Neuroanatomy Draw It To Know It

8. Spinal Canal and Muscle–Nerve Physiology 135

Type Ia

sensory nerve

Motoneuron

Gamma

Muscle

spindle

Extafusal

Supraspinal

input

Plate ending

Nuclear bag (motor) - dynamic

Nuclear chain

Trail ending

(motor) - static

Muscle spindle

Extrafusal

muscle

fiber

Intrafusal

muscle fiber

MUSCLE SPINDLE

MUSCLE TONE

Type Ia, annulospiral (sensory)

Type II,

flower spray

(sensory)

Bag2 fiber

A α

A β

A γ

Aδ

B

C

Ia

Ib

III

II

IV

12-22

5-12

2-8

1-5

<3

<1

70-120

30-70

15-30

5-30

3-15

<2

Diameter Speed

Diameter = micrometers(μm)

Speed = meters/second (m/s)

PERIPHERAL NERVE

CLASSIFICATION

Gasser Lloyd

Aα

motor nerve

Aγ

motor nerve

DRAWING 8-3 Muscle–Nerve Physiology