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The human skull is made up of 22 bones along with ligaments and cartilage. The skull bones are divided into movable and immovable bones. The skull has only 1 movable bone which is called as the mandible or jaw bone.
Figure: Human Skull
What are Skull Bones?
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Skull Bones are the bones that provide structure and support to the face.
- A skull has two types of bones: facial bones and cranial bones.
- There are 8 cranial bones and 14 facial bones present.
- The skull bones are connected by fibrous joints called sutures.
Which Skull Bones are Movable?
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Among all the 22 skull bones, the mandible or the jaw bone is movable.
- The word mandible is derived from the Latin word ‘mandibula’ meaning ‘to chew’.
- It is the largest and the strongest bone of the skull.
- The temporomandibular joint connects this bone to the skull.
- The mandible is responsible for providing structure to the face and chin.
- The jaw bone helps in chewing food.
- The upper jaw bone and the mandible provide support to the teeth.
Things to Remember
- Facial bones are movable and cranial bones are non-movable.
- The fibrous tissues that join the sutures are made up of collagen.
- Another example of facial bone is the nasal bone.
- Ossicles are the bones located in the inner ear.
- The mandible is the largest bone present in the skull.
Sample Questions
Ques. Can you identify the single skull bone that can move? (1 mark)
Ans. The mandible, also known as the jaw, is the only bone in the human skull that can move. This bone is known to be one of the biggest bones in the human skull
Ques. What are auditory ossicles? What purpose do they serve? (2 marks)
Ans. The smallest bones present in the ear are called auditory ossicles. They are three in total: Incus, Stapes, and Malleus.
- These bones transfer the vibration of air into the inner ear process it into sound waves and protect your ear from loud noises.
- The malleus is responsible for transmitting the vibrations from the eardrum to the inner ear.
Ques. Are all the facial bones present in the human skull movable? (2 marks)
Ans. No, not all facial bones present in the human skull are movable.
- The human skull has 22 bones, out of which 14 are the facial bones.
- Among the 14 facial bones, only one bone is movable.
Ques. Which is the largest and the smallest auditory ossicle? Write their functions. (2 marks)
Ans. The malleus is the largest auditory ossicle of all, while stapes are the smallest.
- The role of the malleus is to transfer vibrations from the eardrum to the inner ear.
- The stapes aid in the hearing process. Damage of stapes can cause deafness.
Ques. Mention any five types of facial bones out of the 14. (2 marks)
Ans. The following are the five types of facial bones:
- Lacrible
- Mandible
- Nasal
- Maxilla
- Platine
Ques. Name any four types of cranial bones. (2 marks)
Ans. The following are the four types of cranial bones:
- Occipital
- Parietal
- Frontal
- Temporal
Ques. What does the temporomandibular joint do? (2 marks)
Ans. The temporomandibular joint helps in the movement of the lower jaw.
- It consists of two bones- the temporal bone and jaw bone also known as the mandible.
- The temporal bone forms part of the human skull.
Ques. What is the disorder of the movable skull bone called? (2 marks)
Ans. The disorder of movable skull bone is called the temporomandibular joint disorder.
- A person suffering from such a disorder experiences pain in the jaw movements.
- This is caused by arthritis in the cartilage of the joints.
Ques. Do maxilla and mandible bones have similarities? (2 marks)
Ans. Yes, one similarity is that the maxilla and mandible are present in the skull bones, but they differ in structure and function.
- A mandible is a single bone that connects to the skull through the temporomandibular joint.
- Maxilla contains two bones found at the center part of the face.
Ques. What functions does the skeletal system offer? (3 marks)
Ans. The major functions of the skeletal system include:
- It protects internal body organs like the lungs, heart, spinal cord, etc.
- The skeletal system provides support to the muscles and organs.
- It helps in the proper movement of the body muscles, and organs.
Ques. What are sutures? Are they movable or immovable? (2 marks)
Ans. Sutures are the joints present between the adjacent bones of the skull.
- These are also called cranial sutures that join the bones of the skull.
- Sutures are immovable joints and appear as thin lines on the skull.
Ques. Differentiate between skull and cranium. (3 marks)
Ans. The table below shows the difference between the two:
| Skull | Cranium |
|---|---|
| A bone structure that protects the head. | A part of skull that protects the brain. |
| It consists of 22 bones. | It consists of 8 bones. |
| One of the skull bones called the mandible is movable. | All bones of the cranium are immovable. |
| Functions- protects the brain, and provides support to facial muscles. | Functions- protects brain and cerebral vasculature. |
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