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
◦ Locomotion
◦ Posture
◦ Protection
◦ 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

6. Muscles of Aquatic
Vertebrates

7. The muscles of FISHES are less complex than in
TETRAPODS.
Muscles of Aquatic Vertebrates
7

8. 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.
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.
◦ Serve to open the jaws and
pull the gills downward and
backward.
◦ Evolved from the hypaxial
muscles retaining the
longitudinal orientation of
fibers.
Muscles of Aquatic Vertebrates
10

11. APPENDICULAR MUSCULATURE
◦ (+) Paired appendages (evolved with fins)
Muscles of Aquatic Vertebrates
Dorsal mass of
EXTENSOR:
 Abductors/Levators
 Moving the fins
UPWARD or
FORWARD
 A series of levators
above the pharynx
lift the gill bars.
11

12. Ventral mass of FLEXOR:
◦ Adductors/Depressors
◦ Moving the fins DOWNWARD or BACKWARD
◦ 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

14. Muscles of
Amphibians

15. Axial musculature
Modified from lower aquatic forms
Metameric condition = obscure
Trunk reduced in volume
15

16. 16

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

18. 18

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
◦Dorsal extensor
◦Ventral flexor muscles
◦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

28. 28

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

37. 37

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

39. Epaxials (Tetrapods)
39

40. Hypaxials (Tetrapods) 40

41. Hypaxials (Tetrapods) 41

42. Hypaxials (Tetrapods) 42

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

44. 44

45. Hypobranchial
muscles
45

46. BRANCHIOMERIC MUSCLES
46

47. HYPOBRANCHIAL MUSCLES
47

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

51. 51