1. Comparative Anatomy Muscles
Note Set 8
Chapter 10

2. Muscles Two muscle groups: Somatic muscles Visceral muscles
Operate head, trunk, limbs
Locomotion and orientation
Visceral muscles
Operate visceral skeleton
Digestion and respiratory movements

3. Cranial Nerves to Muscles
Figure 10.1: Facial nerves to muscles
Figure 10.2: Cranial nerves

4. Two Muscle Types Somatic muscles Visceral muscles Skeletal muscle
Striated and voluntary
Visceral muscles
Smooth muscle
Non-striated and involuntary
Exception- branchiomerics (unsegmented)

5. Skeletal Muscles Axial Appendicular Branchiomerics Trunk and tail
Insert on girdles, fins, or limbs
Branchiomerics
Attached to visceral skeleton

6. Axial Shark Amphibians Mammals Epaxial and hypaxial muscles
Body wall muscles
Amphibians
Epaxials above transverse process
Hypaxials along body wall proper
Mammals
Epaxials subdivided
Hypaxials more complex
Figure 10.3: Trunk muscles of vertebrates.

7. Hypaxial and Epaxial Muscles
Figure 10.5: Specific epaxial muscles
Figure 10.4: Epaxial and hypaxial mucles

8. Abdominal Muscle Groups in Amniotes
Epaxials
Transversospinalis, longissimus, iliocostalis
Hypaxials
Dorsomedials, laterals, ventrals
Laterals- external oblique, internal oblique, and transverse abdominus
Ventral- rectus abdominus
Figure 10.6: Epaxial and hypaxial muscles

9. Head Region
Figures 10.7: Myotomes in the head, neck, and thoracic regions of the embryo.
Figure Axial muscle origin and innervation in vertebrate embryo.

10. Head Region In branchial region, somites are broken down
Ventral slips of postbranchial somites become hypobranchial musculature
Hypobranchial muscles give rise to:
Sternohyoid
Sternothyroid
Omohyoid
Tongue muslces
Geniohyoid
Hyoglossus
Styloglossus
Genioglossus
Lingualis propria

11. Appendicular Muscles Extrinsic Intrinsic
Origin on axial skeleton or fascia of trunk
Insert on girdles and limbs
Intrinsic
Origin on girdles or proximal skeletal elements of appendages
Insert on more distal skeletal elements

12. Intrinsic Muscles
Figure 10.9: Intrinsic muscles of pectoral girdle and forelimbs of mammals and their homologues in reptiles.

13. Branchiomerics Arises from lateral plate mesoderm
Mandibular (1st) arch
Hyoid arch
Arches IV to VI

14. Branchiomerics Mandibular (1st) arch Hyoid arch Arches IV to VI
Intermandibularis- digastic
Adductor mandibulae- masseter, temporalis
Hyoid arch
Sphincter colli
Platysma and mimetics
integumentary muscles
Arches IV to VI
Trapezius, sternomastoid,
cleidomastoid
Figure 10.10: Branchiomeric muscles of gnathostomes.

15. Branchiomeric Muscles
Figure 10.11: Branchiomeric muscles and their innervations.

16. Extrinsic Eye Muscles Six eyeball muscles 2 obliques 4 rectus
Superior and inferior on anterior portion
4 rectus
Arise in posterior portion of orbit
Innervated by oculomotor, trochlear, and abducens
Figure 10.12: Innervation of eye muscle in embryo.

17. Extrinsic Eye Muscles
Figure 10.13: Dorsal view of extrinsic muscles of the left eyeball.
Figure 10.14: Lateral view of extrinsic muscles of eyeball in humans.

18. Diaphragm Mammalian muscle structure
Covers lungs and heart in abdominal cavity
Figure 10.15: Human diaphragm.

19. Dermal or Integumentary Muscles
Fish & tailed amphibians- skin is firmly attached to musculature
Sphincter colli- first muscle to move skin
Subdivides down neck- platysma
Extrinsic and intrinsic muscle groups
Figure 10.16: Evolution of mammalian facial muscles. Shows sphincter colli (SC) spreading into platysma (P).

20. Extrinsic Integumentary Muscles Intrinsic Integumentary Muscles
Costocutaneous muscles- allows rectilinear motion (reptiles--snakes)
Panniculus carnosus-sheet surrounds body
Cutaneous maximus- to shake skin (higher mammals)
Patagial muscles- bat wings
Auricularis- moves human ear
Caninus muscle- arises with aggression
Intrinsic Integumentary Muscles
Arrectores plumarum (birds) & arrectores pilorum (mammals)- errects hair and feathers

21. Specialized Muscles Electric organs In fish Modified hypaxial muscles
Figure 10.17: Electric eel.

22. Literature Cited
Figure
Figure
Figure 10.3, 10.8, 10.9, 10.11, 10.12, 10.13, Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.
Figure 10.4 &
Figure 10.6,
Figure
Figure
Figure
Figure