**5. Propioception from a clinical perspective: causes for impaired proprioception**

Proprioception is critical factor for stability, and it is well known it deteriorates in aged people [94]. In fact, the proprioceptive system undergoes significant structural and functional changes with aging which cause a progressive decline in somatosensibility including proprioception [95–97].

Aging courses with muscle weakness from sarcopenia, decrease in the number of intrafusal fibers in muscle spindles, and denervation. All together these facts diminished muscle force and consistently the proprioception which, in turn determinate the increase in falls in the elderly with clinical and public health consequences. The specific relationship between muscle strength and proprioception should be explored further as it may provide a basis for the claim that exercise improves standing stability. Interestingly, to achieve a reduction in the incidence of falls, it is not sufficient to improve muscle strength alone as exercises are required which actually challenge standing stability. These changes might contribute to the frequent falls and motor control problems observed in older adults. On the structural level, muscle spindles in aged humans possess fewer intrafusal fibers, an increased capsular thickness and some spindles which show signs of denervation [98, 99].

A variety of neurological diseases are characterized by irregular, jerky movement or posture due to loss of proprioceptive sensory feedback, a disturbance called afferent ataxia. The affected neurons are primary sensory neurons in the dorsal root ganglia relaying body position and movement (proprioception) to the central nervous system. Proprioception dysfunction can be caused by injuries and disorders

**11**

**Author details**

neurons [100, 101].

Oviedo, Oviedo, Spain

Santiago de Chile, Chile

Oviedo, Oviedo, Spain

José A. Vega1,2\* and Juan Cobo3,4

1 Departamento de Morfología y Biología Celular, Grupo SINPOS, Universidad de

that affect any part of the proprioceptive system between the sensory receptors that send the signals to the parts of the brain that receive and interpret them. The risk of proprioception loss increases as we age due to a combination of natural age-related changes to the nerves, joints, and muscles. Examples of injuries and conditions that can cause proprioceptive deficit include: brain injuries, herniated disc, arthritis, multiple sclerosis (MS), stroke, autism spectrum disorder (ASD), diabetes, peripheral neuropathy, Parkinson's disease, Huntington's disease, ALS (amyotrophic lateral sclerosis), or Lou Gehrig's disease. Joint injuries, such as an ankle sprain or knee sprain, joint replacement surgery, such as hip replacement or knee replacement, Parkinson's disease. Primary proprioceptive neurons may be the target of hereditary, developmental, degenerative, toxic, inflammatory and autoimmune pathology. Accordingly, typical clinical consequences of pathology affecting proprioceptive neurons, in addition to afferent ataxia, include loss of deep tendon (stretch) reflexes and of conscious perception of position and movement of body parts, often associated with loss of perception of vibration [9]. Recently, Dionisi and co-workers have obtained proprioceptive primary sensory neurons from iPSCs, and the generation of intrafusal fibers in vitro are opening new perspectives for the treatment of some ataxia linked to altered primary proprioceptive

3 Departamento de Cirugía y Especialidades Médico-Quirúrgicas, Universidad de

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

2 Facultad de Ciencias de la Salud, Universidad Autónoma de Chile,

4 Instituto Asturiano de Odontología, Oviedo, Spain

\*Address all correspondence to: javega@uniovi.es

provided the original work is properly cited.

*Structural and Biological Basis for Proprioception DOI: http://dx.doi.org/10.5772/intechopen.96787*

*Structural and Biological Basis for Proprioception DOI: http://dx.doi.org/10.5772/intechopen.96787*

*Proprioception*

and after retrieval of memories.

**4.5 The mesencephalic trigeminal nucleus**

in proprioception.

**proprioception**

denervation [98, 99].

proprioception, generate a perception of the body as it actually is at any moment in time, an image which is able to change from moment to moment. It is distinguished from an "off-line" representation constructed, in part, from current sensory inputs, in part, from stored memories and is available to consciousness both immediately

In the last times neuroimaging has strongly contributed to the knowledge of the central activity patterns produced by proprioceptive stimuli, to the recognition of the integration of proprioceptive inputs with inputs from other senses and the identification of central areas involved in the integration [81]. These include regions in the parietal cortex [82–85] including the primary somatosensory cortex [86, 87]. Furthermore, parts of the frontal cortex and insula [88, 89] are involved

The mesencephalic trigeminal nucleus is a sensory structure located at the mesopontine junction and contains the cell bodies of primary order afferent proprioceptors that innervate muscle spindles of the muscles of mastication and other muscles of the head and neck [27, 71]. Whether these primary sensory neurons are generated directly in brain or have a of neural crest origin is stell debated. Classically it has been regarded as a representation of a peripheral sensory ganglion similar to DRG that became incorporated into de brainstem during embryonic development,

It projects to the dorsolateral division of the trigeminal motor nucleus and to the supratrigeminal nucleus, which are involved in humans in the jaw-jerk reflex and

Proprioception is critical factor for stability, and it is well known it deteriorates

Aging courses with muscle weakness from sarcopenia, decrease in the number of intrafusal fibers in muscle spindles, and denervation. All together these facts diminished muscle force and consistently the proprioception which, in turn determinate the increase in falls in the elderly with clinical and public health consequences. The specific relationship between muscle strength and proprioception should be explored further as it may provide a basis for the claim that exercise improves standing stability. Interestingly, to achieve a reduction in the incidence of falls, it is not sufficient to improve muscle strength alone as exercises are required which actually challenge standing stability. These changes might contribute to the frequent falls and motor control problems observed in older adults. On the structural level, muscle spindles in aged humans possess fewer intrafusal fibers, an increased capsular thickness and some spindles which show signs of

A variety of neurological diseases are characterized by irregular, jerky movement or posture due to loss of proprioceptive sensory feedback, a disturbance called afferent ataxia. The affected neurons are primary sensory neurons in the dorsal root ganglia relaying body position and movement (proprioception) to the central nervous system. Proprioception dysfunction can be caused by injuries and disorders

although molecular studies support a central origin for these cells [90, 91].

**5. Propioception from a clinical perspective: causes for impaired** 

in aged people [94]. In fact, the proprioceptive system undergoes significant structural and functional changes with aging which cause a progressive decline in

the periodontal-masseteric reflex [92] (for a review see [93]).

somatosensibility including proprioception [95–97].

**10**

that affect any part of the proprioceptive system between the sensory receptors that send the signals to the parts of the brain that receive and interpret them. The risk of proprioception loss increases as we age due to a combination of natural age-related changes to the nerves, joints, and muscles. Examples of injuries and conditions that can cause proprioceptive deficit include: brain injuries, herniated disc, arthritis, multiple sclerosis (MS), stroke, autism spectrum disorder (ASD), diabetes, peripheral neuropathy, Parkinson's disease, Huntington's disease, ALS (amyotrophic lateral sclerosis), or Lou Gehrig's disease. Joint injuries, such as an ankle sprain or knee sprain, joint replacement surgery, such as hip replacement or knee replacement, Parkinson's disease. Primary proprioceptive neurons may be the target of hereditary, developmental, degenerative, toxic, inflammatory and autoimmune pathology. Accordingly, typical clinical consequences of pathology affecting proprioceptive neurons, in addition to afferent ataxia, include loss of deep tendon (stretch) reflexes and of conscious perception of position and movement of body parts, often associated with loss of perception of vibration [9]. Recently, Dionisi and co-workers have obtained proprioceptive primary sensory neurons from iPSCs, and the generation of intrafusal fibers in vitro are opening new perspectives for the treatment of some ataxia linked to altered primary proprioceptive neurons [100, 101].
