Final answer:
The brain and spinal cord are protected by bones, meninges (dura mater, arachnoid mater, and pia mater), and cerebrospinal fluid, with added chemical protection from the blood-brain and blood-spinal cord barriers.
Step-by-step explanation:
Protective Structures for the Brain and Spinal Cord
The brain and spinal cord are central components of the central nervous system (CNS) and are afforded protection by several structures. The bones of the skull and the vertebrae encase the brain and spinal cord, respectively, providing a rigid protective barrier against physical damage. Additionally, both the brain and the spinal cord are wrapped in a three-layered protective membrane known as the meninges, which include the tough dura mater, the web-like arachnoid mater, and the delicate pia mater.
Beneath the arachnoid mater, cerebrospinal fluid (CSF) circulates within the subarachnoid space, providing not only nutrition and waste removal but also acting as a cushion to absorb shocks. The CSF makes the brain neutrally buoyant, which protects it from minor impacts. Furthermore, the blood-brain barrier and the blood-spinal cord barrier provide chemical protection by controlling the influx of substances from the bloodstream into the nervous tissue.