What Is the Posterior Internal Capsule?

Inner sac: The inner sac is the name of the part of the cerebral cortex that is connected to the brain stem and spinal cord by nerve fibers. Motor nerve fibers and sensory nerve fibers leading to the cerebral cortex are fan-shaped and distributed radially through the inner capsule.

Chinese name: Inner capsule
body parts: A part of the cerebral cortex that passes through the brain stem, etc.

Location: Located between the basal ganglia and thalamus
Literary nouns: Inner capsule
Field: medicine

I. Overview

1. Inner capsule: It is a white matter plate composed of the upper and lower fibers connecting the cerebral cortex, the brain stem, and the spinal cord. On the horizontal section passing through the middle part of the striatum, the inner capsule has a V-shaped opening that points outwards. Those between the dorsal thalamus and the lenticular nucleus are called hind feet; those between the caudate nucleus and the dorsal thalamus, that is, the junction between the fore and hind feet are called knees.

The inner capsule is an important structure located deep in the cerebral hemisphere. Opening outward "<" shaped medulla between the lenticular nucleus, caudate nucleus and thalamus. The inner capsule is divided into three parts: those who are between the lenticular nucleus and the caudate nucleus are called forelimbs, and the forehead bridge passes through; the lenticular nucleus and thalamus are the hind limbs, and there are cortical spinal cord tracts and thalamic cortical tracts from front to back. The occipital-temporal bridge bundle passes, followed by optical radiation and auditory radiation fibers; the middle part is the knee, and the cortical medullary bundle passes.

2. Inner capsule knee: It is the turning point of the anterior and hind limbs of the inner capsule. Among them, the fibers to the motor core of the extraocular muscles are located in the front, and the fibers that reach the motor core of the tongue and facial muscles also extend to the occipital portion of the inner capsule.

Inner capsule 2. Anatomy

It is a thick white matter plate located between the lenticular nucleus, the caudate nucleus, and the thalamus. In the horizontal section of the thalamus, it can be seen that the inner capsule becomes a knee-shaped (V-shaped) white matter band inward, with the knee (tip) facing inward and opening outward. The inner capsule is generally divided into three parts: the shorter forehead (the forelimbs of the inner capsule), which is located between the head of the bean-shaped nucleus and the caudate nucleus; The above two are connected between the caudate nucleus and the thalamus, called the internal capsule knee. The inner capsule occipital region can be divided into three parts according to location: the part between the lenticular nucleus and the thalamus is longer, called the lenticular nucleus; the part that extends to the caudal side to the rear of the lenticular nucleus, is called the posterior lenticular ; In the caudal region, a part of the fiber passes below the lenticular nucleus to reach the temporal lobe, which is called the bottom of the lenticular nucleus (also called the lower part of the lenticular nucleus).

Inner capsule 3. Diseases related to inner capsule

1. Inner capsule 1. Trilateral syndrome:

When a lesion occurs on one of the inner capsules (such as common cerebral hemorrhage or stroke), the clinical syndrome is caused by damage to the thalamus cortex, pyramidal tract, and visual fibers passing through it. It is manifested as lack of lateral eccentric sensation of the lesion, limb paralysis and contralateral isotropic visual hemianopia.

The inner capsule is where the cortex connects the afferent and outgoing fibers of the thalamus, brainstem, and spinal cord. Focal lesions in the inner capsule knees and in the front of the hind limbs damage the pyramidal tract, resulting in contralateral hemiplegia; Focal lesions cause contralateral anaesthesia and isotropic blindness. The simultaneous existence of the three (hemiplegic, hemiplegia, and hemi-blindness) is known as the trilateral syndrome, and the damage to the inner capsule on one side is often accompanied by bilateral horizontal coordinated motion paralysis, which causes the eyes to deviate to the lesion side; the dominant hemisphere capsule Damage also produces motor aphasia. Vascular disease is the most common cause of the inner capsule area.

2. Inner capsule 2. Inner capsule bleeding:

The basal ganglia of the brain is the most common bleeding site. It is called internal capsule hemorrhage because it damages the internal capsule. In addition to the general symptoms of cerebral hemorrhage, patients with internal capsule hemorrhage often turn their heads and eyes to the side of the bleeding lesion, showing "gaze" "Symptoms" and "triple-biased" symptoms, that is, hemiplegia, anaesthesia, and blindness, such as aphasia in dominant hemisphere bleeding. If bleeding does not continue, the patient can often survive and recover to a considerable degree. In severe cases, deep coma and even cerebral hernia formation may occur. The treatment is the same as that for cerebral hemorrhage. Department of common cerebral hemorrhage. Mostly due to hemorrhage of the basal ganglia of the brain and the internal capsule. The main clinical manifestations are head and eye turning to the bleeding side showing gaze lesions and "triple partial" symptoms, that is, hemiplegia, hemiplegia, and blindness. Hemiplegia, paralysis of the contralateral limb at the bleeding site, which is initially delayed paralysis, tendon reflexes disappear; after a few days or weeks, it becomes spastic paralysis, with lower limbs straightening, hypertenoid reflexes, and upper limbs flexing and adducting. Motor neuron hemiplegia. Leaning sensation disorder, the side or side of the lesion has a reduced or missing sensation. Hemi-blindness, contralateral blindness. In addition, if the main cerebral hemisphere lesions may have aphasia. Treatment: Reduce cerebral edema; stop bleeding; symptomatic; if conditions are available, surgery is better under the guidance of CT or MRI positioning.

3. Inner capsule 3. Inner capsule hind limb infarction:

It refers to the occurrence of new cerebral infarction lesions mainly in the hind limbs of the inner capsule. Its clinical manifestations are that the infarct lesions have all or part of the lateral, upper and lower limbs with motor and / or sensory disturbances. No or no history of TIA.

Inclusion criteria: Sudden onset, which meets the diagnostic criteria for cerebral infarction

quasi;

The onset time is within 3 days;

Movement or (and) sensory symptoms on the opposite limb of the lesion, without cortical damage;

CT or MRI of the skull shows that the lesion is only in the hind limb of the inner capsule, and the lesion area is less than 2 cm2;

The patient and his family agreed and were discussed and approved by the hospital ethics committee.

Exclusion criteria:

Except for the hind limb of the inner capsule, other lesions can be seen in the blood supply area of the front and back circulation;

The lesion was found by accident and there were no contralateral limb symptoms;

The inspection cannot be completed and the information is incomplete.

The hindlimb of the inner capsule is a site where motor and sensory fibers are highly concentrated. Infarction of the hindlimb of the inner capsule often damages the corticospinal tract and thalamus cortex at the same time. Sometimes it is a lacunar lesion, but it causes severe sensorimotor damage. difference. Infarcts of the hindlimb of the inner capsule are not uncommon in clinical practice, and a considerable part of patients with progressive stroke are those of the hindlimb of the inner capsule. The lesions have not enlarged during progression, and most of them are lacunar lesions. What are the pathological mechanisms of symptom progression in these patients, and which factors are likely to cause symptom progression. This study explores this. On the imaging site of hindlimb infarction of the inner capsule, Kashihara

The single lesion on the ipsilateral posterior limb infarct on the ipsilateral side of the lateral ventricle body can also be considered to be the posterior limb infarction on the inner capsule. He classified this lesion as lateral type. Patients with a single lesion adjacent to the posterior part of the lateral ventricle within 0.7 cm of the hind limbs are considered to be patients with internal capsule hindlimb infarction.

Inner capsule hind limb infarction belongs to LI from the imaging point of view. General LI is considered a relatively benign type of cerebral infarction because its short-term prognosis is relatively good (low mortality in the acute phase, less neurological damage, faster neurological recovery in the short-term, and lower stroke recurrence in the short-term And short-term impact on quality of life). However, due to the anatomical characteristics of the hindlimb of the inner capsule, the symptoms and manifestations of the infarction at this site are very different from those of ordinary LI. It has severe neurological damage and can leave severe hemiplegia; It has a variety of clinical manifestations; It is a manifestation of CWS .