VERTEBRATE COMPARATIVE ANATOMY OF MUSCULAR SYSTEM

COMPARATIVE ANATOMY OF VERTEBRATE MUSCULAR SYSTEM

BY

ADESEJI WASIU ADEBAYO

08/46KAOO6

ANA 814 – VERTEBRATE COMPARATIVE ANATOMY

DEPARTMENT OF ANATOMY,

UNIVERSITY OF ILORIN. L E C T U R E R : D R A . O. OY E W O P O

Muscular SystemFunctions◦ Locomotion

◦ Posture

◦ Protection

◦ Heat production and thermoregulation

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Vertebrate musclesVoluntary and involuntary

Striated and non striated

Skeletal, smooth and cardiac

Smooth muscle

Skeletal muscle

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Classification of Muscle

Skeletal

found in limbs

Cardiac

found in heart

Smooth

Found in

viscera

Striated, multi- nucleated Striated, 1

nucleus

Not striated, 1

nucleus

voluntary involuntary involuntary

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Muscle Control

Type of

muscle

Nervous

control

Type of

control

Example

SkeletalSkeletal Controlled

by CNS

Voluntary Lifting a

glass

CardiacRegulated

by ANS

Involuntary Heart

beating

Smooth Controlled

by ANS

Involuntary Peristalsis

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Muscles of Aquatic Vertebrates

The muscles of FISHES are less complex than in TETRAPODS.


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AXIAL MUSCULATURE

2 divisions:◦Epaxial (Upper)◦Hypaxial (Lower)

◦ (+) Lateral septum◦ (+) Myomeres◦ (+) Myosepta

◦ MYOMERES become more angled (zig-zag shaped) and are molded into interlocking cones.


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Strap-like hypobranchialmuscles extend from the pectoral girdle to the visceral arches.

◦ Serve to open the jaws and pull the gills downward and backward.

◦ Evolved from the hypaxialmuscles retaining the longitudinal orientation of fibers.


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APPENDICULAR MUSCULATURE◦ (+) Paired appendages (evolved with fins)


Dorsal mass of

EXTENSOR:

Abductors/Levators

Moving the fins UPWARD or FORWARD

A series of levatorsabove the pharynx lift the gill bars.

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Ventral mass of FLEXOR:

◦Adductors/Depressors

◦Moving the fins DOWNWARD or BACKWARD

◦Adductors reduced the internal angles of each visceral arch.


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FISHES have 6 extrinsic eye muscles:


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Muscles of Amphibians

Axial musculatureModified from lower aquatic forms

Metameric condition = obscure

Trunk reduced in volume

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URODELE AMPHIBIANSDo not have epaxial muscles

Their lateral septum is more dorsal in position

Myotomes are primitive

Muscle fibers still course form one myocommata to the next,

The entire epaxial mass formed dorsalis trunci

Myotomes – vertically arranged

Intersegmental bundles

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ANURANS AMPHIBIANSDorsalis trunci become differentiatedinto intertransversarial musclesbetween the transverse processesand interneural muscles betweenneural arches

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HYPAXIAL MUSCLES OF AMPHIBIANSADULT URODELES

Ventral trunk muscles

Beginning from the outside, there are superficial and deep external oblique (course in posteroventral direction)

Internal oblique layer extend in posterodorsal direction

Transversus which fibers almost in a vertical position. It lies next to peritoneum

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SPECIALIZED ANURANSReduced the number of layers in hypaxial trunk muscles

Rectus abdominis is large muscle extending from sternum to pubis

Myocommata have disappeared from the external oblique and transversus but are retained to some extent in the rectus abdominisas tendinous inscriptions

Lastly, the amphibians have muscle that move the to tongue this derived from the hypobranchial muscle

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AXIAL MUSCULATURE

Epaxial muscles

– functions to extend or straighten the spine and provide some lateral flexion.

– lack myosepta and become complex

Reptiles

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AXIAL MUSCULATURE

Hypaxial muscles – functions to bend the spine and provides lateral bending.◦subvertebral group

◦rectus abdominis group

◦ lateral group

Reptiles

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APPENDICULAR MUSCULATURE

more numerous and diverse than in AMPHIBIANS.

Intrinsic muscles

- quadrupedal locomotion◦Dorsal extensor◦Ventral flexor muscles

◦Extrinsic integumentary muscles -inserted on the underside of the dermis.

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Forelimbs

-trapezius muscles derived from the branchialmusculature

-several muscles derived from the axial musculature

-most appendicular muscles are derived directly from appendicular muscles of fish ancestors.

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Hindlimbs

-dorsal and ventral muscle groups are again recognized.

*caudofemoralis- a prominent flexor of the thigh of Reptiles.

Extrinsic eyeball muscles

Eyeball can no longer be rotated around its optical axis.

*pyramidalis-muscles inserted on the upper lids and nictitating membrane of Reptiles.

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Birds Muscular StructureMost birds have approximately 175 different muscles.

The skin muscles help a bird in its flight by adjusting the feathers.

Pygostyle (tail muscle)

The pectorals, or the breast muscles

True Flight

thin, stringy muscles of the vertebral column

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The supracoracoideus works using a pulley like system to lift the wing while the pectorals provide the powerful downstroke.

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Epaxial Muscle

– lack myosepta

– complex

Hypaxial Muscle

– same with all tetrapods

* subvertebral group

– located below transverse process

– ventroflexes the spine

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Anterior ribs

– enlarged

– penetrates external and internal obliques

– forms the intercostals muscle

– ventilation of the lungs

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Lateral group of hypaxial muscle:

- Serrratus

- Levator scapulae

- Rhomboideus

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Branchial muscle

*Ancestor adductor mandibulae of lower vertebrates several muscles in mammals

(-) depressor mandibulae

Digastric muscle (new muscle)

-ventral constrictor of 1st and 2nd arches innervated by 5th and 7th cranial nerves

Stapedial muscle

Muscle of the larynx

Constrictor of the throat36

AXIALMUSCLES

FISHES AMPHIBIANS REPTILES BIRDS MAMMALS

Epaxial(Upper)

Solid mass; above the lateral septum

Muscle masses subdivided and rearranged into

longitudinal muscles





Hypaxial(Lower)

Solid mass; below the lateral septum

2 outer oblique layers; 1 inner

transverse layer; rectus abdominis

2 outer oblique layers and 1 innertransverse layer; rectus abdominis

2 outer oblique layers and 1 innertransverse layer; rectus abdominis

Oblique layers are further subdivided,

separated by intercostal muscles

SeptumTransverse/

Lateral septumDorsally position Linea alba

Myotomes Present Present Absent

Myosepta Present Present Absent Absent

FUNCTION

To produce an undulating motion

that propels the fish through the water

Maintenance of posture, head

movement, and respiration







Comparative Anatomy of Vertebrates Muscular System 38

Epaxials (Tetrapods)

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Hypaxials (Tetrapods) 40

JAWMUSCLES


BranchiomericConstrictors and levator muscles

Associated with mandibular,hyoid and

pharyngeal arches


pharyngeal arches


pharyngeal arches

Highly modified; mandibular, hyoid and

pharyngeal arches

FUNCTIONBreathing and

feeding

Contribute to larynx

(vocalization) and throat





Control vocal functions within

larynx

HypobranchialAttached

posteriorly to pectoral skeleton

Associated withpharyngeal

arches


arches


arches


arches

FUNCTION

Serve to open the jaws and pull

the gills downward and

backward

Movement of the larynx, hyoid

apparatus and tongue







Comparative Anatomy of Vertebrates Muscular System

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Hypobranchial

muscles

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BRANCHIOMERIC MUSCLES46

HYPOBRANCHIAL MUSCLES47

APPENDICULARMUSCLES


Adductor muscles

Dorsal; flexfins

Ventral; recovery

Ventral; recovery

Ventral; recovery

Ventral; recovery

Abductor muscles

Ventral; extend fins

Dorsal;propulsive

Dorsal;propulsive

Dorsal;propulsive

Dorsal;propulsive

Other characteristics

Intrinsic muscles are

limited in number &

undifferentiated

Much more complex than

in fish

More numerous & diverse than

in amphibians

Intrinsic musculature is reduced

Similar to reptiles but

more diverse

FUNCTIONBalance and orientation

Support and locomotion





Recovery Phase- Forward movement and raising of the limb (adduction)– Flexing of arm/leg– Extension of hand/ foot

Propulsive Phase- Backward movement of the limb (abduction)– Extension of arm/leg– Flexion of hand/foot 48

Muscles responsible for

Amphibians Reptiles Mammals

Forelimb abduction

Latissimus dorsi Latissimus dorsiLatissimus dorsi;

Trapezius

Hindlimbabduction

Caudofemoralis CaudofemoralisCaudofemoralis;Biceps femoralis

Propulsive Phase:

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INTEGUMANTARYMUSCLES

REPTILES BIRDS MAMMALS

Specialized Muscles Costo-cutaneous musclesArrector pilli muscles;

patagial muscles

Arrector pilli muscles;patagial muscles

(bats);mimetic muscles

FUNCTIONProvide friction for

locomotionAid in flight control

Involved in facial expression


Patagial muscles

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VERTEBRATE COMPARATIVE ANATOMY OF MUSCULAR SYSTEM

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