Anatomy of internal capsule

1. INTERNAL CAPSULE
Dr. Israa M. Sulaiman
Department of Anatomy
IMS/MSU

2. •Define internal capsule and enumerate the
parts
•Illustrate the internal capsule and describe
the components of each part
•Describe the blood supply and its clinical
importance
OBJECTIVES

3. Gray & White Matter Organization
In brain stem similar
to spinal cord (nuclei
around ventricles, tracts on
outside)
In cerebrum and
cerebellum: white
matter covered with layer of
neural cortex (grey)

4. White Matter of Cerebral hemisphere
Gray surface (cortex) with
white tracts internally
Commissures – connect
corresponding gyri of
the two hemispheres
1) corpus callosum
2) anterior commissure
Projection tracts (fibers)
– connect more or less
vertically
Association tracts (fibers)
connect one gyrus to
another in the same
hemisphere
Coronal section

5. Commissures – connect corresponding gyri of the two
hemispheres
1) corpus callosum
2) anterior commissure
•Association tracts (fibers) connect one gyrus to another in the
same hemisphere

6. Commisural fibres
•Corpus callosum
•Fornix
•Anterior commisure
•Posterior commisure
•Habenular commisure

7. Coronal section

9. Association fibres
•Short association fibres
•Long association fibres
–Superior longitudinal fibres
–Inferior longitudinal fibres
–Cingulum

11. Projection fibres
•Internal capsule

12. Coronal section

13. •Projection fibres
(white matter)
between
•caudate nucleus and
thalamus medially
•lentiform nucleus
laterally
DEFINITION

14. •The Internal
Capsule
•This is a compact
bundle of fibres
through which the
large collections of
fibres pass,
including:
The thalamocortical
and corticothalamic
fibres;
corticopontine,
corticobulbar and
corticospinal fibres
pass through the
internal capsule
lesions.

15. •and then the cerebral peduncles;
•And the fibres projection from the cerebral cortex to the
various nuclei of the extrapyramidal system (e.g., the
putamen and caudate nucleus).
•Shape of the Internal Capsule
•It is a continuous sheet of fibres that forms the medial
boundary of the lenticular nucleus.
•It continues around posteriorly and inferiorly to partially
envelop this nucleus.
•Inferiorly, many of the fibres of the internal capsule funnel
into the cerebral peduncles.

16. •Superiorly, the fibres fan out into the corona radiata.
•Here, they travel in the cerebral white matter to reach their cortical origins
or destinations.
•The entire fibre system is shaped like a trumpet with a large notch cut out of
its bell.
•The notch corresponds to the location of where this sheet of fibres is
interrupted by the lateral sulcus.
•The lenticular nucleus sits where a mute would sit in a trumpet.
•The internal capsule is divided into 5 regions:
•The anterior limb is the portion between the lenticular nucleus and the head
of the caudate nucleus;
•The posterior limb is the portion between the lenticular nucleus and the
thalamus;
•The genu is the portion at the junction of the above 2 parts and is adjacent
to the interventricular foramen;
•The retrolenticular part is the portion posterior to the lenticular nucleus;
•The sublenticular part is the portion inferior to the lenticular nucleus.

17. Portion Description Origin Destination
Anterior Limb
Anterior thalamic
radiation
•Anterior nucleus
•DM
•Cingulate gyrus
•Prefrontal cortex
Genu Relays to motor areas
·VA
·VL
·Premotor cortex
·Primary motor
cortex
Posterior Limb
•Motor pathways:
●
Corticospinal
tract
●
Corticobulbar
tract
2.Somatosensory
relays
•Motor cortex
•VPL/VPM

•Motor pathways:
●
Spinal cord
●
Brainstem
•Somatosensory
relays:
●
Primary
somatosentory
cortex
Retrolenticular
·Association relay
·Optic radiation
•Pulvinar
•LGN
·Association cortex
·Visual cortex
Sublenticular
·Optic radiation
·Auditory radiation
·LGN
·MGN
·Visual cortex
·Auditory cortex

18. CAUDATE NUCLEUS
LENTIFORM NUCLEUS
THALAMUS
Globus palidus
Putamen
CLAUSTRUM
Internal capsule
External capsule
Extreme capsule

20. 1
st
order
2
nd
order
3
rd
order
Internal capsule
Corona radiata

21. Lower motor
Upper motor
Internal capsule
Corona radiata

22. •ANTERIOR LIMB
–Caudate n & lentiform n
•GENU
•POSTERIOR LIMB
–Thalamus & lentiform n
•RETROLENTIFORM
•SUBLENTIFORM
Parts of internal capsule
Caudate n
Lentiform n
Thalamus

23. Parts of internal capsule
Caudate nucleus
Lentiform nucleus
Thalamus
Anterior limb
Posterior limb
Genu
Thalamocortical fibres
Corticopontine fibres
Corticonuclear &
corticospinal fibres
Sublentiform
Retrolentiform

24. Superior

Inferior
Anterior
Posterior
Types of fibres

25. Types of fibres
•Thalamic radiation
–Superior thalamic radiation
–Anterior thalamic radiation
–Posterior thalamic radiation-
–Inferior thalamic radiation-
•Corticospinal
•Corticonuclear
•Cortipontine
–Fronto pontine
–Parieto pontine
–Temporo pontine
•Extrapyramidal
Superior
Inferior
Anterior
Posterior

26. Thalamic radiation
•Thalamocortical fibres
–Thalamic nuclei -project
to ipsilateral cerebral
cortex (except for
reticular nucleus)
•Reach neocortex
•Located entirely within
internal capsule
•Superior-from ventral
nucleus
–Becomes corona radiata
•Anterior-from anterior &
medial nuclei
•Posterior-from optic
radiation
•Inferior-from auditory
radiation

27. COMPONENTS
–ANTERIOR LIMB
•Anterior thalamic radiation
•Frontopontine
–GENU
•Part of superior thalamic
radiation
•Frontopontine
•Corticonuclear
Thalamocortical fibres
Corticopontine fibres
Corticonuclear &
corticospinal fibres
Inferior
Thalamic
radiation
Posterior
Thalamic
radiation

28. COMPONENTS
–POSTERIOR LIMB
•Superior thalamic radiation
•Frontopontine
•Corticonuclear (corticobulbar)
•Corticospinal
•Extrapyrimidal
–RETROLENTIFORM
•Post thalamic radiation - Optic
radiation
•Parieto-pontine
•Temporo-pontine
–SUBLENTIFORM
•Inf thalamic radiation - Auditory
radiation
Thalamocortical fibres
Corticopontine fibres
Corticonuclear &
corticospinal fibres
Inferior
Thalamic
radiation
Posterior
Thalamic
radiation

29. Thalamocortical fibres
Corticopontine fibres
Corticonuclear &
corticospinal fibres
ANTERIOR LIMB
Anterior thalamic radiation
Frontopontine
GENU
Part of superior thalamic radiation
Frontopontine
Corticonuclear
●
RETROLENTIFORM
●
Post thalamic
radiation - Optic
radiation
●
Parieto-pontine
●
Temporo-pontine
●
SUBLENTIFORM
●
Inf thalamic radiation
- Auditory radiation
POSTERIOR LIMB
Superior thalamic radiation
Frontopontine
Corticonuclear (corticobulbar)
Corticospinal
Extrapyrimidal

30. Middle cerebral artery
Anterior cerebral artery
Posterior cerebral artery
BLOOD SUPPLY

31. BLOOD SUPPLY
HORIZONTAL SECTION
•Lateral striate fr middle
cerebral artery
–Ant limb
–Genu
–Post limb
–Basal ganglia
•Medial striate fr anterior
cerebral artery
–Ant limb
–Genu
–Basal ganglia
•Ant choroidal fr internal
carotid
–Post limb
–Retrolenticular part

32. Anterior choroidal A
Middle cerebral A
Anterior cerebral A
Internal carotid A

33. Internal capsule
Lenticulostriate arteries
Middle cerebral artery
Internal carotid artery
Anterior cerebral artery
Medialstriate arteries
CORONAL SECTION

34. Left
middle
cerebral
artery
Right
middle
cerebral
artery
Medial
striate
ACA
Lateral
striate
- MCA
CORONAL SECTION

35. *
Anterior choroidal A
Middle cerebral A
Anterior cerebral A
Medial striate - ACA

36. ANTERIOR LIMB
•Ant cerebral artery through medial striate
br.
•Middle cerebral artery through lateral
striate and lenticulostriate br.
- pass through the lentiform N to supply the striate

37. GENU
•Ant cerebral artery through medial striate
br.
•Middle cerebral artery through lateral
striate and lenticulostriate br.
•Branches of internal carotid artery

38. Internal capsule
Lenticulostriate arteries
Middle cerebral artery
Internal carotid artery
Anterior cerebral artery
Medialstriate arteries
CORONAL SECTION

39. POSTERIOR LIMB
•Middle cerebral artery through lateral
striate and lenticulostriate br.
–Charcot’s artery of cerebral haemorrhage
•Anterior choroidal artery, direct branch of
internal carotid artery
–Long and slender, thus has tendency to get
thrombosis

40. CAUDATE NUCLEUS
LENTIFORM NUCLEUS
THALAMUS
Globus palidus
Putamen
CLAUSTRUM
INTERNAL CAPSULE

41. CAUDATE NUCLEUS
LENTIFORM NUCLEUS
THALAMUS
Globus palidus
Putamen
CLAUSTRUM
EXTERNAL CAPSULE
Projection fibres from
cerebral cortex to
basal ganglia and
midbrain

42. Thalamocortical fibres
Corticopontine fibres
Corticonuclear &
corticospinal fibres
ANTERIOR LIMB
Anterior thalamic radiation
Frontopontine
GENU
Part of superior thalamic radiation
Frontopontine
Corticonuclear
●
RETROLENTIFORM
●
Optic radiation
●
Parieto-pontine
●
Temporo-pontine
●
SUBLENTIFORM
●
Auditory radiation
POSTERIOR LIMB
Superior thalamic radiation
Frontopontine
Corticonuclear (corticobulbar)
Corticospinal
Extrapyrimidal

43. APPLIED ANATOMY
–Microaneurysm to lenticulostriate arteries -
•contralateral side of the body –
–Hemiplegia
–Impaired sensation
–Paralysis of lower half of face
–Thrombosis – recurrent br of ACA
•contralateral side of the body –
–Upper limb
–Paralysis of lower half of face
–Anterior choroidal artery
• may be symptomless – collateral circulation

44. *
Anterior choroidal A
Middle cerebral A
Anterior cerebral A

45. THANK YOU