Anatomy Lab by linzhengnd



           Anatomy Lab
Investigating Skeletal Muscles and Joints of the
                 Chicken Leg
                    Shivani Shah
Anatomy Lab

   1. Skeletal muscles are one of the three different types
      of muscles found in the human body. In appearance
      they are single celled, striated (they have lines on
      the surface), multinucleate and they are pinkish red
      in colour. Their smooth texture help maintains a
      smooth body contour and they are found attached
      to the skin on the face and the end of bones for the
      purpose of support and movement. Skeletal muscles
      are controlled by the nervous system and they
      produce voluntary movement, this means that they
                                                                  Figure 1: Skeletal Muscle found in Chicken Leg
      only produce movement when an individual wants
      them to do so. An example of this type of movement is an individual moving their arm so that
      their palm is drawn close to their shoulder. Specifically, this type of movement is known as
      flexion as the radius (insertion) is drawn closer to the humerus (origin). Skeletal muscles also
      provide four other types of movement; extension, rotation, supination, and dorsiflexion. Aside
      from movement, their three other functions are to generate heat, stabilize joints and maintain
      posture. Skeletal muscles generate heat as they use energy to produce contractions; however
      most of this ATP energy is escaped as heat and is used to regulate the body’s normal body
      temperature. They are able to stabilize joints as these muscle tendons are used to keep joints in
      place. Lastly, they help maintain posture as they continuously make minor adjustments so that
      one has an erect posture despite the fact that the force of gravity is constantly being applied.

                 On the contrary, ligaments are groups of fibrous tissues that prevent bone to bone or
                                                          bone to cartilage contact. This is to avoid the
                                                          friction of two bones or one bone and cartilage
                                                          rubbing against each other. They are made out of
                                                          strands of collagen fibres, and are tightly arranged
                                                          in criss-cross patterns to produce strength and
                                                          stability along these joints, so that they do not
                                                          become loose and prevent tearing from occurring.
                                                          Their main purpose is to ensure that bones are
                                                          properly aligned and abnormal movements of
                                                          these bones are prevented. In other words this
          Figure 2: Strands of white stringy material are
          ligaments found in the chicken leg
                                                          means that they control the range of motion for
                                                          bones, this is to prevent muscle damage. For
       example ligaments prevent the elbow from being able to hyperextend, as they are not able to
       bend backwards.

              Together skeletal muscles and ligaments are effectively used to produce movement in
       the body, as one cannot work without the help of the other. Skeletal muscles are in charge of
       producing the actual movement in the body while the ligament is in charge of ensuring that
        range of the movement is able to occur without any damage. They are also in charge of making
        sure that the joints are stabilized and in place.

    2. Hypertrophy is derived from the ancient Greek
       meaning “excess nourishment.” Along the same
       lines, hypertrophy refers to the increased size of
       organs pertaining to the body due to the
       enlargement of its component cells. Hypertrophy
       can occur in many different parts of the body; the
       heart, breasts, biceps are just a few examples. This
       process usually occurs from excess weight training
       but can also occur from the absorption of
                                                            Figure 3: Enlarged skeletal muscle found in
       hormones. An example of this would be the
                                                            chicken leg due to abnormal hormonal
       enlarged rectus femoris (thigh muscle) found in the  growth
       chicken leg, due to the feeding of chemicals and
       hormones to produce rapid and increased muscle growth.

Atrophy is often referred to as wasting. More specifically, it illustrates the process of degeneration of
either all or one specific aspect of the body. The two most prominent reasons for this to occur is disease
or disuse of that organ or aspect in the body. This is due to lack of nourishment, poor blood circulation,
inadequate nerve connection, and even the absence of
exercise for a long period of time. Precisely, muscular
atrophy is due to the degeneration of myocytes.
Myocytes are the type of cells that are found in muscles,
and they are formed from myoblasts. This degeneration
leads to further complications as this is the reason why
muscles decrease in mass and size. Normally, the
degeneration of myocytes is due to the occurrence of
other complicated diseases such as HIV, and cancer.
This disastrous process leads to the weakening of the
muscles making daily routines very difficult to undergo.
An example of atrophy is cerebral atrophy which is the degeneration of brain tissues and cells which
results in speech and vision impairment.

3. Isotonic exercise includes both concentric and eccentric
phases. The concentric phase consists of the muscle
shortening when the weight is being lifted. The eccentric
phase depicts the aftermath; when the weight is brought
down and under tension the muscle lengthens. It is proven to
tone these muscles and enhance their natural shape.
However, for a short period of time this muscle weakens as
the amount of tension applied to it is so great, for the body to
cope with this weakened muscle the muscle cell divides to replace it making it stronger. An example of
isotonic exercise is lifting weights above our head. On the other hand isometric exercise has to do with
exercises that keep the joint and muscles in a static, stationary state. This occurs when there is tension
on the muscle but nothing allows this muscle to lengthen, this in turn puts strain on the muscle and
eventually strengthens them. An example of isometric exercise is laying on your back and stretching
your legs into the air, and holding them in this position.

4. To lift a heavy load in front of one without causing injury to his back muscle, a co-worker should use
his legs and bend down. When lifting heavy
objects a worker should always lift the object
close to the body as this offers more stability
and balance. He should also ensure that he
keeps his back straight at all times and bend
down with his knees using his legs for
strength and. This is because the legs are
naturally much stronger than the back. It is
also important to tighten the stomach
muscles as this puts less pressure on the
spine and back muscles.

5. It is evident that a professional baseball pitcher has one arm that is
more muscular than the other. This makes sense because it only takes
one arm to pitch the baseball. When pitching, many muscles in the body
are involved to ensure that the pitch is as successful as it can be. First,
the hip bone is rotated to provide more force on the ball, the bicep
muscles also contract during this time, and this means that the biceps
and the brachioradialis move closer together as they are being flexed.
Flexion refers to a muscle movement in which there the angle at the
joint decreases and two muscles are being brought closer together.
Following this, the pitcher has to then extend the brachioradialis to
throw the ball, this means that opposite is happening and the muscular
movement type is extension, as the biceps and the brachioradialis move
further apart, and the angle at the joint increases. The shoulder (deltoid) also rotates to ensure that the
ball travels far and at a fast speed. Furthermore, there is dorsiflexion as when the pitcher is about to
release the baseball from his hand he must take a step up. Therefore, a baseball pitcher would have one
arm that is more muscular than the other because of the constant forces applied to these muscles. The
constant extension, flexion and rotation strengthen these muscles and in turn eventually lead them to
becoming bigger and stronger in comparison to the muscles on the other arm.

Crosswell, J. (2009, April 9). What Muscles are Used in Pitching Softball?. In Livestrong . Retrieved April
26, 2011, from

Ellis-Christensen, T. (2011). What are Ligaments?. In Wisegeek . Retrieved April 24, 2011, from

Ellis-Christensen, T. (2011). What is Hypertrophy?. In Wisegeek . Retrieved April 24, 2011, from

How to Lift Heavy Objects Safely (2011, April 20). In Ehow. Retrieved April 24, 2011, from

Muscle Atrophy- Overview (2008, November 13). In University of Maryland Medical . Retrieved April 23,
2011, from

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