Slide 2 Vesterbys Cat Dissection 2013 Slide 3 Introduction (read
this first) Welcome to cat dissection 2010! Each day will begin
with logging on to your computer, putting on required protective
gear, and removing your cat from the cat house. Attendance is taken
immediately, so be here on time! Make this class a priority and do
not come in late from your previous class or schedule lessons
during this time. You are responsible for letting Mrs. V know if
you are missing a teammate, so attendance can be recorded. Each day
will end with the cat going back into storage, all unneeded/loose
tissue going into a designated container, cleaning of the tools,
sink, and table surface, thorough washing of hands, and return of
all tools and protective gear to correct areas. You are to maintain
a tidy work area. Personal items (books, notebooks, beverages,
etc.) are to be left at your desk. Work diligently to get as much
done each day as possible. Good luck! Slide 4 Step 1: Get dressed.
Use the following check list to judge your attire: shoes that cover
your entire feet goggles covering eyes gloves apron long hair tied
back Slide 5 Muscles of the Lower Leg: 1. Show time!! Expect to be
busier than a three-legged cat in a sandbox. Place your cat in the
pronated position (on its belly). Locate the cats foot and heel.
Make sure the skin is removed down to the heel. Attached to the
calcaneus find a white, shiny, round band of dense connective
tissue (c.t.) the Achilles tendon(39 ). 2. With a dull probe
separate the Achilles tendon from the surrounding tissue. 3. Two
muscles are attached to the Achilles tendon. Gastrocnemius(31) is
the larger, superficial muscle on the posterior surface of the
lower leg. The second calf muscle we will study is named the
soleus(32). It can be identified by the following clues: a) it is
attached to the Achilles tendon; b) it lies beneath gastrocnemius
on the lateral surface of the leg. (Warning: gastrocnemius
separates into right and left heads, near the knee. Dont mistake
one of them for the soleus.) 4. Trace gastrocnemius up the leg. At
the back of the knee, between the heads of the gastrocnemius and
between two of the upper thigh muscles you will find a fat-filled
pit at the back of the knee called the popliteal fossa. Clean the
fat out of the fossa so that you can follow the heads of the
gastrocnemius to the femur. 5. Place the cat into the supinated
position. Locate the tibia at the anterior surface of the lower
hind leg. Tibialis anterior(35) is a good sized, torpedo-shaped
muscle lying just lateral to the tibia. A c.t. sheath (called a
fascia) covers the muscle. Remove enough of the fascia to clearly
see tibialis anterior and free its borders. Follow its tendon
across the ankle to the medial side of the foot. Slide 6 Slide 7
Superficial Muscles of the Medial Thigh: 1. With the cat in the
supinated position, two superficial muscles can be viewed on the
medial surface of the thigh. Sartorius (1) is a thin, flat muscle
covering the anterior, medial surface of the thigh. It goes from
the hip to the patella. Free its sides, lift it up and cut it in
half, to allow viewing of the deeper muscles. 2. The other
superficial muscle is named gracilis (8). It is similar to
sartorius in shape, but covers the posterior medial surface of the
thigh. It originates near the pubic symphysis and inserts on the
lower leg below the patella. Free its border near the patella, so
that the muscle can be folded back like a flap to expose the deeper
muscles. Slide 8 Deep Muscles of the Medial Thigh: 1.
Semimembranosus is one of the three hamstring muscles. It is a
large, thick, blocky muscle lying under gracilis. There is a
natural deep split between it and the adjacent adductor femoris. On
an average-sized cat, semimembranosus is about an inch wide from
its anterior to its posterior border. Warning: A false split can
often be made in the middle of semimembranosus or in the middle of
adductor femoris. 2. Next find two adductor muscles located on the
medial thigh. The fibers of these muscles run from the pubic
symphysis to the femur. Adductor magnus (femoris) is the wide
muscle lying in front of semimembranosus. Adductor longus lies in
front of adductor femoris. It is a narrow band of fibers, which can
be traced to the anterior (and superior) tip of the pubic
symphysis. Slide 9 Muscles of the Anterior Thigh: The four deep
muscles of the anterior thigh make up a group called the quadriceps
femoris muscle group. The key to identifying the members of this
group is to locate rectus femoris. This muscle runs from the hip to
the patella, down the anterior surface of the thigh beneath
sartorius. It is round and more or less cylinder-shaped. Once
rectus femoris is located, vastus lateralis and vastus medialis are
easy to find. They are bulky muscles lying lateral and medial to
rectus femoris. They wrap around it, much like a bun wraps around a
hotdog (rectus femoris being the hotdog). Vastus intermedius is
tricky to locate because rectus femoris covers it up. Cut rectus
femoris in half and pull back the ends. Vastus intermedius is just
underneath rectus femoris. Vastus lateralis and vastus medialis are
in contact with vastus intermedius on its medial and lateral
borders. (The medial border separates poorly.) Push a probe through
vastus intermedius. You should hit the femur underneath.
1.Sartorius 2.Tensor fascia latae 3.Rectus femoris 4.Vastus
medialis 5.Pectineus 6.Adductor longus 7.Adductor femoris
8.Gracilis 9.Semimembranosus 10. -------------------- 11.Vastus
lateralis 12. Iliopsoas 13.Vastus intermedius Slide 10 Muscles of
the Posterior Thigh: 1. Return your cat to the pronated position.
The three muscles at the back of the thigh are called the hamstring
muscle group. The lateral hamstring muscle is called biceps
femoris. This large, thick, flat muscle covers the lateral surface
of the popliteal fossa. It overlaps the lateral head of the
gastrocnemius muscle. Clean enough c.t. and fat off its surface to
find the anterior and posterior borders. 2. At its posterior
border, biceps femoris touches a second hamstring muscle,
semitendinosus. This muscle is a long narrow muscle which passes
from the hip region, along the medial surface of the popliteal
fossa to the medial side of the lower leg. Separate out
semitendinosus. 3. The third hamstring muscle, semimembranosus,
lies anterior and medial to semitendinosus. This muscle lies under
gracilis and was already identified along with the muscles of the
deep medial thigh. 1. sartorius 2. tensor fascia latae (probe under
IT tract) 3. vastus lateralis 4. biceps femoris 5. semitendinosus
6. caudofemoralis (not in humans) 7. gluteus maximus 8. gluteus
medius 9. semimembranosus 10. gracilis Slide 11 Muscles of the Hip
and Butt: Locate the position of the greater trochanter (large
protrusion from the proximal end of the femur) by moving the leg
and pressing on the muscles. You should be able to feel it as a
prominent bony bump. Superior to the greater trochanter find the
iliac crest. Also locate the base of the cats tail. The gluteal
(butt) muscles lie superior to biceps femoris between the tail,
iliac crest and greater trochanter. Now that you know the general
location of the muscles, you must remove the c.t. that obscures
them. First, remove the c.t. and fat down to the shiny dense c.t.
fascia that tightly covers all the muscles in this area. In order
to really find the muscles, the fascia must now be removed. Do this
by lifting up on the fascia and carefully cutting the fibers away
from the backside of it. When you are done, you should be down to
bare muscle fibers. If you removed the fascia completely, the
muscles are fairly easy to locate. Gluteus medius is a large
triangular muscle whose fibers run from the iliac crest to the
greater trochanter. It lies lateral to the base of the cats tail
and sacrum. Gluteus maximus lies along the inferior border of
gluteus medius. It is a smaller muscle running from the base of the
tail to near the greater trochanter. The final muscle found in this
area is named tensor fascia latae. This thin muscle covers the
lateral surface of the hip and blends into a sheet of c.t. called
the iliotibial (IT) tract. 1. sartorius 2. tensor fascia latae with
IT tract 3. vastus lateralis 4. biceps femoris 5. semitendinosus 6.
caudofemoralis (not in humans) 7. gluteus maximus 8. gluteus medius
9. semimembranosus 10. gracilis Slide 12 1. sartorius 2. tensor
fascia latae with IT tract 3. vastus lateralis 4. biceps femoris 5.
semitendinosus 6. caudofemoralis (not in humans) 7. gluteus maximus
8. gluteus medius 9. semimembranosus 10. gracilis Slide 13 The Deep
Muscles of the Back: From the hip to the neck, the vertebrae and
ribs are covered with a thick braided muscle called erector spinae.
This is actually a group of muscles, but we will not learn them
individually. This muscle group is deep to the shoulder muscles. It
approaches the surface in the middle back where it is covered by a
tough white sheath of c.t. called the lumbodorsal fascia. Remove a
small strip of this fascia to get a peek at the erector spinae. The
fascia is actually composed of two layers, so you will need to
remove them both. Slide 14 Muscles of the Abdominal Wall: Place the
cat in the supinated position. Four flat, very thin muscles make up
the abdominal wall. They are hard to identify unless you carefully
observe the direction that the muscle fibers run. Down the middle
of the abdominal wall from the sternum to the pubic symphysis
locate a narrow band of c.t. which makes a white line called the
linea alba. On either side of the linea alba lies a band-like
muscle about one inch wide. This muscle is named rectus abdominis.
It is attached to the lower ribs and sternum on one end and pubic
bones at the other. The fibers in this muscle run lengthwise on the
cat (from head to tail). To see the muscle fibers, remove a piece
of the fascia covering the surface. Dont waste your time cleaning
the whole muscle. The second abdominal muscle we will find is
called external oblique. It is the superficial muscle of the
lateral abdominal wall. It can be found by cleaning c.t. and fat
off the abdominal wall lateral to rectus abdominis. You can be sure
you have it by the direction its fibers run. Starting from the
lower ribs and upper back, the fibers wrap around the cat and pass
down toward the pelvis at about a 45-degree angle. Look through all
of the photos on the following slides, before proceeding. Also
check out the demo-cat! Slide 15 Begin by loosening the connective
tissue with a dull probe, as shown. External oblique Connective
tissue and fat Be careful up here! Dont remove chest muscles! Stay
below the ribs. Slide 16 In this picture, the triangle of loosened
c.t. that the probe was under has been removed. The c.t. over
rectus is hard to remove, so just do it in a small area, External
oblique Transverse abdominis Rectus abdominis Slide 17 External
oblique is loosened and flipped back to show internal oblique. You
do not need to expose as much of the muscles, as shown here, unless
your c.t. happens to come off easily. Ribs-you dont need to go up
this far. Slide 18 The muscle just deep to external oblique is
cleverly called internal oblique. The easiest way to see it is to
free the medial edge of the external oblique next to the rectus
abdominis and peel external oblique back. The fibers of internal
oblique run perpendicular to those of external oblique. The fibers
of this muscle do not extend as far around the cat toward rectus
abdominis as do those of external oblique. The last abdominal wall
muscle lies underneath the internal oblique muscle even further off
to the side. This paper-thin muscle, called transversus abdominis,
can be found by carefully peeling back internal oblique. Its fibers
run more or less across the abdomen perpendicular to those of
rectus abdominis. If you cant find it, look further off to the
side. Slide 19 Superficial Muscles of the Back Latissimus dorsi is
fairly easy to find. It is a wide thin muscle that originates on
the lumbodorsal fascia. Trace the muscle across the ribs and under
the arm to where it is attached to the humerus. Warning: It often
merges with the pectoralis muscles, a skin muscle, c.t. and fat,
just behind the armpit. You will have to do a bit of careful
scraping and cutting to expose this muscle. The cat has three
trapezius muscles called clavotrapezius, acromiotrapezius and
spinotrapezius. They are named from superior to inferior. All three
originate along the midline on the spinous processes of the
vertebrae. Clavotrapezius is a triangular-shaped thin muscle that
originates at the back of the head and neck. It is said to insert
on the clavicle. However, at the clavicle, the same triangular
muscle mass simply changes names and becomes the clavodeltoid
muscle. The border between the clavotrapezius and acromiotrapezius
muscles consists of a fairly wide, clear c.t. partition. You should
be able to find it if you carefully clean c.t. in the right area.
1. External oblique 2. Latissimus dorsi 3. Spinotrapezius 4.
Acromiotrapezius 5. Clavotrapezius 6. Levator scapulae ventralis 7.
Spinodeltoid 8. Acromiodeltoid 9. Clavodeltoid 10. Triceps brachii
(lateral head 11. Triceps brachii (long head) Slide 20 Before
finding the other trapezius muscles, you should locate some
important landmarks on the scapula. By moving the arm, you should
be able to locate the borders of the scapula under the muscles.
Near the shoulder joint, you should be able to find feel a
prominent, hard bump by pressing with your fingers. This bump is
the acromion process. Running more or less inferiorly from the
acromion process is a bony ridge on the scapula, the spine of the
scapula. This ridge can also be located by pressing your fingers
into the muscle. The acromiotrapezius muscle originates between the
scapulae in a thin strong sheet-like tendon called an aponeurosis.
(you may have already removed it). It inserts on the acromion
process and the spine of the scapula. The spinotrapezius muscle is
situated inferior to acromiotrapezius. It inserts on the inferior
part of the spine of the scapula. It overlaps a part of latissimus
dorsi. The border between spinotrapezius and acromiotrapezius is
another indistinct c.t. partition. 1. External oblique 2.
Latissimus dorsi 3. Spinotrapezius 4. Acromiotrapezius 5.
Clavotrapezius 6. Levator scapulae ventralis 7. Spinodeltoid 8.
Acromiodeltoid 9. Clavodeltoid 10. Triceps brachii (lateral head
11. Triceps brachii (long head) Slide 21 Superficial Muscles of the
Shoulder: When you first look at your cats shoulder, you wont see
the muscles as they appear in the picture, because they are
obscured by thick, close-fitting c.t. Clean away this c.t. down to
the muscle fibers. Locate the spine of the scapula, acromion
process, and clavicle, as they will serve as landmarks.
Clavodeltoid has probably already been located, but find it again.
This muscle is continuous with clavotrapezius. Clavodeltoid starts
at the point where clavotrapezius leaves off, on the clavicle.
Clavodeltoid passes over the shoulder joint out to the forearm. It
shares a border with pectoralis major on the anterior surface of
the cats arm. NOTE: This muscle is also referred to as
clavobrachialis. Locate the acromion process. The acromiodeltoid
muscle is a narrow triangular muscle that lies behind clavodeltoid.
It has a narrow base near the acromion process and an insertion
about halfway down the upper arm. The third deltoid muscle,
spinodeltoid, is rather difficult to find unless you did a good job
cleaning c.t. from the region of the spine of the scapula. The
origin of this muscle is along the spine of the scapula. From
there, it runs forward to contact the rear edge of the
acromiodeltoid. 1.Latissimus 2.teres major 3. infraspinatus 4.
5.spinodeltoid 6. Triceps long head 7. triceps lateral head
8.acromiodeltoid 9. Clavodeltoid (clavobrachialis) 10.supraspinatus
11. levator scapulae (ventralis) 12.clavotrapezius 13.sternomastoid
14. acromiotrapezius 15.spinotrapezius Slide 22 Muscles of the Arm
Triceps brachii has three divisions or heads. The long head is the
large, thick muscle along the posterior surface of the arm. The
lateral head is equally easy to find. It is a large thick muscle
mass on the lateral surface of the arm anterior to the long head
and inferior to spinotrapezius. The third, medial head, can best be
found by cutting the lateral head and looking for a relatively
narrow muscle wedged in between the lateral head, the long head and
the humerus. Warning: the medial surface of the brachium is covered
by a thin superficial muscle, epitrochlearis, so the medial head
cant be seen there. Remove and disregard epitrochlearis. Brachialis
is a torpedo-shaped muscle closely associated with acromiodeltoid.
It lies on the anterior lateral surface of the upper arm near the
lateral head of triceps brachii. Clean c.t. and probe to find it.
Biceps brachii lies on the anterior medial surface of the upper
arm. To find it, flop your cat over on its back and move the
pectoralis muscles toward the head. Look for another torpedo-shaped
muscle, but one larger than brachialis. 1. Triceps brachii (lateral
head) 2. Triceps brachii (medial head) 3. Triceps brachii (long
head) 4. Acromiodeltoid 5. Spinodeltoid 6. Clavodeltoid 7.
Brachioradialis (omit) Slide 23 Deep Muscles of the Scapula: Before
you go on, cut the trapezius muscles, latissimus dorsi and the
pectoralis muscles on the side so that you can explore the deep
muscles of the scapula. It is suggested that you save the side you
have already dissected and cut the other side. Three powerful deep
shoulder muscles have the flat surfaces of the scapula as their
origin. Locate the entire spine of the scapula. Move aside the cut
trapezius muscles. Deep to acromiotrapezius, above the spine of the
scapula, is a large muscle supraspinatus (3). It fills the
supraspinous fossa. If you probe through supraspinatus, you will
hit the scapula beneath it. Pull down the cut edge of latissimus
dorsi to expose the region below the spine of the scapula and find
another thick muscle attached to the scapula. It is infraspinatus
(4). It passes anteriorly to the humerus and deep to spinodeltoid.
It fills the infraspinous fossa. Grab the scapula and rotate it out
so the shoulder goes toward the chest. At the same time, bring the
vertebral border of the scapula away from the spine. The purpose of
this operation is to stretch out the rhomboid (11 & 12)
muscles, which lie deep to acromio- and spino- trapezius. Their
fibers run from the spinous processes of the vertebrae to the
vertebral border of the scapula. (Hint: The vertebral border is
perpendicular to the spine of the scapula.) Slide 24 Deep Scapula
Locate the axillary border of the scapula. Teres major (6) is a
chunky round, little muscle that runs along this border up to the
humerus. If you look closely, you should be able to find the
clear-cut separation between teres major and subscapularis. A probe
pushed through supraspinatus, infraspinatus or subscapularis will
hit the scapula. One passed through teres major will not, since it
lies along the edge of the scapula, not on its surface. While the
cat is on its back, find serratus ventralis (4). This muscle has
several finger-like divisions that attach to several of the lower
ribs. Its superior end is attached to the inferior point of the
scapula. Fat often obscures the fingers of this muscle and must be
removed to see them. Now, flip the cat over on its back and flop
its arm and scapula out. The under surface of the scapula, that is
normally next to the ribs, is covered by subscapularis (5), which
fills the subscapular fossa. Slide 25 1.Pectoantebrachialis
2.Pectoralis Major 3.Pectoralis Minor 4.Xiphihumeralis (not in
humans) 5.Linea alba 6.Epitrochlearis 7.Triceps Brachii (long head)
8.Teres Major 9.Subscapularis 10.Serratus Ventralis (anterior in
humans) 11.Latissimus Dorsi Slide 26 Superficial Chest Muscles:
These muscles are hard to dissect because they are thin,
overlapping and are joined tightly together by connective tissue.
First, find the sternum from the manubrium to the xiphoid process.
The chest muscles originate on the sternum. Second, move the cats
arm around to locate its elbow, shoulder, and humerus. The chest
muscles insert along the front of humerus. Now, on one side only,
clean off the c.t. right down to the muscle fibers. Next, its time
for a little feline massage. Give the cat a good rubdown with a
paper towel to dry the chest. If you do this thoroughly, you should
be able to locate the faint white cleavage lines where the muscles
come together. The superior border of the pectoralis major (3) is
in contact with clavodeltoid. The border begins at the tip of the
manubrium and runs out the arm. Locate the cleavage line and
separate these two muscles with careful pulling and cutting. You
will also loosen a cat muscle called pectoantebrachialis (4), that
lies over this area. Now we will look for the hard-to-find cleavage
line between pectoralis major and pectoralis minor. Look for it
along the sternum about three inches below the superior border. At
this cleavage line, pectoralis minor dives under pectoralis major
so the separation you make will go down and forward under
pectoralis major. A warning: inferior to the true pectoralis
major/pectoralis minor cleavage line, there is often a false
cleavage plane that will split pectoralis minor in two. You will
know you have the wrong cleavage plane if it goes in and back
instead of in and forward. Pectoralis minor lies deep to pectoralis
major. Trace it forward to the humerus. Its inferior border is a
fairly distinct line where it makes contact with a muscle we will
not dissect, xiphihumeralis (1). The superior border of pectoralis
minor lies beneath the body of pectoralis major, about halfway
toward the head. This edge can be found by probing under pectoralis
major. Slide 27 Slide 28 Muscles of Chewing: Clean the skin off one
side of the cats head as far forward as the eye, as far backward as
the external auditory meatus (remove the external ear), as far up
as the middle of the top of the head and as far down as the
mandible. Try not to damage nearby structures such as the salivary
glands (see photo on next slide). Now locate the zygomatic arch by
probing. It runs all the way from just below the eye back to the
external auditory meatus. Clean the c.t. and fat off all the way
down to bare bone and muscle. The masseter muscle can now be found
lying inferior to the zygomatic arch. Its upper end attaches to the
arch and its lower end goes around the edge of the mandible to
attach to the inside. The temporalis muscle originates on much of
the side of the cats head and passes underneath the zygomatic arch
to insert on the mandible. Starting near the top of the head,
remove c.t., fat, and superficial skin muscles until you can see
the glistening sheath covering temporalis. Trace the muscle down to
where it passes beneath the zygomatic arch. Slide 29 Slide 30
Notable Structures of the Neck 1. Parotid gland 2. Sublingual gland
3. Submandibular gland 4. Esophagus 5. Tongue 6. Masseter muscle 7.
Larynx 8. Trachea Slide 31 Muscles of the Floor of the Mouth:
Remove the thick layer of c.t. covering the floor of the mouth (the
area under the chin lying between the two halves of the mandible).
The digastric muscles are narrow bands of muscle that lie along
side the inner surface of the mandible. Their fibers run parallel
to the mandible. The mylohyoid muscle makes up the floor of the
mouth. Its fibers originate on the mandible and run toward the
midline to meet there. The lateral edges of mylohyoid are deep to
the digastric muscle and can be separated from it with a dull
probe. 1.Diagastric 2.Mylohyoid 3.Omit 4.Sternohyoid
5.Sternomastoid 6.Clavotrapezius 7.Omit 8.Masseter 9.Cleiodmastoid
Slide 32 Slide 33 Muscles of the Anterior Neck Region These muscles
should be dissected on the side of the cat from which you removed
the ear. The landmarks we will use to find these muscles are the
external auditory meatus, the mastoid process behind it, the
sternum, and the clavicle. The cats clavicle is a tiny bone about
the size of a paper match. It lies between the shoulder and sternum
buried in muscle. Pinch the muscle in this area to locate the
clavicle. The sternomastoid muscle is a strap-like muscle that runs
on the surface of the neck from the mastoid process to the superior
top of the sternum. Unfortunately, this muscle is obscured from
view. At the upper end, a salivary gland and blood vessels get in
the way. The middle part is crossed by a large vein. The entire
neck region is covered by an especially thick layer of c.t. Remove
the c.t. from the surface of the muscle and from between the muscle
and the blood vessel and salivary gland. Once the anterior border
of the muscle is free, start to work your way underneath with a
dull probe. Also, work beneath the muscle from the posterior border
until you have freed the muscle from mastoid process to sternum.
(Warning: Just above the sternum there is often a confusing set of
cross fibers which run from the right to the left across the
sternomastoid muscle. You can safely remove these fibers.) The
cleidomastoid muscle lies deep to the sternomastoid muscle. Trace
it from the clavicle to the mastoid process. Separate the
sternomastoid and cleidomastoid using a dull probe. Slide 34 5:
sternomastoid Slide 35 4: cleidomastoid (3 is sternohyoid)
