Clinically Oriented Anatomy by Moore Keith L. & Agur Anne M & Dalley Arthur F

Author:Moore, Keith L. & Agur, Anne M & Dalley, Arthur F. [Moore, Keith L.]
Language: eng
Format: azw3, epub
ISBN: 9781469825588
Publisher: Lippincott Williams & Wilkins
Published: 2013-02-03T16:00:00+00:00

FIGURE B5.9.

Fracture of Sesamoid Bones

The sesamoid bones of the great toe (Fig. 5.12D) in the tendon of the flexor hallucis longus bear the weight of the body, especially during the latter part of the stance phase of walking. The sesamoids develop before birth and begin to ossify during late childhood. Fracture of the sesamoid bones may result from a crushing injury (Fig B5.10).

FIGURE B5.10.

The Bottom Line

BONES OF LOWER LIMB

Hip bone: Formed by the union of three primary bones (ilium, ischium, and pubis), the hip bones are joined to the sacrum posteriorly and to each other anteriorly (at the pubic symphysis) to form the pelvic girdle. ♦ Each hip bone is specialized to receive half the weight of the upper body when standing and all of it periodically during walking. ♦ Thick parts of the bone transfer weight to the femur. ♦ Thin parts of the bone provide a broad surface for attachment of powerful muscles that move the femur. ♦ The pelvic girdle encircles and protects the pelvic viscera, particularly the reproductive organs.

Femur: Through development, our largest bone, the femur, has developed a bend (angle of inclination) and has twisted (medial rotation and torsion so that the knee and all joints inferior to it flex posteriorly) to accommodate our erect posture and to enable bipedal walking and running. ♦ The angle of inclination and attachment of the abductors and rotators to the greater trochanter allow increased leverage, superior placement of the abductors, and oblique orientation of the femur in the thigh. ♦ Combined with the torsion angle, oblique rotatory movements at the hip joint are converted into movements of flexion–extension and abduction–adduction (in the sagittal and coronal planes, respectively) as well as of rotation.

Tibia and fibula: Our second largest bone, the tibia, is a vertical column bearing the weight of all superior to it. ♦ The slender fibula does not bear weight but, along with the interosseous membrane that binds it to the tibia, is accessory to the tibia in providing an additional surface area for fleshy muscle attachment and in forming the socket of the ankle joint. ♦ Through development, the two bones have become permanently pronated to provide for a stable stance and facilitate locomotion.

Bones of foot: The many bones of the foot form a functional unit that allows weight to be distributed to a wide platform to maintain balance when standing, enable conformation and adjustment to terrain variations, and perform shock absorption. ♦ They also transfer weight from the heel to the forefoot as required in walking and running.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.