Transcript How muscles attach to bone

How Muscles Attach to Bone
Introduction
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Skeletal muscle attaches to bone one of two
ways
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Indirectly: the epimysium extends past the muscle
as a tendon and then attaches to the periosteum of
the bone
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Epimysium: the sheath of connective tissue that
surrounds the exterior of the muscle fibre
Directly: the epimysium adheres to and fuses with
the periosteum
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Periosteum: the outer membrane that covers the bone
Antagonistic Pairs
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Skeletal muscles are arranged as opposing
pairs
While one muscles flexes, the other must
extend to allow for the bone to move
The flexor and extendor are known as
antagonistic muscles
Agonist vs. Antagonist
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The muscle primarily responsible for movement
of a body part is referred to as the agonist
The muscle that counteracts the agonist,
extends or lengthens when the agonist
contracts, is referred to as the antagonist
Example: in elbow flexion, the agonist is the
biceps and the antagonist is the triceps
Origin and Insertion
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When a skeletal muscle contracts, it causes
movement of the bone it is attached to
The point where the muscle attaches to the
more stationary of the bones of the axial
skeleton is called the origin
The point where the muscle attaches to the
bone that is moved most, is called the insertion
Types of Muscle Contraction
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3 different types of muscle contractions
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The term contraction does not necessarily mean that the
muscle has shortened, but rather that tension has been
generated
1. Concentric: occurs when muscle fibres shorten
- example: the biceps shorten when lifting an object
2. Eccentric: occurs when the muscle fibres lengthen
- the biceps lengthens as the same weight is placed back on the
ground
3. Isometric: occurs when the muscle fibres do not change in
length
- when you try to lift an immovable object
Muscle Contraction During Exercise
Isotonic Exercise
- involves concentric contraction (shortening) and
lengthening of the muscle
- Example: weight training with dumbbells and
barbells – as the weight is lifted, the muscle
shortens
- Other examples: chin-ups, push-ups, sit-ups
Isometric Exercise
- Muscle fibres maintain a constant length
- No motion
- These exercises are usually performed against
an immovable object
- Example: pressing your arm into the wall
- These exercises are frequently used in
rehabilitation
Isokinetic Exercise
- Involves using machines to control the speed of
contractions
- These machines allow for force to be exerted at
a constant and pre-set speed
- These types of machines are only used by highperformance training centres and professional
teams
- Not available to the public