1. Comparative Anatomy General Body Plan
Note Set 2
Chapters 2 & 4

2. Pharynx (fair-inks) with slits
Figure 3.1: Pharyngeal arches
lateral view and
(b) ventral cross section.
Pharyngeal arches- associated with slits
Anamniotes (lower vertebrates)- have gill slits
Amniotes- have slits in embryo but gills never form
Endodermal pouches- pharyngeal pouch that grows toward surface of animal
Ectodermal groove- pharyngeal groove on outside that grows toward each pouch

3. Embryo Figure 3.2: Embryo pharyngeal arches.
Figure 3.3: Embryo development at 1 month.

4. Aortic arches housed by pharyngeal arch
In tetrapods, 1st pharyngeal slit becomes auditory tube and middle ear cavity
Aortic arches housed by pharyngeal arch
(b)
Figure 3.4: Early pharyngeal devel.. of shark (a) early stage (b) later stage.

5. 1st (mandibular) arch- mandibular and maxillary portions
Figure 3.5: Fate of the pharyngeal arches.
1st (mandibular) arch- mandibular and maxillary portions
2nd (hyoid) arch
Other arches are numerically named
Most vertebrates have 6 pairs of arches

6. Figure 3.6: Pharyngeal arches.
Each pharyngeal arch contains a cartilage, artery, mesoderm component, and cranial nerve.

7. Body Plan Head Trunk Tail
Figure 3.7: Sagittal section of craniate embryo.

8. Head Head Cephalization- development of sense organs
Protective covering of dermal bone (not replacement bone) or cartilage
Figure 3.8.

9. Trunk
Somites- muscle masses beside notochord; embryonic structures that turn into bone
Coelom- body cavity between gut and body wall, lined by peritoneum
Figure 3.10.
Figure 3.9: Coelom.

10. Trunk (cont.) Other visceral organ cavities: Heart- pericardium
Lungs- pleura
Abdomen- peritoneum
Figure 3.12: Pericardium and pleural cavities.
Figure 3.11: Pericardium cavities.

11. Tail From body to end of the digestive tract Somites and notochord
Innervations
Dorsal and ventral aorta
Food storage, defense, locomotion

12. Pituitary Development
Figure 3.13
Stomodeal ectoderm plate pushes inward and forms pocket (Rathke’s pouch) that leads to anterior lobe
This invagination meets the dienchephalon’s infundibular process which forms the posterior lobe
Figure 3.14

13. Characteristics of Vertebrates
Divided into two superclasses: Pisces and Tetrapoda
Demonstrate bilateral symmetry
Distinguishing features of vertebrates:
Presence of notochord
Pharynx with slits
Dorsal tubular nervous system
Developed vertebrae
Post anal tail

14. Notochord Most primitive endoskeletal structure
Jawless fish- n.c. long and enlarged
Cartilagenous fish- n.c. surrounded by cartilagenous vertebrae
Bony fish and amphibians- n.c. surrounded by larger vertebrae
Amniotes- n.c. almost lost

15. Notochord (cont.) In mammals, between successive centrum are disks
Within disks, the notochord is mostly replaced with pulpy nucleus
Figure 3.15: Vertebrae.
Figure 3.16: MRI scan of notochord.

16. More Vertebrate Features
Dorsal Nervous System
CNS- brain and spinal cord
Anamniotes- 10 pairs of cranial nerves
Amniotes- 12 pairs of cranial nerves
Vertebrae column
Backbones
Post-anal tail
Figure 3.17: Vertebral column.

17. Anatomical Directions
Figure 3.18.
Figure 3.19.

18. Cranial Nerves Olfactory Optic Oculomotor Trochlear Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Amniotes only:
Spinal Accessory
Hypoglossal
Figure 3.20

19. Literature Cited
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Figure 3.4, 3.7, 3.8, 3.10, & Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.
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