Wernicke's area is a portion of the temporal lobe that helps formulate and understand speech. Damage to this area results in patients that are able to talk easily, but have little to no meaning in their speech. Damage to Broca's area would result in the inability to produce speech. Olfactory damage would result in the inability to smell and damage to the motor cortex would result in spontaneous and inappropriate movements. 

Drop foot is observed as an unusual gait, where the foot drops due to weakness in the tibialis anterior, and associated dorsiflexors, or to damage to the deep fibular nerve. The deep fibular nerve innervates the anterior compartment of the lower leg, where the dorsiflexors originate. Injury to this nerve would make a person unable to dorsiflex her ankle, causing it to drag/present as a drop foot.

Tarsal tunnel syndrome occurs when the tibial nerve is compressed against the flexor retinaculum of the foot and or portions of the talus and calcaneus, as these three structures comprise the tarsal tunnel. Typically, patients with tarsal tunnel syndrome will report numbness, pain, and/or a tingling sensation radiating to the hallux.

The axillary nerve is most commonly injured in shoulder dislocations. The radial nerve is more commonly injured in humerus fractures, the long thoracic nerve is more commonly injured with traction injuries, the accessory nerve is more commonly injured iatrogenically (during surgery), and the sciatic nerve is more commonly injured as a result of vertebral misalignment.

A Brown-Séquard lesion affects half of the spinal cord. Because the spinothalamic tracts decussate at or near the vertebral level they provide sensation too, injury to them would cause contralateral deficits in pain and temperature sensation. By the same principle, the dorsal column medial lemniscus does not decussate until it reaches the medulla, so injury to this tract would cause ipsilateral loss of proprioception and vibration sense. Eye movements and hearing are controlled by cranial nerves, so a spinal cord lesion would not affect them. This leaves ipsilateral motor loss as the correct choice.

The long thoracic nerve (C5-C7) innervates the serratus anterior, which connects the scapula to the thorcaic cage. It is also used for abduction above the horizontal position. During a mastectomy this nerve can be injured leading to a "winged" scapula. A winged scapula is a condition in which the shoulder blade protrudes from a person's back in an abnormal position leading to limited functional activity in the adjacent upper extremity.

SMA involves atrophy of skeletal muscles. Werdnig-Hoffmann disease is synonymous with SMA type I, which involves severe, early onset (first few months of birth) SMA. Dubowitz disease is synonymous with SMA type II (intermediate), which involves onset at around 6-18 months age. Kugelberg-Welander disease, also known as juvenile SMA, is synonymous with SMA type III, and involves the affected individual being able to walk without support at some time, but the probable loss of this ability later in life. SMA type IV does not have an associated eponym, and there is no SMA type V.

The destruction of myelin sheath is very common in diseases such as multiple sclerosis. It is believed to be an autoimmune disease in which the body destroys the myelin sheath. Other diseases that may result from demyelination are myasthenia gravis and Tay-Sachs disease. Dementia is a symptom of neurodegenerative diseases such as Alzheimer's disease, which is categorized by the presence of neurofibrillary tangles and beta-amyloid plaques in the brain. Meningitis is the inflammation of the meninges. This disease can be caused by several infectious agents such as viruses and/or bacteria. Muscular dystrophy is a genetic disorder in which the dystrophin gene is mutated, disrupting the physical structure of muscles, causing skeletal muscular weakness and death of the muscle cells. 

GABA is an inhibitory neuron in the brain. When GABA levels are low, the result may be overstimulation of neurons in the brain, which can lead to epileptic seizures or development of clinical anxiety. Dopamine is a neurotransmitter that plays a role in the pleasure-reward system and is linked to schizophrenia and Parkinson's disease. Serotonin is  involved in regulating sensory perception, and onset of sleep and control of mood and emotions. Clinically, serotonin has been implicated in depression and impulsive behavior. Acetylcholine is the neurotransmitter used at the neuromuscular junction. Substance P is a non-opiod neuroactive peptide that is found in the pain pathway in the spinal cord. 

Schizophrenia is thought to be caused by excessive dopamine release or an abnormal sensitivity to dopamine. Therapeutic drugs for schizophrenia either reduce the secretion of dopamine or bind to dopamine receptors so dopamine is unable to bind. GABA is an inhibitory neuron in the brain. When GABA levels are low, the result may be overstimulation of neurons in the brain, which can lead to epileptic seizures or development of clinical anxiety. Serotonin is involved in regulating sensory perception, and onset of sleep and control of mood and emotions. Clinically, serotonin has been implicated in depression and impulsive behavior. Acetylcholine is the neurotransmitter used at the neuromuscular junction. Substance P is a non-opiod neuroactive peptide that is found in the pain pathway in the spinal cord.