TRANSMISSION OF FORCE IN THE UPPER LIMB

 Also called Collar bone  Elongated S-shaped bone  Has no medullary cavity  First long bone to ossify via intramembranous ossification beginning during the 5 th and 6 th embryonic weeks at the shaft  2 nd Ossification ends between 25 and 31 years

 Shaft  Medial two thirds of the shaft is convex anteriorly  The lateral one third is flat and concave anteriorly  Surfaces  Superior surface is smooth and lies just deep to platysma muscle and skin.

 The subclavian groove- Groove for the subclavius muscle in the medial two thirds  Impression for the costoclavicular ligament- Rough depressed oval area that attaches to the 1 st rib and the cla vicle

MUSCLE ATTACHMENT

 Fracture One of the most fractured bones An indirect blow transmitted from an outstretched hand or a fall directly on the shoulder Weakest part of the clavicle is the junction of the medial two thirds and the lateral one third.

 The medial fragment is elevated by the Sternocleidomastoid muscle  The lateral fragment drops

 A function of the clavicle is to transmit forces from the upper limb to the axial skeleton.  Fractures commonly result from a fall on to the shoulder, or onto an outstretched hand.  After fracture, the lateral end of the clavicle is displaced inferiorly by the weight of the arm, and medially, by the Pectoralis Major. The medial end is pulled superiorly, by the sternocleidomastoid muscle.

 The suprascapular nerves (medial, intermedial and lateral) may be damaged by the upwards movement of the medial part of the fracture. These nerves innervate the lateral rotators of the upper limb at the shoulder – so damage results in unopposed medial rotation of the upper limb – the ‘waiters tip’position.

ANTERIOR POSTERIOR

LATERAL

 Fractures of the Scapula Fractures of the scapula are relatively uncommon, and if they do occur, it is an indication of severe chest trauma. They are frequently seen in high speed road collisions, crushing injuries, or sports injuries.  The fractured scapula does not require much intervention, as the tone of the surrounding muscles holds the pieces in place for healing to occur.  WINGING OF THE SCAPULA  The Serratus anterior muscle originates from ribs 2-8, and attaches the costal face of the scapula, pulling it against the ribcage. The long thoracic nerve innervates the serratus anterior.  If this nerve becomes damaged, the scapula protrudes out of the back when pushing with the arm. The long thoracic nerve can become damaged by trauma to the shoulder, repetitive movements involving the shoulder or by structures becoming inflamed and pressing on the nerve.

 SURGICAL NECK FRACTURE  This is a frequent site of fracture (hence the name), this occurs by a direct blow to the area, or by falling on an outstretched hand.  It is important to consider the regional anatomy of this area to assess which vessels and nerves are a risk of damage. The key structures of concern is this scenario are the axillary nerve and posterior circumflex artery.  Damage to the axillary nerve will result in paralysis to the deltoid and teres minor muscles; the patient will not being able to abduct their arm.  The axillary nerve also innervates the skin over the lower deltoid.

 DISTAL HUMERAL FRACTURE  Supracondylar fractures and medial epicondyle fractures are common fracture types of the distal humerus. A supraepicondylar fracture occurs by falling on a flexed elbow. It is a transverse fracture, spanning between the two epicondyle  Direct damage, or swelling can cause interference to the blood supply of the forearm from the brachial artery. The resulting ischaemia can cause Volkmann’s ischemic contracture – uncontrolled flexion of the hand, as flexors muscles become fibrotic and short. There also can be damage to the medial, ulnar or radial nerves.  A medial epicondyle fracture could damage the ulnar nerve, a deformity known as ulnar claw is the result. There will be a loss of sensation over the medial 1 and 1/2 fingers of the hand, on both the dorsal and palmar surfaces.

 Lateral and shorter bone of forearm  Proximally head of radius articulates with capitulum of the humerus.  Head also articulates with radial notch of ulnar head is covered with articular catilage.  The neck of the radius is a constriction distal to the head  Radial tuberosity: demarcates the head from shaft

Pronation – Internal rotary movement of radius on ulna that results in hand moving from palm-up to palm down position Supination – External rotary movement of radius on ulna that results in hand moving from palm-down to palm up position

 Usually a transverse fracture at the same level:  Colle’s fracture: most common fracture. The distal fragment is displaced dorsally  Mechanism: forced dorsiflexion of the outstrecthed hand trying to ease a fall

CARPAL BONES These small bones give flexibility to the wrist. ‘ SHE LOOKS TOO PRETTY TRY TO CHASE HER’ S - Scaphoid (G. skaphé, skiff, boat): a boat-shaped bone L- Lunate (L. luna, moon): a moon-shaped bone T - Triquetrum (L. triquetrus, three-cornered): a pyramidal bone P - Pisiform (L. pisum, pea), a small, pea-shaped bone T - Trapezium (G. trapeze, table): a four-sided bone T- Trapezoid: a wedge-shaped bone C - Capitate (L. caput, head): a head-shaped bone with a rounded extremity is the largest bone in the carpus H - Hamate (L. hamulus, a little hook): a wedge-shaped bone