Meninges and Spinal Cord Introduction A blow to
Meninges and Spinal Cord Introduction A blow to the head may break some blood vessels associated with the brain, and escaping blood may collect beneath the dura mater. Such a subdural hematoma increases pressure between the rigid bones of the skull and soft tissues of the brain. Unless the accumulating blood is evacuated, compression of the brain may lead to functional losses or even death. 1. What are common means or reasons an individual may take a blow to the head? 2. What are ways that we’ve worked to protect people from blows to the head?
Meninges and Spinal Cord Explicit Instruction The CNS is comprised of the brain and spinal cord. Three membranous layers surround the CNS, collectively called the meninges. ◦ Dura mater – the outer layer, made of white dense connective tissue, contains blood vessels, continuous with the periosteum of the bones of the skull. ◦ Arachnoid mater – middle layer, thin, lacks blood vessels. ◦ Pia mater – inner layer, thin, contains blood vessels and nerves, attached to the surface of the brain and spinal cord. ◦ Between the arachnoid and pia maters is a subarachnoid space containing cerebrospinal fluid.
Meninges and Spinal Cord Explicit Instruction The spinal cord begins at the base of the brain and extends to the space between the L 1 -L 2 vertebrae. Structure of the Spinal Cord ◦ Consists of 31 segments, each of which gives rise to a pair of spinal nerves. ◦ The cervical enlargement gives rise to nerves leading to the upper limbs. ◦ The lumbar enlargement gives rise to those innervating the lower limbs. ◦ Two deep longitudinal grooves divide the cord into right and left halves. ◦ White matter, made up of bundles of myelinated nerve fibers (nerve tracts), surrounds a butterfly-shaped core of gray matter housing interneurons. ◦ A central canal contains cerebrospinal fluid.
Meninges and Spinal Cord Explicit Instruction The spinal cord transmits impulses to and from the brain, and houses spinal reflexes. ◦ Ascending Tracts: Sensory Brain ◦ Descending Tracts: Motor Effector ◦ Tract names are based on fibers origin and termination. ◦ Many spinal reflexes also pass through the spinal cord. Reflex Behavior ◦ Reflexes are automatic, subconscious responses to stimuli that help maintain homeostasis (heart rate, blood pressure, etc. ) and carry out automatic responses (vomiting, sneezing, swallowing, etc. ).
Meninges and Spinal Cord Independent Practice 1. What are the meninges? Differentiate between the layers. 2. Explain where cerebrospinal fluid is located. Why might this fluid be located there? 3. Describe the structure of the spinal cord. Be thorough in your description. 4. What are the functions of the spinal cord? 5. Distinguish between an ascending and a descending tract. What do they do?
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