The Spinal Cord

1) Form: External and Internal Organization 

A) External Organization

The spinal cord is housed in boney vertebral column and divided into 5 sections: cervical, thoracic, lumbar, sacral, and coccygeal sections. Spinal nerves emerge from the spinal cord. It is the information superhighway conveying motor (efferent) and sensory (afferent) information between the brain and body. 

The major landmarks include: Dorsal ramus, Ventral ramus, Spinal nerve, Dorsal root, Ventral root, Dorsal horn, Ventral horn, and Anterior median fissure. 

B) Internal Organization

The major landmarks include: Dorsal funiculus, Lateral funiculus, and Ventral funiculus.

The major motor tracts include: Lateral corticospinal (contralateral body movement), Anterior corticospinal (trunk muscles), Rubrospinal (flexor tone), Lateral vestibulospinal (extensor tone) 

The major sensory tracts include: Dorsal columns (fine touch, pressure, proprioception), Spinothalamic (pain, temperature, crude touch), Spinocerebellar (proprioception)

2. Spinal Cord Function 

Relays efferent and afferent information between the brain and body. Reflexes are mediated through the reflex arc.  

3. Spinal Cord Disorders

A) Spinal Cord Injury

Damage to the spinal cord is often through traumatic causes (e.g. car accidents, falls). Vehicular accidents account for 40% of cases. Injury can result in either paresis or plegia. Paraplegia/paresis involves the legs, and  quadriplegia/ quadriparesis involves the arms and legs. Damage can be complete loss of movement or sensation, or incomplete. 

B) Spina Bifida 

A neural tube defect that occurs during development in the womb. There are various severities, and it can result in damage to the lower spinal cord. There are possibilities of paraparesis and bowl and bladder issues.

C) Myelitis 

Inflammation of the spinal cord which can be caused by virus, bacteria, fungi, parasites and toxic agents (e.g., lead poisoning). The different types include: poliomyelitis, which affects gray matter and results in motor loss, leukomyelitis, which affects white matter and results in sensory loss, and transverse myelitis, which affects both gray and white matter and results in a motor and sensory loss.

D) Peripheral Neuropathy 

Inflammation of the peripheral nervous system which results in degenerate of the spinal nerves, typically in the feet. It can be caused by untreated diabetes, toxins, infections, and nutritional issues. It can lead to paresthesia or anesthesia.