Читать книгу A Practical Physiology: A Text-Book for Higher Schools - Albert F. Blaisdell - Страница 17

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Experiment 23. To examine the minute structure of voluntary muscular fiber. Tease, with two needles set in small handles, a bit of raw, lean meat, on a slip of glass, in a little water. Continue until the pieces are almost invisible to the naked eye.

Experiment 24. Place a clean, dry cover-glass of about the width of the slip, over the water containing the torn fragments. Absorb the excess of moisture at the edge of the cover, by pressing a bit of blotting-paper against it for a moment. Place it on the stage of a microscope and examine with highest obtainable power, by light reflected upward from the mirror beneath the stage. Note the apparent size of the finest fibers; the striation of the fibers, or their markings, consisting of alternate dim and bright cross bands. Note the arrangement of the fibers in bundles, each thread running parallel with its neighbor.

Experiment 25. To examine the minute structure of involuntary muscular fiber, a tendon, or a ligament. Obtain a very small portion of the muscular coat of a cow's or a pig's stomach. Put it to soak in a solution of one dram of bichromate of potash in a pint of water. Take out a morsel on the slip of glass, and tease as directed for the voluntary muscle. Examine with a high power of the microscope and note: (1) the isolated cells, long and spindle-shaped, that they are much flattened; (2) the arrangement of the cells, or fibers, in sheets, or layers, from the torn ends of which they project like palisades.

Experiment 26. Tease out a small portion of the tendon or ligament in water, and examine with a glass of high power. Note the large fibers in the ligament, which branch and interlace.

Experiment 27. With the head slightly bent forwards, grasp between the fingers of the right hand the edge of the left sterno-cleido-mastoid, just above the collar bone. Raise the head and turn it from left to right, and the action of this important muscle is readily seen and felt. In some persons it stands out in bold relief.

Experiment 28. The tendons which bound the space (popliteal) behind the knee can be distinctly felt when the muscles which bend the knee are in action. On the outer side note the tendons of the biceps of the leg, running down to the head of the fibula. On the inside we feel three tendons of important muscles on the back of the thigh which flex the leg upon the thigh.

Experiment 29. To show the ligamentous action of the muscles. Standing with the back fixed against a wall to steady the pelvis, the knee can be flexed so as to almost touch the abdomen. Take the same position and keep the knee rigid. When the heel has been but slightly raised a sharp pain in the back of the thigh follows any effort to carry it higher. Flexion of the leg to a right angle, increases the distance from the lines of insertion on the pelvic bones to the tuberosities of the tibia by two or three inches--an amount of stretching these muscle cannot undergo. Hence the knee must be flexed in flexion of the hip.

Experiment 30. A similar experiment may be tried at the wrist. Flex the wrist with the fingers extended, and again with the fingers in the fist. The first movement can be carried to 90°, the second only to 30°, or in some persons up to 60°. Making a fist had already stretched the extensor muscles of the arm, and they can be stretched but little farther. Hence, needless pain will be avoided by working a stiff wrist with the parts loose, or the fingers extended, and not with a clenched fist.

Review Analysis: Important Muscles
Location.	Name.	Chief Function.
Head and Neck.	Occipito-frontalis.	moves scalp and raises eye brow.
Orbicularis palpebrarum.	shuts the eyes.
Levator palpebrarum.	opens the eyes.
Temporal.	raise the lower jaw.
Masseter.	" " " "
Sterno-cleido-mastoid.	depresses head upon neck and neck upon chest.
Platysma myoides.	depresses lower jaw and lower lip.
Trunk.	Pectoralis major.	draws arm across front of chest.
Pectoralis minor.	depresses point of shoulder,
Latissimus dorsi.	draws arm downwards and backwards.
Serratus magnus.	assists in raising ribs.
Trapezius. Rhomboideus.	backward movements of head and shoulder,
Intercostals.	raise and depress the ribs.
External oblique.	various forward movements of trunk
Internal oblique.
Rectus abdominis.	compresses abdominal viscera and acts upon pelvis.
Upper Limbs.	Deltoid.	carries arm outwards and upwards.
Biceps.	flexes elbow and raises arm.
Triceps.	extends the forearm.
Brachialis anticus.	flexor of elbow.
Supinator longus.	flexes the forearm.
Flexor carpi radialis.	flexors of wrist.
Flexor carpi ulnaris.	" " " "
Lower Limbs.	Gluteus maximus.	adducts the thigh.
Adductors of thigh.	draw the leg inwards.
Sartorius.	crosses the legs.
Rectus femoris.	flexes the thigh.
Vastus externus.	extensor of leg.
Vastus internus.	extensor of leg upon thigh.
Biceps femoris.	flexes leg upon thigh.
Gracilis.	flexes the leg and adducts thigh.
Tibialis anticus.	draws up inner border of foot.
Peroneus longus.	raises outer edge of foot,
Gastrocnemius.	keep the body erect, and
Soleus.	aid in walking and running.