For the transverse pericardial sinus, see: pericardial sinus

Pericardial sinus

There are two Pericardial sinuses: transverse and oblique.* The cul-de-sac enclosed between the limbs of the inverted U of the venous mesocardium lies behind the left atrium and is known as the oblique sinus...

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The transverse sinuses (left and right lateral sinuses), within the human head, are two areas beneath the brain which allow blood to drain from the back of the head. They run laterally in a groove

Groove for transverse sinus

Along the internal surface of the occipital bone, running laterally between superior and inferior fossae of the cruciate eminence is the groove for transverse sinus. The transverse sinuses travel along this groove.-External links:*...

 along the interior surface of the occipital bone

Occipital bone

The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...

. They drain from the confluence of sinuses

Confluence of sinuses

The confluence of sinuses or torcular herophili is the connecting point of the superior sagittal sinus, straight sinus, and occipital sinus. It is found deep to the occipital protuberance of the skull. Blood arriving at this point then proceeds to drain into the left and right transverse sinuses...

 (by the internal occipital protuberance

Internal occipital protuberance

Along the internal surface of the occipital bone, at the point of intersection of the four divisions of the cruciate eminence is the internal occipital protuberance. Running transversely on either side is a groove for the transverse sinus.-External links:*...

) to the sigmoid sinuses, which ultimately connect to the internal jugular vein

Internal jugular vein

The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

. See diagram (at right): labeled under the brain as "SIN. TRANS." (for Latin: sinus transversus).

The transverse sinuses are of large size and begin at the internal occipital protuberance

Internal occipital protuberance

Along the internal surface of the occipital bone, at the point of intersection of the four divisions of the cruciate eminence is the internal occipital protuberance. Running transversely on either side is a groove for the transverse sinus.-External links:*...

; one, generally the right, being the direct continuation of the superior sagittal sinus

Superior sagittal sinus

The superior sagittal sinus , within the human head, is an unpaired area along the attached margin of falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses...

, the other of the straight sinus

Straight sinus

The straight sinus , within the human head, is an unpaired area beneath the brain which allows blood to drain from the inferior center of the head outwards posteriorly...

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Each transverse sinus passes lateralward and forward, describing a slight curve with its convexity upward, to the base of the petrous portion

Petrous portion

Petrous portion can refer to:* Petrous portion of the temporal bone* Petrous portion of the internal carotid artery...

 of the temporal bone

Temporal bone

The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...

, and lies, in this part of its course, in the attached margin of the tentorium cerebelli

Tentorium cerebelli

The tentorium cerebelli or cerebellar tentorium is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.-Anatomy:...

; it then leaves the tentorium and curves downward and medialward (an area sometimes referred to as the sigmoid sinus

Sigmoid sinus

The sigmoid sinuses , within the human head, are two areas beneath the brain which allow blood to drain inferiorly from the posterior center of the head. They drain from the transverse sinuses and converge with the inferior petrosal sinuses to form the internal jugular vein...

) to reach the jugular foramen

Jugular foramen

The jugular foramen is a large aperture in the base of the skull. It is located behind the carotid canal and is formed in front by the petrous portion of the temporal, and behind by the occipital; it is generally larger on the right than on the left side....

, where it ends in the internal jugular vein

Internal jugular vein

The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

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In its course it rests upon the squama

Squama

Squama refers to a structure shaped like the scale of a fish. More specifically, it can refer to:* Squama frontalis* Squama occipitalis* Squama temporalis, the squamous portion of the temporal bone* Squamous cell...

 of the occipital

Occipital

The word occipital, in zoology, pertains to the occiput .Occipital is a descriptor for several areas of animal & human anatomy.*External occipital protuberance* Internal occipital crest* Greater occipital nerve...

, the mastoid angle of the parietal

Parietal

Parietal may refer to:*Parietal placentation*Parietal lobe of the brain*Parietal bone of the skull*Parietal scales of a snake lie in the general region of the parietal bone*Parietal cell in the stomach*Parietal pleura...

, the mastoid part of the temporal

Temporal bone

The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...

, and, just before its termination, the jugular process

Jugular process

In the lateral part of the occipital bone, extending lateralward from the posterior half of the condyle is a quadrilateral plate of bone, the jugular process, excavated in front by the jugular notch, which, in the articulated skull, forms the posterior part of the jugular foramen.It serves as the...

 of the occipital

Occipital

The word occipital, in zoology, pertains to the occiput .Occipital is a descriptor for several areas of animal & human anatomy.*External occipital protuberance* Internal occipital crest* Greater occipital nerve...

; the portion which occupies the groove on the mastoid part of the temporal is sometimes termed the sigmoid sinus

Sigmoid sinus

The sigmoid sinuses , within the human head, are two areas beneath the brain which allow blood to drain inferiorly from the posterior center of the head. They drain from the transverse sinuses and converge with the inferior petrosal sinuses to form the internal jugular vein...

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The transverse sinuses are frequently of unequal size, with the one formed by the superior sagittal sinus

Superior sagittal sinus

The superior sagittal sinus , within the human head, is an unpaired area along the attached margin of falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses...

 being the larger; they increase in size as they proceed, from back to center.

On transverse section, the horizontal portion exhibits a prismatic form, the curved portion has a semicylindrical form.

They receive the blood from the superior petrosal sinuses at the base of the petrous portion of the temporal bone

Temporal bone

The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...

; they communicate with the veins of the pericranium by means of the mastoid and condyloid emissary veins; and they receive some of the inferior cerebral and inferior cerebellar veins, and some veins from the diploë

Diploë

Diploë refers to the spongy bone structure of the internal part of short, irregular, and flat bones.In the cranial bones, the layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the...

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The petrosquamous sinus

Petrosquamous sinus

The petrosquamous sinus, when present, runs backward along the junction of the squama and petrous portion of the temporal, and opens into the transverse sinus....

, when present, runs backward along the junction of the squama and petrous portion of the temporal, and opens into the transverse sinus.