OBL HOME | OBL REFERENCES | ||||||||||||||
ABDOMINAL MUSCLES
|
|||||||||||||||
In cartilaginous fish,
the ancestral myotomes were separated into dorsal epaxial and ventral
hypaxial divisions (Weichert, 1970). In higher vertebrates, the hypaxial
musculature is subdivided into a number of muscle groups such as separate
layers of abdominal muscles and intercostals.
The external and internal oblique obliques laterally flex the abdomen.
(Webster, 1974; Weichert, 1970, p.512). |
|||||||||||||||
![]() |
The rectus abdominis flexes the abdomen |
||||||||||||||
The
transversus abdominis is the deepest abdominal muscle; it (like all abdominal
muscles) compresses the abdomen.
|
|||||||||||||||
FROG | |||||||||||||||
![]() |
|||||||||||||||
SALAMANDER |
![]() |
||||||||||||||
Amniotes also develop a longissimus coli and levatores costarum from the
hypaxial musculature (Webster, 1974;
Weichert, 1970, p.512). |
|||||||||||||||
ALLIGATOR |
|||||||||||||||
CHICKEN | |||||||||||||||
![]() |
|||||||||||||||
OPPOSSUM | |||||||||||||||
![]() |
![]() |
||||||||||||||
CAT | |||||||||||||||
![]() |
![]() |
||||||||||||||
![]() |
|||||||||||||||
GOAT |
SHEEP |
||||||||||||||
COW |
pig |
||||||||||||||
MONKEY |
|||||||||||||||
HUMAN MODEL |
![]() |
||||||||||||||
In some fossil amphibians
and in modern amniotes, the external and internal intercostal muscles
develop from the external and internal obliques.
The intercostals muscles are better developed in mammals (Romer,
p. 284). |
|||||||||||||||
ALLIGATOR |
|||||||||||||||
OPOSSUM |
CAT |
||||||||||||||
COW |
|
||||||||||||||
HUMAN MODEL |
|||||||||||||||
In
mammals, the diaphragm forms as a derivative of the rectus abdominis.
Its contraction is responsible for most of the change in the volume
of the thoracic cavity during breathing (Romer, p. 290). |
|||||||||||||||
OPOSSUM |
|||||||||||||||