Locomotion and Movement 3 Flashcards
What is the skeletal system
Skeletal system consists of a framework of bones and a few cartilages.Bone and cartilage are specialised connective tissues.
The former has a very hard matrix due to calcium salts in it and the latter
has slightly pliable matrix due to chondroitin salts. In human beings,
this system is made up of 206 bones and a few cartilages.
what are the 2 bone systems
It is grouped
into two principal divisions – the axial and the appendicular skeleton.
what is the axial skeleton
Axial skeleton comprises 80 bones distributed along the main axis
of the body. The skull, vertebral column, sternum and ribs constitute
axial skeleton.
what is the skull composed of
The skull (Figure 20.6) 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 for the brain. The
facial region is made up of 14 skeletal elements which form the front part
of the skull
CRANIAL BONES(8)
Frontal-1, Parietal-2, Temporal-2, Occipital-1, Etamoid-1, Sphenoid-1.
- FACIAL BONES (14)
Maxilla-2 , Palatine-2, Zygomatic-2, Nasal-2
Lacrymal-2, Inferior turbinals- 2, Mandible-1, Vomer-1.
what are the occipital chondyles
The skull region articulates with the superior region of the vertebral column with the help of two occipital
condyles (dicondylic skull).
what is:
i) hyoid bone
ii) bones in the ear
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
explaon the bones of the vertebral column
Our vertebral column (Figure 20.7) 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
explain the ribs
There are 12 pairs of ribs. Each rib is a
thin flat bone connected dorsally 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 with the
help of hyaline cartilage. The 8th, 9th and 10th
pairs of ribs do not articulate directly with the
sternum but join the seventh rib with the help
of hyaline cartilage. These 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
what is appendicular skeleton
The bones of the limbs alongwith their
girdles constitute the appendicular skeleton.
explain the bones of the limbs
Each limb is made of 30 bones. The bones of
the hand (fore limb) are humerus, radius(outward) and ulna(inward), carpals (wrist bones – 8 in number),
metacarpals (palm bones – 5 in number) and
phalanges (digits – 14 in number) (Figure
20.9). Femur (thigh bone – the longest bone),
tibia(inward,thicker) and fibula(outward), tarsals (ankle bones – 7 in
number), metatarsals (5 in number) and
phalanges (digits – 14 in number) are the
bones of the legs (hind limb) (Figure 20.10). A
cup shaped bone called patella cover the knee
ventrally (knee cap).
what are the girdles
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.
describe pectoral girdle
Each half of
pectoral girdle consists of a clavicle and a
scapula (Figure 20.9). 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 two curvatures. This bone
is commonly called the collar bone.
describe pelvic girdle
Pelvic girdle consists of two coxal bones
(Figure 20.10). 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.
whata re 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. The movability at these
joints vary depending on different factors.
what are fibrous joints
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.
