Proprioception: Sensory functions that transduce stimuli received by proprioceptive receptors in joints, tendons, muscles, and the INNER EAR into neural impulses to be transmitted to the CENTRAL NERVOUS SYSTEM. Proprioception provides sense of stationary positions and movements of one's body parts, and is important in maintaining KINESTHESIA and POSTURAL BALANCE.Somatosensory Disorders: Disorders of sensory information received from superficial and deep regions of the body. The somatosensory system conveys neural impulses which pertain to proprioception, tactile sensation, thermal sensation, pressure sensation, and pain. PERIPHERAL NERVOUS SYSTEM DISEASES; SPINAL CORD DISEASES; and BRAIN DISEASES may be associated with impaired or abnormal somatic sensation.Kinesthesis: Sense of movement of a part of the body, such as movement of fingers, elbows, knees, limbs, or weights.Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Knee Joint: A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.Joint Instability: Lack of stability of a joint or joint prosthesis. Factors involved are intra-articular disease and integrity of extra-articular structures such as joint capsule, ligaments, and muscles.Postural Balance: A POSTURE in which an ideal body mass distribution is achieved. Postural balance provides the body carriage stability and conditions for normal functions in stationary position or in movement, such as sitting, standing, or walking.Anterior Cruciate Ligament: A strong ligament of the knee that originates from the posteromedial portion of the lateral condyle of the femur, passes anteriorly and inferiorly between the condyles, and attaches to the depression in front of the intercondylar eminence of the tibia.Posture: The position or attitude of the body.Range of Motion, Articular: The distance and direction to which a bone joint can be extended. Range of motion is a function of the condition of the joints, muscles, and connective tissues involved. Joint flexibility can be improved through appropriate MUSCLE STRETCHING EXERCISES.Arm: The superior part of the upper extremity between the SHOULDER and the ELBOW.Muscle Weakness: A vague complaint of debility, fatigue, or exhaustion attributable to weakness of various muscles. The weakness can be characterized as subacute or chronic, often progressive, and is a manifestation of many muscle and neuromuscular diseases. (From Wyngaarden et al., Cecil Textbook of Medicine, 19th ed, p2251)Illusions: The misinterpretation of a real external, sensory experience.Spinocerebellar Tracts: Fibers that arise from cell groups within the spinal cord and pass directly to the cerebellum. They include the anterior, posterior, and rostral spinocerebellar tracts, and the cuneocerebellar tract. (From Parent, Carpenter's Human Neuroanatomy, 9th ed, p607)Feedback, Sensory: A mechanism of communicating one's own sensory system information about a task, movement or skill.Psychomotor Performance: The coordination of a sensory or ideational (cognitive) process and a motor activity.Muscle Strength: The amount of force generated by MUSCLE CONTRACTION. Muscle strength can be measured during isometric, isotonic, or isokinetic contraction, either manually or using a device such as a MUSCLE STRENGTH DYNAMOMETER.Ankle Injuries: Harm or hurt to the ankle or ankle joint usually inflicted by an external source.Knee: A region of the lower extremity immediately surrounding and including the KNEE JOINT.Sensation Disorders: Disorders of the special senses (i.e., VISION; HEARING; TASTE; and SMELL) or somatosensory system (i.e., afferent components of the PERIPHERAL NERVOUS SYSTEM).Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Hand: The distal part of the arm beyond the wrist in humans and primates, that includes the palm, fingers, and thumb.Sprains and Strains: A collective term for muscle and ligament injuries without dislocation or fracture. A sprain is a joint injury in which some of the fibers of a supporting ligament are ruptured but the continuity of the ligament remains intact. A strain is an overstretching or overexertion of some part of the musculature.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Orthopedic Equipment: Nonexpendable items used in the performance of orthopedic surgery and related therapy. They are differentiated from ORTHOTIC DEVICES, apparatus used to prevent or correct deformities in patients.Touch: Sensation of making physical contact with objects, animate or inanimate. Tactile stimuli are detected by MECHANORECEPTORS in the skin and mucous membranes.Osteoarthritis, Knee: Noninflammatory degenerative disease of the knee joint consisting of three large categories: conditions that block normal synchronous movement, conditions that produce abnormal pathways of motion, and conditions that cause stress concentration resulting in changes to articular cartilage. (Crenshaw, Campbell's Operative Orthopaedics, 8th ed, p2019)Bandages: Material used for wrapping or binding any part of the body.Gait Apraxia: Impaired ambulation not attributed to sensory impairment or motor weakness. FRONTAL LOBE disorders; BASAL GANGLIA DISEASES (e.g., PARKINSONIAN DISORDERS); DEMENTIA, MULTI-INFARCT; ALZHEIMER DISEASE; and other conditions may be associated with gait apraxia.Ankle Joint: The joint that is formed by the inferior articular and malleolar articular surfaces of the TIBIA; the malleolar articular surface of the FIBULA; and the medial malleolar, lateral malleolar, and superior surfaces of the TALUS.Knee Injuries: Injuries to the knee or the knee joint.Muscle Spindles: Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.Vision, Ocular: The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.Rupture: Forcible or traumatic tear or break of an organ or other soft part of the body.Feedback: A mechanism of communication within a system in that the input signal generates an output response which returns to influence the continued activity or productivity of that system.Artificial Limbs: Prosthetic replacements for arms, legs, and parts thereof.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Oculomotor Muscles: The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.Vibration: A continuing periodic change in displacement with respect to a fixed reference. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Sensation: The process in which specialized SENSORY RECEPTOR CELLS transduce peripheral stimuli (physical or chemical) into NERVE IMPULSES which are then transmitted to the various sensory centers in the CENTRAL NERVOUS SYSTEM.Neck Muscles: The neck muscles consist of the platysma, splenius cervicis, sternocleidomastoid(eus), longus colli, the anterior, medius, and posterior scalenes, digastric(us), stylohyoid(eus), mylohyoid(eus), geniohyoid(eus), sternohyoid(eus), omohyoid(eus), sternothyroid(eus), and thyrohyoid(eus).Eye Movements: Voluntary or reflex-controlled movements of the eye.Robotics: The application of electronic, computerized control systems to mechanical devices designed to perform human functions. Formerly restricted to industry, but nowadays applied to artificial organs controlled by bionic (bioelectronic) devices, like automated insulin pumps and other prostheses.Walking: An activity in which the body advances at a slow to moderate pace by moving the feet in a coordinated fashion. This includes recreational walking, walking for fitness, and competitive race-walking.Torque: The rotational force about an axis that is equal to the product of a force times the distance from the axis where the force is applied.Ligaments, Articular: Fibrous cords of CONNECTIVE TISSUE that attach bones to each other and hold together the many types of joints in the body. Articular ligaments are strong, elastic, and allow movement in only specific directions, depending on the individual joint.Space Perception: The awareness of the spatial properties of objects; includes physical space.Fingers: Four or five slender jointed digits in humans and primates, attached to each HAND.Athletic Injuries: Injuries incurred during participation in competitive or non-competitive sports.Joints: Also known as articulations, these are points of connection between the ends of certain separate bones, or where the borders of other bones are juxtaposed.Functional Laterality: Behavioral manifestations of cerebral dominance in which there is preferential use and superior functioning of either the left or the right side, as in the preferred use of the right hand or right foot.Orientation: Awareness of oneself in relation to time, place and person.Task Performance and Analysis: The detailed examination of observable activity or behavior associated with the execution or completion of a required function or unit of work.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Exercise Therapy: A regimen or plan of physical activities designed and prescribed for specific therapeutic goals. Its purpose is to restore normal musculoskeletal function or to reduce pain caused by diseases or injuries.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Leg: The inferior part of the lower extremity between the KNEE and the ANKLE.Upper Extremity: The region of the upper limb in animals, extending from the deltoid region to the HAND, and including the ARM; AXILLA; and SHOULDER.Adaptation, Physiological: The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Knee Prosthesis: Replacement for a knee joint.