Muscular System 5.1

​Characteristics of Muscles

• ​ Movement – both voluntary & involuntary

• Maintaining posture

• Supporting soft tissues within body cavities

• Guarding entrances & exits of the body

• Thermoregulation

  • Maintaining body temperature

• ​Glycemic Controls

  • Inulin-stimulated glucose disposal muscles uptake glucose from the blood and store ​it as glycogen.

​Types of Muscle Tissue

• ​Skeletal

  • ​Voluntary

  • ​striated

• ​Cardiac

  • ​Involuntary

  • ​striated

• ​Smooth

  • ​involuntary

  • ​non-striated

​Skeletal muscle

• ​Attaches to skeleton

• ​voluntary movement

• ​long cylindrical cells

  • ​forming striations

​Muscle Coverings and Connective Tissue Membranes

• ​Sarcolemma

  • ​plasma cell membrane surrounds the muscle cell

• ​Endomysium

  • ​Connective tissue membrane that surrounds the muscle cell fibers

  • creates space for​nourishment and nerve stimulation

​​Connective Tissue and Fascicles

• ​​Perimysium

  • Surrounds muscle fibers together Fascicles

    ​visible to human eye

• ​Epimysium

  • ​surrounds the entire muscle, forms the tendon sheath

• ​​Fascia

  • ​separates neighboring muscles or muscle groups

​Tendons and Aponeurosis

• ​Extensions of epimysium beyond the muscle fibers

  • ​Tendon

    • ​rope or cord like

  • ​Aponeurosis

    • ​ broad sheet

​Muscle Shapes and Fascicles

• ​Orientation of fascicles determine shape and direction of pull

​Fusiform, Parallel, and Triangular

• Fusiform

  • ​Thick middle with tapered ends (bicep brachii)

• ​Parallel

  • ​uniform width with parallel fascicles. (Sartorius and rectus abdominis)

• ​Convergent (triangular)

  • ​fan shaped, broad at one end and tapered at the other (trapezius and pectoralis major)

​Pennate and Circular

• ​Pennate

  • ​Feathered shaped, more muscle fibers equals more force (rectus femoris and deltoid)

• ​Circular

  • ​form rings to prevent or allow passage (orbicularis oris)

​Attachment Sites

• ​Origin

  • ​The bony attachment that is relatively stationary

• ​Insertion

  • ​The movement or mobile site

There are four characteristics associated with muscle tissue:

​

• ​Irritability

  • ​ Tissue can receive & respond to nerve stimulation

• Contractility

  • Tissue can shorten & thicken

• Extensibility

  • ​Tissue can lengthen

• ​Elasticity

  • ​ After contracting or lengthening, tissue always wants to return to its resting state

​Muscle Contractions

• ​When skeletal muscles contract, they produce an action:

  • Isometric contraction (stays the same length)

  • Isotonic concentric contraction (shorten)

  • Isotonic eccentric contraction (lengthen)

​Functional Groups of Muscles

• ​Agonist

  • ​prime mover, produces most of the force

• ​Synergist

  • ​aids the prime mover

• ​Antagonist

  • ​opposes the prime mover, limits the range of the prime

• ​Antagonistic pair

  • ​pair that work on opposite sides of a joint