The spinal cord is an integral part of the CNS, serving as the main communication pathway between the brain and the rest of the body. It is a long, tubular structure made up of nerve fibres that runs through the vertebral column and controls various motor and sensory functions.

Understanding the spinal cord structure and function is essential for comprehending how signals travel between the brain and body, enabling movements, reflexes, and autonomic functions.

Spinal Cord Anatomy

The human spinal cord is typically 40 cm long and 2 cm wide in adults, extending from the medulla oblongata to the lumbar region of the vertebral column. It is divided into five main regions:

Cervical cord – Located in the neck region.
Thoracic cord – Found in the upper and mid-back.
Lumbar cord – Situated in the lower back.
Sacral cord – At the base of the spine.
Coccygeal – The tail end of the spinal cord.

Each region contains spinal nerves that connect to different parts of the body. There are 31 pairs of spinal nerves, classified as follows:

8 cervical nerves (C1-C8)
12 thoracic nerves (T1-T12)
5 lumbar nerves (L1-L5)
5 sacral nerves (S1-S5)
1 coccygeal nerve (Co1)

These spinal nerves transmit signals between the brain and body, controlling reflexes, muscle movements, and sensory functions.

Spinal Cord Diagram – Labelled and Easy

A labelled spinal cord diagram helps in better visualising its structure. Below is an easy-to-understand spinal cord diagram that shows its different parts.

Key Points:

The spinal cord has different segments, each with specific nerve connections.
It is housed within the vertebral column, which protects it from injuries.
Grey and white matter play distinct roles in sensory and motor functions.

Structure of the Spinal Cord

The spinal cord runs through a hollow cavity inside the vertebral column, protected by three layers of meninges:

Dura mater – The outermost layer.
Arachnoid mater – The middle protective layer.
Pia mater – The innermost layer, closely attached to the spinal cord.

Cross-section of the Spinal Cord

A cross-section of the spinal cord reveals grey and white matter:

Grey matter – Located in the centre, shaped like a butterfly. It contains nerve cells and the central canal filled with cerebrospinal fluid (CSF).
White matter – Surrounds the grey matter, consisting of axons that transmit nerve signals.

The spinal cord structure and function are crucial for relaying sensory (afferent) signals to the brain and motor (efferent) signals from the brain to the body.

Spinal Cord Function

The spinal cord serves as a vital link between the brain and body, performing multiple functions:

Relays messages between the brain and the body.
Controls reflex actions without brain involvement.
Provides structural support to maintain body posture.
Coordinates movement and muscle control.
Regulates autonomic functions, such as heart rate and digestion.
Facilitates pain and temperature sensation transmission.

The spinal cord function is crucial in coordinating reflexes and ensuring smooth bodily movements.

Spinal Cord Injuries

Damage to the spinal cord can cause severe health issues due to the loss of communication between the brain and body. Injuries can be classified as:

1. Complete Injury

Total loss of motor and sensory function below the injury site.
Results in paralysis of affected body parts.

2. Incomplete Injury

Partial loss of function, with some movement or sensation still present.

Types of Paralysis Due to Spinal Cord Injury

Tetraplegia (Quadriplegia) – Affects all four limbs and torso.
Paraplegia – Affects the lower limbs and lower body.

Symptoms include:

Loss of voluntary movements
Numbness or loss of sensation
Reflex abnormalities
Breathing difficulties in severe cases

Early diagnosis and treatment can help in managing spinal cord injuries effectively.

Spinal Cord Nerves & Types

The 31 pairs of spinal nerves are divided into different categories based on their location:

Cervical Nerves (C1-C8) – Control neck, arms, and diaphragm movements.
Thoracic Nerves (T1-T12) – Control chest and upper abdominal muscles.
Lumbar Nerves (L1-L5) – Control lower back, hips, and leg functions.
Sacral Nerves (S1-S5) – Control pelvic organs, lower limbs, and feet.
Coccygeal Nerve (Co1) – Controls the tailbone region.

These spinal cord nerves play a significant role in maintaining motor and sensory functions throughout the body.

Unique Information

1. Role of the Spinal Cord in Reflex Actions: The spinal cord is responsible for reflexes, which are automatic responses to stimuli. The reflex arc involves sensory neurons, interneurons, and motor neurons to execute quick responses.

2. How the Spinal Cord Adapts to Injuries: In some cases, the spinal cord can retrain the brain to use alternative pathways for nerve signal transmission, helping people recover partial movements after injuries.

3. The Spinal Cord and Neuroplasticity: Neuroplasticity enables the spinal cord to form new neural connections even after minor injuries, improving recovery chances.

FAQs on Spinal Cord: Diagram, Structure, Function and Labelled Illustration

1. What is the main function of the spinal cord?

The spinal cord is a communication highway between the brain and body, coordinating movement, reflexes, and sensory processing.

2. How many bones protect the spinal cord?

The spinal cord is protected by 24 vertebrae in adults, though there are 33 bones at birth, some of which fuse over time.

3. What happens if the spinal cord is damaged?

Spinal cord injuries can result in partial or complete paralysis, sensory loss, and loss of reflexes, depending on the severity and location of the injury.