Comparative Anatomyof the Limb

Presented by Dr. Farhana Taher Sumya

Guided by Dr. Zinnat Ara Yesmin

ObjectivesDefine comparative anatomy

Classifiy the phylum chordata

Discuss the limb development of tetrapods

Describe the features of tetrapods

Objectives (contd...)

Explain the structure and function of the limb of tetrapods

Discuss homology and analogy in relation to the limb of tetrapods

Comparative Anatomy

Kingdom: AnimaliaPhylum:chordata

Group: Craniata

Subphylum:

GnasthostomataSu

perclass: Tetrapoda

Class: Mammalia

Class: Aves

Class: Reptilia

Class: Amphibia

Superclass: Pisces

Subphylum:

Agnatha

Group: Acrania

Classification of phylum chordata

Features of Tetrapods

Paired appendages are limb which are pentadactyl

Sternum present

Lung present

Number of skull bone is reduced

Features of Tetrapods (contd…)

Amphibia (e.g: Frog, toad)Pentadactyl limbs and no nails on claws3 chambered heart and lung present

Reptilia (e.g: turtle, lizard, snake)

Pentadactyl limbs with claws except snake and lizards

3 chambered heart and lung present

Aves(Bird)

Limbs with clawsLung present and no urinary bladder

Mammalia (e.g: cat,dog,monkey,human)

Pentadactyl limbs with claws,nails ,hoof at the end of digit

4 chambered heart and lung present

Features of Tetrapods(contd)

Limb development of tetrapodsLimb bud

Apical ectodermal ridge

Apoptosis

Limb bud

Apical ectodermal ridge

Apoptosis

Structure and function of the forelimb of tetrapods

Amphibia Reptilia

Structure and function of the forelimb of tetrapods (contd….)

Aves Mammalia

Structure and function of forelimb of tetrapods (contd….)

Comparison of primates hand

Structure and function of the hindlimb of tetrapods

Amphibia Reptilia

Structure and function of the hindlimb of tetrapods (Contd.)

Aves Mammalia

Structure and function of the hindlimb of tetrapods (Contd.)

Homology

Homology (contd.)

Analogy

Analogy (contd.)

Homology Analogy

Similar in anatomy

dissimilar in anatomy

Doing dissimilar function

Doing similar function

Homology & Analogy

Homology (contd)

We have probably noticed that our arms are shorter than our legs. However, this is not the case in all species. Many species of monkeys, in particular, have longer arms than legs, or some, like dogs and cats, have four limbs all of similar length. This is because the specific function of those limbs differs from humans. Monkeys do a lot more climbing than walking, while dogs and cats use all four limbs to walk and run.

However, despite small differences in function, they still have one upper arm bone, followed by two lower arm bones, wrist bones and finger bones - just like humans. Although, sometimes the length or number of the bones and the shape of the muscles used to move their arms and legs may vary slightly. But, despite slight variations, the order in which they are put together and the general function of motion are similar to those in humans and other mammals.

Homology

The structure which are similar in their morphology, anatomy, genetics and embryology but dissimilar in their function is called homologous structure. The relationship between the homologous structure is called homology.