Muscle Tissue &

OrganizationSports Medicine

Unit 3

MUSCULAR SYSTEM

Muscle Functions

Body Movement

Maintenance of Posture

Temperature Regulation – muscle contraction generates 85% of the body’s heat

Storage and Movement of Materials

Support

Characteristics of Muscle Tissue

Excitability- receive and respond to stimuli

Contractility- ability to shorten and thicken

Extensibility- ability to stretch

Elasticity- ability to return to its original shape after contraction or extension

Types of Muscle

Types of Muscle

Skeletal Muscle

Smooth Muscle Cardiac Muscle

Location Attached to bone

On hollow organs, glands and blood vessels

Heart

Function Move the whole body

Compression of tubes & ducts

Heart contraction to propel blood

Nucleus Multiple, peripheral

Single, central Central & single

Control voluntary involuntary involuntary

Striations yes no yes

Cell Shape Cylindrical Spindle-shaped Branched

Microscopic Anatomy of

Skeletal Muscle

Each muscle- has thousands of muscle fibers in a bundle running from origin to insertion bound together by connective tissue through which run blood vessels and nerves.

Each muscle fiber - contains many nuclei, an extensive endoplasmic reticulum or sarcoplasmic reticulum, many thick and thin myofibrils running lengthwise the entire length of the fiber, and many mitochondria for energy

Sacromere

Sacromere -The basic functional unit of the muscle fiber consists of the array of thick and thin filaments between two Z disks. Thick filaments - with myosin (protein) molecules Thin filaments - with actin (protein) molecules plus smaller amounts of troponin and tropomysin (also proteins). Striations -of dark A bands and light I bands. A bands- are bisected by the H zone with the M line or band running through the center of this H zone. I bands- are bisected by the Z disk or line.

Muscle ContractionAs the muscle contracts -

the width of the I bands and H zones decrease causing the Z disks to come closer together, but there is no change in the width of the A band because the thick filaments do not move.

As the muscle relaxes or stretches - the width of the I bands separate as the thin filaments move apart but the thick filaments still do not move.

Skeletal Fiber OrganizationCircular Muscles

Convergent Muscles

Parallel Muscles

Pennate Muscles

Circular MusclesFibers arranged concentrically around an

opening

Functions as a sphincter to close a passageway or opening

Example: Orbicularis oris (around mouth)

Convergent MusclesTriangular muscle with common attachment site

Direction of pull of muscle can be changed

Does not pull as hard as equal-sized parallel muscle

Example: pectoralis major

Parallel MusclesFascicles are parallel to the long axis of the

muscle

Body of muscle increases in diameter with contraction

High endurance, but not very strong

Example: rectus abdominis or sartorius

Pennate MusclesMuscle body has one or more tendons

Fascicles at oblique angle to tendon

Pulls harder than a parallel muscle of equal sizeUnipennate: all muscle fibers on the same side of

the tendon (example: extensor digitorum)Bipennate: muscle fibers on both sides of the

tendon (example: Interosseous)Multipennate: tendon branches within the muscle

(example: deltoid)

Skeletal Muscles

Origin - Attachment to the more stationary bone by tendon closest to the body or muscle head or proximal (head)

Insertion - attachment to the more moveable bone by tendon at the distal end

During movement, the origin remains stationary and the insertion moves.

The force producing the bending is always a pull of contraction. Reversing the direction is produced by the contraction of a different set of muscles.

As one group of muscles contracts, the other group stretches and then they reverse actions.

Naming of Skeletal Muscles

Muscles are named according to a variety of features:Muscle actionSpecific body regionMuscle attachmentsOrientation of muscle fibersMuscle shape and sizeMuscle heads/tendons of origin

Naming of Skeletal Muscles

Muscle Action:AdductorAbductorFlexorExtensor

Naming of Skeletal Muscles

Specific Body Regions:Oris (mouth)Cervicis (neck)Brachial (arm)Carpi (wrist)Pollicis (thumb)Gluteal (buttocks)Femoris (thigh)Hallus (great toe)

Anterior (toward front)Posterior (toward back)

Superior InferiorSuperficialis (superficial)Profundus (deep)

Naming of Skeletal Muscles

Muscle AttachmentsSternum and clavical (cleido)Between the ribs (intercostal)Subscapular fossa (Subscapularis)Fibula (fibularis longus)Zygomatic bone (zygomaticus major)

Naming of Skeletal MuscleOrientation of muscle fibers

Rectus (straight)Oblique (angled)Orbicularis (circular)

Naming of Skeletal Muscles

Muscle shape and sizeDeltoid (triangular)Quadratus (rectangular)Trapezius (trapezoidal)Longus (long)Brevis (short)Major (larger of two muscles)Minor (smaller of two muscles)Maximus (largest)Medius (medium sized)Minimus (smallest)

Naming of Skeletal Muscles

Muscle heads/tendons of originBiceps (two heads)Triceps (three heads)Quadriceps (four heads)

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