Posterior limb of the internal capsule là gì bao trong năm 2024
Maingard J, Luong D, Bell D, et al. Internal capsule. Reference article, Radiopaedia.org (Accessed on 29 Mar 2024) https://doi.org/10.53347/rID-29687 The internal capsule (TA: capsula interna) is a deep subcortical structure that contains a concentration of afferent and efferent white matter projection fibers. Anatomically, this is an important area because of the high concentration of both motor and sensory projection fibers 1,2. Afferent fibers pass from cell bodies of the thalamus to the cortex, and efferent fibers pass from cell bodies of the cortex to the cerebral peduncle of the midbrain 2. Fibers from the internal capsule contribute to the corona radiata. On this page:The internal capsule is made up of five parts. These are the anterior limb, genu, posterior limb, retrolentiform and sublentiform parts of the internal capsule 1,2:
The blood supply of the internal capsule is variable but is commonly from small perforating branches of the middle cerebral artery and anterior cerebral artery. These include the lateral lenticulostriate arteries and the recurrent artery of Heubner respectively 3. In addition, the anterior choroidal artery from the internal carotid artery supplies the posterior limb and retrolentiform part of the internal capsule 3,4. CT
MRIin term neonates, internal capsule appears as higher T1-weighted and lower T2-weighted intensity when compared to basal ganglia and thalamus 6 The internal capsule, a white matter structure, is a unique location where a large number of motor and sensory fibers travel to and from the cortex. Damage of any kind in this location will cause some relatively unique findings that can allow you to localize the lesions to the internal capule by exam alone. Location The internal capsule is one of the subcortical structures of the brain. Subcortical structures: internal capsule, caudate, putamen, globus pallidus, thalamus, brainstem The anterior limb of the internal capsule separates the caudate nucleus and lenticular nucleus The posterior limb separates the thalamus and lenticular nucleus Types of fibers
Blood Supply
Symptoms and Signs Weakness of the face, arm, and/or leg (pure motor stroke) Known as one of the classic types of lacunar infarcts, a pure motor stroke is the result of an infarct in the internal capsule. Pure motor stroke caused by an infarct in the internal capsule is the most common lacunar syndrome. Upper motor neuron signs hyperreflexia, Babinski sign, Hoffman present, clonus, spasticity Mixed sensorimotor stroke Since both motor and sensory fibers are carried in the internal capsule, a stroke to the posterior limb of the internal capsule (where motor fibers for the arm, trunk and legs and sensory fibers are located) can lead to contralateral weakness and contralateral sensory loss If a patient has weakness +/- sensory deficits, how can you tell whether the stroke is subcortical or cortical? What other symptoms or signs can help you localize the stroke to the internal capsule as opposed to the cortex? A patient who presents with arm and leg weakness may have either a small internal capsule stroke or a large ACA + MCA cortical stroke. Looking at the homunculus in the figure above, the cortical leg area is supplied by the ACA and the arm area is supplied by the MCA. However, the injury to the cortices produces other symptoms and signs that not commonly produced by injury to the subcortical areas. The presence of these cortical signs may exclude an internal capsule stroke: gaze preference or gaze deviation expressive or receptive aphasia visual field deficits visual or spatial neglect If any of these signs are present, the patient may have a cortical stroke, not an internal capsule stroke. |