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Bones of the upper arm
Each arm contains 30 bones namely, humerus, in the upper arm, radius and ulna in the forearm, 8 carpals in the wrist 5 metacarpals in the palm, and 14 phalanges in the fingers. The distal phalange supports a broad, arched horny nail.
Humerus
This is the longest bone of the upper arm which shows a shaft and two extremities. The upper extremity shows the head which articulates with the glenoid cavity of the scapula to form the shoulder joint. The shaft is rounded in its upper part, but becomes flattened from side to side as it approaches the lower extremity. The lower extremity is broad and flat. At its lowest part, the articulating surfaces for the bones of the forearm lie. The trochlea on the inner side is a pulley-shaped surface for articulation with the ulna and the capitulum on the outer side for the articulation with the radius.
Ulna
This a long bone having a shaft and two extremities. It is medial bone of the forearm and is longer than the radius. The head of the ulna is at the lower end. The upper extremity is strong and thick and enters into the formation of the elbow joint. The shaft tapers towards its lower end. It gives attachment to muscles controlling movement of the wrist and fingers.
Radius
The radius is the lateral bone of the forearm. It is a long bone with a shaft and two extremities. It is shorter than the ulna. The upper extremity of the radius is small and shows button-shaped head with a shallow upper surface for articulation with the capitulum of the humerus, the sides of the head articulate with the radial notch of the ulna.
The bones of the hand
These are arranged in groups. The carpals or the bones which enter into the formation of the wrist, are short bones. The metacarpals form the skeleton of the palm of the hand and are long bones. The phalanges or bones of the fingers, are long bones.
Pelvic girdle
The pelvic girdle is the means of connection between the trunk and lower extremities. This girdle is formed by part of the axial skeleton- the sacrum and coccyx being wedged in between the two innominate bones.
The pelvis is divided into the true pelvis or pelvic basin which lies below the brim, and the false pelvis formed by the iliac bones extending above the brim.The hip bone is formed by the fusion of 3 bones: Ilium on upper side, which is broad, Pubis on inner side and Ischium below the pubis.
Bones of the lower limb
The bones of lower limb consists of 31 bones namely, the innominate bone, femur in the thigh, patella in the knee, tibia and fibula in the lower leg, 7 tarsals in the ankle, 5 metatarsals in the sole, and 14 phalanges in the toes. The bones of the leg do not rotate around one another to provide rigidity to the leg.All the bones of the legs are more massive than that of the arms because the legs alone support the body on the ground and are used in locomotion. The broad feet provide an additional stable support in the upright posture.
The innominate bone or hip bone
The innominate bone helps to form the pelvic girdle. They are situated one on each side, uniting in front at the pubis symphysis.
The innominate bone is an irregular flat bone formed by the union of three bones at the acetabulum. It is cup-shaped cavity on the external surface of the bone which receives the head of the femur to form acetabulum hip joint. The uppermost of the three bones which unite here is the ilium, which is the broadest part. The inner side shows the pubis and posterior or below the pubis is the ischium.The illium has two surfaces, a crest and an articulating surface for the sacrum. The crest of ilium is curved and surmounts the bone. This gives attachment to many muscles, including the abdominal muscles.
The pubis consists of a body and two ramii. The body is square in shape and is surmounted by the crest of the pubis.The ischium is the thickest and strongest portion of the bone. The ischial tuberosity of the ischium lies at its lowest point,and on this the trunk rest when sitting. Between the pubis and ischium bones there is a large oval opening, obturator foramen
Innominate Bone
Functions
i) The pelvic girdles join to form bowl like structure and the wide space enclosed between them forms the pelvis which support and protect the abdominal organs.
ii) The pelvic girdles of female are more flexible, broader and shallower than those of male, this is an adaptation for pregnancy and parturition.iii) They provide articulation to the leg bones.
Femur
The femur is the longest bone in the body. It articulates with the acetabulum of the innominate bone to form the formation of the hip joint and from here the bone inclines mediallly to the knee, where it articulates with the tibia.
Patella
The patella is a sesmoid bone developed in the tendon of the quadriceps extensor muscle. The apex of the patella points downwards. The anterior surface of the bone is rough. The posterior surface is smooth and articulates with the patellar surface of the lower extremity of the femur.
Tibia
The tibia or shin bone forms the main skeleton of the leg and lies medial to the fibula. It is a long bone with a shaft and two extremities.
Fibula
The fibula is the lateral bone of the leg. It is a long bone with a shaft and two extremities.
Bones of the Foot
The tarsal bones
The tarsal bones are seven in number and are collectively known as tarsus. They are short bones made up of cancellous bone tissue, with a covering of compact tissue. These bones support the weight of the body while standing.
The metatarsal bones
There are 5 metatarsal bones. These are long bones with a shaft and two extremitiies. The proximal or tarsal extremity articulating with the tarsal bones, and the distal or phalangeal extremity with the base of the proximal phalanges. The first metatarsal is thick and short, and the second metatarsal is the longest.
The Phalanges
The Phalanges are similar to those of the fingers but much shorter.
Bones of Human - Leg
