Appendicular skeleton

The appendicular skeleton includes the bones of the upper and lower limbs and the pectoral and pelvic girdles that support the limbs and connect them to the trunk.
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The appendicular skeleton includes the bones of the upper and lower limbs and the pectoral and pelvic girdles that support the limbs and connect them to the trunk.
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Each upper limb articulates with the trunk through the pectoral girdle, or shoulder girdle, which consists of the clavicle and the scapula.
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The clavicle and scapula position the shoulder joint, help move the upper limb, and provide a base for muscle attachment
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The clavicle is an S-shaped bone that extends between the manubrium of the sternum and the acromion of the scapula. This bone provides the only direct bony connection between the pectoral girdle and the axial skeleton.
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The scapula articulates with the round head of the humerus at the glenoid cavity of the scapula, the glenohumeral joint (shoulder joint). Two scapular processes, the coracoid and the acromion, are attached to ligaments and tendons associated with the shoulder joint. The acromion articulates with the clavicle at the acromioclavicular joint. The acromion is continuous with the scapular spine, which crosses the posterior surface of the scapular body
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The humerus articulates with the glenoid cavity of the scapula. The joint capsule of the shoulder attaches distally to the humerus at its anatomical neck. Two prominent tubercles, the greater tubercle and lesser tubercle, are important sites for muscle attachment. Other prominent surface features include the deltoid tuberosity, site of deltoid attachment; the articular condyle, divided into two articular regions, the trochlea (medial) and capitulum (lateral); the radial groove, marking the path of the radial nerve; and the medial and lateral epicondyles for other muscle attachment
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Distally, the humerus articulates with the ulna (at the trochlea) and the radius (at the capitulum). The trochlea extends from the coronoid fossa to the olecranon fossa
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The ulna and radius are the parallel bones of the forearm. The olecranon of the ulna enters the olecranon fossa of the humerus during straightening (extension) of the elbow joint. The coronoid process of the ulna enters the coronoid fossa during bending (flexion) of the elbow joint.
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The carpal bones of the wrist form two rows, proximal and distal. From lateral to medial, the proximal row consists of the scaphoid, lunate, triquetrum, and pisiform. From lateral to medial, the distal row consists of the trapezium, trapezoid, capitate, and hamate.
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Five metacarpals articulate with the distal carpal bones. Distally, the metacarpals articulate with the phalanges. Four of the fingers contain three phalanges; the pollex (thumb) has only two.
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The pelvic girdle consists of two hip bones, also called coxal bones or pelvic bones; each hip bone forms through the fusion of three bones—an ilium, an ischium, and a pubis.The ilium is the largest of the hip bones. Inside the acetabulum (the fossa on the lateral surface of the hip bone that accommodates the head of the femur) the ilium fuses to the ischium (posteriorly) and to the pubis (anteriorly). The pubic symphysis limits movement between the pubic bones of the left and right hip bonesThe pelvis consists of the two hip bones, the sacrum, and coccyx. It may be subdivided into the greater (false) pelvis and the lesser (true) pelvis. The lesser pelvis encloses the pelvic cavityThe femur is the longest bone in the body. At its rounded head, it articulates with the pelvis at the acetabulum; distally, its medial and lateral condyles articulate with the tibia at the knee joint. The greater and lesser trochanters are projections near the head where large tendons attach to the femur.The patella (kneecap) is a large sesamoid bone that forms within the tendon of the quadriceps femoris. The patellar ligament extends from the patella to the tibial tuberosityThe tibia is the large medial bone of the leg. The prominent rough surface markings of the tibia include the tibial tuberosity, the anterior margin, the interosseous border, and the medial malleolus. The medial malleolus is a large process that gives medial support for the ankle joint.The fibula is the slender leg bone lateral to the tibia. The head articulates with the tibia inferior to the knee, inferior and slightly posterior to the lateral tibial condyle. A fibular process, the lateral malleolus, stabilizes the ankle joint by preventing medial movement of the tibia across the talus.The tarsus, or ankle, includes seven tarsal bones; only the smooth superior surface of the trochlea of the talus articulates with the tibia and fibula. The lateral and medial extensions of the tarsus articulate with the lateral and medial malleoli of the fibula and tibia, respectively. When standing, most of the body weight transfers to the calcaneus; the rest passes to the metatarsals.The basic organizational pattern of the metatarsals and phalanges of the foot is the same as that of the metacarpals and phalanges of the hand.Weight transfer occurs along the longitudinal arch and transverse arch of the foot.Studying a human skeleton can reveal important information such as sex, genetic heritage, medical history, body size, muscle mass, and age.A number of age-related changes and events take place in the skeletal system. These changes begin at about age 3 months and continue throughout life.