Explain The Anatomy Of The Knee Jerk Or Patella

explain The Anatomy Of The Knee Jerk Or Pate

Questionsa12 Pointsexplain The Anatomy Of The Knee Jerk Or Pate

QUESTIONS: A. (12 points) Explain the anatomy of the ‘knee jerk’ (or patellar) reflex caused by tapping the patellar tendon below the right knee, including the parts of the nervous system that respond to the sensory input and cause the motor output. You may do this in list form. Address the following: Which anatomical parts of the spinal cord -- spinal cord region, roots, horns, rami -- are used during the sensory and motor portions of the reflex arc (in order)? Which specific plexus, nerve(s), and muscle(s) are used in the sensory and motor activity? Although the brain is not involved in producing the motor response, which part of the brain is activated so that the person becomes AWARE that the knee was stimulated?

B. (8 points) List the structures involved in taking blood from the left atrium , through relevant heart structures and delivering the blood to the capillaries of the myocardium of the anterior wall of the left ventricle , then back to the right atrium. Include all relevant heart valves , chamber s and major vessels . left atrium 1. ________________________________________ 2. ________________________________________ 3. ________________________________________ 4. ________________________________________ 5. ________________________________________ 6. ________________________________________ myocardial capillaries in anterior left ventricle wall 7. ________________________________________ 8. ________________________________________ right atrium

Paper For Above instruction

The knee jerk, or patellar reflex, is a classic example of a monosynaptic stretch reflex that tests the integrity of the nervous system pathways involved in reflex arcs. Understanding its anatomy involves examining the sensory receptors, nerve pathways, spinal cord components, motor pathways, and the brain's role in conscious awareness. Additionally, detailing the journey of oxygenated blood through the heart to the myocardium and back to the right atrium provides insight into cardiac anatomy and physiology.

Part A: Anatomy of the Knee Jerk or Patellar Reflex

The reflex is initiated by tapping the patellar tendon, which stretches the quadriceps muscle. This stretch is detected by sensory receptors called muscle spindles located within the quadriceps. The sensory impulse is transmitted via afferent fibers of the femoral nerve, which is part of the lumbar plexus.

From the muscle spindles, the sensory neurons enter the spinal cord via dorsal roots of the lumbar spinal nerves, specifically from the L2-L4 segments. Within the spinal cord, the sensory fibers synapse directly onto the alpha motor neurons located in the ventral horn of the gray matter at the same spinal levels – mainly L2-L4. This makes the reflex monosynaptic, with no interneurons involved in the simplest pathway.

The alpha motor neurons then send efferent impulses via the ventral roots, rami, and the femoral nerve to the quadriceps muscle, causing it to contract and produce the knee extension movement. The quadriceps muscle, being the effector, carries out this motor response.

Although the brain is not required for the reflex to occur, the cerebrum’s sensory cortex is activated when the individual becomes aware of the stimulus. Specifically, the perceptual awareness of the tap occurs in the somatosensory cortex of the parietal lobe, allowing conscious recognition of the stimulus and response.

Part B: Blood Flow from the Left Atrium to the Myocardial Capillaries and Back to the Right Atrium

The pathway of blood from the left atrium to the myocardium of the anterior wall of the left ventricle and back to the right atrium involves several structures:

  1. Left atrium
  2. Mitral (bicuspid) valve
  3. Left ventricle
  4. Aortic valve
  5. Aorta (ascending or arch portion, depending on the specific coronary artery branch)
  6. Coronary arteries (specifically the left coronary artery, which supplies the anterior wall of the left ventricle)
  7. Myocardial capillaries in the anterior wall of the left ventricle
  8. Coronary veins, primarily the great cardiac vein, which drain deoxygenated blood from the myocardium

The deoxygenated blood then returns via the coronary veins which drain into the coronary sinus, emptying into the right atrium. Thus, the final structures involved in returning blood to the right atrium are:

  1. Coronary sinus
  2. Right atrium

References

  • Moore, K. L., & Agur, A. M. R. (2018). Clinically Oriented Anatomy (8th ed.). Wolters Kluwer.
  • Hall, J. E. (2016). Guyton and Hall Textbook of Medical Physiology (13th ed.). Elsevier.
  • Snell, R. S. (2019). Clinical Anatomy by Regions (9th ed.). Wolters Kluwer.
  • Ganong, W. F. (2015). Review of Medical Physiology (24th ed.). McGraw-Hill Education.
  • Marieb, E. N., & Hoehn, K. (2018). Human Anatomy & Physiology (11th ed.). Pearson.
  • Guyton, A. C., & Hall, J. E. (2011). Textbook of Medical Physiology (12th ed.). Elsevier.
  • Sherwood, L. (2015). Human Physiology: From Cells to Systems (9th ed.). Cengage Learning.
  • Standring, S. (2016). Gray’s Anatomy: The Anatomical Basis of Clinical Practice (41st ed.). Elsevier.
  • Boron, W. F., & Boulpaep, E. L. (2016). Medical Physiology (3rd ed.). Elsevier.
  • Klabunde, R. E. (2012). Cardiovascular Physiology Concepts (2nd ed.). Lippincott Williams & Wilkins.

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