Chapter 8

Chapter Objectives

After reading this chapter, the student should be able to do the following:

Chapter 8

Chapter at a Glance

Neurophysiology of Proprioception

Central Nervous System Proprioceptor Sites

Balance

Coordination

Agility

Therapeutic Exercise for Proprioception

Summary

Chapter 8

Suggested Lecture Outline

  1. Introduction to proprioception and proprioceptors
    1. Proprioception
      1. Definition: the body's ability to transmit afferent information regarding position sense, to interpret the information, and to respond consciously or unconsciously to stimulation through appropriate execution of posture and movement
      2. Targeted in therapeutic exercise program after flexibility, strength, and endurance have improved
      3. Components of proprioception: agility, balance, and coordination
    2. Proprioceptors
      1. Definition: afferent nerves that receive and send impulses from stimuli within skin, muscle, joints, and tendons to the central nervous system (CNS)
      2. Send information regarding tension of muscle, position of body part, and so on
      3. Are categorized according to their location
  2. Neurophysiology of proprioception
    Key Point: The major categories of proprioceptors are cutaneous receptors, muscle and tendon receptors, and joint receptors. To varying degrees, they all influence proprioception.
    1. Afferent receptors
      1. Definition
      2. Proprioceptive afferent receptors are located in skin, muscles, tendons, and joints (figure 8.2)
    2. Cutaneous receptors
      1. Fast-adapting afferents
        1. Detect sudden changes in speed and movement
      2. Slow-adapting I and II afferents
        1. Produce constant level of stimulation and provide information related to joint and limb position
      3. Injured subjects have an increased reliance on these receptors for proprioception
    3. Muscle spindles and Golgi tendon organs (GTOs)
      1. Produce responses in muscles and tendons where located and also in the corresponding antagonistic and synergistic muscles
      2. GTOs: detect tension, respond to contraction and stretch, produce relaxation
      3. Muscle spindles: respond to stretch, cause contraction
      4. The two work together to cause facilitation to opposing muscles and synergists
      5. Determine joint position because of their muscle-length sensitivity; act as limb stabilizers
    4. Joint receptors
      1. Group II afferents
        1. Large-diameter, myelinated axons with high-speed conduction
        2. Ruffini endings
        3. Pacinian corpuscles
        4. Golgi-Mazzoni corpuscles
      2. Group III (A fibers) and IV (C fibers) afferents
        1. Small-diameter, thinly or nonmyelinated axons with slower conduction
        2. Free nerve endings in soft tissue and articular structures
        3. Are nociceptors that are stimulated by pain and inflammation when joint is placed in any end position
    5. Ligament receptors
      1. Stimulated by ligamentous stress
      2. Produce inhibitory response of agonist muscles
    6. Collaboration of afferent receptors
      1. The afferent nerves in a locale must work together to produce a complete picture of joint position and joint motion for the CNS so that it can process and interpret the input and produce an accurate response
      2. The CNS cannot determine the position of an extremity unless it receives input from all sensory, motor, and joint receptors
  3. CNS proprioceptor sites
    Key Point:After the afferent nerves send their input to the CNS, the body's motor response depends on which of three CNS sites has received the impulse—the spinal cord, the brain stem, or the cerebral cortex.
    1. Spinal cord
      1. Spinal reflex or internuncial connection
      2. Quickest response
    2. Brain stem
      1. Cerebellum: the primary proprioceptive correlation center
      2. Posture and balance
    3. Cerebral cortex
      1. Volitional control
      2. Correct movement is learned and consciously controlled
      3. Slowest response
      4. Becomes automatic response
  4. Balance
    Key Point:Balance involves three systems—the vestibular system, the oculomotor system, and the proprioceptive system. The clinician can perform simple tests to evaluate balance.
    1. Definition: the body's ability to maintain an equilibrium by controlling the body's center of gravity over its base of support
    2. Necessary for static and dynamic activities
    3. Influenced by strength and by sensory input from the CNS
    4. Sensory input
      1. Vestibular system
        1. Vertical and horizontal position and motion
        2. Nystagmus
      2. Oculomotor system
        1. Relative position of body in space
      3. Proprioceptor (somatosensory) system
    5. Balance tests
      1. Romberg test
      2. Stork stand
  5. Coordination
    Key Point:The components of coordination include perception of activity, feedback, repetition, and performance adjustment. Development of coordination involves progression of activities from simple to more complex, as well as repetition.
    1. Definition: the complex process by which a smooth pattern of activity is produced through a combination of muscles acting together with appropriate intensity and timing
    2. Accomplished through a complex neural network of sensory receptors, internuncial neurons, ascending and descending corticospinal pathways, and efferent receptors
    3. Some muscles are stimulated and others inhibited
    4. Timing and intensity of muscle response are key
    5. Strength and proper neural system function are necessary for coordination
      1. Overflow
    6. Components of coordination
      1. Activity perception
      2. Feedback
      3. Repetition
        1. Develop engram
      4. Inhibition
    7. Progression of coordination development
      1. Start with static, simple exercises
      2. Progress to dynamic, more complex exercises
      3. Accuracy of performance is vital in exercise execution
      4. Stop when fatigue begins and coordination decreases
  6. Agility
    Key Point:Agility is an advanced skill that is built on flexibility and strength, followed by coordination and balance.
    1. Definition: the ability to control the direction of a body or its parts during rapid movement
    2. Requires flexibility, strength, power, speed, balance, and coordination
    3. Involves rapid change of direction and sudden stopping and starting
    4. Progression of therapeutic exercise for agility
    5. Activities should resemble the patient's activities
  7. Therapeutic exercise for proprioception
    Key Point:Therapeutic exercises for developing balance, coordination, and agility follow exercises for flexibility and strength gains. Exercises for the lower and the upper extremities progress from simple to complex and emphasize accuracy through repetition.
    1. General principles
      1. Balance is achieved first, then coordination, then agility
      2. Exercises progress from simple to complex
      3. Initial exercises are performed slowly and deliberately in controlled situations
      4. Advancement is made only after the activity is mastered
      5. Progression is to more complex activities and evolves to specific performance activities
        1. Make activity more complex
        2. Perform simple activity at a faster pace
        3. Require a more powerful output
        4. Have patient perform more than one task simultaneously
      6. Goal: perform the activity accurately
        1. Do difficult proprioceptive activities early in exercise session so patient not as fatigued
        2. Repetition
    2. Lower-extremity progression
      1. Stork stand with eyes open
      2. Stork stand with eyes closed
      3. Stork stand on unstable surface
      4. Stork stand on unstable surface with distracting upper-extremity activity
      5. Dynamic activities: lateral movements
      6. Dynamic activities: change-of-direction movements
      7. Dynamic activities: combined balance, coordination, agility activities
      8. Dynamic activities: combined balance, coordination, agility in functional activities
      9. Plyometrics
      10. Functional/Performance-specific activities
    3. Use of braces, sleeves, tape to enhance proprioception
    4. Upper-extremity progression
      1. Passive and active joint repositioning, with eyes open and then closed
      2. Proprioceptive neuromuscular facilitation rhythmic stabilization
      3. Weight-bearing stabilization—from quadruped, to tripod, to biped—without and then with resistance
      4. Straight-plane upper-extremity movements
      5. Multiplane upper-extremity movements
      6. Rubber tubing activities
      7. Plyometrics
      8. Functional/Performance-specific activities

Chapter 8

Classroom/Student Activities

Note: The textbook includes in-depth lab activities on proprioception and neuromuscular control.

  1. When discussing the progression from balance to coordination to agility, list on the board, in a random order, activities that could be used in a therapeutic exercise program. As an extra challenge, add some activities that are clearly related to flexibility, strength, and endurance and therefore should be focused on before proprioceptive exercises. Have the class place the items in the order in which they might begin in a therapeutic exercise program based on the general progression from balance to coordination to agility.
  2. Set up two scenarios for the students—one of a hypothetical patient with an upper-extremity injury and one of a patient with a lower-extremity injury. List on the board possible proprioceptive neuromuscular facilitation exercises for each patient, but do not place them in any specific order. Ask the students to order them in a way that would hypothetically be most appropriate (barring the unknowns of each patient).