The spine (also called the vertebral column or backbone) is the main support structure of the body. It:
-
Supports the head and torso
-
Protects the spinal cord
-
Enables flexible movement
-
Helps maintain balance and posture
🧩 Structure of the Spine
The spine is made up of 33–34 vertebrae (bones), intervertebral discs, and joints. These vertebrae are stacked in a column and connected by ligaments and muscles.
🔹 Five Regions of the Spine:
| Region | Number of Vertebrae | Location | Main Features |
|---|---|---|---|
| Cervical (Neck) | 7 | Neck area | Small and mobile; supports the head |
| Thoracic (Chest) | 12 | Mid-back | Attached to the ribs; less mobile |
| Lumbar (Lower Back) | 5 | Lower back | Large and strong; bears most body weight |
| Sacral (Pelvis) | 5 (fused) | Pelvic area | Fused into one bone: the sacrum |
| Coccygeal (Tailbone) | 4–5 (fused) | End of the spine | Rudimentary; forms the coccyx (tailbone) |
🧱 Structure of a Vertebra
Each vertebra has:
-
Vertebral body – bears weight
-
Vertebral arch – forms the canal for the spinal cord
-
Processes – bony projections for muscle and ligament attachment
-
Vertebral foramen – hole through which the spinal cord passes
🔄 Main Functions of the Spine
| Function | Description |
|---|---|
| Support | Holds up the body and head |
| Protection | Shields the spinal cord from damage |
| Movement | Allows bending, twisting, and flexibility |
| Shock Absorption | Intervertebral discs cushion forces from walking, jumping, etc. |
🧠 Spinal Cord and Nerve System
-
The spinal cord runs inside the vertebral canal.
-
It connects the brain to the rest of the body.
-
Spinal nerves branch out from between vertebrae, controlling:
-
Sensation
-
Muscle movement
-
Organ functions
-
There are 31 pairs of spinal nerves.
🩺 Common Spinal Disorders
| Condition | Description |
|---|---|
| Scoliosis | Sideways curvature of the spine (S- or C-shaped) |
| Kyphosis | Excessive forward curvature (hunchback) |
| Lordosis | Excessive inward curve (swayback) |
| Herniated disc | Spinal disc bulges or ruptures, pressing on nerves |
| Osteochondrosis | Degeneration of discs and cartilage (wear-and-tear) |
| Radiculopathy (sciatica) | Nerve pain from pinched or inflamed spinal nerves |
| Spinal fracture | Broken vertebra due to trauma or osteoporosis |
💡 Interesting Facts About the Spine
-
The spine has a natural S-curve, helping balance and absorb shock.
-
Human height shrinks by 1–2 cm throughout the day due to disc compression.
-
Babies are born with 33 vertebrae, but some fuse to form the sacrum and coccyx.
-
The largest vertebra is usually the 5th lumbar vertebra — it carries most weight.
✅ Summary Table
| Region | Number | Function |
|---|---|---|
| Cervical | 7 | Supports the head; allows neck movement |
| Thoracic | 12 | Protects organs; attaches to ribs |
| Lumbar | 5 | Supports upper body weight; allows bending |
| Sacral | 5 fused | Forms pelvis; provides stability |
| Coccygeal | 4–5 fused | Tailbone; evolutionary remnant |