Final answer:
The trauma/hyperextension neck injury described may involve the accessory nerve and can be evaluated by testing muscle strength and symmetry. Key tests include resistance against neck flexion and shoulder shrug, evaluation of pronator drift, and deep tendon reflexes, which aid in differentiating between UMN and LMN lesions.
Step-by-step explanation:
The patient's symptoms of weakness that is more pronounced in the upper extremities with potential localized deficits in pain and temperature sensation can be assessed using various neurological examinations. To evaluate muscle strength, a patient may be asked to flex and extend the neck or shrug the shoulders against resistance. If there is asymmetry or a difference in muscle strength on one side compared to the other, it suggests potential damage to the motor system on the weaker side. This could be related to spinal nerves and may involve the accessory nerve that innervates key neck muscles like the sternocleidomastoid and trapezius.
Tests such as pronator drift or examining deep tendon reflexes may help differentiate between upper motor neuron (UMN) and lower motor neuron (LMN) lesions. In UMN lesions, signs might include muscle weakness, increased reflexes, and spasticity, which can feature the clasp-knife response. On the other hand, LMN damage often presents with muscle weakness or atrophy, decreased reflexes, and flaccidity.