Chapter 8- Muscular System Flashcards
List three types of muscle
Smooth
Skeletal
Cardiac
Skeletal muscle
Controlled by conscious mind, moves the skeleton
Attached to bone
striations
Cell shape long and cylindrical
multiple nucleus
Needs a functional nerve supply to contract
function- moves the whole body and glycogen storage
Up to 1/2 the body weight
Rapid contractions
Cardiac muscle
Found only in the heart
cell shape - Branched
nucleus - usually single, central
has intercalculate discs
striated
does not need nerve supply
pumps blood through body
Smooth muscle
Carries out unconscious, internal movements of the body
All over the body
No striations
Single cell
Cell shaped- spindle
Has cell to cell attachments
Involuntary and autorhythmic
helps stuff moves in body.
Nerves not necessary for function
Describe the structure and function of tendons
Fibrous connective tissue that attaches muscle to bone
Describe the structure and function of aponeuroses
Attach to muscles or bones by broad sheets of fibrous tissue
Describe the structure and function of ligaments
Bands of connective tissue present in and around synovial joints. Join bones to bones
Prime mover
The muscle that contracts and directly produces a result
(Agonist)
Antagonist
A muscle that contracts and opposes the prime mover
Synergist
A muscle that contracts at the same time as a prime mover and assists it in carrying out a motion
Fixator muscles
Muscles that stabilize joints and allow movements to take place
Abdominal muscles
Support abdominal organs
Help flex the back
Participate in defecation, urination, birth, vomiting, regurgitation
Have a role in respiration
Arranged in layers
- external (less important)-abdominal oblique
-internal (less important) abdominal oblique
-rectus - abdominis
-transverse abdominis
Come together at the linea alba (white line)
Thoracic limb muscles
Function in locomotion
Less important
Deltoid muscle.
Supraspinatus muscle.
Infraspinatus muscle.
Teres minor muscle.
Teres major muscle.
Subscapularis muscle.
Articularis humeri muscle.
Coracobrachialis muscle.
pelvic limb muscles
Functions mostly locomotion
Microscopic anatomy of skeletal muscle
Large cells - not wide but long
multi-nucleated - located at edge of cell just beneath sarcolemma
Made up of lengthwise myofibrils
many mitochondria in extensive network of sarcoplasmic reticulum and transverse tubules
Microscopic anatomy of smooth muscle
Small and spindle-shaped
Single nucleus
Smooth, homogenous appearance
-myosin and actin not arranged in parallel myofibrils
Myosin and actin criss-cross the cell and are attached at both ends to dens bodies
Microscopic anatomy of cardiac
Striated
smaller than skeletal
Single nucleus per skill
securely attached end to end to form intricate, branching networks of cells
-attachment sites are called intercalated discs
List the components and functions of neuromuscular junctions
Site where ends of motor nerve fibers connect to muscle fiber
Synaptic vesicles at the nerve fiber contain nerve acetylcholine
-Motor neuron (axon)
-Muscle fiber (receptor site)
-Synaptic space - cleft
- acetylcholine
(lots of mitochondria)
List and describe the roles of connective tissue in muscles
There are three layers of connective tissue: epimysium, perimysium, and endomysium. Skeletal muscle fibers are organized into groups called fascicles. Blood vessels and nerves enter the connective tissue and branch in the cell. Muscles attach to bones directly or through tendons or aponeuroses.
What happens during muscle contraction and relaxation
Relaxed muscles have myosin and actin filaments that overlap slightly
When stimulated to contract, cross bridges on myosin filaments slide back and forth
actin fillaments on both sides are pulled toward the center of the myosin fillaments
This shortens the sarcomere
Shortening of all end-to-end sarcomeres causes muscle to contract
Differentiate between visceral smooth muscle and multi-unit smooth muscle
Visceral smooth muscle -
-large sheets of cell walls in some hollow organs
multi-unit smooth muscle-
-small, discrete groups of cells
Muscle cells
Fibrous cells designed for contraction
Also called muscle fibers
Fiber composition- myosin and actin
microfilaments slide over one another
Very large
Skeletal - multi-nucleated
Network of sarcoplasmic reticulum
Muscle functions
Provide motion
Maintain posture
Heat the body
Muscle characteristics
Excitable
Contractible
Extendable
Elastic
Gross anatomy of skeletal tissue
Muscle fibers
Fibrous connective tissue
Belly
Tendon (fibrous tissue that connects muscle to bone)
Periosteum
Tendon
Fibrous connective tissue that connects muscle to bone
Epimysium
Connective tissue that covers the muscle
Fascicles
Bundle of muscle fibers
Perimysium
Covers the fascicles of muscle
Contains blood vessels and nerve fibers
Continuous with tendons
Endomysium
Covers the muscle fiber
Myofibril
Long contractile fibers. That make up a muscle fiber. Composed of actin and myosin
Attachments
Origin
- more stable
- Doesn’t move when muscle contracts
-proximal
Insertion
-Most movement when muscle contracts
-more distal
Microfybrils
Form interior of muscle fibers
Made of dark A bands and light I bands
A bands - thick protein filaments- myosin
I bands- thin protein filaments- actin
A series of sarcomeres
Sarcoplasmic Reticulum
Stores calcium ions
Z-line
Disc at each end of a myofibril
Another word for T-tubules
Transverse tubules
Sarcomere
between z-lines of a myofibril section
(contractile unit)
Composed of myosin and actin
Filaments compose various bands
A-bands
H-bands
I-bands
Z-line
H band
Light colored area in the middle of an A band
Physiology of muscle fiber
Nerve impulse travels down a nerve fiber and reaches a neuromuscular junction. Acetylcholine is released and binds to the sarcolemma of the muscle fiber. That starts an impulse that travels through the t-tubules to the interior of the cell. Stored calcium is release from the sarcoplasm. This turns on the contraction process.
Sarcolemma
Cell membrane of a muscle cell
Postsynaptic membrane
Sarcoplasm
cytoplasm of muscle cell
Motor Unit
One motor fiber (axon) and all muscle fibers it innervates
-Muscles that make small, delicate movements have few
-Large muscles may have several hundreds
Naming conventions
Actions (ie flexor)
Shape (ie deltoid)
Location- (ie biceps brachii - located in brachii location)
Direction of fibers (ie rectus means straight)
Number of heads or divisions
Attachment sites
Achilles tendon
Attaches tuber calcis of calcaneus bone of tarsus
All r nothing principle
When stimulated individual muscles fibers contract completely or not at all
Nervous system control the number of muscle fibers it stimulates
- small, fine movements only a few
- large, powerful movements many muscle fibers contract
Muscle contraction phases.
Latent phase - 10 miliseconds (time between nerve stimulus and beginning of contraction)
Contraction phase 40 milliseconds
Relaxation phase - 50 milliseconds
Maximum contraction efficiency
- when nerve impulses arrive 0.1 second apart
-result in a series of complete muscle twitches
Smooth, sustained muscle contractions
-Average out activity of all muscle contractions
Twitches
Single muscle fiber contractions
contractions out of sync with each other
Chemistry of muscles
Aerobic
Adequate oxygen supply
Maximum energy extracted
Glucose+oxygen= H20, COz and to ATP
-Creatine Phosphate converts ADP back to ATP
-Glucose + oxygen help produce ATP and Creatine Phosphate
-glucose stored as glycogen0
-Oxyge0n stored as myoglobin
Anaerobic
Need for oxygen exceeds supply
Lactic acid forms
1 glucose molecule gives us 2 ATP and lots of lactic acid
tonus
Involuntary contraction of small number of motor units
Keeps muscles firm but relaxed
Clinical importance
- depth of anasthesia
Gait
Plantigrade - metatarsal bones flat on ground- primates, bears, rodents, raccoons, kangaroos
Digitigrade -walks on digits or toes- birds, Canidae, Felidae, elephants
Unguligrade - walking on tips of toes/hooves- cattle, horses, sheep, goats
Deltoid
It flexes the shoulder joint. Consists of two parts that join and
act in common.
Less important -The scapular portion covers a majority of
the infraspinatus muscle located below it. The two parts of
the muscle fuse before they insert on the deltoid tuberosity
of the humerus.
Infraspinatus:
It flexes the shoulder joint and abducts the limb at the shoulder
Less important- Muscle that fills the infraspinous fossa caudal to the spine of the scapula.
Supraspinatus:
It extends the shoulder joint.
Less important - Muscle that fills the supraspinous fossa cranial to the spine of the scapula and is wider and longer then the infraspinatus muscle.
Subscapularis
It adducts the llimb at the shoulder and rotates the arm medially. It also functions as a medial collateral ligament to the shoulder
Less important- Muscle that occupies the subscapular fossa on the medial aspect of the scapula
Teres major
It flexes the shoulder.
Less important -Muscle that lies caudal to the subscapularis muscle, and its tendon of insertion joins that of the latissimus dorsi muscle.
Triceps brachii:
It extends the elbow and flexes the shoulder.
Less important - Muscle that makes up the large muscle
mass on the caudal aspect of the humerus
Biceps brachii:
It flexes the elbow and extends the shoulder.
Less important- Muscle located on the craniomedial
aspect of the humerus. It consists of only one head in
animals
Brachialis
It flexes the elbow.
Less important: Muscle located on the lateral side of the humerus. After its origin on the lateral humerus, it courses ddistally following the brachial groove of the humerus, twisting laterally and cranially toward its insertion on the medial side of the proximal radius and ulna
Extensor carpi radialis:
It extends the carpus
Less important -The largest of the craniolateral muscle group. It lies on the cranial aspect of the radius and deep to the brachioradialis muscle as it courses distally.
Lateral digital extensor:
It extends the digital joints.
Less important: Muscle that is smaller than the common digital extensor and lies just caudo-lateral to it.
Extensor carpi ulnaris
It flexes the carpal joint.
Less important- Muscle that lies caudal and lateral to the lateral digital extensor. This is the only flexor that arises on the lateral epicondyle
Abductor pollicis longus:
It extends the carpal joint and abducts the digit.
Less important- Flat triangular muscle that lies wprimarily in the groove between the radius and ulna.
Flexor carpi ulnaris:
It flexes the carpal joint.
Less important: : The most caudal of this musclegroup; lies next to the extensor carpi ulnaris.
Superficial digital flexor
It flexes the carpal and digital joints.
Less important: Muscle that lies caudomedial to the ulna and covers the deep digital flexor
Deep digital flexor
It extends the tarsal joints and flexes the digital joints
Less important: Muscle that originates on the proximal caudal aspect of the tibia and fibula and lies deep to the superficial digital flexor on the caudal aspect of the leg
Flexor retinaculum
The fascia that binds the superficial digital flexor muscle down at the carpus.
Interosseous muscle:
A muscle between two bones
Linea alba
All of the abdominal muscles, organs and tissues come together at the linea. The linea alba contains fewer sensory nerves than the adjacent muscles.
