Posterior inferior cerebellar artery
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The posterior inferior cerebellar artery (PICA) is one of the three vessels that provide arterial supply to the cerebellum. It is the most variable cerebral artery.
Territory
Has a variable territory depending on the size of the AICA. Typically it may supply:
- posteroinferior cerebellar hemispheres (up to the great horizontal fissure)
- cerebellar tonsils : 85% of the time
- biventral lobule : 80%
- neucleus gracilis : 85%
- superior semilunar lobule : 50%
- inferior portion of the vermis
- lower part of the medulla : 50%
Origin
Its origin is also variable
- 18 - 20% arise extracranially, inferior to the foramen magnum
- 10% arise from the basilar rather than vertebral artery
- 2% bilaterally absent
- occasionally loops around the cerebellar tonsil.
Segments
- anterior medullary segment
- from its origin around the inferior aspect of the medullary olive
- lateral medullary segment
- curves forming the 'caudal loop' which is located anteroinferior to the tip of the cerebellar tonsil, but does NOT relate to the tonsilar position.
- the apex of the loop is:
- above foramen magnum in 60% of cases
- at the level of FM in 10%
- and below in 30%
- Its relationship to the vertebral artery is also variable, 84% lateral and 16% medial
- posterior medullary segment
- supratonsillar segment
- junction between the posterior medullary segment and the supratonsillar segment is upwardly convex and is the site of origin of small choroidal branches: it is known as the "choroid point". This point has a constant relationship with the 4th ventricle and was used prior to crossectional imaging to asses for shift in its position.
Branches
- anterior and lateral medullary segments
- small perforating medullary branches (absent in 50%)
- supratonsillar segment
- tonsillohemispheric branch
- inferior vermian branch
NOTE : occasionally a small vertebral will terminate into a common PICA / AICA trunk.
See also
-<p>The <strong>posterior inferior cerebellar artery</strong> (PICA) is one of the three vessels that provide arterial supply to the <a href="/articles/cerebellum">cerebellum</a>. It is the most variable cerebral artery. </p><h4>Territory</h4><p>Has a variable territory depending on the size of the <a href="/articles/anterior-inferior-cerebellar-artery">AICA</a>. Typically it may supply:</p><ul>-<li>posteroinferior <a href="/articles/cerebellum">cerebellar </a>hemispheres (up to the great horizontal fissure)-<ul>-<li>cerebellar tonsils : 85% of the time</li>-<li>biventral lobule : 80%</li>-<li>neucleus gracilis : 85%</li>-<li>superior semilunar lobule : 50%</li>- +<p>The <strong>posterior inferior cerebellar artery</strong> (PICA) is one of the three vessels that provide arterial supply to the <a href="/articles/cerebellum">cerebellum</a>. It is the most variable cerebral artery.</p><h4>Territory</h4><p>Has a variable territory depending on the size of the <a href="/articles/anterior-inferior-cerebellar-artery">AICA</a>. Typically it may supply:</p><ul>
- +<li>posteroinferior <a href="/articles/cerebellum">cerebellar </a>hemispheres (up to the great horizontal fissure)<ul>
- +<li>cerebellar tonsils : 85% of the time</li>
- +<li>biventral lobule : 80%</li>
- +<li>neucleus gracilis : 85%</li>
- +<li>superior semilunar lobule : 50%</li>
-</li>-<li>inferior portion of the vermis </li>-<li>lower part of the medulla : 50%</li>- +</li>
- +<li>inferior portion of the vermis</li>
- +<li>lower part of the medulla : 50%</li>
-<li>18 - 20% arise extracranially, inferior to the <a href="/articles/foramen-magnum" title="Foramen magnum">foramen magnum</a>-</li>-<li>10% arise from the basilar rather than vertebral artery </li>-<li>2% bilaterally absent </li>-<li>occasionally loops around the cerebellar tonsil. </li>- +<li>18 - 20% arise extracranially, inferior to the <a href="/articles/foramen-magnum">foramen magnum</a>
- +</li>
- +<li>10% arise from the basilar rather than vertebral artery</li>
- +<li>2% bilaterally absent</li>
- +<li>occasionally loops around the cerebellar tonsil.</li>
-<li>anterior medullary segment-<ul><li>from its origin around the inferior aspect of the medullary olive</li></ul>-</li>-<li>lateral medullary segment-<ul>-<li>curves forming the 'caudal loop' which is located anteroinferior to the tip of the cerebellar tonsil, but does NOT relate to the tonsilar position.</li>-<li>the apex of the loop is:-<ul>-<li>above foramen magnum in 60% of cases</li>-<li>at the level of FM in 10% </li>-<li>and below in 30%</li>-<li>Its relationship to the vertebral artery is also variable, 84% lateral and 16% medial </li>- +<li>anterior medullary segment<ul><li>from its origin around the inferior aspect of the medullary olive</li></ul>
- +</li>
- +<li>lateral medullary segment<ul>
- +<li>curves forming the 'caudal loop' which is located anteroinferior to the tip of the cerebellar tonsil, but does NOT relate to the tonsilar position.</li>
- +<li>the apex of the loop is:<ul>
- +<li>above foramen magnum in 60% of cases</li>
- +<li>at the level of FM in 10%</li>
- +<li>and below in 30%</li>
- +<li>Its relationship to the vertebral artery is also variable, 84% lateral and 16% medial</li>
-</li>- +</li>
-</li>-<li>posterior medullary segment-<ul><li>ascends posterior to the medulla behind <a href="/articles/glossopharyngeal-nerve">CN IX</a> and <a href="/articles/vagus-nerve-cn-x">CN X</a> and along the posterior medullary velum. </li></ul>-</li>-<li>supratonsillar segment-<ul><li>junction between the posterior medullary segment and the supratonsillar segment is upwardly convex and is the site of origin of small choroidal branches: it is known as the "choroid point". This point has a constant relationship with the 4th ventricle and was used prior to crossectional imaging to asses for shift in its position. </li></ul>-</li>- +</li>
- +<li>posterior medullary segment<ul><li>ascends posterior to the medulla behind <a href="/articles/glossopharyngeal-nerve">CN IX</a> and <a href="/articles/vagus-nerve-cn-x">CN X</a> and along the posterior medullary velum.</li></ul>
- +</li>
- +<li>supratonsillar segment<ul><li>junction between the posterior medullary segment and the supratonsillar segment is upwardly convex and is the site of origin of small choroidal branches: it is known as the "choroid point". This point has a constant relationship with the 4th ventricle and was used prior to crossectional imaging to asses for shift in its position.</li></ul>
- +</li>
-<li>anterior and lateral medullary segments-<ul><li>small perforating medullary branches (absent in 50%)</li></ul>-</li>-<li>supratonsillar segment-<ul>-<li>tonsillohemispheric branch</li>-<li>inferior vermian branch</li>- +<li>anterior and lateral medullary segments<ul><li>small perforating medullary branches (absent in 50%)</li></ul>
- +</li>
- +<li>supratonsillar segment<ul>
- +<li>tonsillohemispheric branch</li>
- +<li>inferior vermian branch</li>
-</li>-</ul><p><strong>NOTE :</strong> occasionally a small vertebral will terminate into a common PICA / AICA trunk. </p><h4>See also</h4><ul><li><a href="/articles/pica-infarct" title="PICA infarct">PICA infarct</a></li></ul>- +</li>
- +</ul><p><strong>NOTE :</strong> occasionally a small vertebral will terminate into a common PICA / AICA trunk.</p><h4>See also</h4><ul><li><a href="/articles/pica-infarct">PICA infarct</a></li></ul>
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