Spinal cord

Main

The spinal cord is a long, thin, tubular bundle of nervous tissue that extends from the brainstem to the lumbar region of the vertebral column. It is a crucial part of the central nervous system, connecting the brain to the rest of the body.

The main functions of the spinal cord are:

• Transmitting nerve signals from the motor cortex to the body

• Relaying sensory information from the body to the brain

• Coordinating reflexes via reflex arcs

The spinal cord consists of the following parts:

• Cervical segments: the uppermost part of the spinal cord, located in the neck region

• Thoracic segments: the middle part of the spinal cord, corresponding to the chest area

• Lumbar segments: the lower part of the spinal cord, located in the lower back

• Sacral segments: the part of the spinal cord situated in the pelvic region

• Coccygeal segments: the smallest and lowest part of the spinal cord, near the tailbone

• Gray matter: the inner portion of the spinal cord containing motor and sensory neurons

• White matter: the outer portion of the spinal cord composed of myelinated nerve fibers

• Spinal nerves: paired nerves that emerge from the spinal cord segments and connect to various parts of the body

Anatomically, the spinal cord is protected by the bony vertebral column and covered by three layers of meninges: the dura mater, arachnoid mater, and pia mater.

Terms

• Central Nervous System (CNS): The part of the nervous system consisting of the brain and spinal cord, which processes and coordinates most of the body's activities. Example: The CNS controls voluntary movements and receives sensory input from the body.

• Motor Cortex: The region of the cerebral cortex involved in planning, control, and execution of voluntary movements. Example: When you decide to wave your hand, the motor cortex initiates the necessary signals to move the muscles in your arm.

• Reflex: An involuntary, rapid, and stereotyped response to a specific stimulus, mediated by a reflex arc. Example: The knee-jerk reflex is triggered when the patellar tendon is tapped, causing the leg to extend.

• Reflex Arc: The neural pathway that mediates a reflex, consisting of a sensory receptor, a sensory neuron, an integration center (usually in the spinal cord), a motor neuron, and an effector organ. Example: In the knee-jerk reflex, the reflex arc involves the patellar tendon (receptor), sensory neuron, spinal cord, motor neuron, and quadriceps muscle (effector).

Analogy

The spinal cord is like a superhighway connecting the brain to the rest of the body. Just as a highway allows vehicles to travel between cities, the spinal cord enables nerve signals to travel between the brain and various parts of the body, facilitating movement, sensation, and reflexes.

Misconception

A common misconception is that hanging upside down or stretching the spine is beneficial for the spinal cord. However, there is no scientific evidence to support this claim, and such practices may even be harmful, potentially causing strain or injury to the spinal cord and surrounding structures.

How to use it

1. Practice good posture to reduce strain on the spine by keeping the body aligned and ensuring that vertical forces remain vertical, minimizing leverage on the spinal cord.

2. Engage in regular exercise, including walking, to strengthen the muscles supporting the spine and promote blood flow, which helps deliver nutrients to the spinal cord.

3. Eat a healthy diet rich in essential nutrients, including vitamin D and protein, which are crucial for maintaining the health of the spinal cord and its surrounding structures.

Facts

• The spinal cord is about 18 inches (45 cm) long in adults.

• There are 31 pairs of spinal nerves that emerge from the spinal cord segments.

• The spinal cord ends at the level of the first or second lumbar vertebra in adults.

• The diameter of the spinal cord ranges from 13 mm in the cervical and lumbar regions to 6.4 mm in the thoracic area.

• The spinal cord weighs approximately 35 grams.