An anatomical diagram illustrating the arterial supply of the brain from an inferior (basal) perspective, specifically highlighting the Circle of Willis and its contributing vessels. The diagram shows the bilateral internal carotid arteries branching into the middle cerebral (MCA) and ophthalmic arteries. Centrally, the anterior cerebral arteries (ACA) are seen originating and coursing medially into the longitudinal fissure, connected by the anterior communicating artery (ACoA). The posterior circulation is depicted with the vertebral arteries merging into the basilar artery, which subsequently divides into the posterior cerebral arteries (PCA). Posterior communicating arteries (PCoA) are shown forming the critical anastomotic link between the internal carotid and posterior cerebral systems. The diagram is superimposed on the ventral surface of the brain, demonstrating the spatial relationship of these vessels to the frontal, temporal, and occipital lobes, as well as the cerebellum and brainstem. This illustration is an educational resource for understanding neurovascular anatomy and the territories susceptible to ischemic stroke.

The image consists of two panels (a and b) illustrating the anatomy of the Circle of Willis at the base of the brain. Panel (a) is an anatomical diagram showing a standard arterial configuration with a dotted yellow circle highlighting the junction of the basilar artery and the posterior cerebral artery (PCA). Panel (b) is a clinical photograph of a post-mortem anatomical specimen showing the cerebral vasculature. A dotted yellow circle in panel (b) highlights a vascular anomaly: a duplication of the P1 segment of the posterior cerebral artery. In this region, the arterial pathway consists of two parallel, distinct vascular channels rather than a single vessel. The broader anatomical context displays the basilar artery, internal carotid arteries (ICA), anterior cerebral arteries (ACA), and communicating arteries (ACoA and PCoA). The image is intended for medical education in neuroanatomy and neuroradiology to demonstrate normal anatomical variants and congenital anomalies of the cerebral collateral circulation.

This medical visual content consists of an anatomical diagram (a) and a corresponding clinical photograph of a cadaveric dissection (b) illustrating neurovascular anatomy. The focus is on the Circle of Willis, specifically demonstrating a congenital vascular variation known as aplasia of the A1 segment of the anterior cerebral artery (ACA). In both panels, a yellow dotted circle highlights the area where the right A1 segment should connect the internal carotid artery to the anterior communicating artery (ACoA). The absence of this segment results in an incomplete Circle of Willis, which has clinical significance for collateral cerebral blood flow. The diagram (a) clearly depicts the major components of the cerebral arterial circle, including the basilar artery, posterior cerebral arteries, internal carotid arteries, and the intact left A1 and A2 segments. The clinical photograph (b) provides a real-world view of the same anatomical deficiency at the base of the brain. This material is designed for advanced medical education in neuroanatomy and radiology, emphasizing common vascular anomalies.

This composite educational resource compares anatomical configurations of the Circle of Willis (CoW) in fetal and adult cadaveric specimens. The image consists of two clinical photographs of brain base specimens and a central schematic diagram focusing on the posterior segment of the cerebral arterial circle. The 'Fetal configuration' (left) shows the ventral brainstem and diencephalon with visible vasculature. The accompanying central schematic labels the pre-communicating part of the carotid origin (PCA-P1c) and the pre-communicating part of the basilar origin (PCA-P1b), connected by an 'intermediate communicating artery' (ICoA). This configuration highlights an accessory vascular bridge within the P1 segment of the posterior cerebral artery. The 'Adult configuration' (right) illustrates a more mature vascular pattern with larger calibres and increased tortuosity. Arrows point to the bifurcation sites and anatomical segments. The comparison focuses on the morphological evolution and persistence of the ICoA, which can influence the hemodynamics of the posterior circulation. This material serves as a reference for anatomical variations in neurovascular anatomy and surgical planning.

This infographic presents a standardized International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) worksheet, also known as the ASIA (American Spinal Injury Association) chart. The diagram illustrates a neurological examination of a patient with a spinal cord injury (SCI) and a superimposed non-SCI condition (old left tibia/fibula fracture). It displays motor and sensory scores for the right and left sides across C2 to S4-5 segments. Sensory evaluation includes light touch and pin prick scores, while motor evaluation covers key muscle groups in the upper (C5-T1) and lower (L2-S1) extremities. A central anatomical diagram maps dermatomes and key sensory points. Specific findings highlight a motor score of 1* for the left L5 (long toe extensor), with a comment box indicating this should be treated as normal for classification due to the peripheral injury. The worksheet includes binary assessments for Voluntary Anal Contraction (VAC) and Deep Anal Pressure (DAP), as well as calculated total scores for motor and sensory function, serving as a critical diagnostic tool for determining the Neurological Level of Injury (NLI) and ASIA Impairment Scale (AIS) grade.

This is a completed International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) form, commonly known as the ASIA (American Spinal Injury Association) Impairment Scale. The document consists of structured data tables and anatomical diagrams used to assess motor and sensory function following a spinal cord injury. The 'Motor' section evaluates key muscle groups for the upper (C5-T1) and lower (L2-S1) limbs on a 0-5 scale. This patient exhibits significant motor recovery, scoring 47/50 in the upper limb and 50/50 in the lower limb. The 'Sensory' section records light touch and pin prick scores for dermatomes C2-S4/5, using a 0-2 scale (absent, altered, normal). Sensory recovery is notably more limited than motor, with total scores of 27 for light touch and 9 for pin prick, indicating incomplete and asymmetric sensory preservation. The anatomical diagrams illustrate key sensory points across the body. The final assessment classifies the injury as an ASIA Impairment Scale (AIS) grade D, representing an incomplete spinal cord injury with preserved motor function below the neurological level.

Educational infographic and clinical assessment form titled 'International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI)', commonly known as the ASIA Impairment Scale. The visual includes a structured data entry form for documenting neurological levels (C2 through S4-5) across motor and sensory domains. The 'Motor Key Muscles' section uses a 0-5 numerical scale to evaluate muscle strength, specifically listing indicators such as elbow flexors (C5), wrist extensors (C6), and ankle plantar flexors (S1). The 'Sensory Key Points' section includes two dermatome maps (anterior and posterior views of the human body) highlighting specific points for testing Light Touch and Pin Prick sensations, scored on a 0-2 scale (0=Absent, 1=Altered, 2=Normal). The form provides sections for calculating Motor and Sensory indices and determining the ASIA Impairment Scale grade (A-E). This diagnostic tool is used in neurology and orthopedics to standardize the evaluation of spinal cord injury severity and recovery progression.

An ISNCSCI (International Standards for Neurological Classification of Spinal Cord Injury) assessment worksheet documenting a mid-thoracic spinal cord injury. The central diagram displays human dermatomes and key sensory points. The worksheet records bilateral motor and sensory scores (Light Touch and Pin Prick) from C2 to S4-5. In this specific clinical case, the right upper extremity sections (C6, C7, C8, and T1) contain 'NT*' (Not Testable) notations due to a right forearm amputation, with a comment indicating these should be treated as normal for classification purposes. Sensory and motor levels show normal function (score 2 or 5) down to T6, followed by impaired sensation (score 1) at T7 and complete loss of function (score 0) from T8 through the sacral segments. Sacral sparing indicators—Voluntary Anal Contraction (VAC) and Deep Anal Pressure (DAP)—are marked as 'No'. The image illustrates the methodology for classifying spinal cord injuries when confounded by non-SCI-related physical impairments like amputation.

This medical schematic diagram illustrates four pre-clinical spinal cord injury (SCI) models in axial cross-section, highlighting damaged regions (translucent red overlay), motor tracts (opaque red), and sensory tracts (blue). 1. Cord Hemisection Model: Shows damage isolated to one lateral half of the spinal cord, characteristic of Brown-Séquard syndrome, affecting both motor and sensory tracts on the ipsilateral side. 2. Cord Transection Model: Depicts complete injury across the entire cord diameter, resulting in total disruption of all motor and sensory pathways. 3. Dorsal Column Crush Model: Features localized damage concentrated in the posterior (dorsal) funiculus, primarily affecting ascending sensory tracts. 4. Weight Drop Contusion Model: Displays a diffuse, central injury zone impacting the grey matter and surrounding white matter tracts, simulating clinical traumatic contusion. The diagram serves as an educational tool for comparing injury patterns across experimental models used in neurotrauma research and their resulting impact on anatomical tracts.

This figure provides a detailed anatomical and schematic overview of a dorsal hemisection of the thoracic spinal cord (T8 level), focusing on the corticospinal tract (CST). Panel A is a confocal microscopy image of a spinal cord cross-section counterstained with Neurotrace. A white dashed line delineates the lesion border, showing a clear separation between the dorsal area affected by the hemisection and the intact ventral region. Panel B is a corresponding schematic diagram illustrating the anatomical distribution of CST components. It highlights the main CST (dark green) located at the base of the dorsal funiculus, the dorsolateral CST (medium green) in the lateral funiculus, and the ventral CST (light green) near the ventral midline. The dashed line in the schematic reflects the lesion from Panel A, demonstrating that a dorsal hemisection interrupts the main and dorsolateral CST components while leaving the ventral CST spared. This visual is designed to teach the structural consequences of spinal cord injury on descending motor pathways.

This composite diagnostic image features an axial cross-sectional graphic of the cervical spinal cord anatomy superimposed on a radiological background. The illustration uses color-coded regions to delineate primary white matter tracts: the dorsal column-medial lemniscus system is shown in blue (posteriorly), the lateral corticospinal tracts in red (laterally), the anterior corticospinal tracts in yellow (medial-anteriorly), and the anterolateral system (spinothalamic tract) in green (anterolaterally). A white outline represents the central grey matter of the spinal cord. White asterisks are strategically placed on the left hemicord tracts (blue, red, yellow, and green regions) to indicate the site of anatomical damage associated with a left-sided spinal cord lesion. This visual aid is designed to explain the pathophysiology of Brown-Séquard syndrome, illustrating how a hemicord injury affects specific ascending and descending pathways, leading to ipsilateral motor/proprioceptive loss and contralateral pain/temperature loss.

Anatomical and neurosurgical illustration depicting primary surgical approaches to the brainstem, segmented by axial planes. The left side of the image shows a sagittal view of the brainstem and cerebellum, color-coded into three main regions: the midbrain (red), the pons (green), and the medulla (blue). Three corresponding axial cross-sections are displayed on the right, mapped to these regions. The midbrain section (red frame) illustrates the Pterional (Pt), Orbitozygomatic (OZ/miniOZ), Subtemporal (ST), and Supracerebellar Infratentorial (SCIT) approaches. The pons section (green frame) demonstrates the Subtemporal (ST), Transtemporal (TT), Retrolabyrinthine (RL), Retrosigmoid (RS), and Suboccipital Transtelovelar (SOTV) routes. The medulla section (blue frame) highlights the Far Lateral (FL), Retrosigmoid (RS), and Suboccipital Transtelovelar (SOTV) trajectories. Arrows indicate the surgical vectors relative to the neuroanatomy, including the cerebellum, brainstem nuclei, and surrounding cranial structures, serving as a guide for selecting operative corridors based on lesion localization within the brainstem.

Educational panel illustrating the anatomy of the glossopharyngeal nerve (CN IX) and its relationships in the medulla oblongata. Figure (a) is an anatomical diagram of a transverse section of the medulla at the level of the inferior olive, highlighting efferent nuclei—nucleus ambiguus (1) and inferior salivatory nucleus (2)—and afferent nuclei—solitary nucleus (3) and spinal trigeminal nucleus (4). Other shown structures include the dorsal motor nucleus of vagus (5), pyramidal tract (6), and hypoglossal nerve (7). Figure (b) is a schematic drawing of the lower cranial nerves (1: spinal, 2: CN IX, 3: vagus, 4: hypoglossal) showing their course from the brainstem to the jugular foramen in relation to the pons (P), pyramid (Py), and occipital bone (OB). Figures (c) and (d) provide clinical correlation via a Nissl-stained micrographic slice and an axial T2-weighted MRI, respectively. These images demonstrate the retro-olivary groove (rog), inferior olivary nucleus (O), and inferior cerebellar peduncle (icp), identifying the precise exit point and internal nuclear organization of the glossopharyngeal nerve within the upper medulla.

This medical illustration comprises two detailed anatomical sketches of the human brainstem from Jakob's Atlas of the Nervous System (1901). On the left, a sagittal section illustrates the vertical orientation of the brainstem, extending from the superior midbrain and diencephalon regions down through the bulbous pons and narrowing into the medulla oblongata. The sketch uses fine stippling and hatching to differentiate tissue densities, highlighting fiber tract trajectories and the prominent ventral protrusion of the pons. On the right, an axial cross-section through the pons is shown. This view reveals the internal architecture of the pontine tegmentum and the basilar part of the pons. The left side of the axial view is heavily shaded to demonstrate the dense arrangement of transverse pontine fibers and corticospinal tracts, while the right side features anatomical labels and light outlines to designate specific nuclei and nerve pathways. This historical clinical imaging reference is utilized in neuroanatomy education to map critical nuclei and tracts relevant to neurosurgical planning and the study of brainstem lesions.

This diagnostic image provides a comprehensive anatomical overview of the human brainstem using T1-weighted MRI. On the left, a mid-sagittal section highlights the vertical arrangement of the midbrain, pons, and medulla. Key landmarks labeled include the tectum, cerebral aqueduct, tegmentum, and the fourth ventricle. Boundary demarcations such as the pontomesencephalic sulcus and the pontomedullary sulcus are clearly identified. To the right, four corresponding axial cross-sections are presented to illustrate internal and adjacent structures at specific levels. The superior axial view (midbrain) labels the mamillary bodies, cerebral peduncle, and periaqueductal grey. The second view (upper pons) identifies the basilar artery, trigeminal nerve, and fourth ventricle. The third view (lower pons/junction) shows the facial and vestibulocochlear nerves alongside the middle cerebellar peduncle. The most caudal axial view (medulla) highlights the vertebral arteries. This educational graphic is designed to teach brainstem spatial relationships, neuroanatomy, and neuroradiological landmarks for clinical localization.

**Imaging Modality:** Magnetic Resonance Imaging (MRI), axial T2-weighted section. **Anatomical Region:** Axial section at the level of the craniocervical junction, specifically focusing on the medulla oblongata and posterior fossa. **Observed Pathology:** There is a focal, well-defined area of hyperintensity located in the right dorsolateral aspect of the medulla oblongata. The lesion is consistent with an acute or subacute ischemic infarct in the territory of the posterior inferior cerebellar artery (PICA) or the vertebral artery. **Characteristic Visual Features:** * **Signal Intensity:** High T2 signal (hyperintense) relative to the surrounding brainstem parenchyma. * **Localization:** Precise involvement of the lateral medullary segment, characteristic of Lateral Medullary Syndrome (Wallenberg Syndrome). * **Mass Effect:** Minimal to no significant mass effect or displacement of the fourth ventricle/medulla midline is observed in this section. * **Surrounding Structures:** The cerebellum and surrounding cisterns appear unremarkable at this level. **Key Diagnostic Features:** The specific dorsolateral medullary localization of the hyperintense signal is the hallmark radiologic finding for PICA territory infarction, correlating clinically with Wallenberg Syndrome.

**Imaging Modality:** Magnetic Resonance Imaging (MRI) **Anatomical Plane:** Sagittal view **Anatomical Region:** Brain and upper cervical spine **Key Observations:** - **Parenchymal Findings:** The image demonstrates a T1-weighted sagittal section of the brain. There is a visible area of altered signal intensity within the posterior fossa, specifically involving the dorsolateral aspect of the medulla oblongata and the inferior portion of the cerebellum. - **Vascular Distribution:** The location of the lesion is highly characteristic of an infarct within the territory of the posterior inferior cerebellar artery (PICA). - **Associated Structures:** The sagittal view provides clear visualization of the brainstem (midbrain, pons, and medulla), the fourth ventricle, and the cerebellar hemispheres. The cortical sulci and gyri, corpus callosum, and pituitary gland appear within normal limits on this section. **Clinical Significance:** This radiologic pattern is consistent with a lateral medullary infarct, the anatomical substrate for Wallenberg’s syndrome. Key diagnostic cues include the localized involvement of the medulla, which typically results from PICA or vertebral artery occlusion. **Primary Keywords:** MRI, T1-weighted, sagittal, medulla oblongata, cerebellum, PICA infarct, lateral medullary syndrome, Wallenberg’s syndrome.

A coronal slice of a brain MRI using Diffusion-Weighted Imaging (DWI). The image displays the cerebrum, ventricular system, and posterior fossa structures, including the brainstem and cerebellum. A yellow arrow points to a localized focal area of high signal intensity (restricted diffusion) measuring approximately 4 mm in the left lateral medulla. This hyperintense lesion is characteristic of an acute ischemic infarct within the vascular territory of the posterior inferior cerebellar artery (PICA). The find represents Wallenberg syndrome (lateral medullary syndrome) pathology. The background shows moderate cortical and central atrophy, consistent with chronic ischemic changes or age-related involution. This diagnostic image is intended for educational use in neurology and radiology to demonstrate small-vessel stroke localization in the brainstem.