The Golgi tendon organ (GTO) (also called Golgi organ, tendon organ, neurotendinous organ or neurotendinous spindle) is a proprioceptive sensory receptor organ that senses changes in muscle tension. It lies at the origins and insertion of skeletal muscle fibers into the tendons of skeletal muscle. It provides the sensory component of the Golgi tendon reflex.
The Golgi organ is not to be confused with the Golgi apparatus, which is an organelle in the eukaryotic cell, or the Golgi stain, which is a histologic stain for neuron cell bodies. All of these are named after the Italian physician Camillo Golgi.
|Golgi tendon organ|
Labeled diagram of Golgi tendon organ from the human Achilles tendon.
|Latin||Organum sensorium tendinis|
|Anatomical terms of microanatomy|
The body of the organ is made up of strands of collagen that are connected at one end to the muscle fibers and at the other merge into the tendon proper. Each tendon organ is innervated by a single afferent type Ib sensory nerve fiber (Aɑ fiber) that branches and terminates as spiral endings around the collagen strands. The Ib afferent axon is a large diameter, myelinated axon. Each neurotendinous spindle is enclosed in a capsule which contains a number of enlarged tendon fasciculi (intrafusal fasciculi). One or more nerve fibres perforate the side of the capsule and lose their medullary sheaths; the axis-cylinders subdivide and end between the tendon fibers in irregular disks or varicosities (see figure).
When the muscle generates force, the sensory terminals are compressed. This stretching deforms the terminals of the Ib afferent axon, opening stretch-sensitive cation channels. As a result, the Ib axon is depolarized and fires nerve impulses that are propagated to the spinal cord. The action potential frequency signals the force being developed by 10 to 20 of the many motor units within the muscle. This is representative of whole muscle force.
The Ib sensory feedback generates spinal reflexes and supraspinal responses which control muscle contraction. Ib afferents synapse with interneurons that are within the spinal cord that also project to the brain cerebellum and cerebral cortex. The autogenic inhibition reflex assists in regulating muscle contraction force. It is associated with the Ib. Tendon organs signal muscle force through the entire physiological range, not only at high strain.
During locomotion, Ib input excites rather than inhibits motoneurons of the receptor-bearing muscles, and it affects the timing of the transitions between the stance and swing phases of locomotion. The switch to autogenic excitation is a form of positive feedback.
Until 1967 it was believed that Golgi tendon organs had a high threshold, only becoming active at high muscle forces. Consequently, it was thought that tendon organ input caused "weightlifting failure" through the clasp-knife reflex, which protected the muscle and tendons from excessive force.However, the underlying premise was shown to be incorrect by James Houk and Elwood Henneman in 1967.
Afferent nerve fibers refer to axonal projections that arrive at a particular region; as opposed to efferent projections that exit the region. These terms have a slightly different meaning in the context of the peripheral nervous system (PNS) and central nervous system (CNS).
In the PNS, afferent and efferent projections are always from the perspective of the spinal cord (see figures). PNS afferents are the axons of sensory neurons carrying sensory information from all over the body, into the spine. PNS efferents are the axons of spinal cord motor neurons that carry motor-movement signals out of the spine to the muscles.In the CNS, afferent and efferent projections can be from the perspective of any given brain region. That is, each brain region has its own unique set of afferent and efferent projections. In the context of a given brain region, afferents are arriving fibers while efferents are exiting fibers.Camillo Golgi
Camillo Golgi (Italian: [kaˈmillo ˈɡɔldʒi]; 7 July 1843 – 21 January 1926) was an Italian biologist and pathologist known for his works on the central nervous system. He studied medicine at the University of Pavia (where he later spent most of his professional career) between 1860 and 1868 under the tutelage of Cesare Lombroso. Inspired by pathologist Giulio Bizzozero, he pursued research in nervous system. His discovery of a staining technique called black reaction (sometimes called Golgi's method or Golgi's staining in his honour) in 1873 was a major breakthrough in neuroscience. Several structures and phenomena in anatomy and physiology are named for him, including the Golgi apparatus, the Golgi tendon organ and the Golgi tendon reflex. He is recognized as the greatest neuroscientist and biologist of his time.Golgi and the Spanish biologist Santiago Ramón y Cajal were jointly given the Nobel Prize in Physiology or Medicine 1906 "in recognition of their work on the structure of the nervous system".Central pattern generator
Central pattern generators (CPGs) are biological neural circuits that produce rhythmic outputs in the absence of rhythmic input. They are the source of the tightly-coupled patterns of neural activity that drive rhythmic motions like walking, breathing, or chewing. The ability to function without input from higher brain areas still requires modulatory inputs, and their outputs are not fixed. Flexibility in response to sensory input is a fundamental quality of CPG driven behavior. To be classified as a rhythmic generator, a CPG requires:
"two or more processes that interact such that each process sequentially increases and decreases, and
that, as a result of this interaction, the system repeatedly returns to its starting condition."CPGs have been found in practically all vertebrate species investigated, including human.Cervicoaxillary canal
The Cervicoaxillary canal is the passageway that extends between the neck and the upper extremities through which the long thoracic nerve and other structures pass.Its structure is defined by being posteriorly bordered by the scapula, anteriorly by the clavicle, and medially by the first rib. The long thoracic nerve traverses this passageway in addition to axillary blood vessels and the brachial plexus. This nerve arises in the neck from the fifth, sixth, and seventh cervical roots, C5, C6, and C7. It then enters the canal in the axilla.Clasp-knife response
Clasp-knife response refers to a Golgi tendon reflex with a rapid decrease in resistance when attempting to flex a joint, usually during a neurological examination. It is one of the characteristic responses of an upper motor neuron lesion. It gets its name from the resemblance between the motion of the limb and the sudden closing of a claspknife after sufficient pressure is applied.Electrotherapy (cosmetic)
Cosmetic electrotherapy is a range of beauty treatments that uses low electric currents passed through the skin to produce several therapeutic effects such as muscle toning in the body and micro-lifting of the face. It is based on electrotherapy, which has been researched and accepted in the field of rehabilitation, though the "scientific and medical communities have tended to sideline or dismiss the use of electrotherapy for healthy muscles".The use of electricity in cosmetics goes back to the end of the 19th century, almost a hundred years after Luigi Galvani discovered that electricity can make the muscle in a frog's leg twitch (see galvanism). Subsequent research in electrophysiology has been carried out by people such as Robert O. Becker, Dr Björn Nordenström, a former chair of the Nobel Selection Committee for Medicine, and Dr Thomas Wing, who invented some of the first micro-current devices.George Goodheart
George Joseph Goodheart, Jr., D.C. (August 18, 1918 – March 5, 2008) was a chiropractor who invented taping and applied kinesiology.Golgi
Golgi may refer to:
Camillo Golgi (1843–1926), Italian physician and scientist after whom the following terms are named:
Golgi apparatus (also called the Golgi body, Golgi complex, or dictyosome), an organelle in a eukaryotic cell
Golgi tendon organ, a proprioceptive sensory receptor organ
Golgi's method or Golgi stain, a nervous tissue staining technique
Golgi alpha-mannosidase II, an enzyme
Golgi cell, a type of interneuron found in the cerebellum
Golgi I, a nerve cell with a long axon
Golgi II, a nerve cell with a short or no axon
Golgi (crater), a lunar impact crater
Córteno Golgi, an Italian villageGolgi tendon reflex
The Golgi tendon reflex is a normal component of the reflex arc of the peripheral nervous system. In a Golgi tendon reflex, skeletal muscle contraction causes the antagonist muscle to simultaneously lengthen and relax. This reflex is also called the inverse myotatic reflex, because it is the inverse of the stretch reflex. Though muscle tension is increasing during the contraction, alpha motor neurons in the spinal cord supplying the muscle are inhibited. However, antagonistic muscles are activated.Interneuron
An interneuron (also called internuncial neuron, relay neuron, association neuron, connector neuron, intermediate neuron or local circuit neuron) is a broad class of neurons found in the human body. Interneurons create neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS). They have been found to function in reflexes, neuronal oscillations, and neurogenesis in the adult mammalian brain.
Interneurons can be further broken down into two groups: local interneurons and relay interneurons. Local interneurons have short axons and form circuits with nearby neurons to analyze small pieces of information. Relay interneurons have long axons and connect circuits of neurons in one region of the brain with those in other regions. The interaction between interneurons allow the brain to perform complex functions such as learning, and decision-making.Muscle energy technique
Muscle Energy Techniques (METs) describes a broad class of manual therapy techniques directed at improving musculoskeletal function or joint function, and improving pain. METs are commonly used by manual therapists, osteopaths, physical therapists, chiropractors, athletic trainers, osteopathic physicians, and massage therapists.Historically, the concept emerged as a form of osteopathic manipulative diagnosis and treatment in which the patient's muscles are actively used on request, from a precisely controlled position, in a specific direction, and against a distinctly executed physician counterforce. It was first described in 1948 by Fred Mitchell, Sr, D.O. Muscle energy techniques are used to treat somatic dysfunction, especially decreased range of motion, muscular hypertonicity, and pain.Nerve conduction velocity
Nerve conduction velocity is an important aspect of nerve conduction studies. It is the speed at which an electrochemical impulse propagates down a neural pathway. Conduction velocities are affected by a wide array of factors, including age, sex, and various medical conditions. Studies allow for better diagnoses of various neuropathies, especially demyelinating conditions as these conditions result in reduced or non-existent conduction velocities.Nuclear chain fiber
A nuclear chain fiber is a specialized sensory organ contained within a muscle. Nuclear chain fibers are intrafusal fibers that, along with nuclear bag fibers, make up the muscle spindle responsible for the detection of changes in muscle length.
There are 3–9 nuclear chain fibers per muscle spindle that are half the size of the nuclear bag fibers. Their nuclei are aligned in a chain and they excite the secondary nerve. They are static, whereas the nuclear bag fibers are dynamic in comparison. The name "nuclear chain" refers to the structure of the central region of the fiber, where the sensory axons wrap around the intrafusal fibers.
The secondary nerve association involves an efferent and afferent pathway that measure the stress and strain placed on the muscle (usually the extrafusal fibers connected from the muscle portion to a bone). The afferent pathway resembles a spring wrapping around the nuclear chain fiber and connecting to one of its ends away from the bone. Again, depending on the stress and strain the muscles sustains, this afferent and efferent coordination will measure the "stretch of the spring" and communicate the results to the central nervous system.
A similar structure attaching one end to muscle and the other end to a tendon is known as a Golgi tendon organ. However, Golgi tendon organs differ from nuclear chain and nuclear bag fibers in that they are considered in series rather than in parallel to the muscle fibers.Proprioception
Proprioception ( PROH-pree-o-SEP-shən), is the sense of the relative position of one's own parts of the body and strength of effort being employed in movement. It is sometimes described as the "sixth sense".In humans, it is provided by proprioceptors in skeletal striated muscles (muscle spindles) and tendons (Golgi tendon organ) and the fibrous membrane in joint capsules. It is distinguished from exteroception, by which one perceives the outside world, and interoception, by which one perceives pain, hunger, etc., and the movement of internal organs.
The brain integrates information from proprioception and from the vestibular system into its overall sense of body position, movement, and acceleration. The word kinesthesia or kinæsthesia (kinesthetic sense) strictly means movement sense, but has been used inconsistently to refer either to proprioception alone or to the brain's integration of proprioceptive and vestibular inputs.
Proprioception has also been described in other animals such as vertebrates, and in some invertebrates such as arthropods. More recently proprioception has also been described in flowering land plants (angiosperms).Somatosensory system
The somatosensory system is a part of the sensory nervous system. The somatosensory system is a complex system of sensory neurons and pathways that responds to changes at the surface or inside the body. The axons (as afferent nerve fibers) of sensory neurons connect with, or respond to, various receptor cells. These sensory receptor cells are activated by different stimuli such as heat and nociception, giving a functional name to the responding sensory neuron, such as a thermoreceptor which carries information about temperature changes. Other types include mechanoreceptors, chemoreceptors, and nociceptors which send signals along a sensory nerve to the spinal cord where they may be processed by other sensory neurons and then relayed to the brain for further processing. Sensory receptors are found all over the body including the skin, epithelial tissues, muscles, bones and joints, internal organs, and the cardiovascular system.
Somatic senses are sometimes referred to as somesthetic senses, with the understanding that somesthesis includes the sense of touch, proprioception (sense of position and movement), and (depending on usage) haptic perception.The mapping of the body surfaces in the brain is called somatotopy. In the cortex, it is also referred to as the cortical homunculus. This brain-surface ("cortical") map is not immutable, however. Dramatic shifts can occur in response to stroke or injury.Spinal interneuron
A spinal interneuron, found in the spinal cord, relays signals between (afferent) sensory neurons, and (efferent) motor neurons. Different classes of spinal interneurons are involved in the process of sensory-motor integration. Most interneurons are found in the grey column, a region of grey matter in the spinal cord.Triceps reflex
The triceps reflex, a deep tendon reflex, is a reflex as it elicits involuntary contraction of the triceps brachii muscle. It is initiated by the Cervical (of the neck region) spinal nerve 7 nerve root (the small segment of the nerve that emerges from the spinal cord). The reflex is tested as part of the neurological examination to assess the sensory and motor pathways within the C7 and C8 spinal nerves.Type Ia sensory fiber
A type Ia sensory fiber, or a primary afferent fiber is a type of afferent nerve fiber. It is the sensory fiber of a stretch receptor found in muscles called the muscle spindle, which constantly monitors how fast a muscle stretch changes. (In other words, it monitors the velocity of the stretch).