Part 6: Spinal Cord & Neurological Disorders

What does the spinal cord consist of?

Central nervous system tissue enclosed within the vertebral column from the foramen magnum to L1.

What is the main function of the spinal cord?

To provide two-way communication between the brain and the rest of the body.

What protects the spinal cord?

Bone (vertebrae), meninges, and cerebrospinal fluid (CSF).

How many pairs of spinal nerves are there?

31 pairs that attach to the spinal cord by paired roots.

What are the cervical and lumbar enlargements?

Regions where nerves serving the upper and lower limbs emerge.

What is the cauda equina?

A collection of nerve roots at the inferior end of the vertebral canal, resembling a horse’s tail.

What does gray matter in the spinal cord consist of?

Neuron cell bodies (soma), unmyelinated processes, and neuroglia.

What does white matter in the spinal cord consist of?

Myelinated and unmyelinated nerve fibers that form ascending and descending tracts.

What are the posterior (dorsal) horns of gray matter?

They contain interneurons that receive sensory input from the dorsal root.

What are the anterior (ventral) horns of gray matter?

They contain somatic motor neurons that send impulses to skeletal muscles.

What are the lateral horns of gray matter?

They contain autonomic (sympathetic) motor neurons.

How are the dorsal and ventral halves of the gray matter organized?

Dorsal half is sensory; ventral half is motor.

What do the dorsal and ventral roots fuse to form?

Spinal nerves.

What are the four zones evident within the gray matter?

Somatic sensory (SS), visceral sensory (VS), visceral motor (VM), and somatic motor (SM).

What is the function of ascending tracts in white matter?

They carry sensory information to the brain.

What is the function of descending tracts in white matter?

They carry motor commands from the brain to effectors.

What is the nonspecific ascending pathway?

A pathway that transmits pain, temperature, and crude touch sensations within the lateral spinothalamic tract.

What is paralysis?

The loss of motor function due to spinal cord injury or disease.

What is flaccid paralysis?

A condition where lower motor neurons are damaged, causing loss of voluntary and involuntary movement with muscle atrophy.

What is spastic paralysis?

A condition where upper motor neurons of the motor cortex are damaged, causing irregular muscle stimulation without voluntary control.

What is spinal cord transection?

A complete cross section of the spinal cord resulting in total motor and sensory loss below the injury site.

What is paraplegia?

Paralysis of the lower limbs caused by a spinal cord injury between T1 and L1.

What is quadriplegia?

Paralysis of all four limbs due to a spinal cord injury in the cervical region.

What is poliomyelitis (polio)?

A viral infection that destroys anterior horn motor neurons, leading to muscle weakness and paralysis.

What are early symptoms of poliomyelitis?

Fever, headache, muscle pain, weakness, and loss of reflexes.

Can poliomyelitis be prevented?

Yes, with vaccination.

What is amyotrophic lateral sclerosis (ALS)?

A progressive neuromuscular disease that destroys anterior horn motor neurons and fibers of the pyramidal tract.

What are the symptoms of ALS?

Loss of the ability to speak, swallow, and breathe.

How long do most ALS patients survive after onset?

Usually less than five years.

What causes ALS?

Malfunctioning genes related to glutamate transport or superoxide dismutase enzyme.

What is a cerebrovascular accident (CVA) or stroke?

A condition where blood flow to the brain is blocked, leading to brain tissue death.

What are common causes of stroke?

Blockage of a cerebral artery, hemorrhage, edema, or atherosclerosis.

What is a transient ischemic attack (TIA)?

A temporary episode of reversible cerebral ischemia (“mini-stroke”).

What is the only approved drug treatment for stroke?

Tissue plasminogen activator (TPA), which dissolves clots.

What is Alzheimer’s disease?

A progressive, degenerative brain disorder that causes memory loss, confusion, and dementia.

What is Parkinson’s disease?

A degenerative disorder caused by loss of dopamine-producing neurons in the substantia nigra.

What is Huntington’s disease?

A hereditary disorder caused by accumulation of the protein huntingtin, leading to degeneration of the basal nuclei and uncontrollable movements.

What are three major degenerative brain disorders?

Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease.