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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