Muscular System Flashcards
are contractile and supply force for motility (heat production)
Stimulated by nerve impulses
Final determinants of posture, aid in movement of viscera
Muscles
why are muscles Difficult to establish homologies due to
Variability in muscle shape
Splitting or merging of muscles
O, I & A may change
Main Functions of muscles
Supply force for movement
Acted as movers and levers for every action with the aid of the skeleton
Restrain motion and hold the body in position
Contraction of the viscera
Heat production (temperature regulation)
Classification of Muscles
color
location
controlled by the nervous system
embryonic origin
microscopic appearance
Muscles are classified according to their color
red and white muscles
This classification has fallen out of favor because such a color distinction alone underestimates the complexity of muscles
Muscles are classified according to their color
type of muscles that are classified according to their location
muscles that move bones or cartilages
Somatic muscles
type of muscles that are classified according to their location
control the activity of organs, vessels and ducts
Visceral muscles
type of muscles that are classified by the way in which they are controlled by the nervous system
Voluntary muscles are under immediate conscious control
involuntary muscles are not under immediate conscious control
muscles arise from what three embryonic origins
mesenchyme
Paired hypomere
paraxial mesoderm
muscles arise from three embryonic origins
embryonic origins from which smooth muscles within the wall of the blood vessels and some viscera develop
mesenchyme
muscles arise from three embryonic origins
embryonic origins that are differentiated into smooth muscle layers of the alimentary tract and its derivatives
Paired hypomere
muscles arise from three embryonic origins
embryonic origins that are from which most of the skeletal muscles develop
paraxial mesoderm
Types of Muscles that are classified by their general microscopic appearance
skeletal, cardiac, and smooth muscle
Structure of Skeletal Muscle
Belly
Fascia
Origin and insertion
Types of Skeletal Muscle as to Action
Agonist or prime mover
Antagonist
Synergist
Fixator
Types of Skeletal Muscle as to Action
principal mover for specific action
Agonist or prime mover
Types of Skeletal Muscle as to Action
for opposite movement
Antagonist
Types of Skeletal Muscle as to Action
helps the stabilize the movement of one joint and inhibit undesirable movements
Synergist
Types of Skeletal Muscle as to Action
fixes the position of the limb when the movement is occurring
Fixator
Types of Skeletal Muscles as to Specific Function
Flexors
Extensors
Adductors
Abductors
Pronators
Supinators
Elevators or levators
Depressors
Constrictors
Dilators
Sphincters
Types of Skeletal Muscles as to Specific Function
bend a limb or one part of a limb against another
Flexors
Types of Skeletal Muscles as to Specific Function
straighten a limb or one of its component parts
Extensors
Types of Skeletal Muscles as to Specific Function
draw a part toward a median line or toward a neighboring part or limb
Adductors
Types of Skeletal Muscles as to Specific Function
draw a part away from a median line or from a neighboring part or limb
Abductors
Types of Skeletal Muscles as to Specific Function
turn or rotate a part downward on its axis as in the palm of the hand
Pronators
Types of Skeletal Muscles as to Specific Function
turn or rotate a part forward and upward on its axis as in the palm of the hand
Supinators
Types of Skeletal Muscles as to Specific Function
raise or lift a part as when the lower jaw in closing the mouth
Elevators or levators
Types of Skeletal Muscles as to Specific Function
lower or depress a part as when the lower jaw in opening the mouth
Depressors
Types of Skeletal Muscles as to Specific Function
draws part together or compress a space such as the pharynx and the abdomen
Constrictors
Types of Skeletal Muscles as to Specific Function
widens an opening or a space
Dilators
Types of Skeletal Muscles as to Specific Function
contrictors surrounding an opening such as mouth, pylorus and anus
Sphincters
Basis in Naming Skeletal Muscles
Direction of fibers
Location or position
Number of divisions
Shape
Origin and insertion
Action
Size
Some combination
During muscle evolution, some muscles have fused with one another, others have split into distinct new muscles, some have become reduced in prominence, and other have changed their points of attachment and hence their evolution
true
In order to trace the evolution of individual muscle, several criteria for recognizing ___________ muscles must be used
homologous
Criteria for Establishing Muscle Homology
Attachment similarity
Functional similarity
Similarity in embryonic origin
Innervation similarity
Alterations in Muscles
Splitting
Fusion
Reduction in size
Change in point of attachment
Skeletal muscles of the trunk and tail
Extend forward beneath the pharynx as hypobranchial muscles and in amniotes as tongue muscles
Do not include branchiomeric or appendicular muscles
Axial Muscles
most evident in fish and aquatic amphibians where the axial muscles are used in locomotion
relating to or consisting of several similar segments or somites characteristics of Axial Muscles
Metameric
because of their embryonic origin (arise from segmental mesodermal somites)
Axial Muscles are also described as
Segmental
Axial Muscles (9)
1 - epaxials (red)
2 - hypaxials
3 - external oblique
4 - internal oblique
5 - transversus abdominis
6 - rectus abdominis
7 - trapezius
8 - dorsalis scapulae
9 - latissimus dorsi
Trunk and Tail Muscles of Fishes
Musculature of the body wall and tail of fishes consists of __________ separated by myosepta to which the longitudinally directed muscle fibers attach
myomeres
Trunk and Tail Muscles of Fishes are divided into _______ and ________ portions by a horizontal skeletogenous septum
First and foremost role of this musculature is for locomotion
epaxial
hypaxial
Agnathans
Muscular system of lampreys is more primitive than other vertebrates
__________ is lacking, thus the prominent axial musculature is not divided into epaxial and hypaxial divisions
lateral septum
Each myotome contributes one muscle segment called ________
myomere
Agnathans
The short fibers of the myomeres are inserted on partitions of connective tissues called ___________, which lie between successive myomeres
myosepta
Agnathans
The ventral portions of myomeres behind the pharynx turn forward _____ the hypobranchial musculature
above
Agnathans
Branchial muscles are not prominent
Muscles encircling the specialized mouth and tongue are _____ but not _______ with muscles of higher vertebrates
prominent
homologous
Gnathostomous Fishes
Musculature of jawed fishes is more advanced but less complex than _____
tetrapods
Gnathostomous Fishes
Strong axial muscles ________ and tail from side to side during swimming
flex the spine
Gnathostomous Fishes
Myomeres become __________ to extend the action of each myomere over several vertebrae and to assure that muscle fibers can all shorten at equal rates
more angled (zig-zag shaped) and are molded into interlocking cones
Gnathostomous Fishes
Epaxial muscles continue to the skull as __________
epibranchial muscles
Gnathostomous Fishes
Strap-like ___________ extend from the pectoral girdle to the visceral arches
Serve to open the jaws and pull the gills downward and backward
Evolved from the hypaxial muscles retaining the longitudinal orientation of fibers
hypobranchial muscles
Trunk and Tail Muscles of Tetrapods
As the limbs take over the propulsive role, the limb muscles _______ and the axial musculature _______ and become more related to the skeleton for dorsoflexion and ventroflexion of the spine
enlarge
decreases
Trunk and Tail Muscles of Tetrapods
what happens to the Myosepta
regress and disappear
Trunk and Tail Muscles of Tetrapods
Muscles _________ that span from two to many vertebrae
develop long fibers
Trunk and Tail Muscles of Tetrapods
Certain muscles form_______ and other becomes ______
sheet-like layers
associated with the pectoral girdle
__________ muscles of amphibians other than anurans are conservative
Myosepta are still present but in vertical orientation instead of angled
Epaxial muscles