Foramen spinosum

Thursday, October 19, 2017

The foramen spinosum is a paired orifice, which is found on the greater wing of the sphenoid bone, one on each side of the base of the skull. In other words, it is located anteriorly to the sphenoid bone spine. Function: the foramen spinosum serves as a passageway to the nervus spinosus, which is the meningeal branch of the mandibular nerve, and to the middle meningeal artery. The nervus spinosus innervates the meninges, and the middle meningeal artery supplies the dura mater.

Location of the foramen spinosum in the base of the human skull
image from usf edu

Zygomatic arteries

Wednesday, October 18, 2017

The zygomatic arteries are oxygen-rich blood vessels that originate from the lacrimal artery, which, in turn, arises from the ophthalmic artery. They are usually two branches that come off as lateral projections of the lacrimal. Then they further fork into smaller caliber vessels. Function: they supply the zygomatic bone and other structures.

Blood supply to the frontal lobe

Friday, October 6, 2017

The human brain frontal lobe is supplied by the middle cerebral and anterior cerebral arteries. Both of them are branches of the internal carotid artery. The pre-central, the pars triangularis, the inferior frontal, the middle frontal, and the superior frontal gyrus of the frontal lobe receive oxygen-rich blood from the pre-rolandic artery and the pre-frontal arteries, all of which come off the M4 or cortical segment of the middle cerebral artery.

The orbitofrontal cortex of the frontal lobe is supplied by the lateral frontobasal artery, which is also a branch of M4 segment of the middle cerebral artery. Meanwhile, the orbitofrontal and the frontopolar artery, which arise from the anterior cerebral artery, supply also the orbitofrontal and other regions of the pre-frontal lobe. The pericallosal artery of the anterior cerebral artery supply the medial (internal) surface of the frontal lobe, the area that partially surrounds the corpus callosum.

Lacrimal artery

Tuesday, October 3, 2017

The lacrimal artery is an oxygen-rich blood vessel which arises from the ophthalmic artery. It runs parallel and above the lateral rectus muscle in the orbit. It supplies the lacrimal gland with oxygenated blood. Branches: zygomatic arteries.

Blood supply to the brain

Saturday, September 30, 2017

The blood supply to the human brain is carried out by two main arteries; the internal carotid artery, which is a paired blood vessel, and the basilar artery. Both arteries carried oxygenated blood pumped by the heart left ventricle during the systole.

The internal carotid artery arises from the common carotid artery, on each side of the neck, carrying up about 60% of the oxygenated blood volume the brain needs. Having given off the ophthalmic artery as the first branch, it divides into the anterior cerebral, middle cerebral, and posterior communicating artery, forming the circle of Willis at the base of the brain. The middle cerebral artery is the most important one because of the large volume of oxygenated blood it carries, supplying not only the basal ganglia, but also a large portion the cerebral cortex.

The basilar artery is formed by the union of the right and left vertebral arteries in the posterior part of the skull, at the base of the encephalon. Having given off vital branches, such as the pontine, which supply the pons, and the cerebellar arteries, it forks into the two posterior cerebral arteries, which join the circle of Willis.

Collateral ganglia

Wednesday, September 27, 2017

The collateral ganglia are a small network of three nerve-cell ganglia which are part of the autonomic nervous system. Connected with the abdominal organs, they are located right on frontal surface of the abdominal aorta, surrounding the base of the great arteries that supply the gastroinstestinal tract, right at the point where they arise from the aorta. They are the celiac ganglion, which surrounds the celiac arterial trunk; the superior mesenteric ganglion, which is at the base of the superior mesenteric artery, which supplies the small intestine; and the inferior mesenteric ganglion, located around the base of the inferior mesenteric artery, which supplies the large intestine.

The collateral ganglia innervates the abdominal organs of the digestive system, including the gastroinstestinal tract organs. They are part of a network of nervous fibers that surround the big arteries that come off the abdominal aorta, forming the sympathetic abdominal plexuses of the autonomic nervous system, like the celiac, mesenteric, hypogastric plexuses. The collateral ganglia's afferent fibers are preganglionic fibers that run through the sympathetic chain without establishing synaptic connection in there.



Importance of steam in our civilized world

Monday, September 25, 2017

Most of us think of steam as something primitive, as something of the past used in rudimentary steam engines during the industrial revolution. We might also think of steam as the natural agent for the formation of clouds before the rain, or as the water gas used in old locomotive engines for the transportation of passengers in the 19th century. However, the importance of steam in our daily lives of our civilized world lies in electrical power generation. Without it, we go back to the Middle Ages, technologically speaking.

The vapor stage of water, when pressurized through a pipe, is used in thermal and nuclear power plants to propel steam turbines, whose shafts are coupled to generators, which generates alternating current. About 80% of the electricity used world wide is produced with the use of pressurized steam. Think of your PC, microwave oven, refrigerator, LC tv, your rechargeable cell phone and tablet batteries, etc; all these electrical appliances and gadgets used electricity coming from AC current generators driven by steam turbines.

In order to produce steam, we need a boiler. In a nuclear power plant, the boiler is plainly called steam generator, which is contained in the containment building, right beside the nuclear reactor. The nuclear reactor holds the uranium rods that generates heat through a controlled nuclear reaction. The nuclear reaction heat from the uranium rods is used to produce water vapor in the steam generator. The water vapor is then used to propel the turbines which, in turn, drive the generators. The AC current from the generators is then sent to the transformers to stabilize it. In a thermal power station, the boiler uses either coal or natural gas to produce generate the heat necessary to produce vapor. The LM6000 was the most common turbine used to drive the generator in the United States of America.