The internal capsule is divided into superior and inferior parts. It is located medially between the caudate nucleus and thalamus, and laterally between the lentiform nucleus. It contains ascending and descending tracts that connect the cortex to lower brain structures. The internal capsule has anterior, genu, posterior, retrolentiform, and sublentiform parts that contain different tracts. We need to learn about the internal capsule because it is important for understanding the pathways involved in motor and sensory functions.
11. PART DESCENDING TRACTS ASCENDING TRACTS
Anterior limb Frontopontine fibres
Anterior thalamic radiation
(fibres from ant. & med.
nuclei of thalamus)
Genu
Corticonuclear fibres
(a part of pyramidal tract; motor
nuclei of cranial nerves)
Ant. part of superior
thalamic radiation
(fibres from post. ventral
nucleus of thalamus)
Posterior limb
a) Corticospinal tract (pyramidal
tract; upper limb, trunk &
lower limb)
b) Corticopontine fibres
c) Corticorubral fibres
a) Superior thalamic
radiation
b) Fibres from globus pallidus
to subthalamic nucleus
Retrolentiform part
a) Parietopontine &
occipitopontine fibres
b) Fibres from sup. colliculus &
pretectal region
Posterior thalamic radiation:-
a) Optic radiation (mainly)
b) Fibres connect thalamus
to parietal & occipital
lobes (partly)
Sublentiform part
a) Parietopontine &
temporopontine fibres
b) Fibres between temporal lobe
& thalamus
a) Auditory radiation
b) Fibres connect thalamus to
temporal lobe
