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CH 9 THE MUSCULAR SYSTEM
chapter 9 - the muscular system
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Anatomy
05/31/2010

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Term

Muscular System

Definition
Skeletal muscle tissue is primary type of tissue
Term

Functions of Muscular System

Definition

 

1.Skeletal movement 
2.Maintains posture / position 
3.Supports soft tissue 
4.Controls opening / exits of body 
5.Maintains body temperature
Term

 

 

Organization of Skeletal Muscle Tissue

Definition

1.Muscle Cell

2.Connective Tissue of Muscle

Term

 

 

Organization of Skeletal Muscle Tissue-

Muscle Cell

Definition

 

a.Multinucleated 
b.Sarcolemma - membrane 
c.Sarcoplasm - cytoplasm 
d.Satellite cells 
e.Very large - up to 16” long
Term

 

 

Organization of skeletal muscle tissue-

 Connective Tissue of Muscle

Definition

1. Epimysium

2. Perimysium

3. Endomysium

4. Tendon

5. Aponeuroses

Term

Organization of skeletal muscle tissue-

 Connective Tissue of Muscle

 

Epimysium

Definition
dense irregular CT that surrounds entire muscle 
Term

Organization of skeletal muscle tissue-

 Connective Tissue of Muscle

 

Perimysium

Definition
divides the muscle into internal compartments each containing a fascicle; location of blood vessels and nerves
Term

Organization of skeletal muscle tissue-

 Connective Tissue of Muscle

 

Endomysium

Definition
surrounds each fiber; binds each fiber to neighbor capillaries; location of satellite cells
Term

Organization of skeletal muscle tissue-

 Connective Tissue of Muscle

 

Tendon

Definition
at the ends of a muscle the collagen fibers of the 3 layers converge to form a fibrous tendon and attach muscles to bone
Term

Organization of skeletal muscle tissue-

 Connective Tissue of Muscle

 

Aponeuroses

Definition
tendons that form thick flattened sheets that cover the surface of a muscle
Term

 

Muscle Fiber

Definition

-arrangement has a significant effect on the

•power

•range

•speed of movement

-within a fascicle are parallel to each other (but fascicles arent always parallel to each other

 

Term

Muscle Fiber Arrangements

 

Parallel Muscles

Definition

-fascicles are parallel

-most common arrangement

- Central body (belly) portion of muscle gets wider during contraction

-tension depends on the number of myofibrils

-biceps brachii

Term

Muscle Fiber Arrangements

 

Convergent Muscles

Definition

-fascicles are stretched over a large area but converge to one point for attachment 

-Versatile muscle that can change the direction of pull by selectively stimulating only specific muscle groups 

-When all the muscles contract at once they do not generate as much tension because they cancel out 

-Pectoralis muscles 

Term

Muscle Fiber Arrangement

 

Pennate Muscles

Definition

-one or more tendons run through the body of the muscle and the fascicles form an oblique angle to the tendon 

-Do not pull tendon as far 

-Contain more muscle fibers than a similar-sized parallel muscle and therefore produce more tension

-Rectus femoris 

Term

Muscle Fiber Arrangement

 

Circular Muscles

 

Definition

-aka sphincters

- are concentrically around an orifice or recess 

-Orbicularis oris

Term
Points of attachment
Definition

Origin - muscle begins; bone or structure that remains stationary after contraction or is proximal to the insertion 

Insertion - muscle ends; movable end or distal to the origin 

Tricep - inserts on the olecranon process of the ulna and originates in the shoulder 

Term
Actions of muscles
Definition

-agonist

-synergist

-antagonist

Term
Agonist
Definition

-prime mover

- muscle contraction produces a particular movement; biceps brachii is an agonist producing flexion at the elbow 

Term
Synergist
Definition

-assist an agonist muscle by providing additional pull or stability to the point of origin;

-latissimus dorsi (agonist) has little strength when arms are fully extended above head but teres major (synergist) helps initiate movement

Term
Antagonist
Definition

-actions oppose agonist;

-when agonist contracts the antagonist will stretch but not completely relax - this tension controls the speed and smoothness of the agonist contraction;

triceps brachii is the antagonist to the biceps brachii

Term
naming - direction
Definition

-some names include reference to the orientation of the muscle fibers 

-Rectus - straight (parallel) fibers; rectus abdominis and rectus femoris 

-Transversus - fibers run across body axis

Term
naming-shape and features
Definition

-some muscles are named after their shape or specific features 

-Bi-, tri-, and quadriceps - refer to the number of tendons of origin 

-Deltoid - triangular  

-Longus / longissimus - long muscles

Term
naming - position
Definition

- muscles can be named based on their location in the body 

-Superficials or externus - visible at the surface 

-Internus or profundus - deeper

Term
naming - origins/insertions
Definition
- the first part of the name indicates the origin and the latter part is the insertion
Term
naming-action
Definition

-some muscles are named based on the movement they cause           

a.Extensor 
b.Flexor
Term
Movement of bones, joints, & muscles depends on more than just the presence of a large or small muscle
Definition

-Components of movement 

-Lever - rigid structure (bone) that moves 

-Fulcrum - the fixed point (joint) that the lever moves in respect to 

-Applied force - the effect of muscular contractions 

-Classes of levers (Fig. 9.15)  

-First class - seesaw type of movement (forward / backwards movement of head)

-Second class - resistance is located between the fulcrum and applied force (i.e. wheelbarrow; plantar flexion) 

-Third class - force is applied between the resistance and fulcrum; most common in the body (flex forearm)