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Each spinal nerve receives a branch called a gray ramus communicans (pl.: rami communicantes) from the adjacent paravertebral ganglion of the sympathetic trunk. The gray rami communicantes contain postganglionic nerve fibers of the sympathetic nervous system and are composed of largely unmyelinated neurons.
General somatic afferents conduct impulses of pain, touch and temperature from the surface of the body through the dorsal roots to the spinal cord, and impulses of muscle sense, tendon sense and joint sense from the deeper structures.
The muscles that one particular spinal root supplies are that nerve's myotome, and the dermatomes are the areas of sensory innervation on the skin for each spinal nerve. Lesions of one or more nerve roots result in typical patterns of neurologic defects (muscle weakness, abnormal sensation, changes in reflexes) that allow localization of the ...
Branches of the cervical plexus, which include the phrenic nerve, innervate muscles of the neck, the diaphragm, and the skin of the neck and upper chest. The brachial plexus contains ventral rami from spinal nerves C5–T1. This plexus innervates the pectoral girdle and upper limb. The lumbar plexus contains ventral rami from spinal nerves L1–L4.
Afferent nerve cell bodies bring information from the body to the brain and spinal cord, while efferent nerve cell bodies bring information from the brain and spinal cord to the rest of the body. The cell bodies create long sympathetic chains that are on either side of the spinal cord. They also form para- or pre-vertebral ganglia of gross anatomy.
The last four cervical spinal nerves, C5 through C8, and the first thoracic spinal nerve, T1, combine to form the brachial plexus, or plexus brachialis, a tangled array of nerves, splitting, combining and recombining, to form the nerves that subserve the upper-limb and upper back. Although the brachial plexus may appear tangled, it is highly ...
Sectional organization of spinal cord. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. [3] [4] Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, and continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous ...
Just outside the spinal cord, thousands of afferent neuronal cell bodies are aggregated in a swelling in the dorsal root known as the dorsal root ganglion. [1] [2] All of the axons in the dorsal root, which contains afferent nerve fibers, are used in the transduction of somatosensory information.