Superior sagittal sinus
Encyclopedia
The superior sagittal sinus (also known as the superior longitudinal 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
. Cerebrospinal fluid
drains through arachnoid granulations into the superior sagittal sinus
and is returned to venous circulation. See diagram (at right): labeled above the brain as "SIN. SAGITALLIS SUP." (for Latin: sinus sagittalis superior).
, through which it receives a vein from the nasal cavity, it runs from anterior to posterior, grooving the inner surface of the frontal
, the adjacent margins of the two parietal lobes, and the superior division of the cruciate eminence of the occipital lobe
. Near the internal occipital protuberance
, it drains into the confluence of sinuses
and deviates to either side (usually the right). At this point it is continued as the corresponding transverse sinus.
It is triangular in section, narrow in front, and gradually increases in size as it passes backward.
Its inner surface presents the openings of the superior cerebral veins
, which run, for the most part, obliquely forward, and open chiefly at the back part of the sinus, their orifices being concealed by fibrous folds; numerous fibrous bands (chordæ Willisii) extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces (venous lacunæ) in the dura mater near the sinus.
There are usually three lacunæ on either side of the sinus: a small frontal, a large parietal, and an occipital, intermediate in size between the other two.
Most of the cerebral veins from the outer surface of the hemisphere open into these lacunæ, and numerous arachnoid granulations (Pacchionian bodies) project into them from below.
The superior sagittal sinus receives the superior cerebral veins
, veins from the diploë
and dura mater
, and, near the posterior extremity of the sagittal suture, veins from the pericranium, which pass through the parietal foramina.
Falx cerebri
The falx cerebri, also known as the cerebral falx, so named from its sickle-like form, is a strong, arched fold of dura mater which descends vertically in the longitudinal fissure between the cerebral hemispheres....
. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to 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...
. Cerebrospinal fluid
Cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...
drains through arachnoid granulations into 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...
and is returned to venous circulation. See diagram (at right): labeled above the brain as "SIN. SAGITALLIS SUP." (for Latin: sinus sagittalis superior).
Anatomy
Commencing at the foramen cecumForamen cecum (frontal bone)
The frontal crest of the frontal bone ends below in a small notch which is converted into a foramen, the foramen cecum , by articulation with the ethmoid....
, through which it receives a vein from the nasal cavity, it runs from anterior to posterior, grooving the inner surface of the frontal
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
, the adjacent margins of the two parietal lobes, and the superior division of the cruciate eminence of the occipital lobe
Occipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
. Near 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:*...
, it drains into 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...
and deviates to either side (usually the right). At this point it is continued as the corresponding transverse sinus.
It is triangular in section, narrow in front, and gradually increases in size as it passes backward.
Its inner surface presents the openings of the superior cerebral veins
Superior cerebral veins
The superior cerebral veins, numbering eight to twelve, drain the superior, lateral, and medial surfaces of the hemispheres. They are predominantly found in the sulci between the gyri, but can also be found running across the gyri....
, which run, for the most part, obliquely forward, and open chiefly at the back part of the sinus, their orifices being concealed by fibrous folds; numerous fibrous bands (chordæ Willisii) extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces (venous lacunæ) in the dura mater near the sinus.
There are usually three lacunæ on either side of the sinus: a small frontal, a large parietal, and an occipital, intermediate in size between the other two.
Most of the cerebral veins from the outer surface of the hemisphere open into these lacunæ, and numerous arachnoid granulations (Pacchionian bodies) project into them from below.
The superior sagittal sinus receives the superior cerebral veins
Superior cerebral veins
The superior cerebral veins, numbering eight to twelve, drain the superior, lateral, and medial surfaces of the hemispheres. They are predominantly found in the sulci between the gyri, but can also be found running across the gyri....
, 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...
and dura mater
Dura mater
The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...
, and, near the posterior extremity of the sagittal suture, veins from the pericranium, which pass through the parietal foramina.