#Class 4 - The Muscular System

Epimysium

Outermost dense layer surrounds the entire muscle

(epi a prefix meaning "upon" or "over"; mysium refers to muscle tissue)

Perimysium

Connective tissue around the muscle fascicles (bundles of muscle cells)

Endomysium

Thin connective tissue surrounding individual muscle fibers (cells);

Deepest layer in skeletal muscle

Tendon

Flexible tissue that attaches a muscle to the bone;

; extensions of the three coverings attaching the muscle to the periosteum of the bone (EPI-PERI-ENDO=mysium)

3 Types of Muscle Tissue

Skeletal muscle, Cardiac muscle, and Smooth muscle

Skeletal muscle tissue characteristics (3)

Multi-nucleated

Striated

Voluntary

Cardiac muscle tissue characteristics (4)

One nucleus

Striated

Intercalated discs

Involuntary

Visceral (smooth muscle)

One nucleus

No striations

Involuntary

4 Properties of Muscle Tissue

1. Electrical Excitability

2. Contractility

3. Extensibility

4. Elasticity

Aponeurosis

Wide flat tendon that connects muscle to the part it moves

(ie. Palmar aponeurosis)

Skeletal muscles produce movements by [blank]

Exerting force on the tendons

Origin vs. Insertions

Origin: attachment of the muscle tendon to stationary bone (Typ. Proximal)

Insertion: attachment of the other tendon to the moving bone (Typ. Distal)

Name the lever type

Second class lever (FLE)

Load is between the fulcrum and the effort

Mechanical advantage

Name the lever type

Third class lever (FEL)

Effort is between the fulcrum and the load

Mechanical disadvantage

Name the lever type

First class lever (EFL)

The fulcrum is between the effort and the load

Mechanical advantage / disadvantage

Parallel

Fascicles parallel to longitudinal axis of muscle; terminate at either end in flat tendons

Fusiform

Fascicles nearly parallel to longitudinal axis of muscle; terminate in flat tendons; muscle tapers towards tendons

Circular

Fascicles in concentric circular arrangement; enclose an orfice (opening) - form sphincter muscles

ie. Oribicularis oculi muscle

Triangular

Fasicles spread over broad area converge at thick central tendon

ie. Pectoralis major

Pennate

Fascicles on one side of tendon

ie. Extensor digitorum longus muscle

Bipennate

Fascicles arranged on both sides of centrally positioned tendons

ie. Rectus femoris muscle

Multipennate

Fascicles attach obliquely from many directions to several tendons

ie. Deltoid muscle

Agonist

Prime mover in a muscle action, responsible for the majority of the movement

Antagonist

Stretches and yields to the effects of the prime mover

Synergist (2)

Muscles that assist the agonist in performing a movement

Prevent unwanted movements

Subcategory: Fixators - stabilizing origin of prime mover