Meninges of the Brain 13. Identify the meningeal (or associated) structures described below: 1. outermost meninx covering the brain; composed of tough fibrous connective tissue 2. innermost meninx covering the brain; delicate and highly vascular 3. structures instrumental in returning cerebrospinal fluid to the venous blood in the dural sinuses 4. structure that forms the cerebrospinal fluid 5. middle meninx; like a cobweb in structure 6. its outer layer forms the periosteum of the skull 7. a dural fold that attaches the cerebrum to the crista galli of the skull 8. a dural fold separating the cerebrum from the cerebellum
The Correct Answer and Explanation is :
Here are the structures described in your query related to the meninges of the brain:
- Outermost meninx covering the brain; composed of tough fibrous connective tissue:
- Answer: Dura mater
- Explanation: The dura mater is the outermost and thickest of the three meningeal layers. It is made of dense fibrous connective tissue that provides strength and protection for the brain. The dura mater consists of two layers: the outer layer adheres to the skull, while the inner layer forms partitions within the cranial cavity.
- Innermost meninx covering the brain; delicate and highly vascular:
- Answer: Pia mater
- Explanation: The pia mater is the innermost layer of the meninges, consisting of a thin, delicate membrane. It is highly vascular, containing blood vessels that supply nutrients to the brain and spinal cord. It closely adheres to the surface of the brain and spinal cord, following their contours.
- Structures instrumental in returning cerebrospinal fluid to the venous blood in the dural sinuses:
- Answer: Arachnoid villi (or granulations)
- Explanation: The arachnoid villi are small, finger-like projections of the arachnoid mater that protrude into the dural sinuses. These villi act as one-way valves, allowing cerebrospinal fluid (CSF) to pass from the subarachnoid space into the venous blood within the dural sinuses, effectively returning the CSF to the bloodstream.
- Structure that forms the cerebrospinal fluid:
- Answer: Choroid plexus
- Explanation: The choroid plexus is a network of specialized ependymal cells located in the ventricles of the brain. These cells are responsible for the production of cerebrospinal fluid (CSF). The choroid plexus filters blood plasma, secreting it into the ventricles to form CSF.
- Middle meninx; like a cobweb in structure:
- Answer: Arachnoid mater
- Explanation: The arachnoid mater is the middle layer of the meninges. It is a delicate, web-like membrane that sits between the dura mater and pia mater. The subarachnoid space, which contains cerebrospinal fluid, is found beneath the arachnoid mater.
- Its outer layer forms the periosteum of the skull:
- Answer: Dura mater
- Explanation: The dura mater’s outer layer is called the periosteal layer, and it is firmly attached to the inner surface of the skull. This layer provides a protective layer and is continuous with the periosteum of the skull bones.
- A dural fold that attaches the cerebrum to the crista galli of the skull:
- Answer: Falx cerebri
- Explanation: The falx cerebri is a large dural fold that extends vertically between the two hemispheres of the cerebrum. It attaches to the crista galli of the ethmoid bone and helps to anchor the brain within the cranial cavity.
- A dural fold separating the cerebrum from the cerebellum:
- Answer: Tentorium cerebelli
- Explanation: The tentorium cerebelli is a horizontal dural fold that separates the cerebrum from the cerebellum. It helps provide structural support and protects the cerebellum from the pressure exerted by the cerebrum.
In summary, the meninges play a crucial role in protecting and supporting the brain and spinal cord. Each of these structures has distinct functions related to the structural and physiological integrity of the central nervous system.