 40% of the face. The maxillary and the transverse facial artery irrigate the remainder 60% with oxygenated blood. The facial artery arises from the anterior side of the external carotid, slightly above the lingual artery.

From its point of origin, the facial artery travels forwards and upwards, running under the posterior belly of the digastric muscle and the stylohyoid muscle. Then it extends into the submandibular triangle, piercing the submandibular gland. Next it runs laterally, curving around the border of the body of mandible and turning upwards onto the side of the face. Then stretches obliquely towards the medial angle of eye between the superficial and deep muscles of facial expression, sending small collateral branches that supply the masseter, zygomaticus major, buccinator, levator anguli oris, and levator labii superioris muscle. Finally, the facial ends up as the angular artery, which is its terminal branch.

Along its course, the facial artery gives off the following branches: a) ascending palatine artery, which supplies the soft palate and the lateral wall of pharynx; b) tonsillar branch, which brings oxygenated blood to the tonsils; c) inferior labial artery, which irrigates the lower lip; d) superior labial artery, which supplies the upper lip; e) submental artery, which supplies the mylohyoid muscle and sublingual gland; f) branches to the submandibular gland; g) angular artery, which is the terminal branch supplying the muscles and skin of side of nose.

Below, picture showing the facial artery as it arises from the external carotid (about 1 cm above the lingual artery)

 

Lingual Artery

The lingual artery is a paired blood vessel which supplies the tongue. It arises from the anterior side of external carotid artery, slightly above the point of origin of the superior thyroid and below the facial artery.

The lingual artery first runs upwards, ascending over the greater horns of the hyoid bone. Then it travels forwards and medially, reaching the inferior surface of tongue. Piercing this organ, it enters deep into its muscles. Along its course, the lingual artery is covered first by the posterior belly of the digastric muscle and the stylohyoid muscle. Then it runs deeply under the hyoglossus muscle and the middle constrictor muscle of pharynx.

Branches

The lingual artery gives off the following branches: 1) suprahyoid artery, which supplies the hyoid bone and the adjoining soft tissues; 2) dorsales linguae branches, which bring oxygenated blood to the mucous membrane of tongue and the tonsil; 3) sublingual branch, supplying the sublingual gland and adjoining muscles; 4) profunda artery of tongue, which is the continuation or terminal branch of the lingual artery, conveying blood to the genioglossus muscle and the inferior longitudinal muscle of tongue, ending up in the apex of this organ.

Below, picture of neck and face (right side), showing the lingual artery as it arises from the external carotid.

Superior Thyroid Artery

The superior thyroid artery is a paired blood vessel which lies in anterior aspect of neck. It mainly supplies the thyroid gland. It originates from the anterior side of external carotid at the level of the greater horns of the hyoid bone. Thus, it is the first branch given off by the external carotid just after this artery arises from the common carotid.

The superior thyroid artery first runs up some millimeters, then it curves medially and downwards, swerving to the upper pole of the lateral lobe of thyroid gland, where it ends up by dividing into an anterior and a posterior branch. In the gland, it anastomoses with branches of the inferior thyroid artery, which arises from the thyrocervical trunk.

Along its course, the superior thyroid artery gives off several branches: 1) the infrahyoid artery, which supplies oxygenated blood to the hyoid bone; 2) sternomastoid branch, which provides blood to the sternocleidomastoid muscle; 3) the superior laryngeal artery, which brings blood to the thyrohyoid muscle, the epiglottis and the mucous membrane of the larynx; 4) the cricothyroid branch, which supplies the cricothyroid muscle, forming an arched anastomosis with the contralateral branch.

Below, an schematic picture of the neck, exhibiting the external carotid and the superior thyroid artery

External Carotid Artery

The external carotid artery is one of the two main branches into which the common carotid divides, the other being the internal carotid artery. It supplies oxygenated blood to the face, mouth, tongue and external parts of the head.

The external carotid originates at the level of the upper border of thyroid cartilage. Then it runs upward in the neck, first slightly anterior to the internal carotid, then lateral to it. At the end of its course, when it reaches the level of the ear, it forks into the superficial temporal and maxillary artery within the parotid gland.

In its first portion, the external carotid artery lies superficially and is covered by platysma and the superficial layer of the cervical fascia. Then, as it ascends, it passes behind the posterior belly of the digastric muscle and the stylohyoid muscle. Slightly higher, it fits into the retromandibular fossa in which it enters the parotid gland.

Branches

As it runs up the neck, the external carotid artery gives off six smaller branches: 1) the superior thyroid artery, which supplies the thyroid gland; 2) the ascending pharyngeal artery, which irrigates the pharynx; 3) the lingual artery, supplying the tongue; 4) the facial artery, which provides a large area of face with oxygenated blood; 5) the occipital artery; and 6) the posterior auricular artery.

Below, schematic pictures of the external carotid artery and its branches

Systemic Circulation

The systemic circulation is a complex closed circuit of blood vessels which supplies oxygenated blood to every tissue of the body and returns deoxygenated blood from the tissues back to the heart. The oxygenated blood is transported by arteries, and the returning blood flows through the veins. Meanwhile, the capillaries, which are the smallest vessels, constitute the bridge which communicates the arterioles (tiny arteries) with the venules (smallest veins).

In the diagram of the systemic and pulmonary circulation located at the bottom of the post, you can see the heart at the center of the system, since it is the organ that pumps the blood, keeping it circulating (flowing) through the whole system of blood vessels to keep the body tissues alive. Therefore, the blood flows away from the heart and return. It receives oxygen-rich blood from the lungs into its left atrium and its left ventricle pumps it to the rest of the body through the aorta. Arteries and arterioles supply this oxygenated blood to all the organs and body tissues, from which oxygen-poor blood returns to the right atrium of the heart through the superior and inferior vena cava.

Red in color, the arteries are the blood vessels that carry oxygenated blood away from the heart to the rest of the body, with the aorta being the main one, which gives off all the arterial branches as it curves and then descends down the trunk and abdomen. But there is one exception, the pulmonary artery, which carries oxygen-poor blood from the heart to the lungs, where it is oxygenated. So, in medicine, any blood vessel that transports blood away from the heart is called artery.

Veins are the blood vessels that carry oxygen-poor (deoxygenated) blood to the heart, but with the exception of the pulmonary veins, which carry oxygen-rich blood from the lungs to the left atrium. Thus, in medicine, any vessel through which blood flows towards the heart is called vein. The mesenteric and portal veins are other exceptions, because the blood they carry do not go straight towards the heart but straight towards the liver, where the nutrient-rich blood from digestion is processed and metabolized by the liver before going into the general circulation.

Below, a diagram of the systemic circulation

Hepatic Portal System

The hepatic portal system is the network of veins that drains oxygen-poor and nutrients-rich blood into the liver. This system of venous blood vessels is made up of three main veins: 1) the splenic; 2) the superior mesenteric; and 3) the portal vein, with the first two ones joining one another to give rise to the third one. However, there are important venous tributaries which drain into each one of these three big veins, contributing to the portal system network of special veins.

The splenic vein also receives blood from the pancreatic, the left gastroepiploic, short gastric, and the inferior mesenteric vein. Let us remember that the splenic drains the spleen, and the others the stomach and large intestine respectively. Meanwhile, secondary tributaries carry nutrient-rich blood from the small intestine into the superior mesenteric vein, which joins the splenic.

As mentioned above, the portal vein arises from the union of the superior mesenteric and splenic vein. The portal, in turn, also receives blood directly from the left gastric and right gastric vein just before it enters the liver, where it divides into two main branches that keep giving off smaller branches until they form a network of venules and capillaries.

All these venous blood vessels that constitute the hepatic portal system are special veins. They are special for two reasons; firstly, they carry nutrients and hormones-rich blood. Secondly, they do not drain towards and into the cava vein, as it is the case with all the other ordinary veins. They drain into the liver, where all the nutrients (proteins, fatty acids, glycerol, glucose, minerals) are metabolized by the liver into the vital substances our body cells need. Only when they have been metabolically processed, these essential contents are carried in the venous blood by the hepatic veins into the inferior cava.

Below, diagram drawing of the veins that compose the hepatic portal system.

Hepatic Portal Vein

The hepatic portal vein is the venous trunk that carries nutrients-rich blood into the liver. It arises from the union of the splenic and the superior mesenteric vein, with the former draining the spleen and pancreas, and the latter the small intestine and colon respectively. Right before they join together to form a trunk, the splenic vein receives blood from the last portion of large intestine (descending colon and rectum) via the inferior mesenteric.

The hepatic portal vein conveys not only deoxygenated blood but also the nourishing byproducts of digestion into the liver, where they are metabolized by the hepatocytes mitochondria into vital products necessary for the maintenance of all the body tissues. What makes this vein different from the rest of the veins is the fact that it does not run straight into the venous bloodstream of the cava vein, but into the liver instead.

As it runs upwards, the portal vein takes a rather oblique course to the right of the porta hepatis, which is a transverse narrow opening located between the quadrate lobe and the caudate lobe. Thus, having entered the liver, this thick venous trunk splits into a left and a right branch, then into smaller ones, with each one of them dividing into even smaller venous branches until they become venules. This is how the portal vein ends up in the portal capillaries which penetrates throughout the whole hepatic parenchyma.

All three veins that drain into the liver (superior mesenteric, splenic, and hepatic portal) and their smaller branches are make up the portal system. We have to make it clear that the other veins the drain the liver into the cava vein are not part of the portal system.

Below, the portal vein with the rest of the veins that merge into it to make up the portal system.

Inferior Mesenteric Vein

The inferior mesenteric vein is a venous blood vessel which drains a small portion of the transverse colon, the descending colon, and the rectum. It receives oxygen-poor blood from the left colic vein, the sigmoid veins, the left and right rectal vein, and the middle and inferior rectal veins, all of which drain these parts of the large intestine as they get together to form this thick venous vessel of the digestive system.

The inferior mesenteric vein begins in the cavity of the true pelvis as the superior rectal vein. Then it runs upwards, parallel to the inferior mesenteric artery, and joins the splenic vein, emptying the blood it carries into it. The splenic in turn joins the superior mesenteric vein to form the hepatic portal vein. Thus, this blood vessel is part of the hepatic portal system.

The inferior mesenteric is located behind the peritoneum and, as it ascends, it forms a small arch, whose convexity is directed to the left. After receiving the left colic vein, it swerves to the right, passing immediately to the left of the duodenojejunal flexure under the pancreas, where it finally joins the splenic vein. In some cases, it does not unite with the splenic but empties its content directly into the portal vein.

Below, a diagram and drawing of the inferior mesenteric vein.

Superior Mesenteric Vein

The superior mesenteric vein is an important vessel of the digestive system. It carries nutrient-rich and deoxygenated blood from the small intestine, the caecum, and the ascending and transverse colon to the hepatic portal vein. Thus, it is part of the portal system.

The superior mesenteric receives blood from a network of smaller venous branches that drain the intestines. These small branches join to form a long common trunk, which extends to the right of the superior mesenteric artery, with its side branches running side by side with this artery branches. Then,
it runs upwards behind the pancreas and the stomach to meet the splenic vein, with which it forms the hepatic portal vein and the hepatic portal system that runs into the liver. 

The superior mesenteric vein is different from the other veins in the body, because it does not drains straight towards the cava vena but towards the liver. The reason for this is that it conveys blood containing rich nutrients, which are the products of digestion; these nutrients have to be metabolized by the liver first before returning to the heart through the cava vein.

Beginning at the ileocaecal junction, the superior mesenteric vein receives the following secondary tributaries: the jejunal and ileal veins (about 18 in number), the right colic veins, the middle colic vein, and the right gastroepiploic vein. In most individual, the pancreaticoduodenal vein drains directly into the portal vein.

Below, diagram of the superior mesenteric vein and its branches. You can see the portal and splenic vein and the splenic vein. They are not blue as usually are depicted because they do not run into the cava vein but into the portal.

Splenic Vein

The splenic vein is a deoxygenated blood vessel which drains the spleen, pancreas, stomach, and greater omentum. It is formed in the hilum of the spleen by the confluence of several smaller branches that come out of this organ. Then it receives blood from the left gastroepiploic vein, which drains part of the stomach, as well as from the pancreatic, the inferior mesenteric and the short gastric vein.

The splenic vein joins the superior mesenteric to form the hepatic portal vein, which together make up the portal system of veins. The portal system does not empty its content into the vena cava; it carries the deoxygenated blood into the liver instead. However, this blood is rich in nutrients, like amino acids, fatty acids, vitamins, glucose, minerals etc, as they are the products of digestion. These nutrients are processed and metabolized in the liver.

Vessels draining into the splenic vein

Besides the above-described veins, which formed the portal system, the following vessels drain directly into splenic vein: the pancreatic, pancreaticoduodenal, prepyloric, gastroepiploic, and the left and right gastric veins, which in turn receive the veins of the pylorus.

Below, a drawing of the digestive system organs and the special veins that make up the portal system, which include the splenic vein.

 

Branches of Popliteal Artery

The branches of popliteal artery form a complex network of blood vessels which supply the bones, ligaments, and the muscles and their tendons of the knee-joint region. They do not include the descending genicular artery, because this blood vessel arises from the distal portion of femoral artery. Along its course, the popliteal, which is the continuation of the femoral, gives off the following arteries:

1) Lateral superior genicular artery– It arises from the lateral aspect of the popliteal and then runs laterally under the biceps femoris distal end and above the lateral condyle of femur, dividing into several secondary branches.

2) Lateral inferior genicular artery– It also emerges from the lateral side of popliteal, traveling laterally underneath the lateral head of gastrocnemius muscle and around the condyle of tibia.

3) Medial superior genicular artery– Being the contralateral of the lateral superior genicular, it originates from the medial aspect of popliteal, running medially under the tendons of semimembranosus and adductor magnus muscle and around the medial condyle of femur.

4) Medial inferior genicular artery– It also runs medially, lying under the medial head of the gastrocnemius muscle.

5) Middle genicular artery– It arises from the anterior side of popliteal; then it travels forwards, perforating the knee-joint capsule to supply the synovial membrane and cruciate ligaments.

6) Sural artery– Two or three in number, it originate from posterior side of popliteal, running either medially or laterally, sending smaller branches that supply the tissues of the knee.

7) Superior muscular branches– They are four or five in number, originating from the upper portion of popliteal, supplying the distal portions of the biceps femoris, semitendinosus, and semimembranosus muscle.

8) Anterior tibial artery– It arises from the popliteal as one of its two terminal branches, with the other being the posterior tibial, right below the knee joint.

9) Posterior tibial artery– It is also one of the two terminal branches of the aforesaid main artery.

Below, drawing/diagram showing the branches of the popliteal artery, with the thigh and leg muscles.

See popliteal artery

Perineal Artery

The perineal artery is an oxygen-rich blood vessel of the pelvic floor region. It originates from the internal pudendal, which in turn arises from the internal iliac artery. It arises slightly distal to the inferior rectal artery as it usually stretches behind the superficial transversus perineal muscle.

From its point of origin in the pudendal canal, the perineal artery runs medially (inwardly) and anteriorly, giving off several branches, supplying the scrotum, ischiocavernosus, the bulbospongiosus, the transverse perineal muscle, and the posterior wall of septum. All these terminal branches anastomoses with the external pudendal arteries.

Below, diagram of pelvic floor arteries, showing the perineal artery