This medical anatomical diagram illustrates the three-dimensional structure of the cranial meninges and the pia-arachnoid complex (PAC). The cross-sectional drawing is labeled with five distinct layers: (a) the thick, outermost dura mater; (b) the thinner arachnoid mater; (c) the subarachnoid space (SAS); (d) the pia mater; and (e) the underlying brain tissue. A primary focus is the subarachnoid space, which contains a network of fibrous arachnoid trabeculae and a large, cylindrical blood vessel. The trabeculae are shown as thin, branching collagenous strands that bridge the space between the arachnoid and pia mater, providing mechanical stability. The diagram highlights the spatial relationship between the leptomeninges (arachnoid and pia) and the underlying neural parenchyma, with a scale bar indicating a 100 µm reference. This illustration is intended for educational use in neuroanatomy and pathophysiology to demonstrate the mechanical protection of the brain and the distribution of cerebrospinal fluid pathways.

This medical anatomical diagram illustrates the layers of the human meninges and the organization of the subarachnoid space. The lower panel displays a sagittal view of the head, identifying internal structures such as the lateral, third, and fourth ventricles, alongside circumventricular organs including the pineal gland and posterior pituitary. The upper panel provides a high-magnification cross-sectional view of the cranial protective layers. From superficial to deep, it depicts the skull, the dura mater (consisting of periosteal and meningeal layers containing lymphatic vessels), the arachnoid mater, and the subarachnoid space filled with cerebrospinal fluid (CSF). The arachnoid trabeculae are shown spanning the subarachnoid space to connect with the pia mater. Below the pia mater, the glia limitans is illustrated, formed by astrocytic foot processes that interface with the underlying brain parenchyma and cortical blood vessels. This diagram is designed to explain leptomeningeal anatomy and the fluid dynamics between the ventricular system, subarachnoid space, and the blood-brain barrier interface.

Anatomical and Pathophysiology Diagram illustrating the immunological landscape of the central nervous system (CNS) borders during steady-state and ischemic stroke. The primary cross-section depicts the spatial arrangement of the meninges: the skull, dura mater (containing meningeal lymphatic vessels and superior sagittal sinus), arachnoid mater, arachnoid space with trabeculae, and the pia mater overlying the brain parenchyma. The diagram highlights the distribution of innate lymphoid cells (ILCs), showing NK cells, ILC1, ILC2, and ILC3 residing primarily within the dural meninges. NK-derived IFN-γ is shown diffusing across the tight-junction-restricted arachnoid and pia mater to interact with astrocytes. In the deeper brain, the choroid plexus within the ventricles is shown to harbor ILC1 and ILC2 subsets. An inset titled 'Ischemic stroke' demonstrates the recruitment and accumulation of various ILCs at the border of an infarct core, emphasizing their role in neuroinflammatory responses. The illustration serves as an educational tool for neuroimmunology, detailing the interface between the peripheral immune system and the CNS.

This clinical photograph captures a microsurgical dissection of the spinal meninges, demonstrating the anatomical differentiation between the dura mater and the arachnoid mater. In the center of the frame, the spinal cord appears as a prominent, whitish, cylindrical structure with visible fine vascularization on its surface. Surgical forceps are used to retract and distinguish two distinct layers: the dura mater (labeled '1') and the arachnoid mater (labeled '2'). The dura mater (1) is visualized as a thicker, more opaque, and slightly reddish fibrous membrane, reflecting its dense collagenous composition and relative resistance to manipulation. In contrast, the arachnoid mater (2) is depicted as a thinner, more translucent, and whiter membrane underlying the dura. The surrounding surgical field contains exposed paraspinal muscles and subcutaneous tissues, appearing reddish and fleshy with a glistening texture due to the presence of biological fluids. This image serves as an educational reference for neurosurgical anatomy, specifically the layered structure of the spinal meninges and the plane of dissection required to access the subarachnoid space.