contractility properties of muscle tissue excitability extensibility elasticity skeletal –...

• Contractility

Properties of Muscle Tissue

• Excitability

• Extensibility

• Elasticity

Skeletal – attached to bone

3 Types of Muscle Tissue

Cardiac – the heart

Smooth – internal organs blood vessels

Functions of Skeletal Muscle

• Movement of Body

• Heat Production

• Controls Entrances and Exits to Body

• Protection

Micro-Anatomy of Skeletal Muscle

• Muscle cell = muscle fiber

• Fascicle = bundle of muscle fibers

• Whole muscle = bundle of fascicles

Connective Tissue of Skeletal Muscle

• Endomysium => covers a muscle fiber

• Perimysium => covers fascicles

• Epimysium => covers whole muscle

Naming of Skeletal Muscle

• Size– Maximus

– Minimus

– Major

– Minor

– Longus

– Brevis

• Shape– Deltoid (triangle)

– Teres (round, cylinrical)

– Trapezius (trapezoidal)

– Rhomboideus (rhomboidal)

• Location– Abdominis

– Femoris

– Brachii

– Capitis

– Pectoralis

– Intercostal

– Digitorum

• Relative Position– Lateral

– Medial

– Internal

– External

– Superficialis

– Profundis

• Action– Abductor

– Adductor

– Flexor

– Extensor

– Pronator

– Supinator

– Levetor

– Depressor

• Number of Heads

– Biceps

– Triceps

– Quadriceps

• Orientation of Muscle

– Rectus

– Transversus

– Oblique

• Origin and Insertion

– sternocleidomastoid

– coracobrachialis

– Brachioradialis

Classification by Orientation of Fascicles

1) Circular:

2) Parallel:

3) Convergent:

b) Fusiform (Spindle-shaped):

a) Strap-like:

- e.g. orbicularis oris

- e.g. sartorius, rectus abdominis

- e.g. biceps brachii

- e.g. pectoralis major

4) Pennate Muscles:

a) Unipennate:

b) Bipennate:

c) Multipennate:

- e.g. extensor digitorum

- e.g. rectus femoris

- e.g. deltoid

Levers are rigid structures that

move on a fixed point,

called a fulcrum (F).

• Bones act as levers.

The role of levers is to Confer Advantage.

In the body:

• Joints act as the fulcrum.

• The Effort arm (E) is powered by muscular contraction.

• The Resistance (R) is the weight of the body

part being moved.

Also in the body:

• Each Lever System needs a:

Fulcrum, Effort arm and Resistance.

• Increase speed or distance of body part moved.

• Increase the force applied to the movement.

A Lever System can:

But never both!

OR

1st Class Lever: EFR

Effort Arm

E

E

E

E

2nd Class Lever: FRE

E

E

3rd Class Lever: FER

The Neuromuscular Junction

Motor Unit Recruitment