Which of the following fiber tracts passes through the anterior limb of the internal capsule?

Explanation

## Fiber Composition of the Anterior Limb of the Internal Capsule **Key Point:** The anterior limb of the internal capsule primarily contains **thalamocortical and corticothalamic fibers** connecting the thalamus to the frontal cortex, particularly the **dorsomedial thalamus to the prefrontal cortex**. ### Anatomical Organization of the Internal Capsule The internal capsule is divided into three main regions, each with distinct fiber content: | Region | Primary Fiber Content | Secondary Content | |--------|----------------------|-------------------| | **Anterior Limb** | Thalamocortical fibers (dorsomedial thalamus ↔ prefrontal cortex) | Frontopontine fibers | | **Genu** | Corticobulbar tract fibers | Thalamocortical fibers (VPM thalamus ↔ face area) | | **Posterior Limb** | Corticospinal tract (motor) | Thalamocortical fibers (VPL thalamus ↔ motor cortex); sensory radiations | **High-Yield:** The anterior limb connects the **dorsomedial thalamus** (involved in cognition, emotion, and memory) to the **prefrontal cortex**. Lesions here affect executive function, personality, and emotional regulation rather than motor or sensory function. ### Clinical Correlation **Clinical Pearl:** Anterior capsular strokes are less common than posterior capsular strokes but produce behavioral and cognitive changes rather than the classic motor deficits seen with posterior limb involvement. Patients may present with personality changes, apathy, or executive dysfunction. ### Distinction from Other Regions - The **posterior limb** carries descending motor fibers (corticospinal tract) and ascending sensory fibers (thalamic radiations)—this is why posterior capsular strokes cause hemiparesis and hemisensory loss. - The **genu** carries corticobulbar fibers affecting facial and bulbar muscles. - The **anterior limb** is purely cognitive/emotional in function.