Muscle Lab

Muscle L

;ab Preparation for dissection Complete the following coloring sheets. You must use the colors that I designate for the muscles listed below Human coloring sheets Muscles of the neck and oral cavity (p 65) Muscles of the thorax and abdomen (p. 69) Muscles of the thorax and abdomen (posterior) (p. 73) Muscles of the thigh (p. 89) Muscles the lower leg (p. 93) Fetal Pig coloring sheets Lateral view muscles Chest view muscles Leg view muscles The 20 muscles you must know Lateral view muscles Splenius-red Masseter-blue Triceps brachii-green Deltoid-yellow Brachiocephalic-purple latissmus dorsi-brown external oblique-black gluteus medius-orange biceps femoris-pink spinotrapezius-gray Chest view muscles

Biceps brachii-aqua Superficial pectoralis-lavender Deep pectoral (anterior and posterior)-yellow green Sternohyoid-blue green Leg view muscles Tensor fascia latae-peach Vastus lateralis-tan Semimembranosis-gold Semitendonosis-light blue Gastrocnemius-navy blue Tibialis anterior-maroon If you have chosen the alternative to dissection, disregard the next section, but please look at the answer sheet for other parts of this assignment

Fetal Pig Dissection Equipment Pig Dissecting tray Dissecting kit Paper towels Dissecting pins Rubber bands

Similarity to human structure -- Pigs are mammals. Consequently, all of the major structures found in humans are present in the fetal pig. With proper directions, they can all be readily found, especially with large, full term fetal pig specimens. There are some differences in structural details, mostly relatively minor in nature.

Muscles of the pig vs. humans In almost every case, fetal pigs have the same muscles as humans, with some small variations in the size and location of some muscles related to the fact that pigs are quadrupedal and humans are bipedal. For example, the major chest and abdominal muscles found in humans are present in the pig. There are some differences in the location of chest muscles that attach to the shoulder girdle. In the hind limb, the pig has the same muscles as humans in the major thigh muscle groups: quadriceps

femoris and the hamstrings. In the hip, however, there are some differences in the gluteal muscles.

Educational advantages of dissection 1. Dissection is a hands-on, investigatory kind of activity for students. Historically, dissection has been the principle tool of investigation for anatomists(2). Dissection allows students to "test the truthfulness" of what they see in books.(3) 2. Dissection engages students in "observational and kinesthetic learning that instills a recognition an appreciation for the three dimensional structure of the animal body, the interconnections between organs and organ systems, and the uniqueness of biological material."(2) 3. Dissection impresses on students the normal variation that is present in the natural world. No two fetal pigs, even though they are perfectly normal, will look exactly the same. In fact, to do well on practicals, students MUST look at several examples of each structure in different animals. Occasionally, quite significant anatomical variations (anomalies) will be noticed. Most would function perfectly normally. This helps to develop "students' powers of observation."(3)

HOUSEKEEPING All pig parts go either into a specimen bag or into the trash. DO NOT leave pig parts in the sink Wrap your pig in wet paper towels before storing. Aprons are available, but you will be responsible for cleaning and storing you apron properly. Goggles are optional unless you are wearing contacts and the fumes are irritating your eyes or if you have some kind of eye disease or infection-then YOU MUST wear goggles. All tables or lab benches must be thouroughly washed down at the end of the period. You must wash your dissection tools and dry them at the end of the period. You must wash your hands at the end of the period ANY INJURY MUST BE REPORTED IMMEDIATELY TO THE TEACHER!

Getting started cm

in

Age in days

1.1

.433

21

1.7

.669

35

2.8

1.01

49

4.0

1.57

56

22.0

8.66

100

30.0 +

11.8

Full term 112-115

The first step is to measure the pig to establish its age. A full term pig is approximately 112-115 days old. The scientific name of the domestic pig is Sus scrofa, which is the same species as the European wild hog.

The pig has been shipped curled in the fetal position; so you may have to tie the legs down to adequately expose the ventral surface. Make incisions along the forearms, up the middle of the neck, at the edge of the jaw and neck, down the midsection, and down the legs as illustrated below. These incisions only cut the skin and the fascia (the layer of connective tissue around muscles and muscle groups). One must be careful not to cut too deeply at this point other wise the muscles will be damaged.

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What's pink on the inside and transparent on the outside? Answer: A pig in a sandwich bag

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What do you do with your pig when he loses his tail? Answer: Take him to any 're-tail' store.

START HERE>>>>>>

The next step is to remove the pig’s skin. This must be done with great care to avoid damaging underlying muscle tissue. Do not use a scalpel or any other sharp tool for this job. A blunt probe or your fingers work best!!! Use scissors to cut off pieces of loose skin.

You do not need to remove the skin of the “hands”, tail, back of the head and feet. Dispose of all skin in the trash NOT the sink

Finding a muscle and its parts You must know the general origins and insertions for all of the muscles in your list. You can determine these in the following manner: 1. Find the general location of the muscle. Let's use the biceps brachii as an example. You should know by now that the biceps brachii is located on the anterior aspect of the arm. 2. Contract the muscle. Your forearm should move up towards your arm when you contract the biceps brachii muscle. 3. Determine the movement. When you contract your biceps brachii, the angle at your elbow decreases as your forearm moves up towards your arm. This type of movement is called flexion. 4. Feel the muscle. You should be able to determine that the biceps brachii runs the length of your arm from the shoulder to the forearm. Now contract the muscle. The end of the muscle that moves the forearm towards the arm is the insertive end. 5. Determine the insertion and origin. You have just determined that the general insertion of the biceps brachii is the forearm. Now you must determine the origin. You felt the muscle extend up to the shoulder, so you should deduce that the general origin of the biceps brachii is the pectoral girdle.

Finding and Isolating the Muscles The proper dissection of muscles involves carefully separating one muscle form the other so that they can be identified. (Also called isolating a muscle) Some muscles will need to be transected (cut) to view muscles underneath them. To dissect (isolate) a muscle you should remove all clear connective tissue and free it so that it is only attached at the ends. If you look carefully, you will see the directions of the muscle fibers. Use these to help you to figure out where one muscle ends and another begins. Pulling in slightly different directions on two adjoining muscles will usually allow you to see the natural line of cleavage (separation). Be patient with yourself, this is tough! Once you have identified the cleavage line use your blunt probe to break through the connective tissue that connects the muscles. If the muscles separate cleanly, you have found the correct cleavage line. If the separation is ragged or “chewed up” looking then try the muscle on the other side of the animal (if there is one!) I have chosen major muscles that will be the easiest to dissect.

Actual Pig Muscle Dissection Pig trunk and leg muscles Place pig on its back Remove fat and fascia from the neck and chest areas

Anterior neck muscle Sternohyoid-The sternohyoid is a thin double strap like muscle that runs along the midline of the neck from the chin to the superficial pectoral muscle. You will see large masses of thymus tissue under this muscle. Isolate this muscle from the surrounding muscles. Masseter-is a large rounded muscle found below and in front of the ear. It originates on the zygomatic process and inserts on the mandible. Isolate this muscle from the surrounding muscles.

Chest muscles Superficial pectoralis-is a thin flat band of muscle that can be seen rising from the sternum covering the deeper pectoral muscles. Once you identify and isolate this muscle you will need to transect it to see the muscles under it. Anterior and posterior deep pectoralis-is under the superficial pectoralis. The posterior deep pectoralis is inferior to the superficial pectoralis. It runs between the sternum and the ribs. It’s fibers run in a diagonal direction. The anterior deep pectoralis is a strap like muscle, again under the superficial pectoralis. It extends from the posterior deep pectoral over the shoulder to the scapula. Release this muscle from the adjoining muscles.

Abdominal muscles

External oblique-A sheet like muscle that covers the lower belly. It runs from the Latissmus dorsi down to the animal’s crotch area. DO not isolate this muscle at this time.

Place pig on its side Trunk and Chest Muscles Brachiocephalic-A triangle shaped muscle, just below the pig’s ear. It inserts on the humerus and originates on the skull. Release this muscle from the adjoining muscles. Spinotrapezius-is the most posterior of the shoulder muscles. It runs from the thoracic vertebrae (origin) to the scapula (insertion). Isolate this muscle from the surrounding muscles. Latissmus dorsi-covers a large portion of the lateral surface. This muscle is thin and sheet like. On the dorsal side it is covered by the spinotrapezius. The muscle originates on the vertebrae, and runs downward where it insets on the humerus. DO not isolate this muscle at this time. Deltoid-is a thin band that inserts on the humerus. It originates on the scapula. It lies directly posterior to the anterior deep pectoral muscle. Isolate this muscle from the surrounding muscles. What's pink, dirty, and goes putt, putt, putt? Answer: A pig trying to play golf Splenius-is found to the back (caudal to) of the ear. It is surrounded by the rhomboid on the top and the serratus ventralis on the bottom. Isolate this muscle.

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Why is the letter 'K' like a pig's tail? Answer: because it's at the end of pork.

The Forelimb Muscles Place pig on back remove the fat and fascia from the arm Biceps brachii-is very small in the pig. It originates on the radius and inserts on the shoulder (scapula). It is immediately superior to the triceps brachii in this position. Isolate this muscle.

Place pig on side Triceps brachii-runs along the posterior of the humerus. It is large and fleshy. Two separate “heads” the long and the lateral are visible from your view. All heads originate on the humerus and insert on the ulna. Isolate the long and lateral heads. Transect the lateral (lower) head exposing the third (medial) head.

The Hind limb Muscles Remove fat and fascia from the leg. Do not cut through the fascia lata which is a tough white covering in the front of the thigh from the hip to the leg. Tensor fascia latae-is wide and thin at its origin on the iliac crest and narrows out as it approaches its insertion on the fascia latae. Isolate and transect this muscle. Gluteus medius-is found under the tensor fascia latae that you just transected. It is a thick, fleshy muscle. It originates on the lower back and inserts on the top of he femur. Isolate this muscle. The Biceps femoris, the semitendonosis and the semimembranosis together form the hamstring group of the leg. Biceps femoris-is a large triangular muscle immediately anterior to the tail and runs down the thigh. Both heads originate on the ischium and one head inserts on the femur and the other on the proximal tibia. Isolate and transect this muscle. This will reveal he next 3 muscles. Semitendonosis-is the lowest of the three muscles revealed. It originates on the pelvis and inserts on the tibia. Isolate this muscle. Examine how the insertion end is mostly tendon-thus its name. Semimembranosis-is the central muscle revealed. It is a large muscle partly covered by the semitendonosis. It originates on the pelvic girdle and inserts on the tibia. Isolate this muscle.

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Did you hear about the fellow who was arrested yesterday for stealing a pig? He would have gotten away with his crime, but the pig squealed.

Vastus lateralis-is the uppermost of the 3 muscles. It is a large muscle, part of the quadriceps group. It originates on the femur and inserts on the patella. Isolate this muscle. Gastrocnemius-is posterior to the lower leg. It is large, rounded and fleshy. It originates on the femur and inserts on the Achilles’ tendon of the calcaneous. Isolate this muscle. Tibialis anterior-is anterior to the tibia. It originates on the proximal tibia and inserts on the second metatarsal. Do not isolate this muscle at this time. •

How do you keep a pig from oinking in the back seat of your car? Answer: put him in the front.