The human skeleton is the internal framework of the body.
- It is made up of around 270 bones at birth – these overall declines to around 206 bones by the adult years after some bones get fused.
- The bone mass in the skeleton reaches optimum density around age 21.
- The human skeleton can be divided into 2 parts, axial skeleton, and appendicular skeleton.
1) Axial Skeleton
The axial skeleton consists of the skull, the vertebrae, the ribs, and the rib cage.
Skull:
It is comprised of the cranium and facial bones. The cranium includes 8 bones, 4 unpaired, and 2 paired which protect the brain. Parietal and temporal are paired bones, whereas frontal, occipital, sphenoid, and ethmoid are unpaired bones. Besides that, there are 14 facial bones of which 6 are paired and 2 unpaired. The paired facial bones are maxilla, zygomatic, nasal, lacrimal, palatine, and inferior concha. The unpaired facial bones are mandible and vomer.
Vertebral Column:
The vertebral column extends from the skull to the pelvis to form the foundation, which protects the spinal cord. Typically, the vertebral column has 4 curvatures, which offer more strength than does the straight column. The vertebral column includes 33 vertebrae. The vertebrae are named according to their place in the body, viz, cervical, thoracic, lumbar, and pelvic.
The cervical vertebrae consist of 7 vertebrae which depend on the neck region. The first two cervical vertebrae are the atlas vertebra and the axis vertebra. There are twelve thoracic vertebrae found in the thoracic region, five in the lumbar region, and nine in the pelvic area which forms 2 sets, sacrum, and coccyx. The sacrum is formed by the fusion of the anterior five vertebrae, whereas the coccyx is formed by the fusion of four posterior vertebrae.
Rib Cage:
It is made up of twelve sets of ribs that articulate with the thoracic vertebrae. Ten of them connect anteriorly with the sternum, either straight or through the costal arch. The lower two sets of ribs are called “floating ribs” because they do not attach to the sternum. The chest supplies support to a semi-vacuum chamber called the “chest cavity”.
2) Appendicular Skeleton
The appendicular skeleton includes a pectoral girdle and appendages (forelimbs), and pelvic girdle and appendages (hind limbs).
Pectoral Girdle and Fore Limb:
The pectoral girdle makes up the scapula, suprascapular, and clavicle. The clavicle connects the scapula with the sternum. The forelimb includes the humerus, radius, and ulna, 8 carpals, 5 metacarpals, and 14 phalanges. The humerus forms a ball and socket joint with the scapula, while at the distal end humerus forms the hinge joint with radius and ulna.
The radius and the ulna at their distal end form a multistage joint with eight wrist bones called carpals. 5 metacarpals form the structure of the palm of the hand. Five rows of the phalanges are connected to the metacarpals. They support the fingers.
Pelvic Girdle and Hind Limb:
The pelvic girdle connects the hind limb to the vertebral column. It includes 2 coxal bones. Each is formed by the fusion of 3 bones ilium, ischium, and pubis. The pelvic girdle supports the pelvic region. The hind limb consists of 1 femur, 2 tibia,s and fibula, 7 tarsals 5 metatarsals, and 14 phalanges. The femur is the proximal bone that forms a hip joint with the hipbone, it is a ball and socket joint.
The femur is the longest and strongest bone present in the human body. At the distal end, the femur forms a knee joint with the proximal end of 2 parallel bones called tibia and fibula. The distal end of the tibia and fibula form a joint with seven tarsals, which are also distally connected to five metatarsal bones of the ankle. Five rows of the fourteen phalanges of the toes are connected to metatarsals.
MCQs with Answers: Bones in Human Skeleton
- What is the total number of bones in the human body at birth?
- a) 200
- b) 250
- c) 270
- d) 300
- Answer: c) 270
- At what age does the bone mass in the human skeleton reach optimum density?
- a) 18
- b) 21
- c) 25
- d) 30
- Answer: b) 21
- How many parts is the human skeleton divided into?
- a) 1
- b) 2
- c) 3
- d) 4
- Answer: b) 2
- Which part of the skeleton consists of the cranium and facial bones?
- a) Vertebral Column
- b) Rib Cage
- c) Appendicular Skeleton
- d) Skull
- Answer: d) Skull
- How many facial bones are there in the human skull?
- a) 10
- b) 12
- c) 14
- d) 16
- Answer: c) 14
- Which region of the vertebral column consists of 12 vertebrae?
- a) Thoracic
- b) Lumbar
- c) Cervical
- d) Pelvic
- Answer: a) Thoracic
- What are the two sets formed by the vertebral column in the pelvic area?
- a) Lumbar and Sacrum
- b) Sacrum and Coccyx
- c) Cervical and Thoracic
- d) Thoracic and Lumbar
- Answer: b) Sacrum and Coccyx
- How many sets of ribs articulate with the thoracic vertebrae?
- a) 8
- b) 10
- c) 12
- d) 14
- Answer: c) 12
- Which bones are called “floating ribs” in the rib cage?
- a) First two pairs
- b) Last two pairs
- c) Middle two pairs
- d) All of the above
- Answer: b) Last two pairs
- What does the chest cavity support in the rib cage?
- a) Heart
- b) Lungs
- c) Liver
- d) All of the above
- Answer: d) All of the above
- Which part of the skeleton is considered the appendicular skeleton?
- a) Skull
- b) Vertebral Column
- c) Rib Cage
- d) Pectoral Girdle and Fore Limb
- Answer: d) Pectoral Girdle and Fore Limb
- What bones make up the pectoral girdle?
- a) Scapula, Suprascapular, and Clavicle
- b) Ilium, Ischium, and Pubis
- c) Humerus, Radius, and Ulna
- d) Femur, Tibia, and Fibula
- Answer: a) Scapula, Suprascapular, and Clavicle
- How many carpals are there in the human body?
- a) 5
- b) 8
- c) 12
- d) 14
- Answer: b) 8
- Which bone forms a ball and socket joint with the scapula in the forelimb?
- a) Humerus
- b) Radius
- c) Ulna
- d) Clavicle
- Answer: a) Humerus
- What is the proximal bone that forms a hip joint with the hipbone in the hind limb?
- a) Femur
- b) Tibia
- c) Fibula
- d) Coxal Bone
- Answer: a) Femur
- How many bones fuse to form the sacrum in the vertebral column?
- a) 3
- b) 4
- c) 5
- d) 6
- Answer: b) 4
- Which region of the vertebral column consists of the atlas and axis vertebrae?
- a) Lumbar
- b) Thoracic
- c) Cervical
- d) Sacral
- Answer: c) Cervical
- What is the function of the clavicle in the pectoral girdle?
- a) Connects the scapula with the sternum
- b) Forms a joint with the humerus
- c) Supports the pelvic region
- d) Connects the ribs to the thoracic vertebrae
- Answer: a) Connects the scapula with the sternum
- Which part of the appendicular skeleton supports the pelvic region?
- a) Femur
- b) Pelvic Girdle
- c) Tibia
- d) Fibula
- Answer: b) Pelvic Girdle
- How many metacarpals form the structure of the palm of the hand?
- a) 5
- b) 8
- c) 10
- d) 12
- Answer: a) 5
- What is the only longest and strongest bone present in the human body?
- a) Ulna
- b) Femur
- c) Tibia
- d) Humerus
- Answer: b) Femur
- Which bones are connected to the metatarsals in the hind limb?
- a) Phalanges of the toes
- b) Tibia and Fibula
- c) Tarsals
- d) Femur
- Answer: a) Phalanges of the toes
- What is the function of the coccyx in the vertebral column?
- a) Supports the head
- b) Provides flexibility to the spine
- c) Forms a joint with the sacrum
- d) None of the above
- Answer: d) None of the above
Frequently Asked Questions (FAQs) – Bones in Human Skeleton
1. How many bones are in the human skeleton at birth?
- Answer: Around 270 bones.
2. How many bones are there in the adult human skeleton?
- Answer: Around 206 bones after some fusion occurs.
3. When does the bone mass in the skeleton reach optimum density?
- Answer: Around age 21.
4. What are the two main parts of the human skeleton?
- Answer: Axial skeleton and appendicular skeleton.
5. What does the axial skeleton include?
- Answer: The skull, vertebrae, ribs, and rib cage.
6. How many facial bones are there in the cranium, and how are they classified?
- Answer: 14 facial bones, 6 paired (maxilla, zygomatic, nasal, lacrimal, palatine, and inferior concha) and 2 unpaired (mandible and vomer).
7. What is the function of the vertebral column?
- Answer: It forms the foundation, providing protection to the spinal cord.
8. How many curvatures does the typical vertebral column have?
- Answer: Four curvatures.
9. What are the two sets formed by the pelvic area in the vertebral column?
- Answer: Sacrum and coccyx.
10. How many sets of ribs make up the rib cage, and what are the lower two sets called?
- Answer: Twelve sets of ribs; the lower two sets are called “floating ribs.”
11. What is the semi-vacuum chamber in the chest called?
- Answer: The chest cavity.
12. What does the appendicular skeleton consist of?
- Answer: Pectoral girdle and appendages (forelimbs), and pelvic girdle and appendages (hind limbs).
13. What bones make up the pectoral girdle?
- Answer: Scapula, suprascapular, and clavicle.
14. Which bone connects the scapula with the sternum in the pectoral girdle?
- Answer: Clavicle.
15. What is the function of the femur in the hind limb?
- Answer: It forms a hip joint with the hipbone and is the longest and strongest bone in the human body.
16. How many tarsals make up the hind limb?
- Answer: Seven tarsals.
17. What connects the tibia and fibula at their distal end in the hind limb?
- Answer: A joint with seven tarsals.
18. How many phalanges are connected to the metatarsals in the toes?
- Answer: Fourteen phalanges.
Summary – Bones in Human Skeleton
The human skeleton, comprising approximately 270 bones at birth, undergoes fusion to reach around 206 bones in adulthood. The bone mass attains optimal density around age 21. The skeleton is categorized into two parts: the axial skeleton, encompassing the skull, vertebrae, ribs, and rib cage, and the appendicular skeleton, comprising the pectoral girdle, forelimbs, pelvic girdle, and hind limbs.
Axial Skeleton
- Skull: Comprising the cranium and facial bones, it protects the brain, with paired (parietal, temporal) and unpaired (frontal, occipital, sphenoid, ethmoid) bones.
- Vertebral Column: Extending from skull to pelvis, it provides the foundation for the spinal cord, with 33 vertebrae named cervical, thoracic, lumbar, and pelvic.
- Rib Cage: Twelve sets of ribs articulate with thoracic vertebrae, supporting a semi-vacuum chamber called the chest cavity.
Appendicular Skeleton
- Pectoral Girdle and Fore Limb: Comprising scapula, suprascapular, and clavicle, with humerus, radius, ulna, carpals, metacarpals, and phalanges forming the forelimb.
- Pelvic Girdle and Hind Limb: Connecting hind limb to the vertebral column, it includes 2 coxal bones (ilium, ischium, pubis). The hind limb comprises femur, tibia, fibula, tarsals, metatarsals, and phalanges, with the femur as the longest and strongest bone.
The tutorial provides a comprehensive understanding of the human skeleton’s structure, its axial and appendicular components, and the functions of individual bones in supporting and protecting vital organs.