Identify the brain and spinal cord as the CNS
Locate both components of the central nervous system.
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Recall cell membranes, diffusion, sensitivity and the difference between cells, tissues and organs.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does CNS stand for?
What you will learn
- The CNS has two named components
- Separate central structures from peripheral nerves
Identify the brain and spinal cord as the CNS
| Feature | Meaning |
|---|---|
| A | Brain: CNS |
| B | Spinal cord: CNS |
| C | Nerves outside brain and spinal cord: PNS |
| Protection | Vertebral bones are distinct from the cord |
The CNS has two named components
The central nervous system, abbreviated CNS, consists of the brain and the spinal cord. Both components are required in the mammalian nervous-system account. The brain lies within the skull, while the spinal cord extends within the vertebral column and connects with peripheral nerves at different levels.
The spinal cord is nervous tissue, not another name for the backbone. Vertebrae are bones surrounding and protecting the cord. A diagram of the skeletal spine alone therefore does not identify every nervous-system component. In the original schematic, A points to the brain and B to the spinal cord, using leaders ending on the neural structures.
Separate central structures from peripheral nerves
Nerves outside the brain and spinal cord belong to the peripheral nervous system, or PNS. They connect receptors and effectors in different body regions with central processing. The distinction is between central structures and peripheral connections; it is not a rule that the CNS contains only sensory functions while the PNS contains only motor functions.
A schematic body outline gives relative position and organisation, not a detailed section of every region. It can show the brain, cord and branching nerves without establishing exact nerve counts or sizes. When asked to describe CNS composition, answer brain and spinal cord explicitly rather than only saying the important middle part of the nervous system.
Sources for this lesson
Pause and explain
Which pair makes up the CNS?
Worked example
Name both components of the mammalian CNS.
Show the worked solution
- Include the structure in the skull.
- Include the neural structure within the vertebral column.
Answer The CNS consists of the brain and spinal cord.
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Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State both named components of the mammalian CNS.
Give me a hint
Two central structures are required.
Compare my reasoning
- Name the brain.
- Name the spinal cord.
Brain and spinal cord.
Look for these in your work
- Name both
- Keep them as nervous structures
Identify A and B in the original central-system schematic.
Give me a hint
Trace the leaders to neural tissue.
Compare my reasoning
- A ends on the brain within the head.
- B ends on the cord extending down the trunk.
A brain; B spinal cord.
Look for these in your work
- Identify both labels
- Use the leader endpoints
Correct: the spinal cord is simply the chain of vertebral bones.
Give me a hint
Distinguish protected tissue from protective structure.
Compare my reasoning
- The spinal cord is nervous tissue.
- Vertebral bones surround and protect it.
The spinal cord is nervous tissue forming part of the CNS; vertebral bones protect it but are not the spinal cord.
Look for these in your work
- Separate tissue and bone
- Retain CNS membership
Common mistakes
- Equating the spinal cord with vertebral bones.
- Omitting the brain or spinal cord.
What can you explain now?
Which pair makes up the CNS?
Compare with the explanation
Brain and spinal cord
Both required components are present.
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Make it stick
Name both CNS structures and distinguish the spinal cord from vertebral bones.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.