VERTEBRATE COMPARATIVE ANATOMY OF MUSCULAR SYSTEM
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The document provides an overview of the comparative anatomy of the muscular system across vertebrates from fishes to mammals. It describes how axial, appendicular, jaw, and integumentary muscles have evolved across classes. Key changes include the increasing complexity of axial musculature, the derivation of appendicular muscles from axial precursors, and the specialization of jaw and facial muscles in mammals.
VERTEBRATE COMPARATIVE ANATOMY OF MUSCULAR SYSTEM
- 1. COMPARATIVE ANATOMY OF VERTEBRATE MUSCULAR SYSTEM BY ADESEJI WASIU ADEBAYO 08/46KAOO6 ANA 814 – VERTEBRATE COMPARATIVE ANATOMY DEPARTMENT OF ANATOMY, UNIVERSITY OF ILORIN. LECTURER: DR A.O. OYEWOPO
- 2. Muscular System Functions â—¦ Locomotion â—¦ Posture â—¦ Protection â—¦ Heat production and thermoregulation 2
- 3. Vertebrate muscles Voluntary and involuntary Striated and non striated Skeletal, smooth and cardiac Smooth muscle Skeletal muscle 3
- 4. 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 4
- 5. Muscle Control Type of muscle Nervous control Type of control Example SkeletalSkeletal Controlled by CNS Voluntary Lifting a glass Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis 5
- 7. The muscles of FISHES are less complex than in TETRAPODS. Muscles of Aquatic Vertebrates 7
- 8. AXIAL MUSCULATURE 2 divisions: â—¦Epaxial (Upper) â—¦Hypaxial (Lower) â—¦ (+) Lateral septum â—¦ (+) Myomeres â—¦ (+) Myosepta â—¦ MYOMERES become more angled (zig-zag shaped) and are molded into interlocking cones. Muscles of Aquatic Vertebrates 8
- 9. Muscles of Aquatic Vertebrates 9
- 10. Strap-like hypobranchial muscles extend from the pectoral girdle to the visceral arches. â—¦ Serve to open the jaws and pull the gills downward and backward. â—¦ Evolved from the hypaxial muscles retaining the longitudinal orientation of fibers. Muscles of Aquatic Vertebrates 10
- 11. APPENDICULAR MUSCULATURE â—¦ (+) Paired appendages (evolved with fins) Muscles of Aquatic Vertebrates Dorsal mass of EXTENSOR: ï‚— Abductors/Levators ï‚— Moving the fins UPWARD or FORWARD ï‚— A series of levators above the pharynx lift the gill bars. 11
- 12. Ventral mass of FLEXOR: â—¦ Adductors/Depressors â—¦ Moving the fins DOWNWARD or BACKWARD â—¦ Adductors reduced the internal angles of each visceral arch. Muscles of Aquatic Vertebrates 12
- 13. FISHES have 6 extrinsic eye muscles: Muscles of Aquatic Vertebrates 13
- 15. Axial musculature Modified from lower aquatic forms Metameric condition = obscure Trunk reduced in volume 15
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- 17. URODELE AMPHIBIANS Do 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 17
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- 19. ANURANS AMPHIBIANS Dorsalis trunci become differentiated into intertransversarial muscles between the transverse processes and interneural muscles between neural arches 19
- 20. HYPAXIAL MUSCLES OF AMPHIBIANS ADULT 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 20
- 21. SPECIALIZED ANURANS Reduced 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 abdominis as tendinous inscriptions Lastly, the amphibians have muscle that move the to tongue this derived from the hypobranchial muscle 21
- 23. AXIAL MUSCULATURE Epaxial muscles – functions to extend or straighten the spine and provide some lateral flexion. – lack myosepta and become complex Reptiles 23
- 24. AXIAL MUSCULATURE Hypaxial muscles – functions to bend the spine and provides lateral bending. ◦subvertebral group ◦rectus abdominis group ◦lateral group Reptiles 24
- 25. APPENDICULAR MUSCULATURE more numerous and diversethan in AMPHIBIANS. Intrinsic muscles - quadrupedal locomotion â—¦Dorsal extensor â—¦Ventral flexor muscles â—¦Extrinsic integumentary muscles - inserted on the underside of the dermis. 25
- 26. Forelimbs -trapezius muscles derived from the branchial musculature -several muscles derived from the axial musculature -most appendicular muscles are derived directly from appendicular muscles of fish ancestors. 26
- 27. 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. 27
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- 30. Birds Muscular Structure Most 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 30
- 31. The supracoracoideus works using a pulley like system to lift the wing while the pectorals provide the powerful downstroke. 31
- 33. Epaxial Muscle – lack myosepta – complex Hypaxial Muscle – same with all tetrapods * subvertebral group – located below transverse process – ventroflexes the spine 33
- 34. Anterior ribs – enlarged – penetrates external and internal obliques – forms the intercostals muscle – ventilation of the lungs 34
- 35. Lateral group of hypaxial muscle: - Serrratus - Levator scapulae - Rhomboideus 35
- 36. 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 throat 36
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- 38. AXIAL MUSCLES FISHES AMPHIBIANS REPTILES BIRDS MAMMALS Epaxial (Upper) Solid mass; above the lateral septum Muscle masses subdivided and rearranged into longitudinal muscles Muscle masses subdivided and rearranged into longitudinal muscles 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 inner transverse layer; rectus abdominis 2 outer oblique layers and 1 inner transverse layer; rectus abdominis Oblique layers are further subdivided, separated by intercostal muscles Septum Transverse/ Lateral septum Dorsally 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 Maintenance of posture, head movement, and respiration Maintenance of posture, head movement, and respiration Maintenance of posture, head movement, and respiration Comparative Anatomy of Vertebrates Muscular System 38
- 43. JAW MUSCLES FISHES AMPHIBIANS REPTILES BIRDS MAMMALS Branchiomeric Constrictors and levator muscles Associated with mandibular, hyoid and pharyngeal arches Associated with mandibular, hyoid and pharyngeal arches Associated with mandibular, hyoid and pharyngeal arches Highly modified; mandibular, hyoid and pharyngeal arches FUNCTION Breathing and feeding Contribute to larynx (vocalization) and throat Contribute to larynx (vocalization) and throat Contribute to larynx (vocalization) and throat Control vocal functions within larynx Hypobranchial Attached posteriorly to pectoral skeleton Associated with pharyngeal arches Associated with pharyngeal arches Associated with pharyngeal arches Associated with pharyngeal arches FUNCTION Serve to open the jaws and pull the gills downward and backward Movement of the larynx, hyoid apparatus and tongue Movement of the larynx, hyoid apparatus and tongue Movement of the larynx, hyoid apparatus and tongue Movement of the larynx, hyoid apparatus and tongue Comparative Anatomy of Vertebrates Muscular System 43
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- 48. APPENDICULAR MUSCLES FISHES AMPHIBIANS REPTILES BIRDS MAMMALS Adductor muscles Dorsal; flex fins 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 FUNCTION Balance and orientation Support and locomotion Support and locomotion Support and locomotion Support and locomotion Comparative Anatomy of Vertebrates Muscular System 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
- 49. Muscles responsible for Amphibians Reptiles Mammals Forelimb abduction Latissimus dorsi Latissimus dorsi Latissimus dorsi; Trapezius Hindlimb abduction Caudofemoralis Caudofemoralis Caudofemoralis; Biceps femoralis Propulsive Phase: 49
- 50. INTEGUMANTARY MUSCLES REPTILES BIRDS MAMMALS Specialized Muscles Costo-cutaneous muscles Arrector pilli muscles; patagial muscles Arrector pilli muscles; patagial muscles (bats); mimetic muscles FUNCTION Provide friction for locomotion Aid in flight control Involved in facial expression Comparative Anatomy of Vertebrates Muscular System Patagial muscles 50
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