Week 2: ANS and Diaphragm Flashcards
Somatic Nervous System
It is our voluntary or conscious nervous system, and can be divided into sensory or motor. One neuron spinal cord into/from the tissue that it is innervating.
The sensory division innervates the body walls, limbs, and skin.
The motor division goes to skeletal muscles.
Autonomic Nervous System
It is the “Subconscious” or “involuntary” nervous system. Two neurons from the spinal cord to target.
Innervation of viscera, blood vessels, glands, and smooth muscle
Motor Somatic Neuron (efferent neuron) location of the cell body
Ventral Horn
Sensory Somatic Neuron (afferent neuron) location of the cell body
Dorsal Root Ganglion
Sympathetic Ganglion is located
adjacent to the body of the vertebra all the way along the vertebral column.
Pain from paired viscus is referred to skin…
on the same side because visceral sensory neurons enters spinal cord segment from one side
Pain from unpaired viscera is referred to skin in the midline. Why?
Because the nerve supply for this viscera arrives at both sides of the spinal cord simultaneously. This is due to the origin of the unpaired viscera, as they develop in the midline but migrate away from it (associated orifices -mouth, anal canal remain in the midline).
Why is there no deep fascia around the thorax?
There is no continuous layer of deep fascia around the thorax, so as not to impede inspiration.
What unique mechanism prevents fatigue of the intercostal muscles?
The involuntary sequential recruitment of alternate muscle fibres.
Which muscle(s) is (are) responsible for quiet RESPIRATION?
Diaphragm and intercostal muscles.
The external intercostals help to elevate the sternal and raise the ribs, and the medial intercostal muscles help to raise the ribs. These muscles are most active during quiet inspiration.
Lateral intercostals are most active in quiet expiration.
Which muscle(s) is (are) responsible for quiet expiration?
None, usually quiet expiration is passive through the elastic recoil of lungs and ribs. Sometimes the internal intercostals will help.
Which muscle(s) is (are) responsible for forced expiration?
Abdominal muscles
How is forced expiration clinically significant for a patient that went through abdominal surgery?
Forced expiration is the basis of a cough. As abdominal muscles assist with that, patients that undergo surgery in the abdominal area should refrain from coughing due to pain or risk of opening.
Pain from the central diaphragm is referred to
C3, 4 and 5 dermatomes over the neck and upper limb (phrenic nerve).
Pain from the peripheral diaphragm is referred to
Dermatomes of the thoracic wall (intercostal nerves).
