Myology Flashcards
Functions of the skeletal muscle
Movement
Posture
What does stimulation do?
Maintains a state of muscle contraction “tonus” for movement of blood and lymph
What is the function of stabilizing joints?
Prevents unwanted movements
How do skeletal muscles maintain posture?
By stabilizing the flexible muscles
Certain muscles work in opposition to ______
Gravity
Certain muscles work in opposition to ______
Gravity
Examples of movements of body contents
Respiration
Circulation
Alimentation
Child Birth
Indication of emotional states
Alimentation
Digestion– GI tract, defecation and urination
Functions of Muscles
Movements of body contents
maintain continence
Generates heat by shivering
Homeostasis
Maintain proper body function with proper environment
EX: enzymes need to function
Where is the term muscle derived from?
“mus” or “mys” for mouse
Muscle is classfied as a __________
Specialized connective Tissue
What is each muscle composed of?
Skeletal muscle tissue, CT and nervous tissue
Why do muscles contract?
To produce body movement in response to nerves or hormone stimulation
What are the 3 types of muscles
Smooth, cardiac and skeletal
Smooth Muscle
Not striated
Associated with viscera
Ex: arrector pili m. and detrusor m.
Cardiac Muscles
Striated
The heart (myocardium) and the bases of the major vessels
Skeletal Muscle
Striated
Generally attached to bone
Usually under voluntary control
Denervation Atrophy
The absence of a functional nerve supply
The muscle will not attract
Motor Unit
The neuron plus the muscle fiber it innervates
How does a muscle produce a stronger contraction?
The nervous system activates more motor units
How much of the body does the carcass takes up?
50% of the body
Where are most skeletal muscles attached?
the bone
What other places are skeletal muscles attached to?
The pharynx, skin and the esophagus
EX: cutaneous trunci
Formation of the muscle:
Fiber –> Fascicles (bundles)–> muscle
What is the binding substance within muscles?
Loose CT
Myofiber
Muscle cell
Endomysium
Small amounts of loose CT surrounding individual muscle fiber
Fascicle bundle
groups of muscle fibers
Perimysium
Loose CT surrounding muscle fascicles
Epimysium
Loose or dense CT surround an entire muscle
Skeletal Muscle structure
CT merges at the end of the muscle “belly” to form the tendon (dense regular connective tissue- attach to bone)
What is the importance of these CT arrangements
To make sure they all contract simultaneously
Joints of the Forelimb
Synsarcosis
Shoulder
Elbow
Carpus
Fetlock
Digital
Agonist
Prime movers
Principal muscles executing the particular joint movement
Ex: triceps brachii (elbow)
Where does the agonist exert its action?
Distal Joint
Antagonist
Actively opposing the prime mover
Maintains some tension on a joint and limits the range of the agonist
Synergists
Assists the prime mover
Doesn’t facilitate or oppose a movement
Fixators
It prevents the bone from moving
Stabilizes joints rather than promoting movement
Ex: biceps brachii (elbow)
How do you name different muscles?
Attachments
Shape
Size
Function
Location/ position
Number of heads
Number of bellies
Tendons
Accessory structures
Low metabolic activity (poorly vascularized)
Attaches muscle to bone
Dense regular connective tissue
When can the tendon be damaged?
Damaged by excessive pressure or friction and when change direction over bony prominences
Where does the tendon attach the muscle?
To the periosteum of the bone
Aponeurosis
Broad, flat tendon sheet-like union
Bursa
Fluid-filled cushions at danger sites
Bursa synovialis
Small fluid-filled sacs located between tendons and stress points
Tendon Sheath
Fluid filled cylinders surrounding tendons over stress points
Where is inflammation in the tendon common?
Inflammation of synovial bursae and sheath is common
Occur where they are required
Retinaculum
Accessory structure
Condensed deep fascia over carpus or tarsus
Prevents webbing
Annular Ligaments
Condensed deep fascia over the digits
What are the forms of protection for tendons?
Sesamoid bones and patella
Sesamoid bones
Ossification of cartilage in tendons for extra strength at stress points
Moves tendon away from axis
Patella
Prevents wear and displaces tendon from axis of joint
Lipomas
Palpable from skin surface
Abnormal aggregates of normal fat with capsule around
Not life threatening
Infiltrate lipoma
Unencapsulated fatty tumor
Deeply attached to muscle fascia
Palpable featrures
Tendon of origin of biceps
Deltoid tuberosity
Superficial cervical L. node
Axillary L. node
