Sunday, January 8, 2012

Muscles of Neck

Muscles of the Shoulder & Neck:

Acromiodeltoid: This is an elongated slender muscle extending over the anterior surface of the shoulder to the forelimb. To find this muscle you must expose the lateral surface of the upper forelimb and shoulder area by pulling back the skin first. Then toward the very top of the shoulder near the brachiocephalic, you must once again find the point of separation and break through it using the probe to separate out the muscle. Then find the other separation point about a half an inch below and break through it to isolate the muscle.

Masseter muscle: This is located on the neck of the pig slightly above the muscles of the throat. To locate this muscle, you do not have to do anything other than see where your previous throat muscles are located and look at the area slightly above them on either the left or right of the pig and there it is.

Muscles of Shank

Muscles of the shank:
The muscles of the shank are exposed once the skin is removed and can be identified once separated from one another.
Medial View of the Gastonemius:
Lateral View of the Gastronemious:

Gastronemius: This is the large muscle in the calf. To isolate this muscle, use your probe to remove all fat and connective tissue around the shank and lower hind leg so that you will be able to clearly see the separation points of the muscles in the area. On the lateral side, look for a separating point that runs vertically from the middle of the hind leg and break through it with your probe. This should go through to other side separating the muscle from the bone and other muscles attached to it.



Soleus: This muscle lies deep in the gastronemius. Once the gastronemius is isolated, look inside towards the middle of it for a separation point under the fat and connective tissue and break through once found. Keep breaking through the connective tissue to the other separation point to isolate. You may pull out (do not detach) the muscle for a better view if needed.


Tibialis anterior: This is the most ventral muscle of the shank and lies upon the tibia. Once the skin is removed this muscle is easily identifiable and is located at the front of the shank under the knee and above the ankle. Find the two separating points in the front under the fat and connective tissue and break through them to expose the wide muscle of the tibia.

This group of deeper muscles of the lower hind leg originates from the tibia and the distal end of the femur:
Extensor digitorum longus: This muscle is shaped like a narrow band and ends as a long, tough tendon. It is located beside the tibialis major and can be found by locating the edge of the muscle from the separation point between it and the tibialis and continuing to break the connective tissue from underneath to the next separating point from its neighboring muscle.
*Be sure not to rip the muscle off on the other hand as it does turn to a thin tendon on the bottom.
Peroneus longus: This muscle can be located beside the extensor digitorum longus and can be found in the same way as well. All you have to do is follow the separation point from the first side that has already been exposed all the way through to other with your probe separating out the muscle from the others.


Peroneus tertuis: This is the last of the deeper muscles of the shank located next to the peroneus longus. It can be found by locating the last separation point by breaking through the connective tissue and isolating the thin muscle.




Muscles of the Neck and Throat

The muscles of the neck and throat include the Sternohyoideus, Sternothyroideus, and the Sternomastoideus.


Sternohyoideus
Sternohyoideus Close up



The Sternohyoideus is the most ventral. To isolate this muscle:
-Remove any connective tissue to reveal the underlying muscle.

-Locate the edges of the Sternohyoid and use blunt probe to gently separate from the muscles located under it.

-There is one band of the Sternohyoid muscle on either side of the Sternothyroideus.
















Sternothyroideus





The Sternothyroideus is located under the Sternohyoid. To isolate this muscle:

-Cut and reflect the sternohyoid and use blunt probe to separate the muscle from the connective tissue surrounding it.

-Find the flaps of the Sternothyroid and use blunt probe to gently separate from the connective tissue a little.  




Sternomastoideus



The Sternomastoideus is the large “U” shaped muscle located in the ventral and lateral surfaces of the neck. To isolate this muscle:

-Use blunt probe to move any remaining connective tissue.

-Insert blunt probe into the neck, in between the Sternohyoideus and Sternothyroideus and the side of the head.

-Look for the “U” shaped muscle.

Muscles of the Lower Forelimb


Muscles of the Lower Forelimb include the Extensor carpi ulnaris, Extensor digitorum lateralis, Extensor digitorum communis, Extensot carpi radialis and the Brachioradialis. The muscles are located along the lower forelimb and work together to extend and flex the foot and the digits.

-To isolate these muscles remove the connective tissue from the lower forelimb with a blunt probe.

-Look for the muscle separations and use blunt probe to separate the different muscles. 

The muscle are labeled in order below:


Extensor carpi ulnaris

Extensor digitorum lateralis

Extensor digitorum communis


Extensot carpi radialis

Brachioradialis

Muscles of the Upper Forelimb

The Muscles of the upper forelimb include the Triceps Brachii lateral head, the Triceps Brachii long head and the Biceps Brachii.

Upper arm ans shoulder



Triceps Brachii (long head and lateral head)
















The Triceps Brachii is located on the proximal end of the humerus, on the arm below the shoulder. The Triceps Brachii lateral head and the Triceps Brachii long head work to extend the forelimb at the elbow. To isolate these muscles:

-Remove the connective tissue on the arm covering the muscles.

-Look for the edges of the muscles and use the blunt probe to separate and isolate the two triceps Brachii muscles

Biceps Brachii






The Biceps Brachii is located on the radius and the ulna, lies deep to the pectoral and the Brachial muscles. It works to flex the antebracium. To isolate this muscle:

-Remove the connective tissue on the forearm with the blunt probe.
-Look for the edge of the muscle and separate from connective tissue with a blunt probe. 

Muscles of Thigh

Muscles of Thigh:
After the skinning process, the skin is then pulled back exposing the underlying muscle of the thigh, leg and shank. Use your blunt probe to rip through the remaining connective tissue as well as fat to expose more of the individual muscles underneath. Make sure not to rip the muscles by only ripping through layers you are able to see your probe through.


Tensor fasciae latae: This muscle arises from the iliac crest of the thigh and is located above the gluteus medius toward the back of the big. In order to find this muscle, you must expose the lateral surface of the thigh using the process given above. After, look to see where the separations of the muscles are by locating the weakest point to break through using your blunt probe. Push down on the area to make things underneath easier to see and look for a dark extended line in between two pink muscles which is an opening that will allow you to cut through the connective tissues and isolate the muscle.


Vastus lateralis: This muscle is best seen on the lateral surface after the biceps femoris and tensor fasciae latae muscles have been cut and reflected. It originates on the lateral surface of the femur. To find the muscle you must separate it from the rectus femoris which is the first muscle on the thigh beside the tensor fasciae latae and gluteus medius. Find the point of separation at the bottom of the tensor fasciae latae from before and follow through with the blunt probe clearing away the fat and connective tissue. This will separate the bottom half of the rectus femoris and top of the vastus lateralis thus leading to the isolation of both of them.
Lateral View of Rectus femoris:
Medial view of Rectus femoris:
Rectus femoris: This is the first muscle in the thigh that is thick and located on the anterior medial side. It originates from the ilium. In order to locate and isolate the muscle, all you have to do is follow the steps above in the process of isolating the vastus lateralis. Find the point of separation following that of the tensor fasciae latae and continue with the blunt probe clearing away the fat and connective tissue until the muscle is exposed.
Biceps femoris: This is a very large and thick muscle which covers most of the lateral surface of the thigh. It lies posterior to the tensor fasciae latae and below the gluteus maximus. To locate and isolate this muscle, you must first locate the bottom half of the gluteus maximus which will also be the top half of your muscle. To do so, you again look for the opening or separation point by following the darkened line in between the muscles and ripping through it with your blunt probe. Once you have done so, the top of the muscle will be exposed and you will be able to identify the angle it lies in. From there, locate the bottom half of the muscle which will be towards the butt of the pig and once again find the opening to separate and isolate the muscle.


Gluteus Medius: This is a thick and narrow muscle located right below the tensor fasciae latae and lies deep in the gluteus maximus. It originates from the lumbodorsal and gluteal fascia and inserts in the greater trochanter of the femur. Because the top half of the muscle has already been separated from the tensor fascia latae, you now only have to separate the bottom half. In order to isolate this muscle, you must once again locate the opening between the neighboring muscle below and tare through it using your probe separating it from the other and therefore exposing the muscle.


Semitendinosus: This muscle along with the next may be seen superficially on both lateral and medial sides but their major parts are hidden. The semitendinosus on the other hand bisects the biceps femoris and reflects its ends. To isolate it, you only have to locate the bottom half of it since the top is already separated from the biceps femoris. The bottom of it can be found closer to the anus of the pig almost on the medial side where you will find the separation point between its neighboring muscle to cut through. You might need to hold the area with some tweezers so that it does not move too much while separating and isolating as well.


Semimembranosus: This is another large muscle of the thigh which lies posterior and medial to the semitendinosus. You are also able to see this muscle on the medial surface of the thigh. To isolate it, use your probe to remove connective at the opening of the previous separation from the semitendinosus and continue along until it comes out from the other end exposing the other point of separation and isolating the muscle.
Two broad, thin superficial muscles which are visible in the anterioventral thigh area are:
Sartorius: This muscle occupies the anterior half of the thigh and is a flattened band about a half inch wide. You can find it in between its neighboring muscles which are the adductor magnus which is anterior to the semimembranosus and the vastus medialis which is on the opposite side of the vastus lateralis. Look for the separation point in that area by poking around with your probe, clearing away connective tissue, until you find a spot it is able to break through that is not muscle and then cutting through it.
Gracilis: This is the second medial superficial thigh muscle which is also broad and thin. It covers the posterior position of the medial thigh. This muscle can be exposed in the beginning of the dissection when skinning the thigh area. Once the skin is removed, you will notice a muscle which attaches from a point just anterior to the external gentalia up to the shank. Remove the fat and connective tissue surrounding it with a probe to isolate the muscle and see it more clearly.
Vastus medialis: This is a small mass of muscle sticking closely to the rectus femoris. It originates from the head of the femur. To find the muscle, take a look at the lateral side where the vastus lateralis separates from the rectus femoris and use the probe to cut through connective tissue and a little bit of the muscles until you get to the other side. Once the separation point is exposed on the medial side, follow it until the muscles are separated.
Adductor magnus: This is a triangular muscle which lies anterior to the semimembranosus. To find the first separation point, follow that of the semimembranosus all the way down breaking through any connective tissue and fat until you see the edge of the muscle. From the top of it, use the probe to find the other separation point which creates a triangular shape and follow through until you have exposed the muscle.






Muscles of the Chest and Abdomen





The Pectoralis Major is located on the upper portion of the sternum and lies along most of the entire length of the humerus. It works to move forelimb towards the chest. To isolate the muscle:

-Remove any connective tissue on the chest area near the upper forelimb.

-The muscle lies extensively and the striations of the flap of muscle are relatively easy to see.

-The Pectoralis Major will have to be cut and reflected in order to examine the underlying muscle.

Muscles of the Back, Neck, and Shoulder

Muscles that need to be found and isolated: Latissiumus Dorsi, Trapezius, Brachiocephalic, Rhomboideus cervicis, Romboideus capitus, Deltoid, Splenius.

Shoulder Medial View

Latissiumus Dorsi















The Latissiumus Dorsi is a muscle located on the extensively on the dorsal surface (armpit area). It works to move the forelimb. To isolate this muscle:

-Locate a separation between the muscles and use blunt probe to separate the muscle from the underlying connective tissue.



Trapezius


Trapezius and back & shoulder view





The Trapezius is located on and near the first ten thoracic vertebrae. It works to move the forelimb anteriorly. To isolate this muscle:

-Use blunt probe to apply some force on the muscles of the back/ should region of pig, looking for the thin edge of a triangular shaped muscle.

-Follow the line of the muscle, and using blunt probe, poke through the connective tissue.

-Use blunt probe to separate the Trapizuis from the connective tissue.



Brachiocephalic


Brachiocephallic and neck overview















The Brachiocephalic is located from the back of the skull to the humerus. It works to move the forelimb anteriorly. To isolate this muscle:

-Remove some of the connective tissue from the neck area with the blunt probe.

-Make sure that the skin is cut up high enough towards the ear.

-Look for a single striated band of muscle that extends deep towards the head.



View of Neck Muscles



Romboideus cervicis
































The Romboideus cervicis is located near the vertical vertebrae. It works with the Romboideu capitis to hold the scapula in place and it moves it forward. To isolate this muscle:
-Remove some for connective tissue on the surface of the neck.

-Look for a band of muscle that is located on or towards the cervical vertebrae.
-Separate the muscle from the underlying connective tissue.

Romboideus capitis





The Romboideus capitis is located near the ear area, at the back of the skull to the left of the Romboideus cervicis. It works with the Romboideus cervicis to hold the scapular in place and to move it forward. To isolate this muscle:

-Remove some for connective tissue on the surface of the neck and look for the band of muscle towards the ear and into the head.

-Separate the muscle from the underlying connective tissue.




Splenius





The Splenius is located in the back of the neck and lies deep to the Romboideus cervicis and the Romboideus capitis muscles. It works to extend the head and to flex it laterally. To isolate this muscle:
-Fully isolate the Romboideus capitis and Romboideus cervicis muscle and push them to the side. The splenius lies right under those two muscles



Deltoid Muscles




The Deltoid muscles are located on the shoulder, and on the scapular towards the spine. It works to raise humerus. To isolate this muscle:
-Remove the layers of fat and connective tissue from the shoulder and scapula area.

-Look for the edges of the different muscle and use you blunt probe to separate the muscles of the Deltoid.

Skinning

tool kit
blunt probe and scissors

Materials:
- Scissors
- Blunt Probe
- Tweezers (If necessary)







fetal pig with skin attached
fetal pig: skinned
Skinning the Pig:

- Use scissors to make an incision in the skin and cut medially from the jaw to the umbilical cord.
*Be sure to cut through the skin only and not the underlying muscle.

- Cut around the umbilical cord and proceed down to the point slightly above the external gentalia.

- As you cut, lift the skin and use a blunt probe to separate the skin from the underlying muscles by cutting through the connective tissue that is attaching the two together.

- Continue this process up to the dorsal side of the pig.

- Cut along the medial surface of the forelimbs and hind limbs and extend to the wrists and ankles.

-Use the probe once again to separate the skin from the muscle in that area.

- Turn the pig over and complete the skinning of the limbs and half of the dorsal surface leaving the other side of the pig in case of any mistakes.