David has sustained an injury to his neck that has resulted in the complete loss of sensation to the posterior side of his upper arm and an inability to extend his index finger. which nerve has most likely been damaged as a result of his injury?

Answer;

Radial nerve

Explanation

-The nerve that is most likely to be damaged as a result of his injury is the radial nerve.

-The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb.

-It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

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