Download The Muscular System

The Muscular System
Chapter 7
• One of the 4 basic tissues of body
Muscle
• Epithelial, connective, muscle, nervous
• Made up of cells that can shorten or
contract
• Three different types of muscle that are all
controlled or influenced by the
_____________ system.
• ________________ muscle
Controlled by conscious mind and moves bones of
skeleton.
• _________________ muscle
Found only in heart
• _________________ muscle
Found throughout body (intestines, lungs, blood vessels,
etc..) but controlled by unconscious mind
Basic Terminology
• ________- generally refers to muscle
• Myology, myositis
• ________- refers to muscles at the cellular level
• Sarcoplasm, sarcolemma
Skeletal
Muscle
• Moves the bones of the skeleton
• __________- can be controlled be
conscious mind
• __________- microscopically visible
striped pattern of alternating light and
dark bands that run the length of a
muscle cell. Cells can have multiple
nuclei.
Skeletal Muscle
Gross Anatomy
• The thick central portion is called the
___________.
• Muscles have two attachment sites:
• _______________________- the end
that is generally more stable than the
other. Does not move when muscle
contracts.
• _______________________- site that
undergoes most of the movement
during contraction.
• Most muscles attach to bone via
__________.
• Bands of ________ _______connective
tissue made of collagen fibers
APONEUROSIS
•Some muscles are unique because they
attach to bone or other muscles by a
broad sheet of fibrous tissue called an
APONEUROSIS
•The most prominent aponeurosis is
the ________ _________
•runs along an animal’s ventral midline
from sternum to pubis.
•Connects abdominal muscles from right
and left sides
•Common site for abdominal surgical
incisions
Muscle Actions
• Skeletal muscles contract when stimulated to do so by a
nerve impulse.
• Muscles usually work in groups
• An _____________ or prime mover describes a muscle or
muscle group that directly produces a desired movement.
• __________________- a muscle that contracts at the same time
as a prime mover and assists it in carrying out action.
• An _______________ is a muscle or muscle group that
directly opposes the action of a prime mover.
• _____________- stabilizes joints to allow other movements to
take place.
Muscle Naming Conventions
• Muscles are generally named by physical characteristics:
• Action
• Example: deep digital flexor
• Shape
• Example: trapezius
• Location
• Example: biceps brachii
• Direction of Fibers
• Rectus abdominis- rectus means straight
• Number of heads or Divisions
• Example: triceps brachii
• Attachment sites
• Sternocephalicus- originates on sternum, inserts on head
Connective Tissue
Terminology
• _________________- each
individual skeletal muscle fiber is
surrounded by this delicate
connective tissue layer.
• _________________- groups of
skeletal muscle fibers
• _________________- connective
tissue that binds together
individual fibers into fascicles.
• _________________- fibrous
connective tissue that surrounds
groups of fascicles.
• Muscle cells (also called fibers)
Microscopic Anatomy
of Skeletal Muscle
• Are very large in size
• Have a threadlike or fiberlike
shape.
• Usually are multi-nucleated
• Made up of smaller myofibrils
composed of
_______________ (thin) and
_____________ (thick)
filaments
• Contractile proteins
(myofilaments)
• Network of sarcoplasmic
reticulum (similar to ER)
• Stores ____________ for
muscle contraction
•___ band- large dark band made up of
myosin filaments
•___ Band- large light band made up of
actin filamaments
•____ line- dark band in center of I band,
disk that is viewed as a line and is
attachment site for actin filaments.
•____________- area from one z line to
the next z line. Basic contracting unit of
skeletal muscle. When all sarcomeres
contract, leads to overall muscle fiber
shortening.
• Initiation of Muscle
Contraction and Relaxation
• Nerve impulse travels down
motor neuron, reaches
neuromuscular junction, and
acetylcholine is released into
synaptic space.
• Acetylcholine binds to
receptors on surface of
sarcolemma (cell membrane)
of the muscle fiber.
• This starts impulse that
travels along sarcolemma
and through the T tubules to
the interior of the cell.
cont’d….
•Once impulse reaches
sarcoplasmic reticulum it
causes release of stored
calcium ions (Ca++) into the
sarcoplasm (cytoplasm).
•As Calcium diffuses into
myofibrils, initiates contraction
process which is powered by
ATP.
•As contraction occurs,
Calcium is pumped back out
of myofibrils which shuts down
contraction process.
• Both relaxation and
contraction requires energy
Mechanics of Muscle Contraction
• When a muscle fiber is relaxed,
actin and myosin overlap a little.
• When stimulated _______
________ (levers on the myosin
filaments) ratchet back and forth
and pull the actin filaments on both
sides toward center of the myosin
filaments.
• Sliding of filaments shortens
sarcomere, thereby causing
contraction.
Characteristics of Muscle Contraction
• _____-____-_____________ principle
• An individual muscle fiber either contracts completely
when it receives an impulse or not at all.
• Movements can vary in strength due to number of
muscle fibers stimulated.
• small movements only require a few fibers to contract,
whereas larger, powerful movements require more fibers
• Nervous system sends out impulse based on muscle
__________ - or idea of how many fibers need to be
stimulated for that particular activity.
• ex: shooting a basketball vs. knitting a sweater
Phases of twitch contraction
(contraction of a single muscle fiber)
• 1. _______________ phase
• Brief pause between nerve stimulus and beginning of
actual contraction (lasts about 0.01 seconds)
• 2. ________________ phase
• Actual contraction is taking place (lasts about 0.04
seconds)
• 3. ________________ phase
• When cells go back to a relaxed state (lasts about 0.05
seconds)
• Some fibers are relaxing while others contract, so smooth muscle
contractions can occur
Chemistry of Muscle Contraction
• _______ is the energy source for actin and myosin to contract.
• Produced by the many ________________.
• ATP that has become ADP can recharge back to ATP when creatine
phosphate (CP) splits and donates a phosphate.
• Glucose and oxygen are also needed for contraction.
• Stored in form of glycogen and myoglobin for aerobic metabolism.
• Anaerobic metabolism produces ___________ acid
Heat Production
• Muscular activity is one of the major heat-generating
mechanisms that the body uses to maintain its
temperature.
• Shivering (small spasms of contraction) helps to
prevent hypothermia
Cardiac
Muscle
• ______________ due to lack of conscious
control and _______________ due to
microscopic appearance
• Contain myofibrils
• Only found within the heart (walls)
• Much smaller than skeletal muscles cells and
only contain one nuclei per cell
• Are longer than wide and have multiple
branches forming a network of cells.
• Contain _________ _________- gap
junctions where cells attach one to
another.
• Transmit impulses from cell to cell.
• This allows entire groups of cells to
contract together at the same time.
• Dark, transverse
Physiology of
Cardiac
Muscle
• No external nerve stimulation required to
contract.
• Rate and rhythm of contraction is due to (SA
node) _______ ______ (pacemaker) of heart
located in the wall of the right atrium.
• Impulse follows a controlled path through the
conduction system of the heart, making cells
contract in rapid, wavelike fashion down a
controlled path.
• This helps to squeeze blood out of chambers
of the heart
• _____________ System stimulates heart to
beat harder and faster as part of "fight or flight
response”
• _____________ System inhibits cardiac
function, causing heart to beat more slowly
and with less force, part of “feed or breed”
response.
Smooth Muscle
•
______________ due to lack of conscious
control and _______________ due to lack
of striations.
• Found in two forms:
• _________________ smooth muscle
• Large sheets of cells in the walls of
hollow organs
• _________________ smooth muscle
• Small, discrete groups of cells make
delicate movements.
Smooth microscopic muscle anatomy
• Small with single nucleus.
• Actin and myosin are present, but
are not arranged in parallel.
• criss-cross cell and are attached
to _____________ bodies that
are similar to Z lines of skeletal
muscle.
• Cell balls up as it contracts
Visceral Smooth Muscle
• Found in walls of many soft internal
organs that are known as viscera.
• Uterus, bladder, intestines, stomach
• Instead of fine movements, work in
waves of motion.
• Does not need external stimulation.
• If stretched, will contract.
• ______________ nervous system
decreases activity, _____________
nervous system increases activity
Multiunit Smooth Muscle
• Individual cells or small
groups of cells that produce
fine and delicate movements
• Ex: blood vessel walls,
within the eye, small
airways
• Also under influence of the
autonomic nervous system
• CUTANEOUS MUSCLES
• Muscle in the connective tissue beneath the
skin
• Thin, broad, and superficial
• Serves to twitch the skin
• Cutaneous trunci
HEAD AND NECK MUSCLES
• HEAD: enables chewing
• Masseter
• NECK: support head, allow neck to flex, extend, and move head
laterally
• Trapezius
• Brachiocephalicus (we will call this muscle the Clavotrapezius and
Clavodeltoid/Clavobrachialis in dissection
• Sternocephalicus (Sternomastoid and Sternohyoid)
ABDOMINAL MUSCLES
• Support the abdominal organs
• Flex/arch the back
• Allow straining for defecation, urination, parturition, vomiting,
regurgitation
• Assist in respiration
• Arranged in layers from superficial to deep:
•
•
•
•
External abdominal oblique
Internal abdominal oblique
Rectus abdominis
Transversus abdominis
• Each side of 4 muscles comes together at linea alba
THORACIC LIMB MUSCLES
• Function in locomotion
• Shoulder region:
• Latissimus dorsi
• Pectorals
• Deltoid
• Arm:
• Brachialis
• Biceps brachii
• Triceps brachii
PELVIC LIMB MUSCLES
• Function in locomotion
• Thigh region:
• Gluteals
• Hamstrings (caudal thigh):
• Biceps femoris
• Semimembranosus
• Semitendinosus
• Quadriceps femoris (cranial thigh)
•
•
•
•
Rectus femoris
Vastus lateralis
Vastus medialis
Vastus intermedius
• Leg
• Gastrocnemius
MUSCLES OF RESPIRATION
• Increase and decrease the size of
the thoracic cavity to bring air into
and out of the lungs
• Inspiratory muscles:
• Diaphragm
• External intercostals
• Expiratory muscles:
• Internal intercostals
• Abs