The deep fibular nerve is also known as the deep peroneal nerve. The deep fibular nerve supplies branches to the tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallicus longus. The common fibular nerve is derived from spinal nerves L2-L4 and branches off to the superficial and deep fibular nerves. Damage to the fibular nerve is often caused by traumatic injury to the lateral knee; this results in a foot drop which causes the affected person to walk with a high stepping gait. 

The sciatic nerve is a large nerve that runs through the buttocks and down the lower limb. The sciatic nerve innervates skin of the leg, and muscles in the posterior thigh, leg, and foot. The sciatic nerve is derived from spinal nerves L4-S3. Damage to the sciatic nerve would result in impaired hip extension and knee flexion. It would also lead to a loss of plantar/dorsiflexion and inversion and eversion of the foot.

The obturator nerve innervates skin of the medial aspect of the thigh. It is also responsible for the motor innervation of the adductor muscles of lower extremity (external adductor longus, adductor brevis, adductor magnus, and gracillis). The obturator nerve is derived from spinal nerves L2-L4. Damage to the obturator nerve would result in weakness in adduction and lateral swinging of the leg due to unopposed abductors.

The axillary nerve, which originates from the C5 and C6 spinal roots, provides motor innervation to the deltoid and teres minor muscles, both abductors of the shoulder. It also provides sensory input to the lower deltoid via  the superior lateral cutaneous nerve. Damage to this nerve is a possible complication during an axillary dissection. If a patient had sustained an injury to this area they would have difficulty abducting or raising the arm laterally. 

Hydrocephalus is an abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain. It can be caused by one of three mechanisms: impaired flow of CSF, decreased reabsorption, or excessive production. Hydrocephalus may cause increased intracranial pressure inside the skull. It is most common among infants and the elderly.

Brain herniations are a dangerous and potentially fatal. They occur when there is a very high pressure within the skull (via mass effect from hemorrhage, trauma, or tumors) that occurs when a part of the brain is pushed/squeezed across structures within the skull. There are three main types of herniation of brain tissue. Subfalcine, uncal transtentorial, and tonsillar herniations. The subfalcine herniation is also called the cingulated herniation, this occurs when the innermost part of the frontal lobe is scraped under a portion of the falx cerebri. The uncal transtentorial herniation involves the uncus (innermost part of the temporal lobe) moving the tentorium so far that is pushes against the brainstem. A tonsillar herniation is also called a “downward cerebellar herniation,” and occurs when the cerebellar tonsils are pushed downward through the foramen magnum.

The deep fibular (also called peronal) nerve traverses the posterior side of the lower leg. The deep fibular nerve supplies tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus. After the ankle joint, a branch of the deep fibular nerve innervates digitorum brevis and extensor hallucis brevis. 

Damage to the deep fibular nerve (often via traumatic injury to the lateral knee) results in a foot drop. Foot drop inhibits the patient to clear toes off the ground during the swing stage of walking. 

Damage to nerve roots can cause weakness, paralysis, pain, and numbness to muscles and areas innervated by the affected nerve root. When nerves of the cervical region are involved, pain is usually the first symptom to develop. Pain typically will increase gradually before other symptoms of ridiculopathy present. Due to the way nerve roots exit the vertebrae, in the cervical region the nerve root affected usually correlates to the lower vertebrae. In this case there is a narrowing of the C3/C4 space and thus the C4 nerve is affected. 

The S1 nerve is most likely to be irritated by a posteriolateral herniation of the intervertebral disc between L5 and the sacrum. To best understand this, recall that in the lumbar spine the spinal nerve exits below the associated vertebrae. Disc herniation occurs when the anulus fibrosus tears (often due to age related degeneration, lifting injuries, or trauma) and the soft nucleus pulposus is displaced and puts pressure of the nerve. Additionally the tear in the anulus fibrosus can cause the release of inflammatory mediators which will also irritate the nerve. 

Damage to nerve roots can cause weakness, paralysis, pain, and numbness to muscles and areas innervated by the affected nerve root. When nerves of the lumbar region are involved, lower back pain is usually the first symptom to develop. Pain typically will increase gradually before other symptoms of radiculopathy present. Due to the way nerve roots exit the vertebrae, in the lumbar region the nerve root affected usually correlates to the upper vertebrae. In this case there is a narrowing of the L2/L3 space and thus the L2 nerve is affected.