Skeletal Muscles Flashcards
Four common characteristics of muscle cells
o Excitability
Respond to a stimulus such as nerve impulses
o Contractibility
Shorted in length when stimulated
o Extensibility
Stretch when pulled
o Elasticity
Return to their original shape and length after contraction or extension
Three primary functions of muscles
o Provide motion
o Maintain posture
o Generate heat
Three types of muscles
skeletal, cardiac, smooth
Which type of muscle:
Controlled by conscious mind
Moves the bones of the skeleton
Nervous system gives orders and muscular system carries out the order
Skeletal
Which type of muscle:
Found only in the heart
Control center is “built in” and doesn’t need the nervous system to give orders
Cardiac
Which type of muscle:
Found all over the body
Carries out most of the unconscious, internal movements that they body needs to maintain itself in good working order.
Control center is “built in” and doesn’t need the nervous system to give orders
Smooth
voluntary striated muscle
Skeletal muscles
Fibrous connective sheath that surrounds the muscle
Epimysium
Thick central portion of the muscle
Belly
Connect muscle to bone
Fibrous connective tissue bands
Tendons
Alternative to tendons, to attach muscle to bone
Broad band of fibrous connective tissue
o Aponeuroses
o Most prominent aponeuroses
Runs lengthwise down the ventral midline (belly where abs would connect)
Linea alba
Attachment site is more stable, moves less when muscles contract
Origin of muscle
Attachment site undergoes most of the movement when muscles contract
Insertion of muscle
What are the three steps of muscle contraction?
Nerve impulses stimulate muscle >
muscle contracts (shortens) >
By pulling on attachment sites (origin and insertion), contraction of the muscle produces movement of bone and other structures.
Skeletal muscles rarely act ______
alone
Skeletal muscles usually work in ______ with certain muscles producing most of the ________ while other muscles _______ nearby joints and provide _______ over body movements
groups
desired movement
stabilize
smooth control
Muscle role:
Muscle or muscle group that directly produces a desired movement
Agonist (prime mover)
Muscle role:
Muscle or muscle group that directly opposes the action of the agonist
Antagonist
Muscle role:
Through partial contractions, can help smooth out the movements of agonist
Antagonist
Muscle role:
Can contract forcefully at the same time as the agonist, resulting in rigidity and lack of motion
Antagonist
Muscle role:
Skeletal muscle that contracts at the same time as an agonist and assists it in carrying out its action
Synergist
Muscle role:
Muscles that stabilize joints to allow other movements to take place
Fixator
How many muscles roles can skeletal muscles fulfill?
all four roles at one time or another
Not in the skin but located in the connective tissue (fascia) just beneath it
Little or no attachment to bones
Thin, broad and superficial
Cutaneous muscle
Serve only to twitch the skin (ex: get rid of insects landing on skin)
Cutaneous trunci
Control facial expression
Enable chewing (mastication)
Move sensory structures such as eyes and ears
help support the _____ and allow the ______ to flex, extend and move the ______ laterally
Head and neck muscles
*Action is to close the jaw
*Most powerful of the chewing muscles
*Located in the cheek area of the skull
Masseter muscle
*Two of the main muscles that extend (raise) the head and neck
Splenius and Trapezius Muscles
*Pulls the front leg forward
*Extends the head and neck
*Fairly large, strap like muscle
*Runs from proximal area of the humerus up to the base of the skull
Brachiocephalicus Muscle
*Acts to flex (lower) the head and neck
*Smaller, straplike muscle that extends from the sternum to the base of the skull
oDo not have to be particularly large or strong because gravity helps lower the head and neck
Sternocephalicus Muscle
Which skeletal muscle group is arranged in layers?
Abdominal skeletal muscles
What are the layers, from external to internal, of the abdominal skeletal muscles?
*External abdominal oblique
*Internal abdominal oblique
*Rectus abdominis
*Transverse abdominis
Abdominal skeletal muscle, Fibers run caudoventral direction (backward and downward)
External abdominal oblique
Abdominal skeletal muscle, Fibers run cranioventral direction (forward and downward)
Internal abdominal oblique
Abdominal skeletal muscle, Forms the floor (ventral portion) of the muscular abdominal wall
Rectus abdominis
Abdominal skeletal muscle, Deepest of abdominal muscles, Fibers run directly downward in a ventral direction to insert on the linea alba
Transverse abdominis
oBroad, triangular muscle that extends from the spinal column down to its insertion on the humerus
oFlexes the shoulder
*Latissimus dorsi
oTwo muscles; one superficial and one deep
oLocated on each side of the sternum
oBoth extend from the sternum to the humerus
oActs as adductor muscles (inward movers) of the front leg
Pectoral
oTriangular shape and extends from the lateral portion of the scapula down to the humerus
oAn abductor muscle (outward mover) and flexes the shoulder joint
Deltoid
oTwo proximal head attachments
oExtends from the distal end of the scapula to the proximal end of the radius
oFlexes the elbow joint when flexed
*Biceps brachii
oThree proximal head attachments
oGoes from the distal scapula and proximal humerus down to the olecranon process (point of the elbow)
oExtends the elbow joint
*Triceps brachii
oExtends the carpus and is located over the radius
Extensor carpi radialis
oFlexes the digit and is located beneath some of the other digital flexor muscles
*Deep Digital Flexor
Which muscles function mostly in locomotion?
Pelvic and thoracic limb muscles
*Help propel the body forward by extending the ______ joint (pulling the leg forward)
muscles of the hip joint
o Extend from the bones of the pelvis down to the trochanters of the femur
gluteal
oThree muscles located on the caudal part of the thigh region
oHelp extend the hip joint
Hamstring
What three muscles make up the hamstring?
Biceps femoris muscle
Semimembranosus muscle
Semitendinosus muscle
*Main extensor muscle of the stifle joint
*Cranial part of the thigh region
*Composed of four heads
*Bring the leg forward to prepare for the next stride
quadriceps femoris
oLandmark muscle in some species
oPowerful extensor muscle of the hock
oExtends from the caudal portion of the distal end of the femur and inserts on the calcaneal tuberosity of the fibular tarsal bone (the point of the hock)
oEquivalent to human calf muscle
*Gastrocnemius
aka the Achilles tendon
Gastrocnemius tendon
Muscles that increase and decrease the size of the thoracic cavity
skeletal muscles of respiration
Muscles that increase the size of the thoracic cavity when they contract
inspiratory muscles
_______ is drawing air into the lungs
inspiration
What are the two inspiratory muscles?
Diaphragm
External intercostal muscles
When contracted, flattens out and pushes the abdominal organs caudally
Diaphragm
When contracted, they rotate the ribs upward and forward
External intercostal muscles
_______ is pushing air out of lungs by collapsing the rib cage
expiration
Which muscles decrease the size of the thoracic cavity?
Expiratory muscles
What are the expiratory muscles?
Internal intercostal muscles
Abdominal muscles
When contracted, they rotate the ribs backward
o Internal intercostal muscles
When contracted, they push the abdominal organs against the caudal side of the diaphragm
Abdominal muscles
Which muscles increase and decrease the size of the thoracic cavity?
Skeletal muscles of respiration
