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Epineurium
The epineurium is the outermost layer of dense irregular connective tissue surrounding a peripheral nerve. It usually surrounds multiple nerve fascicles as well as blood vessels which supply the nerve. Smaller branches of these blood vessels penetrate into the perineurium. In addition to blood vessels which supply the nerve, lymphocytes and fibroblasts are also present and contribute to the production of collagen fibers that form the backbone of the epineurium. In addition to providing structural support, lymphocytes and fibroblasts also play a vital role in maintenance and repair of the surrounding tissues. When the spinal nerve leaves the vertebral canal via an intervertebral foramen, two layers of the spinal meninges, the arachnoid and the dura invaginate the nerve to form a dural sleeve of connective tissue, which is the epineurium. The outer portion of this sleeve comprises the external epineurium which permits longitudinal nerve excursion and absorption of longitudina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epineurial Repair
Epineurial repair is a common surgical procedure to repair a nerve laceration via the epineurium, the connective tissue surrounding nerve fibers originating from the spinal cord. It is intended to allow the restoration of sensory function. When a nerve is lacerated or cut, repair is done by sewing the cut ends together through the epineurium to increase the potential of the Anatomical terms of location#Proximal and distal, proximal part growing correctly along the route the degrading Anatomical terms of location#Proximal and distal, distal part leaves behind. Usual sensation and mobility will not be an immediate result because nerves grow at a rate of approximately 1 millimeter per day, so it will take a few months to notice the final outcome.Semer, Nadine B. "Nerve and Vascular Injuries of the Hand." Practical Plastic Surgery for Nonsurgeons. Philadelphia: Hanley & Belfus, 2001. 313-19. Print. Research in use of nerve grafts and nerve growth factors is being done to speed recovery t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoneurium
The endoneurium (also called endoneurial channel, endoneurial sheath, endoneurial tube, or Henle's sheath) is a layer of delicate connective tissue around the myelin sheath of each myelinated nerve fiber in the peripheral nervous system. Its component cells are called endoneurial cells. The endoneuria with their enclosed nerve fibers are bundled into groups called nerve fascicles, each fascicle within its own protective sheath called a perineurium. In sufficiently large nerves multiple fascicles, each with its blood supply and fatty tissue, may be bundled within yet another sheath, the epineurium. The endoneurium contains a liquid known as endoneurial fluid, which contains little protein. In the peripheral nervous system the endoneurial fluid is notionally equivalent to cerebrospinal fluid in the central nervous system. Peripheral nerve injuries commonly release increased amounts of endoneurial fluid into surrounding tissues; these can be detected by magnetic resonance neurography ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nerve Fascicle
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. In the central nervous system (CNS) a bundle of nerve fibers is called a nerve tract, and in neuroanatomy different tracts in the spinal cord are bundled into fasciculi such as the medial longitudinal fasciculus. In the spinal cord fasciculi are bundled into columns called funiculi such as the anterior funiculus. See also * Epineurium * Nervous tissue Nervous tissue, also called neural tissue, is the main tissue component of the nervous system. The nervous system regulates and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perineurium
The perineurium is a protective sheath that surrounds a nerve fascicle. This bundles together axons targeting the same anatomical location. The perineurium is composed from fibroblasts. In the peripheral nervous system, the myelin sheath of each axon in a nerve is wrapped in a delicate protective sheath known as the endoneurium. Fascicles, bundles of neurons, are surrounded by the perineurium. Several fascicles may be in turn bundled together with a blood supply and fatty tissue within yet another sheath, the epineurium. This grouping structure is analogous to the muscular organization system of epimysium, perimysium and endomysium. Structure The perineurium is composed of connective tissue, which has a distinctly lamellar arrangement consisting of one to several concentric layers. The perineurium is composed of perineurial cells, which are epithelioid myofibroblasts. Perineurial cells are sometimes referred to as myoepithelioid due to their epithelioid and myofibroblastoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perineurium
The perineurium is a protective sheath that surrounds a nerve fascicle. This bundles together axons targeting the same anatomical location. The perineurium is composed from fibroblasts. In the peripheral nervous system, the myelin sheath of each axon in a nerve is wrapped in a delicate protective sheath known as the endoneurium. Fascicles, bundles of neurons, are surrounded by the perineurium. Several fascicles may be in turn bundled together with a blood supply and fatty tissue within yet another sheath, the epineurium. This grouping structure is analogous to the muscular organization system of epimysium, perimysium and endomysium. Structure The perineurium is composed of connective tissue, which has a distinctly lamellar arrangement consisting of one to several concentric layers. The perineurium is composed of perineurial cells, which are epithelioid myofibroblasts. Perineurial cells are sometimes referred to as myoepithelioid due to their epithelioid and myofibroblastoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connective Tissue In The Peripheral Nervous System
Nervous tissue, also called neural tissue, is the main tissue (biology), tissue component of the nervous system. The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS) comprising the branching peripheral nerves. It is composed of neurons, also known as nerve cells, which receive and transmit impulses, and neuroglia, also known as glial cells or glia, which assist the propagation of the Action potential, nerve impulse as well as provide nutrients to the neurons. Nervous tissue is made up of different types of neurons, all of which have an axon. An axon is the long stem-like part of the Cell (biology), cell that sends action potentials to the next cell. Nerve fascicle, Bundles of axons make up the nerves in the PNS and nerve tract, tracts in the CNS. Functions of the nervous system are sensory system, sensory input, integration, co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tibial Nerve
The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus. Structure Popliteal fossa The tibial nerve is the larger terminal branch of the sciatic nerve with root values of L4, L5, S1, S2, and S3. It lies superficial (or posterior) to the popliteal vessels, extending from the superior angle to the inferior angle of the popliteal fossa, crossing the popliteal vessels from lateral to medial side. It gives off branches as shown below: * Muscular branches - Muscular branches arise from the distal part of the popliteal fossa. It supplies the medial and lateral heads of gastrocnemius, soleus, plantaris and popliteus muscles. Nerve to popliteus crosses the popliteus muscle, runs downwards and laterally, winds around the lower border of the popliteus to supply the deep (or anterior) surface of the popliteus. This nerve also supplies the tibialis posterior muscle, superior tibiofibular joint, tibia bone, intero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurosurgery
Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and peripheral nervous system. Education and context In different countries, there are different requirements for an individual to legally practice neurosurgery, and there are varying methods through which they must be educated. In most countries, neurosurgeon training requires a minimum period of seven years after graduating from medical school. United States In the United States, a neurosurgeon must generally complete four years of undergraduate education, four years of medical school, and seven years of residency (PGY-1-7). Most, but not all, residency programs have some component of basic science or clinical research. Neurosurgeons may pursue additional training in the form of a fellowship after residency, or, in some cases, as a senior resid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axon
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons (pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the peripheral and central neurons. Nerve fibers are classed into three typesgroup A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotmesis
Neurotmesis (in Greek tmesis signifies "to cut") is part of Seddon's classification scheme used to classify nerve damage. It is the most serious nerve injury in the scheme. In this type of injury, both the nerve and the nerve sheath are disrupted. While partial recovery may occur, complete recovery is impossible. Symptoms Symptoms of neurotmesis include but are not limited to pain, dysesthesias (uncomfortable sensations), and complete loss of sensory and motor function of the affected nerve. Anatomy Neurotmesis occurs in the peripheral nervous system and most often in the upper-limb (arms), accounting for 73.5% of all peripheral nerve injury cases. Of these cases, the ulnar nerve was most often injured. Peripheral nerves are structured so that the axons are surrounded by most often a myelinated sheath and then an endoneurium. A perineurium surrounds that and the outermost layer is considered the epineurium. When injury occurs, "local vascular trauma leads to hemorrhage and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroma
A neuroma (; plural: neuromata or neuromas) is a growth or tumor of nerve tissue. Neuromas tend to be benign (i.e. not cancerous); many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms. Neuromas can arise from different types of nervous tissue, including the nerve fibers and their myelin sheath, as in the case of genuine neoplasms (growths) like ganglioneuromas and neurinomas. The term is also used to refer to any swelling of a nerve, even in the absence of abnormal cell growth. In particular, traumatic neuroma results from trauma to a nerve, often during a surgical procedure. Morton's neuroma affects the foot. Neuromas can be painful, or sometimes, as in the case of acoustic neuromas, can give rise to other symptoms. Neoplasms * Acoustic neuroma - a slow-growing, benign tumor of the acoustic nerve. Symptoms, which most often start after the age of 30, can include dizziness, headache, vertigo, loss of balance, ringing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schwannoma
A schwannoma (or neurilemmoma) is a usually benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves. Schwannomas are homogeneous tumors, consisting only of Schwann cells. The tumor cells always stay on the outside of the nerve, but the tumor itself may either push the nerve aside and/or up against a bony structure (thereby possibly causing damage). Schwannomas are relatively slow-growing. For reasons not yet understood, schwannomas are mostly benign and less than 1% become malignant, degenerating into a form of cancer known as neurofibrosarcoma. These masses are generally contained within a capsule, so surgical removal is often successful. Schwannomas can be associated with neurofibromatosis type II, which may be due to a loss-of-function mutation in the protein merlin. They are universally S-100 positive, which is a marker for cells of neural crest cell origin. Schwannomas of the head and neck are a fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
