evolution of locomotory system Flashcards
what are the changes from aquatic to terrestrial locomotion
- Shape and position of bones
- Movement of muscle masses
- Movement of nerves that supply them
____ muscles have become more important that ____ muscles
limb, trunk
epaxial muscles
above spinal cord
hypaxial muscles
below spinal cord
in amphibia, reptiles, and birds describe the pectoral girdle
Coracoid
Clavicle
Scapula
in mammals describe the pectoral girdle
- Clavicle in primates, moles, etc, NOT in domestic animals (except cat)
- Coracoid reduced to process on scapula
- Scapula developed spine for muscle attachment
pelvic girdle in amphibia, reptiles, birds AND mammals
- 2 os coxae consisting of ilium, ischium and pubis
- Early reptiles more vertical
pelvic girdle in mammals
- Ilium projects cranially
- Ischium for muscle attachment caudally
- Pubis joined ventrally; pelvic symphysis
limb bones in fish, reptiles and mammals
- Fish; Limbs horizontal
- Reptiles; Humerus and femur horizontal and radius/ulna, tibia/ fibula vertical
- Mammals; All vertical
2 major events during transition reptile to mammal limb bones
- Humerus and femur directed vertically
- Rotation of the limbs:
Ulna lateral → caudal
Radius medial → cranial
Musculo-spiral groove in humerus
Hind limb simpler
(double twists occurs)
describe the twisting of muscles that occurred in forelimb
- In reptiles
Doral muscle mass
Ventral muscle mass - In mammals; forelimb twisted:
Dorsal muscle mass became caudal above elbow and cranial below elbow
Ventral muscle mass became cranial above elbow and caudal below elbow
- nerves follow this twist
describe muscle twist in hindlimbs
- Dorsal muscle mass → cranial
- Ventral muscle mass → caudal
Nerves twist
- Followed muscle masses
- Specific nerves associated with specific muscle masses
