What arteries supply the thalamus and the posterior limb of the internal capsule (PLIC)?

Arterial Supply to the Thalamus and Posterior Limb of Internal Capsule

The thalamus receives blood from four main arterial groups arising from the posterior circulation, while the posterior limb of the internal capsule (PLIC) is supplied primarily by the anterior choroidal artery along its entire length, with additional contributions from lenticulostriate branches of the middle cerebral artery anteriorly.

Thalamic Arterial Supply

The thalamus is supplied by four distinct arterial groups, all originating from the posterior circulation 1, 2, 3:

1. Paramedian (Thalamoperforate) Arteries

• Arise from the P1 segment of the posterior cerebral artery 4, 3
• Supply the medial portion of the thalamus along the lateral wall of the third ventricle 4
• Infarcts in this territory involve the medial thalamic structures 4

2. Thalamotuberal (Pre-mamillary) Arteries

• Supply the anterior pole of the thalamus 4, 3
• Variations in origin are rare 3
• Infarcts manifest as anterior thalamic lesions 4

3. Thalamogeniculate Arteries

• Origin varies: 53% arise from the posterior cerebral artery and 43% from the posterior choroidal arteries 3
• Supply the posterolateral portion of the thalamus 4, 3
• Critical for lateral thalamic function 4

4. Posterior Choroidal Arteries (Lateral Branches)

• Include both posteromedial and posterolateral choroidal arteries 1, 3
• The posteromedial choroidal artery is usually single and provides perforating branches to the medial thalamus 3
• The posterolateral choroidal artery is frequently multiple and supplies the superior aspect of the thalamus 3
• Supply the most posterolateral and dorsolateral portions of the thalamus 4
• Pulvinar branches arise from posterolateral choroidal arteries in two-thirds of cases and from posteromedial choroidal arteries in one-third 3

Posterior Limb of Internal Capsule (PLIC) Arterial Supply

Primary Supply: Anterior Choroidal Artery

The anterior choroidal artery supplies the entire length of the PLIC, including both the anterior one-third and posterior two-thirds 5:

• A 2019 study of 90 consecutive patients with isolated PLIC infarction demonstrated that the anterior choroidal artery supplies the full length of the PLIC 5
• Proximal branch occlusions cause anterior-type infarcts (anterior one-third of PLIC), occurring in 7.7% of cases 5
• Distal branch occlusions cause posterior-type infarcts (posterior two-thirds of PLIC), occurring in 51.1% of cases 5
• Combined infarcts involving the full PLIC length occurred in 10.6% of cases 5

Anatomical Correlations

• Anterior-type PLIC infarcts involved the medial pallidum in 71.4% of cases but spared the lateral thalamus 5
• Posterior-type PLIC infarcts involved the medial pallidum in only 13% but affected the lateral thalamus in 71.7% of cases 5
• The anterior choroidal artery provides cisternal branches to the lateral thalamus and can contribute to pulvinar vascularization via plexiform branches through the temporal horn 3

Clinical Pitfall

The traditional teaching that only the posterior two-thirds of the PLIC is supplied by the anterior choroidal artery is incorrect—the entire PLIC receives blood from this vessel, though anterior infarcts are less common (7.7% vs 51.1% for posterior infarcts) 5.