sinus venosus

(noun)

A large quadrangular cavity that precedes the atrium on the venous side of the chordate heart. In humans, it exists distinctly only in the embryonic heart, where it is found between the two venae cavae.

Related Terms

Examples of sinus venosus in the following topics:

  • Development of the Heart

    • The human venous system develops mainly from the vitelline veins, the umbilical veins and the cardinal veins, all of which empty into the sinus venosus.

  • Development of the Cardiovascular System

    • The human venous system develops mainly from the vitelline,umbilical, and cardinal veins, all of which empty into the sinus venosus.

  • Carotid Sinus Syncope and Massage

    • The carotid sinus is a localized dilation of the internal carotid artery at its origin, the common carotid artery .
    • The carotid sinus often has atherosclerotic plaques.
    • Massage of the carotid sinus, or carotid sinus massage, is used to diagnose carotid sinus syncope.
    • The carotid sinus can also be oversensitive to carotid sinus massage.
    • Carotid sinus syncope sometimes accompanies convulsive seizures because of the intensity of the carotid sinus reflex when pressure builds in one or both carotid sinuses.

  • Arrhythmia

    • In normal electrical activity, each heart beat originates as an electrical impulse from a small area of tissue in the right atrium of the heart called the sinus node or sino-atrial node or SA node.
    • This may be caused by a slowed signal from the sinus node (sinus bradycardia), a pause in the normal activity of the sinus node (sinus arrest), or by blocking of the electrical impulse on its way from the atria to the ventricles (AV block or heart block).
    • Schematic diagram of normal sinus rhythm for a human heart as seen on ECG.

  • Sinusitis

    • In addition to the severity of disease, sinusitis can be classified by the sinus cavity that it affects.
    • Frontal: can cause pain or pressure in the frontal sinus cavity (located above eyes), or a headache.
    • Sinus infection can spread through veins or by direct extension to close structures.
    • Sinusitis may extend to the central nervous system where it may cause cavernous sinus thrombosis, retrograde meningitis, and epidural, subdural, and brain abscesses.

  • Veins of the Head and Neck

    • Formed at the base of the brain from the inferior petrosal sinus and the sigmoid sinus, the internal jugular vein runs down the side of the neck adjacent to the internal carotid artery.

  • Proprioceptor Regulation of Breathing

    • During stretch receptor activation, the inhibitory signal that travels through the vagus nerve is also sent to  the sinus-atrial node of the heart.
    • When this process is cyclical it is called a sinus arrhythmia, which is a generally normal physiological phenomenon in which there is short-term tachycardia during inspiration.
    • Sinus arryhthmias do not occur in everyone, and are more common in youth.
    • The sensitivity of the sinus-atrial node to the inflation reflex is lost over time, so sinus arryhthmias are less common in older people.

  • Fetal Circulation

    • About half of this enters the fetal ductus venosus and is carried to the inferior vena cava, while the other half enters the liver proper from the inferior border of the liver.

  • Development of the Urinary System

    • The urinary bladder develops from the upper end of the urogenital sinus, which is continuous with the allantois.
    • The lower ends of the metanephric ducts are incorporated into the wall of the urogenital sinus and form the trigone of the bladder.

  • Abducens (VI) Nerve

    • At the tip of the petrous temporal bone, it makes a sharp turn forward to enter the cavernous sinus.
    • In the cavernous sinus it runs alongside the internal carotid artery.