APPLIED ANATOMYAPPLIED ANATOMY

UPPER LIMBUPPER LIMB

Part onePart one

Breast-Applied anatomy

Developmental abnormalities are not uncommon

An abscess of the breast should be opened by a radial incision to avoid cutting across a number of lactiferous ducts. Such an abscess may rupture from one fascial compartment into its neighbours, and it is important at operation to break down any loculi which thus form in order to provide ample drainage.

App anatomy of breast cont. Dimpling of the skin over a carcinoma of the breast results from malignant infiltration and fibrous contraction of Cooper’s ligaments as these pass from breast to skin, their shortening results in tethering of the skin to the underlying tumor. This may also occur, however, in chronic infection, after trauma and, very rarely, in fibroadenosis, so that skin fixation to a breast lump is not necessarily diagnostic of malignancy.

App anatomy of breast cont.

Retraction of the nipple, if of recent origin, is suggestive of involvementof the milk ducts in the fibrous contraction of a scirrhous tumour

The excision of a breast carcinoma by radical mastectomy involves the removal of a wide area of skin around the tumour, all the breast tissue, the pectoralis major (through which lymphatics pass to the internal mammary chain), the pectoralis minor (which lies as a gateway to the axilla), and the whole axillary contents of fatty tissue and contained lymph nodes. This excision also removes the bulk of the lymphatics from the arm which pass along the anterior and medial aspects of the axillary vein. A few lymph vessels from the upper limb

BonesBones

--Clavicle The weakest point along the clavicle is the junction

of the middle and outer third. Transmission of forces to the axial skeleton on the shoulder or hand may prove greater than the strength of the bone at this site and this indirect force is the usual cause of fracture

When fracture occurs, the trapezius is unable to support the weight of the arm so that the characteristic of the patient with a fractured clavicle is that of a man supporting his sagging upper limb with his opposite hand. The lateral fragment is not only depressed but also drawn medially by the shoulder adductors, principally the teres major, latissimus dorsi and pectoralis major

The pronator teres is inserted midway along the radial shaft. If the radius is fractured proximal to this, the proximal fragment is supinated (by the action of the biceps) and the distal fragment is pronated by pronator teres. The fracture must, therefore, be splinted with the forearm supinated so that the distal fragment is aligned with the supinated proximal end. If the fracture is distal to the midshaft, the actions of biceps and the pronator muscles more or less balance and the fracture is, therefore, immobilized with the forearm in the neural position

The humerusthe lower end of the humerus is

angulated forward 45° on the shaft. This is easily confirmed by examining a lateral radiograph of the elbow, when it will be seen that a vertical line continued downwards along the front of the shaft bisects the capitulum. Any decrease of this angulation indicates backward displacement of the distal end of the humerus and is good radiographic evidence of a supracondylar fracture.

The radius and ulna The pronator teres is inserted midway along

the radial shaft. If the radius is fractured proximal to this, the proximal fragment is supinated (by the action of the biceps) and the distal fragment is pronated by pronator teres. The fracture must, therefore, be splinted with the forearm supinated so that the distal fragment is aligned with the supinated proximal end. If the fracture is distal to the midshaft, the actions of biceps and the pronator uscles more or less balance and the fracture is, therefore, immobilized with the forearm in the neural position .

The important role of pronator teres in radial fractures. (a) In proximal fractures, above the insertion of pronator teres, the distal fragment is pronated. Such a fracture must be splinted in the supinated position. (b) When the fracture is distal to pronator teres insertion, the action of this muscle on the proximal fragment is cancelled by the supinator action of biceps. This fracture is, therefore, held reduced in the neutral position, midway between pronation and supination.

The force of a fall on the hand produces different effects in different age groups; in a child it may cause a posterior displacement of the distal radial epiphysis, in the young adult the shafts of the radius and ulna may fracture, or the scaphoid may fracture whereas, in the elderly, the most likely result will be a Colles’ fracture. In the last injury, the radius fractures about 1|in (2.5|cm) proximal to the wrist joint; the distal fragment is displaced posteriorly and usually becomes impacted. The shortening which results brings the styloid processes of the radius and ulna more or less in line with each other.

The olecranon process may be fractured by direct violence but more often it is avulsed by forcible contraction of the triceps, which is inserted into its upper aspect. In these circumstances the bone ends are widely displaced and operative repair, to reconstruct the integrity of the elbow joint, becomes essential.

A subcutaneous bursa is constantly present over the olecranon and is likely to become inflamed when exposed to repeated trauma. Students and coal miners share this hazard so that olecranon bursitis goes by the nicknames of ‘student’s elbow’ or ‘miner’s elbow’.

The bones of the hand

A fall on the hand may dislocate the rest of the carpal arch backwards from the lunate which, as commented on above, is wide-based anteriorly (perilunate dislocation of the carpus). The dislocated carpus may then reduce spontaneously, only to push the lunate forward and tilt it over so that its distal articular surface faces forward (dislocation of the lunate).

The scaphoid may be fractured by a fall on the palm with the hand abducted, in which position the scaphoid lies directly facing the radius.The blood supply of the scaphoid in one-third of cases enters distally along its waist so that, if the fracture is proximal, the blood supply to this small proximal fragment may be completely cut off with resultant aseptic necrosis of this portion of bone

The carpal tunnel syndrome

The carpal tunnel syndrome.’ The flexor retinaculum forms the roof of a tunnel the floor and walls of which are made up of the concavity of the carpus. Packed within this tunnel are the long flexor tendons of the fingers and thumb together with the median nerve (Fig. 126). Any lesion diminishing the size of the compartment—for example, an old fracture or arthritic change—may result in compression of the median nerve, resulting in paraesthesiae, numbness and motor weakness in its distribution. Since the superficial palmar branch of the nerve is given off proximal to the retinaculum,there is usually no sensory impairment in the palm.

JointsThe shoulder

Dislocation of the shoulder

The wide range of movement possible at the shoulder is achieved only at the cost of stability, and for this reason it is the most commonly dislocated major joint. Its inferior aspect is completely unprotected by muscles and it is here that, in violent abduction, the humeral head may slip away from the glenoid to lie in the subglenoid region, whence it usually passes anteriorly into a subcoracoid position

The axillary nerve, lying in relation to the surgical neck of the humerus ,may be torn in this injury.

The head of the humerus is drawn medially by the powerful adductors of the shoulder; its greater tubercle, therefore, no longer remains the most lateral bony projection of the shoulder region, being replaced for this honour by the acromion process. The normal bulge of the deltoid over the greater tubercle is lost; instead there is the characteristic flattening of this muscle.

In reducing the dislocation by Kocher’s method the elbow is flexed and the forearm rotated outwards; this stretches the subscapularis which is holding the humeral head internally rotated. The elbow is then swung medially across the trunk, thus levering the head of the humerus laterally so that it slips back into place.

The deformity of shoulder dislocation. The dislocated head of the humerus is held adducted by the shoulder girdle muscles and internally rotated by subscapularis.

In the Hippocratic method, the foot is used as a fulcrum in the axilla, traction and adduction being applied to the forearm; in this way the humeral head is levered outwards into its normal position.

The elbow joints

The joint capsule of the right elbow—lateral aspect.

The elbow joint is safely approached by a vertical posterior incision which divides the triceps expansion.

As the capsule is relatively weak anteriorly and posteriorly it will be distended at these sites by an effusion, particularly posteriorly, since the anterior aspect is covered by muscles and dense deep fascia. Aspiration of such an effusion is readily performed posteriorly on one or other side of the olecranon.

The annular ligament is funnel-shaped in adults, but its sides are vertical in young children. Asudden jerk on the arm of a child under the age of 8 years may subluxate the radial head through this ligament (‘pulled elbow’). Reduction is easily affected by firm supination of the elbow which ‘screws’ the radial head back into place.

Posterior dislocation of the elbow may occur as a result of the indirect violence of a fall on the hand. Occasionally the coronoid process of the ulna is fractured in this injury, being snapped off against the trochlea of the humerus. Characteristically, the triangular relationship between the olecranon and the two humeral epicondyles is lost

Reduction is effected by traction to overcome the protective spasm of the muscles acting on the joint, together with flexion of the elbow, which levers the humero-ulnar joint back into place.

The wrist jointThe wrist joint

Fractures of distal radius.ADULTS CHILDREN

Colle’s fracture. 1. Fracture distal radial epiphysis

Smith’s fracture. 2. Fracture distal radial mataphysis

Barton’s fracture. Radial styloid fracture.

SMITH’S FRACTURE

This is the reverse of Colle’s fracture, the distal fragment is flexed rather than dorsiflexed. It is uncommon. It is due to a fall on the dorsum of the palmar -flexed wrist or due to a backward fall on the outstretched hand

BARTON’S FRACTURE:

This is an intra articular fracture of the distal radius with anterior displacement of a small fragment along with the carpus. Redisplacement is very common after closed reduction. The fracture is best managed by open reduction and application of an Ellis T – plate.

RADIAL STYLOID FRACTURE (CHAUFFER’S FRACTURE):

This injury occurs following a direct blow on wrist or occasionally following a fall on the wrist . The fracture line is transverse extending laterally from the articular surface of radius and the fracture is more often undisplaced.

FRACTURES IN CHILDREN

FRACTURE DISTAL RADIAL EPIPHYSISFRACTURE DISTAL RADIAL EPIPHYSIS :This is child’s Colle’s fracture. Due to separation of the distal radial epiphysis resulting in a displacement similar to the Colle’s fracture.

FRACTURE DISTAL RADIAL METAPHYSISFRACTURE DISTAL RADIAL METAPHYSIS: This may occur at any level proximal to the epiphyseal plate. The fracture may be of the greenstick variety or may be complete.

SCAPHOID FRACTURE

The commonest injury of the carpus. Injury occurs following a fall on the outstretched hand, typically in young adults.

Clinical features : patient presents with pain in the wrist, but function of the wrist may not be grossly impaired. On examination, there will be a tenderness over the scaphoid in the anatomical snuff box, a little swelling and no bruising. These physical signs suggest a ‘sprained wrist’ rather than a fractures

Brachial plexus injuriesBrachial plexus injuries Deformities of the hand. (a) Radial palsy -wrist

drop. (b) Ulnar nerve

palsy-‘main engriffe’ or claw hand.

(c) Median nerve palsy-monkey’s hand’.

(d) Volkmann’s contracture-another claw hand deformity.

The pale blue areas represent the usual distribution of anaesthesia.

Dupuytren’s contracture results from a fibrous contraction of the palmar aponeurosis, particularly of the 4th and 5th fingers.

Presented by

DANA

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