Comparative Anatomy Script – Vertebral Column

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We will start with the human vertebra.  The human vertebra has seven cervical vertebrae, twelve thoracic and five lumbar.   Below the lumbar vertebra there are four to five fused vertebrae known as the sacrum.  The sacrum is a part of the pelvic girdle.  Then we have the tailbone called the coccyx, which are four to seven vertebrae.

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The function of the vertebra in humans is for support, attachment of ribs and locomotion.  Most of our movement is limited to our cervical spine and lumbar spine.  There is a little bit of movement in our thoracic spine but most of the function is for attachment of ribs and helping form our thoracic cage.

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You can see that the vertebra houses the spinal cord, which is a protective mechanism.  You can also see the spinal nerves coming out at the levels of the cervical, thoracic and lumbar levels.  There will also be sacral nerves as well.

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Lets compare this to other animals.  We are now going to look at Avian vertebra, which is adapted for flight.  It has limited movement to prevent the loss energy during flight. 

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In the cervical region there can be eight to twenty-five vertebrae depending on the size of the bird.  This skeleton shown is a pigeon so it is on the smaller side.  The cervical spine is very flexible and birds can turn their heads up to 180 degrees.  The cervical spine is very flexible and aids as a shock absorber.  It also aids in reaching food on the ground and maintaining the center of gravity when changing positions from flight to standing. 

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The next region is the dorsal region, which is similar to the thoracic region in humans.   It has attachments for ribs and is about six to ten vertebrae.  There is no movement in this region unlike humans. 

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The next area is the synsacrum, which is specific to birds and is similar to the sacrum in humans.  It is about ten to twenty-two fused vertebrae.  It is fused to the pelvis for support during bipedal motion.

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The next region is the caudal region, which is five to ten fused vertebrae.  This area is similar to the coccyx in human but functions for attachment of feathers and control during flight.  And finally at the end we have a pygostyle, which is four to seven fused vertebrae.  It also has attachments for feathers and behavioral adaptations, such as mating practices.

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The next tetrapod is a frog, which is part of the amphibia family.  The vertebra of a frog is very short and doesn’t have much of a neck region.  Most of the movement of the frog is limited to the pelvic region.  Most of their motion is in a vertical plane. 

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In the cervical region there is one cervical vertebra, which limits the head movement to ventral and dorsal movements.

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Next we get into the dorsal region.  This is similar to the thoracic region in humans except there are no attachments for ribs.  It contains four to eight vertebrae with not much movement.

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The last vertebra is the sacral vertebra.  There is only one vertebra and is attached to the pelvis via the sacroiliac joint.  Most movement of the frog occurs here, especially during jumping.

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The last part of the frog is the urostyle, which is a remnant of the tail that was lost during development.  It is similar to the coccyx in humans.

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The next tetrapod is the turtle from the reptilia family.  The spine is used for movement on land and water.  The cervical spine consists of eight vertebrae.  It is very flexible so the head can fold back into the carapace (shell). 

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The dorsal region is similar to the thoracic region in humans.   It has attachments for ribs, which attach to the carapace. 

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The sacrum is next and consists of two to three fused vertebrae.  This is attached to the pelvis for locomotion of lower limbs. 

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Finally we have the caudal vertebrae, which is similar to the coccyx in humans.  It consists of twelve or more vertebrae.  Males tend to be longer than females.

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