A Medical Student Is Confused When Learning That the Muscle

question 1

Multiple Choice

A medical student is confused when learning that the muscle of the diaphragm is innervated by the phrenic nerves,based on the level of origin of these nerves from the CNS.What is the explanation of how this innervation occurs during embryogenesis?

• A) The phrenic nerves arise in the cervical region in association with the septum transversum and cervical myotomes, and as the myotomes migrate more caudally, they carry their innervation with them.
• B) The muscle of the diaphragm arise late in development and cannot grow back to the thoracic spinal cord because the spinal nerves have already formed at this level, so they grow more cranially to the cervical region.
• C) The thoracic nerves initially supplying the diaphragm die during development and are replaced by new nerves that grow from the cervical region.
• D) The muscle of the diaphragm arises from the thoracic myotomes but secretes a chemoattractant that specifically attracts cervical spinal nerves.
• E) The muscle of the diaphragm arises from the thoracic myotomes but secretes a chemorepellent that specifically repels thoracic spinal nerves.

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Definitions:

Null Hypothesis

A statement or hypothesis that suggests there is no statistical significance between the two variables being studied or no effect of an experimental variable.

P > 0.05

Indicates that the probability of obtaining the observed data, or more extreme, under the null hypothesis is greater than 5%, suggesting results are not statistically significant.

T Test

A statistical test used to compare the means of two groups to determine if they are significantly different from each other.

P < 0.05

Indicates that the probability of obtaining the observed data, or more extreme, under the null hypothesis is less than 5%, suggesting statistically significant results.