A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.
A motor nerve is a nerve located in the central nervous system (CNS), usually the spinal cord, that sends motor signals from the CNS to the muscles of the body. This is different from the motor neuron, which includes a cell body and branching of dendrites, while the nerve is made up of a bundle of axons. Motor nerves act as efferent nerves which carry information out from the CNS to muscles, as opposed to afferent nerves, which send signals from sensory receptors in the periphery to the CNS. Efferent nerves can also connect to glands or other organs/issues instead of muscles. In addition, there are nerves that serve as both sensory and motor nerves called mixed nerves.
The spinothalamic tract is a part of the anterolateral system or the ventrolateral system, a sensory pathway to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.
The spinocerebellar tract is a nerve tract originating in the spinal cord and terminating in the same side (ipsilateral) of the cerebellum.
The dorsal root of spinal nerve is one of two "roots" which emerge from the spinal cord. It emerges directly from the spinal cord, and travels to the dorsal root ganglion. Nerve fibres with the ventral root then combine to form a spinal nerve. The dorsal root transmits sensory information, forming the afferent sensory root of a spinal nerve.
The vestibulospinal tract is a neural tract in the central nervous system. Specifically, it is a component of the extrapyramidal system and is classified as a component of the medial pathway. Like other descending motor pathways, the vestibulospinal fibers of the tract relay information from nuclei to motor neurons. The vestibular nuclei receive information through the vestibulocochlear nerve about changes in the orientation of the head. The nuclei relay motor commands through the vestibulospinal tract. The function of these motor commands is to alter muscle tone, extend, and change the position of the limbs and head with the goal of supporting posture and maintaining balance of the body and head.
In the spinal cord, the most lateral of the bundles of the ventral nerve roots is generally taken as a dividing line that separates the antero-lateral region into two parts: an anterior funiculus , between the anterior median fissure and the most lateral of the ventral nerve roots; and a lateral funiculus, between the exit of these roots and the posterolateral sulcus.
The most lateral of the bundles of the anterior nerve roots is generally taken as a dividing line that separates the anterolateral system into two parts. These are the anterior funiculus, between the anterior median fissure and the most lateral of the anterior nerve roots, and the lateral funiculus between the exit of these roots and the posterolateral sulcus.
The anterior grey column is the front column of grey matter in the spinal cord. It is one of the three grey columns. The anterior grey column contains motor neurons that affect the skeletal muscles while the posterior grey column receives information regarding touch and sensation. The anterior grey column is the column where the cell bodies of alpha motor neurons are located.
The lateral vestibular nucleus is the continuation upward and lateralward of the principal nucleus, and in it terminate many of the ascending branches of the vestibular nerve.
The rhomboid fossa is a rhombus-shaped depression that is the anterior part of the fourth ventricle. Its anterior wall, formed by the back of the pons and the medulla oblongata, constitutes the floor of the fourth ventricle.
The projection fibers consist of efferent and afferent fibers uniting the cortex with the lower parts of the brain and with the spinal cord. In human neuroanatomy, bundles of axons called tracts, within the brain, can be categorized by their function into association fibers, projection fibers, and commissural fibers.
The medullary pyramids are paired white matter structures of the brainstem's medulla oblongata that contain motor fibers of the corticospinal and corticobulbar tracts – known together as the pyramidal tracts. The lower limit of the pyramids is marked when the fibers cross (decussate).
A nerve fascicle, is a bundle of nerve fibers belonging to a nerve in the peripheral nervous system. A nerve fascicle is also called a fasciculus. A nerve fascicle is enclosed by perineurium, a layer of fascial connective tissue. Each enclosed nerve fiber in the fascicle is enclosed by a connective tissue layer of endoneurium. Bundles of nerve fascicles are called fasciculi and are constituents of a nerve trunk. A main nerve trunk may contain a great many fascicles enclosing many thousands of axons.
The cells of the dorsal nucleus of vagus nerve are spindle-shaped, like those of the posterior column of the spinal cord, and the nucleus is usually considered as representing the base of the posterior column. It measures about 2 cm. in length, and in the lower, closed part of the medulla oblongata is situated behind the dorsal nucleus of the vagus; whereas in the upper, open part it lies lateral to that nucleus, and corresponds to an eminence, named the vagal trigone, in the rhomboid fossa.
Funiculus is any cord-like structure in anatomy or biology, and may refer to:
The medial vestibular nucleus is one of the vestibular nuclei. It is located in the medulla oblongata.
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and entering the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around 45 cm (18 in) long in adult men and around 43 cm (17 in) long in adult women. The diameter of the spinal cord ranges from 13 mm in the cervical and lumbar regions to 6.4 mm in the thoracic area.
A nerve tract is a bundle of nerve fibers (axons) connecting nuclei of the central nervous system. In the peripheral nervous system this is known as a nerve, and has associated connective tissue. The main nerve tracts in the central nervous system are of three types: association fibers, commissural fibers, and projection fibers. A tract may also be referred to as a commissure, decussation, pathway or fasciculus. A commissure connects the two cerebral hemispheres at the same levels, while a decussation connects at different levels.
On either side of the posterior median sulcus of the spinal cord, and at a short distance from it, the posterior nerve roots are attached along a vertical furrow named the posterolateral sulcus. The portion of the medulla spinalis which lies between this and the posterior median sulcus is named the posterior funiculus.
