The upper limb (Osciology) Lufukuja G

The upper limb… The upper limb consists of four segments: Shoulder Arm Forearm Hand Lufukuja G

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The upper limb… The pectoral (shoulder) girdle is a bony ring, incomplete posteriorly, formed by the scapulae and clavicles and completed anteriorly by the manubrium of the sternum (part of the axial skeleton). Lufukuja G

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Bones of the Upper Limb Lufukuja G

Clavicle The clavicle (collar bone) connects the upper limb to the trunk. The shaft of the clavicle has a double curve in a horizontal plane. Its medial half is convex anteriorly, and its sternal end is enlarged and triangular where it articulates with the manubrium of the sternum at the sternoclavicular (SC) joint. Its lateral half is concave anteriorly, and its acromial end is flat where it articulates with the acromion of the scapula at the acromioclavicular (AC) joint. The medial two thirds of the shaft of the clavicle are convex anteriorly, whereas the lateral third is flattened and concave anteriorly. These curvatures increase the resilience of the clavicle and give it the appearance of an elongated capital S. Lufukuja G

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Clavicle… The superior surface of the clavicle, lying just deep to the skin and platysma muscle in the subcutaneous tissue, is smooth. The inferior surface of the clavicle is rough because strong ligaments bind it to the 1st rib near its sternal end and suspend the scapula from its acromial end. Lufukuja G

Clavicle… Ossification of the Clavicle The clavicle is the first long bone to ossify (via intramembranous ossification) and the last to be fully formed, beginning during the 5th and 6th embryonic weeks from medial and lateral primary centers that are close together in the shaft of the clavicle. The ends of the clavicle later pass through a cartilaginous phase (endochondral ossification) Applied Anatomy Sometimes fusion of the two ossification centers of the clavicle fails to occur; as a result, a bony defect forms between the lateral and the medial thirds of the clavicle. Awareness of this possible congenital defect should prevent diagnosis of a fracture in an otherwise normal clavicle Lufukuja G

Scapula The scapula (shoulder blade) is a triangular flat bone that lies on the posterolateral aspect of the thorax, overlying the 2nd and 7th ribs Lufukuja G

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Scapula… The convex posterior surface of the scapula is unevenly divided by a thick projecting ridge of bone, the spine of the scapula, into a small supraspinous fossa and a much larger infraspinous fossa. The concave costal surface of most of the scapula forms a large subscapular fossa. Lufukuja G

Humerus The humerus (arm bone), the largest bone in the upper limb, articulates with the scapula at the glenohumeral joint and the radius and ulna at the elbow joint. The proximal end of the humerus has a head, surgical and anatomical necks, and greater and lesser tubercles. The spherical head of the humerus articulates with the glenoid cavity of the scapula. Lufukuja G

Humerus… Lufukuja G

Humerus… The shaft (body) of the humerus has two prominent features: the deltoid tuberosity laterally, for attachment of the deltoid muscle, and the oblique radial groove (groove for radial nerve, spiral groove) posteriorly, in which the radial nerve and deep artery of the arm lie as they pass anterior to the long and between the medial and lateral heads of the triceps brachii muscle The inferior end of the humeral shaft widens as the sharp medial and lateral supraepicondylar (supracondylar) ridges form and then end distally in the especially prominent medial epicondyle and the lateral epicondyle, providing for muscle attachment Lufukuja G

BONES OF THE FOREARM Lufukuja G

Bones of the Forearm The ulna and radius together make up the second unit of a two-unit articulated strut (the first unit being the humerus), projecting from a mobile base (shoulder) that serves to position the hand. Proximally, the larger medial ulna forms the primary articulation with the humerus, whereas distally, the shorter lateral radius forms the primary articulation with the hand via the wrist. Lufukuja G

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Applied anatomy Because the ulna does not reach the wrist, forces received by the hand are transmitted from the radius to the ulna via the interosseous membrane. A complete fracture of the distal 2 cm of the radius is called a Colles fracture. - most common fracture of forearm - most common fracture in people older than 50 years - distal radial fragment is often comminuted (broken into pieces) - ulnar styloid process is often avulsed (broken off) - posterior displacement of distal radial fragment results in a “dinner fork deformity” Lufukuja G

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BONES OF THE HAND Lufukuja G

Bones of the hand The wrist, or carpus, is composed of eight carpal bones (carpals) arranged in proximal and distal rows of four. These small bones give flexibility to the wrist. The carpus is markedly convex from side to side posteriorly and concave anteriorly. Augmenting movement at the wrist joint, the two rows of carpals glide on each other; in addition, each bone glides on those adjacent to it Lufukuja G

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Applied anatomy Fracture of the Scaphoid The scaphoid is the most frequently fractured carpal bone. It often results from a fall on the palm when the hand is abducted Pain occurs primarily on the lateral side of the wrist, especially during dorsiflexion and abduction of the hand. Owing to the poor blood supply to the proximal part of the scaphoid, union of the fractured parts may take at least 3 months. Avascular necrosis of the proximal fragment of the scaphoid (pathological death of bone resulting from inadequate blood supply) may occur and produce degenerative joint disease of the wrist. In some cases, it is necessary to fuse the carpals surgically (arthrodesis). Lufukuja G

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