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PinkMonkey Online Study Guide-Biology
(D) Leg or Hindlimb bones
(a) Femur (Thigh bone).
(Figure 20.19). (1) It is the longest and strongest bone in the
body, and consists of upper end, shaft and lower end. (2) The head
articulates with the acetabulum the of hip bone giving a secure joint
but with less freedom of movement. Below the head is the neck, greater
and lesser trochanter, and a small depression called the foveas,
or pit. (3) The shaft is narrow in the center with nutrient foramen.
(4) The lower end of the femur articulates with the tibia and patella.
It consists of thick medial and lateral condyles separated
from each other by an inter condylar fossa or notch. (5)
This notch lies within the capsule of the knee joint and gives attachment
to ligaments. (6) The patella (knee cap) is a flattened,
triangular bone present in front of the knee joint, and its posterior
surface articulates with femoral condyles.
Click here to enlarge
Figure 20.19 Femur Figure
20.20 Tibia-Fibula
(b) Tibia - Fibula
(Figure 20.20)
(1) These are bones of the shank (lower leg) the
tibia on the medial and fibula on the lateral side of the leg. (2)
The tibia is stronger and transmits body weight from femur to the foot.
The fibula is long but slender and does not articulate with either patella
or femur. (3) The upper end of the tibia is broad and consists
of medial and lateral condyles and a tuberosity. The tibia takes part
in formation of several joint, knee, ankle and superior and inferior-tibio-fibular
joints. The lower end is smaller and has a strong process (medial malleolus).
(4) In the fibula, the upper end is rounded with a circular
facet for articulation with fibular faced on lateral condyle of tibia.
The styloid process is a small blunt process. The lower end of the fibula
is expanded, flat and is called the "lateral malleolus."
(c) Tarsal Bones
(1) These are seven bones of the ankle which form
the skeleton of the posterior part of the foot. They are arranged in two
rows.
(2) Proximal row has (a) Talus and (b) Calcaneus.
(3) Distal row has (a) Medial cuneiform,
(b) Intermediate cuneiform, (c) Lateral cuneiform and (d) Cuboid.
These are adapted for supporting weight. (d) Metatarsals and Phalanges
The foot has five metatarsals, which correspond to the metacarpals of
the palm; and 14 phalanges - two in the big toe and three in the other
toes.
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SUMMARY
(1) The skeleton has basic functions like support,
protection, movement and locomotion, muscle attachment, hemopoiesis
and storage of calcium and phosphate. (2) The adult human skeleton
consists of 206 bones. (3) The entire skeleton is divided into the
axial skeleton (skull, ear, ossicles, hyoid bone, vertebral column,
sternum and ribs) and appendicular skeleton (bones of pectoral girdle,
pelvic girdle, arms and legs). (4) The femur is the longest and
strongest bone, and the stapes is the smallest bone in the body.
(5) Adult male and female skeletons can be identified by the differences
in the structures of the skull, sacrum, coccyx and pelvis.
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Table of Contents
20.0 -
Introduction
20.1 -
Axial Skeleton
20.2 -
Appendicular Skeleton
Chapter
21
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