MYOLOGY
The Study of Muscles
I. Introduction
A. There are 650 Skeletal muscles in the body that comprise about 40% of the body weight
B. Characteristics
Excitability – capacity to generate electrical impulses ( Action Potential )
Contractility – capacity to shorten its length
C. Functions of the Muscular System
Voluntary Movement
Maintenance of Body Posture
Heat Production
Breathing – includes diaphragm and intercostal muscles
II. Gross Structure of the Skeletal Muscles
A. Belly of the Muscle (See Figure 1)
B. Tendons
Attach the muscles to the periosteum
of the bone
Tendon of Origin
Called “head” or “ceps”
Attachment to the less
movable structures
Tendon of Insertion
The “tail” of the muscle
Attachment to the more
movable structure
III. Fascia of the Muscle
A. Epimysium
Fibrous Connective Tissue sheath
that encloses the entire belly of the
muscle
B. Perimysium
Loose Connective Tissue sheath that surrounds only a bundle (fascicle) of muscle fibers
C. Endomysium
Loose Connective Tissue that surround each individual muscle fibers
IV. Blood Supply and Nerve Supply (Innervation) to Muscle
A. Blood vessels and nerve fibers in the connective tissue fascia of the muscle branch to the individual muscle
fibers
B. Innervation of Muscle Fibers
Proprioceptors – sensory neurons that supply muscles
Proprioception – Kinesthesia, sensation of movement
Input Signal
Somatic Motor Neurons – motor neurons that permits voluntary excitation of skeletal muscle fibers
Each somatic motor neuron innervates several hundred skeletal muscle fibers (called Motor unit)
Output Signal
V. Group Actions of Muscles
A. Agonist (prime mover) – muscle that causes a desired action
B. Synergist (helper) – muscle that acts with an agonist
C. Antagonist – muscle that has opposite action of the agonist
D. Fixator – Muscle that stabilizes body position and decrease unnecessary movement
VI. Skeletal-Muscular Disorders and Disease
A. Skeletal and Muscular Disorder
Muscle Agenesis – congenital failure of muscle development
Hernia – protrusion of the abdominal viscera through a weakened area of the abdominal musculature
Handum_ 1|2
The Study of Muscles
I. Introduction
A. There are 650 Skeletal muscles in the body that comprise about 40% of the body weight
B. Characteristics
Excitability – capacity to generate electrical impulses ( Action Potential )
Contractility – capacity to shorten its length
C. Functions of the Muscular System
Voluntary Movement
Maintenance of Body Posture
Heat Production
Breathing – includes diaphragm and intercostal muscles
II. Gross Structure of the Skeletal Muscles
A. Belly of the Muscle (See Figure 1)
B. Tendons
Attach the muscles to the periosteum
of the bone
Tendon of Origin
Called “head” or “ceps”
Attachment to the less
movable structures
Tendon of Insertion
The “tail” of the muscle
Attachment to the more
movable structure
III. Fascia of the Muscle
A. Epimysium
Fibrous Connective Tissue sheath
that encloses the entire belly of the
muscle
B. Perimysium
Loose Connective Tissue sheath that surrounds only a bundle (fascicle) of muscle fibers
C. Endomysium
Loose Connective Tissue that surround each individual muscle fibers
IV. Blood Supply and Nerve Supply (Innervation) to Muscle
A. Blood vessels and nerve fibers in the connective tissue fascia of the muscle branch to the individual muscle
fibers
B. Innervation of Muscle Fibers
Proprioceptors – sensory neurons that supply muscles
Proprioception – Kinesthesia, sensation of movement
Input Signal
Somatic Motor Neurons – motor neurons that permits voluntary excitation of skeletal muscle fibers
Each somatic motor neuron innervates several hundred skeletal muscle fibers (called Motor unit)
Output Signal
V. Group Actions of Muscles
A. Agonist (prime mover) – muscle that causes a desired action
B. Synergist (helper) – muscle that acts with an agonist
C. Antagonist – muscle that has opposite action of the agonist
D. Fixator – Muscle that stabilizes body position and decrease unnecessary movement
VI. Skeletal-Muscular Disorders and Disease
A. Skeletal and Muscular Disorder
Muscle Agenesis – congenital failure of muscle development
Hernia – protrusion of the abdominal viscera through a weakened area of the abdominal musculature
Handum_ 1|2
