1. But Why?????
Because studying the rat muscles is almost like studying the human muscle system
Comparative Anatomy
Many of the names and functions of the rat’s muscles are the same as the human

2. What up with rats?
They originated in Asia and migrated to Europe in the mid 1500s
They made it to America by stowing away on ships, then spread across the continent into many habitats
Today they are a nuisance because they eat fruits and grains that humans need , attack small animals , and live in crowded urban areas.

3. Rats are Valuable Used for scientific and medical research
Comparative Anatomy allows students to study the rat and apply knowledge to human anatomy, without dissecting a human…

4. Comparative Anatomy

5. Rat Taxonomy Scientific Name: Rattus norvegicus (genus species)
Common Name: Rat
Kingdom- Animalia
Phylum- Chordata
Class- Mammalia
Order- Rodentia

6. Rat Dissection General Information
Rat Guide: Gives you the information necessary to do the lab
Worksheet: Where you will record any information, Exam Grade, will be left here every day.
Rat Practical: at the end of the dissection. Will have to identify muscles on the rat. Exam Grade
Daily exit ticket on the worksheet as each section is completed. Will need to rehearse the muscles and point them out to me.
Daily Participation Grades also will be taken.

7. Dissection Worksheet Turn in one per partner
Will be left here every day
The entire section will need to be complete before sign off can occur
It is best to work the section questions and table the day before you dissect that set of muscles
Utilize google or the anatomy book to determine equivalent muscle names and functions for the rat and human

8. Dissection Equipment Common Equipment
Scissors, scalpel, dissecting pins, dissecting needle, forceps, dull probe, dissecting pan, gloves, apron, safety glasses

10. External Anatomy Do you remember the anatomical directions?
Toward the midline
Toward the back (upper surface of body)
Toward the tail
Toward the side
Farthest from the
point of attachment
Toward the belly (underside of body)
Closest to the point of attachment
Toward the head

11. External Features
Know these external features for the practical!!!!

12. External Features Mammary Papillae Urethral, Vaginal Orifice Pinna
Anus
Nares
Vibrissae

13. Objective for the Day Review prior day and prepare for quiz
Observe and then apply the steps for skinning the rat
Reinforce the steps for clean up
Dissect the head and throat muscles and compare them to the human muscle system
Prepare for the next class by comparing chest and medial muscles

14. Skinning the Rat
Make a small snip into the skin layer only

15. Skinning the Rat
Following the dashed lines in your guide, make a mid ventral incision being careful to lift the skin as you cut. Keep the tips of the scissors pointed up.

16. Skinning the Rat
Use your dull probe to separate the skin from the muscle layer. Complete the rest of the cuts by following the drawing in your packet.

17. Steps to Remove the Skin
After completing all the ventral cuts, loosen all skin away form the muscle layer below
Some subcutaneous muscles may have to be cut to completely loosen the skin from the trunk area
The layer of skin will not be completely removed. It will be used to cover the rat up for storage overnight. Snug as a bug in a rug.

18. CLEAN UP PROCEDURE A. Wrap up the rat in its own skin
B. Place it in your labelled Ziploc bag
C. Spray the rat with preservative
D. Place the bag in designated box outside of Mrs. B’s door
E. Clean up tools, rinse them (no soap), pat them dry, and sort them back into the correct tray
F. Rinse the dissecting tray and stagger stack the trays on the side of the sink to dry overnight
G. Wipe down your table and throw away all trash
H. Help others clean up
I. Return to the room to continue working on worksheet until the end of class

19. Head and Throat Muscles
Masseter
Mylohyoid
(beneath the digastric)
Digastric
Sternohyoid
Sternomastoid
Sternomastoid

20. Chest and Medial Muscles of the Front Leg
Biceps Brachii
Pectoralis Major
Epitrochlearis
Pectoralis Minor

21. Shoulder and Lateral Muscles of the Front Leg
Brachialis
Flexors
Extensors
Extensors
Extensors
Flexors
Extensors
Extensors
Flexors

22. Shoulder and Lateral Muscles of the Front Leg
Lattisimus Dorsi
Acromiotrapezius
Spinotrapezius
Spinodeltoid
Acromiodeltoid
Clavotrapezius
Cleidobrachialis
Serratus ventralis
Triceps Brachii

23. Hip and Lateral Muscles of the Hind Leg
Gluteus superficialis
Semitendinosus
Biceps femoris

24. Hip and Lateral Muscles of the Hind Leg
Gastrocnemius
Soleus
Tibialis Anterior

25. Hip and Medial Muscles of the Hind Leg
Rectus Femoris
Pectineus
Vastus medialis
Adductor longus
Adductor magnus
and brevis
Gracilis

26. Abdominal Muscles External Oblique Internal Oblique
Transversus abdominis ( not shown), is layer below the internal oblique
Rectus abdominis