3 Muscle Tissue Types
Skeletal
Cardiac
Smooth
Skeletal Muscles
- Striated, Multinucleated, & Voluntary. Found attached to bone to move Body
Cardiac
Striated, Uninucliate, involuntary
Found in myocardium of the heart to move blood.
Smooth
Forms sheets, non-striated, involuntary, uninucliate. Found in hollow organs (blood vessels, respiratory ducts, digestive organs, urinary organs, reproductive organs, iris of eye to move fluids or substances in those hollow tubes.)
Functions of Skeletal Muscular System
1. Movement: Moving the skeleton and other body parts.
2. Maintaning Posture
3. Stabalize joints
4. Generate heat by shivering
Sarcolemma
Membrane covering Muscle Cell and containing bundles of rod-like myofibrils inside.
Myofibril
one of many contractile filaments that make up a striated muscle fiber and is composed of linearly arranged, repeating unitis called sarcomeres
Sarcomeres
Contractile units of cell and shorten (contract) the cell made up of contractile protein filaments:
Actin, Thin Filiaments
Myosin, Thick Filiaments
Contraction requirements of skeletal muscle cell Sarcomere
Nervous stimulation (electrical signal from motor neuron, outside the cell, releasing neurotransmitter (Acetycholine))
2. Calcium (chemical signal throughout the cell)
3. ATP (energy source for contraction)
4. Power depends on total number of muscle cells
Acetycholine
A neurotransmitter associated with voluntary movement, sleep and wakefulness.
Muscle Cells are organized by 4 connective tissue layers within the muscle
1. Endomysium
2. Perimysium
3. Epimysium
4. Tendon
Net result- movement of the bone
Endomysium
Connective tissue layer that surrounds individual muscle cells. Connects sarcolemma to perimysium
Perimysium
Dense fibrous connective tissue, surrounds a group of muscles cells (Fascicle) connects to epimysium
Epimysium
Dense Fibrous connective tissue, surrounding the entire muscle. Connects to tendon
Tendon
Connects to periosteum around bone. Net result- movement of the bone
How does contraction of muscle cells result in force being applied to a body part?
When sarcomeres in muscle cell are contracted (contractile protein Actin sliding over contractile protein myosin in sarcomere) then sarcolemma is moved. Sarcolemma movement causes connective tissue layers (Endomysium, perimysium, epimysium) to be moved. M
Connection of muscles to skeletal system.
1.Insertion: the bone that moves
2. Origin: the immovable or less movable bone.
Contraction is always a movemement of insertion towards the origin.
Interactions of Skeletal muscles
Muscles pull bones. they do not pusch. There are groups of muscles with opposing actions:
-Flexors and Extensors
-Adductors and abductors
-Pronators and supinators
Prime Mover/Agonist
The muscle that provides the major force for providing a specific movement.
Antagonist
The muscle that opposes, or reverses, a particular movement.
If the prime mover is contracted, the antagonist is relaxed. They are usually on the opposite side of the bone or joint.
Synergist
Muscles that assist the action of the agonist
Promotes the same movement
Reduces undesirable or unnecessary movements that might occur
Fixator
A synergist that immobilizes the bone
Naming of Skeletal Muscles May Include
1. Location
2. Shape of the Muscles
3. Relative Size
4. Direction of Fibers
5. Location of Origin and / or Insertion
6. Action
Name by Location of Bone ex.
1. Frontalis, tibialis, femoris, Temporalis, abdominis, brachialis
Superficial -externus or superficialis
Deep -internus or profundus
Name by Shape of Muscles
Trapezius, Deltoid, Serratus anterior, rhomboids
Name by Relative size of Muscles
Maximus = Largest
Minimus = Smallest
Medius = Mid-size
Longus = Long
Brevis = Short
Name of Muscles by direction of fibers
Rectus - Fibers run parallel to midline-straight
Transversus - Perpendicular to Midline
Oblique - Diagonally or at an angle
Name of Muscles by Location of Origin and /or insertions
Sternocleidomastoid: Origin-sternum and clavicle, inserion- mastoid process Mylohyoid - insertion on hyoid, origin on mandible.
Name of Muscles by Action
Adductor longus and adductor magnus
Muscles of Face - Facial Expression
Zygomaticus, Orbicularis Oculi, *Orbicularis Oris
Muscles of Face Swallowing and Mastication
*Masseter and Temporalis, digastric
Muscles of Head and Neck Movements
Sternocleidomastoid, splenius
Muscles of Trunk Movement
*Rectus abdominis
Internal and external oblique
Erector spinae group
Muscles moving the Pectoral Girdle
Pectoralis minor
Serratus anterior
Trapezius
levator scapulae
rhomboids
Muscles of Arm Movements
*Deltoid
Latisimus Dorsi
*Pectoralis Major
Muscles of Forearm and Hand Movements
*Biceps Brachii
*Triceps Brachii
Muscles of Thigh and Leg Movements
Sartorius
Gracilis
adductor magnus
adductor longus
*iliopsoas
tensor fasciae latae
*gluteus maximus
gluteus medius
rectus femoris
vastus lateralis
vastus medialis
biceps femoris
*semitendinosus/Semimembranosus
Muscles of Foot Movement
*gastrocnemius
tibialis anterior
Masseter
Elevates mandible when chewing and slightly protracts it
Rectus abdominis
Flexes vertibral column, runs down medial stomach
Temporalis
muscle extending from the temporal fossa to the coronoid process of the mandible
Pectoralis Major
Adducts and medially rotates the arm; flexes and extends humerus
Biceps Brachii
a muscle that flexes and supinates the forearm
Triceps Brachii
the skeletal muscle having three origins that extends the forearm when it contracts
Gluteus Maximus
heaviest muscle in body, extends/straightens leg at hip during walking
iliopsoas
hip flexor, deep in pelvis; a composite of two muscles
Sternocleidomastoid
one of two thick muscles running from the sternum and clavicle to the mastoid and occipital bone
Semitendinosus
Flexes leg at the knee and extends thigh at the hip; belongs to the hamstring group