University:
Camosun College
Course:
BIOL 252 | Pathophysiology for Nursing 1
Academic year:

2024
Views:

415

Pages:

2
Author:

Aysha A.

Nerve Fiber Classification Erlanger-Gasser System: Nerve fibers are classified based on the diameter of the axon and the thickness of the myelination. Larger diameter fibers are categorized first. Axon Types: Aα Fibers: These fibers innervate muscle fibers that organize and end in tendons, with a thick fiber present in the middle. This sensory organ embedded within the muscle is called the muscle spindle, which senses changes in muscle length. Aγ Fibers: These fibers are part of the muscle spindle that sense tension drop in muscle tendons. The sensory organ in the tendon is called the Golgi tendon organ. Extrafusal Muscle Fibers: Muscle fibers outside the muscle spindle. Intrafusal Muscle Fibers: Muscle fibers within the muscle spindle. Proprioception: This term refers to the sensory perception of the position and movement of the body, particularly changes in the length of muscle fibers. Muscle Spindle Structure: Muscle spindles have two types of fibers: Nuclear Bag Fibers Nuclear Chain Fibers These fibers contain sensory endings: Annulospiral Ending (Primary Ending, Ia fiber): When the muscle gets stretched or compressed, these fibers detect the change in length and send action potentials (APs) to the spinal cord. Flower Spray Ending (Secondary Ending, II fiber): These fibers respond to steady, prolonged stretches of muscle fibers. Types of Muscle Spindle Fibers: Type Ia Fibers: Responsible for dynamic proprioception, sensing sudden changes in the length of muscle fibers. Also known as dynamic fibers due to their role in detecting rapid changes. Type II Fibers: Responsible for static proprioception, providing continuous information about the muscle's position. Also known as static fibers as they detect the steady-state length of muscles. Both Type Ia and Type II fibers are classified as afferent fibers because they carry sensory information to the spinal cord. Afferent Fiber Pathways: Afferent fibers travel from the spinal cord to muscle fibers through pathways labeled as Aα, Aβ, and Aγ fibers, connecting to intrafusal and extrafusal fibers to communicate sensory information. Proprioception Function: Proprioception involves detecting changes in the length of muscle fibers and the position of the body, which is crucial for maintaining posture, balance, and coordinated movements.