cardiovascular system

Topics: Internal jugular vein, Common carotid artery, Subclavian artery Pages: 34 (8674 words) Published: October 1, 2014
CARDIOVASCULAR SYSTEM OF THE HEAD NECK
The cardiovascular system consists of the heart,
blood vessels, and the approximately 5 liters of
blood that the blood vessels transport. Responsible
for transporting oxygen, nutrients, hormones, and
cellular waste products throughout the body, the
cardiovascular system is powered by the body’s
hardest-working organ — the heart, which is only about the size of a closed fist. Even at rest, the average heart easily pumps over 5 liters of blood throughout the body every minute.

The skull is a bony structure in the head of most
vertebrates (in particular, craniates) that supports
the
structures
of
the face and
forms
a
protective cavity for the brain. The skull is
composed of two parts: the cranium and
the mandible. The skull forms the anterior most
portion of the skeleton and is a product
of encephalization, housing the brain, many
sensory structures (eyes, ears, nasal cavity), and the feeding system. Functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to help the brain use auditory cues to judge direction and distance of sounds. In some animals, the skull also has a defensive function (e.g. horned ungulates); the frontal bone is where horns are mounted.

Eyes are the organs of vision. They detect light and
convert
it
into
electro-chemical
impulses
in neurons. The simplest photoreceptor cells in
conscious vision connect light to movement. In
higher
organisms
the
eye
is
a
complex optical system which collects light from

the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96%

of animal species possess a complex optical system.[1] Imageresolving eyes are present inmolluscs, chordates and arthropods. Retromandibular vein
Veins return blood to the heart for eventual
oxygenation by the lungs. They contain valves that
prevent a backup of the blood, or prevent blood
from flowing back away from the heart. The
retromandibular vein is a branch of the jugular
veins. The jugular veins go up the neck and join with
the facial veins. The retromandibular vein is formed
at the joining of the maxillary vein and the superficial temporal vein in front of the ear. The facial veins drain blood from the face and return it to the heart for oxygenation. The retromandibular vein divides into two branches, anterior and posterior. The anterior portion proceeds forward to the anterior facial vein, and together they join to form the common facial vein. The posterior joins the posterior auricular vein to become the external jugular. Studies of cadavers have shown that in some cases, the retromandibular vein runs a slightly different course on the right and left sides of the face. This can make it difficult when surgery is performed involving the retromandibular vein and the facial nerves, because the vein can run on different facets of the nerves.

External carotid artery
The external carotid arteries supply oxygenated
blood to the head. There is one external carotid
artery on the right side of the neck and one on the
left side of the neck. Each begins at the common
carotid artery and moves up the neck until it divides
into the superficial temporal artery and the
maxillary artery. The occipital artery, posterior
auricular artery, facial artery, superior thyroid artery and maxillary artery also branch off of the external carotid artery. These arteries supply blood to the thyroid, larynx, salivary glands, tongue, nose, lips, chin, palate, neck, face, ears, and lower portion of...
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