Skeleton System Class 7 Science Notes and Questions

Please refer to Skeleton System Class 7 Science notes and questions with solutions below. These revision notes and important examination questions have been prepared based on the latest Science books for Class 7. You can go through the questions and solutions below which will help you to get better marks in your examinations.

Class 7 Science Skeleton System Notes and Questions

Skeletal system consists of a framework of bones and a few cartilages. Bone and cartilage are specialised connective tissues. In human beings, this system is made up of 206 bones and a few cartilages. It is grouped into two principal divisions – the axial and the appendicular skeleton.

Axial skeleton:-

Axial skeleton comprises of 80 bones distributed along the main axis of the body. The skull, vertebral column,
sternum and ribs constitute axial skeleton. The skull is composed of two sets of bones cranial and facial, that
totals to 22 bones. Cranial bones are 8 in number. They form the hard protective outer covering, cranium. The
facial region is made up of 14 skeletal elements which form the front part of the skull. A single U-shaped bone
called hyoid is present at the base of the buccal cavity and it is also included in the skull. Each middle ear contains
three tiny bones – Malleus, Incus and Stapes, collectively called Ear Ossicles. The skull region articulates with
the superior region of the vertebral column with the help of two occipital condyles (dicondylic skull)

Our vertebral column is formed by 26 serially arranged units called vertebrae and
is dorsally placed. It extends from the base of the skull and constitutes the main
framework of the trunk. Each vertebra has a central hollow portion (neural canal)
through which the spinal cord passes. First vertebra is the atlas and it articulates
with the occipital condyles. The vertebral column is differentiated into cervical
(7), thoracic (12), lumbar (5), sacral (1-fused) and coccygeal (1-fused) regions starting
from the skull. The number of cervical vertebrae are seven in almost all mammals
including human beings. The vertebral column protects the spinal cord, supports
the head and serves as the point of attachment for the ribs and musculature of
the back. Sternum is a flat bone on the ventral midline of thorax. There are 12 pairs of ribs. Each rib is a thin flat bone connecteddorsally to the vertebral column and ventrally to the sternum. It has two articulation surfaces on
its dorsal end and is hence called bicephalic.First seven pairs of ribs are called
true ribs.Dorsally,they are attached to the thoracic vertebrae and ventrally connected to the sternum withthe help of hyaline cartilage. The 8th, 9th and10th pairs of ribs do notarticulate directly with the sternum but join the
seventh rib with the help by hyalin cartilage.Thes are called vertebrochondral (false) ribs.
Last 2 pairs (11th and 12th) of ribs are not connected ventrally and are therefore,
called floating ribs. Thoracic vertebrae, ribs and sternum together form the rib cage.

Appendicular skeleton:-
The bones of the l imbs along with their girdles constitute the appendicular
skeleton. Each limb is made of 30 bones. The bones of the hand (fore limb) are
humerus, radius and ulna, carpals (wrist bones – 8 in number), metacarpals (palm
bones – 5 in number) and phalanges (digits – 14 in number) . Femur (thigh bone – the longest bone), tibia and fibula, tarsals (ankle bones 7 in number), metatarsals (5 in number) and phalanges (digits – 14 in number)
are the bones of the legs (hind limb) . A cup shaped bone called patella cover the
knee ventrally (knee cap).

Pectoral and Pelvic girdle bones help in the articulation of the upper and the
lower limbs respectively with the axial skeleton. Each girdle is formed of two
halves. Each half of pectoral girdle consists of a clavicle and a scapula

Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the
second and the seventh ribs. The dorsal, flat, triangular body of scapula has a slightly elevated
ridge called the spine which projects as a flat, expanded process called the acromion. The
clavicle articulates with this. Below the acromion is a depression called the glenoid cavity which
articulates with the head of the humerus to form the shoulder joint. Each clavicle is a long slender
bone with the curvatures. This bone is commonly called the collar bone

Pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones – ilium, ischium and
pubis. At the point of fusion of the above bones is a cavity called acetabulum to which the thigh bone articulates. The
two halves of the pelvic girdle meet ventrally to form the pubic symphysis containing fibrous cartilage

Joints:
Joints are points of contact between bones, or between bones and cartilages. Force
generated by the muscles is used to carry out movement through joints,
where the joint acts as a fulcrum. Joints have been classified into three major
structural forms, namely, fibrous, cartilaginous and synovial.

Fibrous joints do not allow any movement. This type of joint is shown by the flat
skull bones which fuse end-to-end with the help of dense fibrous connective tissues
in the form of sutures, to form the cranium. In

cartilaginous joints, the bones involved are joined together with the help of
cartilages. The joint between the adjacent vertebrae in the vertebral column is of
this pattern and it permits limited movements.

Synovial joints are characterised by the presence of a fluid filled synovial cavity between the articulating
surfaces of the two bones. Such an arrangement allows considerable movement. These joints help in
locomotion and many other movements. Ball and socket joint (between humerus and pectoral girdle).
Hinge joint (knee joint), Pivot joint (between atlas and axis), Gliding joint (between the carpals) and
Saddle joint (between carpal and metacarpal of thumb) are some examples

MCQs for NCERT Class 7 Science Skeleton System

Question: Pelvic girdle is present in –
(A) Shoulder bone
(B) humerus
(C) thigh
(D) None of these

Question: The total number of canines in the permanent dental set of human is –
(A) 12
(B) 8
(C) 6
(D) 4

Question: The number of floating ribs, in the human body, is –
(A) 6 pairs
(B) 5 pairs
(C) 3 pairs
(D) 2 pairs

Question: Cranium of human contains a total of –
(A)8 bones
(B) 12 bones
(C) 14 bones
(D) 20 bones

Question: Which of the following components is a part of the pectoral girdle ?
(A) Ilium
(B) Sternum
(C) Acetabulum
(D) Glenoid cavity

Question: Appendicular skeleton includes all except
(A) hind limbs
(B) forelimbs
(C) vertebral column
(D) pectoral and pelvic girdles

Question: Acetabulum is present in _ _ joint –
(A) Hip
(B) Knee
(C) Elbow
(D) Shoulder

Question: The ends of two bones are connected by
(A) Muscles
(B) Ligaments
(C) Tendons
(D) Calcified

Question: In man, the coccygeal bones is found in –
(A) Skull
(B) Pelvic girdle
(C) Pectoral girdle
(D)Vertebral column

Question: Our chest is enclosed by –
A) 8 pairs of ribs
(B) 10 pairs of ribs
(C) 12 pairs of ribs
(D) 14 pairs of ribs

Question: The skull is made up of –
(A) 18 bones
(B) 22 bones
(C) 24 bones
(D) 5 bones

Question: Bones require –
(A) calcium
(B) protein
(C) carbohydrate
(D) fats

Question: Longest bone in our body is –
(A) Tibia
(B) Femur
(C) Radius
(D) Humerus

Question: Creature which has maximum number of ribs is –
(A) snake
(B) cow
(C) man
(D) dog

Question: The vertebral column is composed of _ __ring like bones –
(A) 33
(B) 37
(C) 39
(D) 43

Question: Total number of bones present in human skeleton is –
(A) 23
(B) 206
(C) 207
(D) 205

Question: Where is the funny bone situated ?
(A) elbow
(B) knees
(C) feet
(D) neck

Question: The number of ring shaped bones in the vertebral column is –
(A) 30
(B) 206
(C) 33
(D) 36

Question: Which of the following is an example of an immovable joint ?
(A) Bones in the wrist
(B) Bones in the face
(C) Bones in the upper part of the skull
(D) Bones in the shoulder

Question: A person is able to sit squatting on the ground because of the presence of –
(A)ball and socket joints at knees
(B) ball and socket joints at hips
(C) sliding joints at hips
(D) immovable joints at hips

Question: Ball and socket joint is found in –
(A) knee
(B) shoulder
(C) foot
(D) elbow

Question: Human bones are made up of –
(A) Calcium
(B) Phosphorous
(C) Calcium & Phosphorous
(D) Calcium & Magnesium

Question: Tendons join –
(A) muscles to muscles
(B) bones to muscles
(C) bones to bones
(D) none of the above

Question: Which of the following is an example of Hinge joint ?
(A) Hip joint
(B) Shoulder joint
(C) Joints between bones of the backbone
(D) knee joint

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