Comparative Anatomy
Muscles
Note Set 8
Chapter 10
Muscles
Two muscle groups:
 Somatic muscles
Operate head, trunk, limbs
 Locomotion and orientation


Visceral muscles
Operate visceral skeleton
 Digestion and respiratory movements

Cranial Nerves to Muscles
Figure 10.1: Facial nerves to muscles
Figure 10.2: Cranial nerves
Two Muscle Types

Somatic muscles
Skeletal muscle
 Striated and voluntary


Visceral muscles
Smooth muscle
 Non-striated and involuntary
 Exception- branchiomerics (unsegmented)

Skeletal Muscles

Axial


Appendicular


Trunk and tail
Insert on girdles, fins, or limbs
Branchiomerics

Attached to visceral skeleton
Axial

Shark
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.
Hypaxial and Epaxial Muscles
Figure 10.4: Epaxial and hypaxial mucles
Figure 10.5: Specific epaxial muscles
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
Head Region
Figures 10.7: Myotomes in the head, neck,
and thoracic regions of the embryo.
Figure 10.8- Axial muscle origin and
innervation in vertebrate embryo.
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
Appendicular Muscles

Extrinsic
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

Intrinsic Muscles
Figure 10.9: Intrinsic muscles of pectoral girdle and forelimbs of mammals and their
homologues in reptiles.
Branchiomerics




Arises from lateral plate mesoderm
Mandibular (1st) arch
Hyoid arch
Arches IV to VI
Branchiomerics

Mandibular (1st) arch
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.
Branchiomeric Muscles
Figure 10.11: Branchiomeric muscles and their innervations.
Extrinsic Eye Muscles

Six eyeball muscles

2 obliques
 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.
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.
Diaphragm


Mammalian muscle structure
Covers lungs and heart in abdominal cavity
Figure 10.15: Human diaphragm.
Dermal or Integumentary Muscles


Fish & tailed amphibiansskin is firmly attached to
musculature
Sphincter colli- first muscle
to move skin


Subdivides down neckplatysma
Extrinsic and intrinsic
muscle groups
Figure 10.16: Evolution of mammalian facial
muscles. Shows sphincter colli (SC) spreading into
platysma (P).
Extrinsic 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
Specialized Muscles

Electric organs
In fish
 Modified hypaxial muscles

Figure 10.17: Electric eel.
Literature Cited
Figure 10.1http://www.city.ac.uk/optometry/Biolabs/cranial%20nerves/cranial_nerves_lab.htm
Figure 10.2- http://mywebpages.comcast.net/epollak/PSY255_pix/PSY255_pix.htm
Figure 10.3, 10.8, 10.9, 10.11, 10.12, 10.13, 10.16- Kent, George C. and Robert K. Carr.
Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.
Figure 10.4 & 10.5- http://www.mut.ac.th/~vet/Anat-html/muscle/muscle.html
Figure 10.6, 10.10- http://people.eku.edu/ritchisong/342notes6.htm
Figure 10.7- http://connection.lww.com/products/sadler/imagebank.asp
Figure 10.14- http://www.bmb.leeds.ac.uk/illingworth/motors/myosin.htm
Figure 10.15- http://whyfiles.org/204endurance_training/2.html
Figure 10.17- http://www.aqua.org/animals_electriceel.html