spinal nerve

Examples of spinal nerve in the following topics:

• Sensory-Somatic Nervous System

  • Humans have 12 cranial nerves, nerves that emerge from or enter the skull (cranium), as opposed to the spinal nerves, which emerge from the vertebral column.
  • Spinal nerves transmit sensory and motor information between the spinal cord and the rest of the body.
  • Each of the 31 spinal nerves (in humans) contains both sensory and motor axons.
  • Spinal nerves contain both sensory and motor axons.
  • Explain the role of the cranial and spinal nerves in the sensory-somatic nervous system

• Spinal Cord

  • The spinal cord is a bundle of nerves that is connected to the brain and relays information from the brain to the body and vice versa.
  • Connecting to the brainstem and extending down the body through the spinal column is the spinal cord: a thick bundle of nerve tissue that carries information about the body to the brain and from the brain to the body.
  • The spinal cord is contained within the bones of the vertebral column, but is able to communicate signals to and from the body through its connections with spinal nerves (part of the peripheral nervous system).
  • Spinal cord injuries are notoriously difficult to treat because spinal nerves do not regenerate, although ongoing research suggests that stem cell transplants may be able to act as a bridge to reconnect severed nerves.
  • Researchers are also looking at ways to prevent the inflammation that worsens nerve damage after injury.

• The Nervous System

  • The nervous system is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves).
  • The vertebrate central nervous system (CNS) contains the brain and the spinal cord .
  • The spinal cord is the information superhighway, connecting the brain with the rest of the body through the peripheral nerves.
  • The peripheral nervous system consists of nerves that are connected to the brain (cranial nerves) and nerves that are connected to the spinal cord (spinal nerves).
  • The innermost layer is the pia mater, which directly covers the brain and spinal cord.

• Human Axial Skeleton

  • The vertebral column, or spinal column, surrounds and protects the spinal cord, supports the head, and acts as an attachment point for the ribs and muscles of the back and neck.
  • Each vertebral body has a large hole in the center through which the nerves of the spinal cord pass.
  • There is also a notch on each side through which the spinal nerves, which serve the body at that level, can exit from the spinal cord.
  • The names of the spinal curves correspond to the region of the spine in which they occur.
  • (b) Spinal curves increase the strength and flexibility of the spine.

• Neurons and Glial Cells

  • The CNS contains the brain and spinal cord.
  • Echinoderms, such as sea stars, have nerve cells that are bundled into fibers called nerves.
  • One interesting difference between the nervous systems of invertebrates and vertebrates is that the nerve cords of many invertebrates are located ventrally (near the abdomen), whereas the vertebrate spinal cords are located dorsally (near the back).
  • (a) In cnidarians, nerve cells form a decentralized nerve net.
  • (b) In echinoderms, nerve cells are bundled into fibers called nerves.

• Characteristics of Chordata

  • Animals in the phylum Chordata share four key features: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
  • It is located between the digestive tube and the nerve cord, providing skeletal support through the length of the body.
  • The dorsal hollow nerve cord derives from ectoderm that rolls into a hollow tube during development.
  • In contrast to the chordates, other animal phyla are characterized by solid nerve cords that are located either ventrally or laterally.
  • The nerve cord found in most chordate embryos develops into the brain and spinal cord, which comprise the central nervous system.

• Phylum Chordata

  • A notochord, or a longitudinal, flexible rod between the digestive tube and the nerve cord .
  • A dorsal nerve cord which develops from a plate of ectoderm that rolls into a tube located dorsal to the notochord.
  • Other animal phyla have solid nerve cords ventrally located.
  • A chordate nerve cord splits into the central nervous system: the brain and spinal cord.
  • For example, tunicate larvae have both a notochord and a nerve cord which are lost in adulthood .

• Glia

  • Scientists have recently discovered that they also play a role in responding to nerve activity and modulating communication between nerve cells.
  • They have been shown, through calcium-imaging experiments, to become active in response to nerve activity, transmit calcium waves between astrocytes, and modulate the activity of surrounding synapses.
  • Ependymal cells line fluid-filled ventricles of the brain and the central canal of the spinal cord.
  • They are involved in the production of cerebrospinal fluid, which serves as a cushion for the brain, moves the fluid between the spinal cord and the brain, and is a component for the choroid plexus.

• Excitation–Contraction Coupling

  • The deadly nerve gas Sarin irreversibly inhibits acetycholinesterase.
  • Each skeletal muscle fiber is controlled by a motor neuron, which conducts signals from the brain or spinal cord to the muscle.
  • Because neuron axons do not directly contact the motor-end plate, communication occurs between nerves and muscles through neurotransmitters.

• Thermoreception

  • End-bulbs are found in the conjunctiva of the eye, in the mucous membrane of the lips and tongue, and in the epineurium of nerve trunks.
  • In addition to Krause end bulbs that detect cold and Ruffini endings that detect warmth, there are different types of cold receptors on free nerve endings.
  • The thermoreceptor pathway in the brain runs from the spinal cord through the thalamus to the primary somatosensory cortex.
  • Warmth and cold information from the face travels through one of the cranial nerves to the brain.
  • Describe the various types of receptors used for thermoreception:  Krause end bulbs, Ruffini endings, free nerve endings