With the exception of the big toe, each digit contains a proximal, intermediate, and distal phalange; the big toe lacks an intermediate phalange.
The length of the phalanges decreases distally. The arches of the foot are formed by the tarsal and metatarsal bones; they dissipate impact forces and store energy for the subsequent step. The arches of the foot are formed by the tarsal and metatarsal bones.
Strengthened by ligaments and tendons, the elastic properties of arches allow the foot to act as a spring, dissipating impact forces and storing energy to be transfered into the subsequent step improving locomotion. The two longitudinal arches and a transverse arch are maintained by the interlocking shapes of the foot bones, strong ligaments, and pulling muscles during activity.
The slight mobility of these arches when weight is applied to and removed from the foot makes walking and running more economical in terms of energy. Excessive strain on the tendons and ligaments of the feet can result in fallen arches or flat feet. The longitudinal arch of the foot can be broken down into several smaller arches. The main arches are the antero-posterior arches, which may, for descriptive purposes, be regarded as divisible into two types—a medial and a lateral.
As can be examined in a footprint, the medial longitudinal arch curves above the ground. It is made by the calcaneus, the talus, the navicular, the three cuneiforms, and the first, second, and third metatarsals.
Its summit is at the superior articular surface of the talus. Its two extremities or piers, on which it rests in standing, are the tuberosity on the plantar surface of the calcaneus posteriorly, and the heads of the first, second, and third metatarsal bones anteriorly. The chief characteristic of this arch is its elasticity, due to its height and to the number of small joints between its component parts.
Its weakest part i. The ligament is strengthened medially by blending with the deltoid ligament of the ankle joint, and is supported inferiorly by the tendon of the tibialis posterior, which is spread out in a fan-shaped insertion and prevents undue tension of the ligament or such an amount of stretching as would permanently elongate it.
The arch is further supported by the plantar aponeurosis, by the small muscles in the sole of the foot, by the tendons of the peroneus longus and the tibialis anterior and posterior, and by the ligaments of all the articulations involved. In contrast, the lateral longitudinal arch is very low. It is composed of the calcaneus, the cuboid, and the fourth and fifth metatarsals. Its summit is at the talocalcaneal articulation, and its chief joint is the calcaneocuboid, which possesses a special mechanism for locking and allows only a limited movement.
The most marked features of this arch are its solidity and its slight elevation. Two strong ligaments—the long plantar and the plantar calcaneocuboid—the extensor tendons, and the short muscles of the little toe preserve its integrity. While these medial and lateral arches may be readily demonstrated as the component antero-posterior arches of the foot, the fundamental longitudinal arch is contributed to by both, and consists of the calcaneus, cuboid, third cuneiform, and third metatarsal: all the other bones of the foot may be removed without destroying this arch.
In addition to the longitudinal arches, the foot presents a series of transverse arches. The arches are complete at the posterior part of the metatarsus and the anterior part of the tarsus, but in the middle of the tarsus they present more of the characteristics of concavities.
These are directed downward and medially, so that when the medial borders of the feet are placed in apposition, a complete tarsal dome is formed. The transverse arches are strengthened by the interosseous, plantar, and dorsal ligaments; by the short muscles of the first and fifth toes especially the transverse head of the adductor hallucis , and by the peroneus longus, whose tendon stretches between the piers of the arches.
Privacy Policy. Skip to main content. Skeletal System: Parts of the Skeleton. Search for:. The Lower Limb. Femur The Thigh The femur—the bone of the upper leg—is the longest bone in the human body and one of the strongest.
Learning Objectives Describe the femur. Key Takeaways Key Points The femur is the longest bone in the human skeleton. It functions in supporting the weight of the body and allowing motion of the leg. The femur articulates proximally with the acetabulum of the pelvis forming the hip joint, and distally with the tibia and patella to form the knee joint.
Key Terms condyle : A smooth prominence on a bone where it forms a joint with another bone. Patella The Knee The patella knee cap is the bone between the fibula and femur.
Learning Objectives Identify the purpose of the patella. Key Takeaways Key Points The primary functions of the patella are to enhance leg extension and protect the joint of the knee. The patella is a bone embedded within a tendon. The space on each side of the knee between the femoral condyle and the tibial condyle is occupied by a crescent shaped piece of cartilage, a The space in the middle, the intercondylar notch is occupied by the two cruciate ligaments.
The intercondylar notch and its contents divide the knee joint into two almost separate halves. On the back of the patella the articular surface is divided into facets. Avatar icon Avatar icon Sign In. Already a Subscriber? Required Required. Forgot Password? Enter an Access Code. Sign in via: Open Athens Shibboleth. Become a subscriber to watch this video.
If you have received this message in error for example, you have purchased a new subscription or activated a trial , please log out and log back in to start a new session and receive access. Arthritis occurs when that joint cartilage becomes damaged or thin. Orthopedic Specialists of Seattle Blog. The bones are connected with four main ligaments: ACL.
0コメント