CUBITAL FOSSA and its contents. [1].pptx

Cubital fossa and its contents

1. CUBITAL FOSSA Dr William Arora ANATOMY PG 2 SHKM GMC NUH

2. CUBITAL FOSSA L. CUBITUS = ELBOW The cubital fossa is a triangular hollow in front of the elbow. Its base is horizontal and directed upward, whereas its apex is directed downward. It corresponds to the lower half of the popliteal fossa of the lower limb.

3. BOUNDARIES Lateral : Medial border of the brachioradialis muscle. Medial : Lateral border of pronator teres muscle. Base : An imaginary horizontal line, joining the front of two epicondyles of the humerus. Apex : Meeting point of the lateral and medial boundaries. Here the brachioradialis overlaps the pronator teres. Floor : It is formed by 2 muscles, brachialis(upper) and supinator. Roof : It is formed from the deep fascia of the forearam reinforced on the medial side by the bicipital aponeurosis.

4. CONTENTS The cubital fossa is actually a narrow space and therefore, its contents are displayed only if the elbow is extended and its margins are pulled apart. The contents of the cubital fossa from the medial to lateral side are: 1. Median nerve : It leaves the fossa by passing between the 2 heads of pronator teres. 2. Brachial artery : It terminates in the fossa at the level of the neck of radius by dividing into the radial and ulnar arteries. The radial artery is superficial and leaves the fossa at the apex. The ulnar artery is deep and passes deep to the pronator teres.

5. 3. Biceps tendon : It passes backward and laterally to be attached on the radial tuberosity. 4. Radial nerve : It lies in the gap between the brachialis medially and the brachioradialis laterally. At the level of lateral epicondyle, it divides into two terminal branches: a) a superficial branch called the superficial radial nerve b) a deep branch called the deep radial nerve/posterior interosseous nerve.

6. APPLIED ANATOMY CLINICAL SIGNIFICANCE OF CUBITAL FOSSA a) Venepuncture of cubital veins : The venepuncture is a clinical method to pierce vein by a needle for either intravenous injection or removal of blood for doing a laboratory test. The most common site for venepuncture is cubital fossa as it houses 3 superficial veins : Cephalic vein, Basilic vein and Median cubital vein .

7. Out of these, median cubital vein is most preferred. The median cubital vein is the vein of choice. This is because it is : Most prominent vein in the body Tends to remain stationary for being connected to deep veins by a perforating vein. Does not usually collapse during shock

8. Lies more superficially and not accompanied by a nerve, hence skin over it is less sensitive. Hence, venepuncture is less painful. Underlying bicipital aponeurosis acts as a hard platform, when elbow is extended and protects the underlying median nerve and brachial artery from injury. b) The brachial artery in these region is easily located medial to biceps tendon and auscultated universally for hearing Korokoff sounds while recording the blood pressure manually.

9. c) To deal with the fractures around elbow, viz. supracondylar fracture of the humerus. The contents of cubital fossa especially the brachial artery and median nerve are vulnerable in supracondylar fracture of the humerus. d) The contents of cubital fossa particularly median nerve and brachial artery are likely to get injured in supracondylar fracture of humerus.

10. Injuries of radial nerve The radial nerve may be injured at three sites : A) in the axilla B) in the spiral groove C) at the elbow A) Injury of radial nerve in the axilla In the axilla, the radial nerve may be injured by the pressure of the upper end of crutch (crutch palsy).

11. A Characteristics clinical features in such cases will be as follows - Motor loss - Loss of extension of elbow - due to paralysis of triceps. Loss of extension of wrist (wrist drop) - due to paralysis of wrist extensors.This causes wrist drop due to unopposed action of flexor muscles of the forearm. Loss of extension of digits - due to paralysis of extensor digitorum, extensor indicis, extensor digiti minimi and extensor pollicis longus.

12. Loss of supination in extended elbow because supinator and brachioradialis are paralysed but supination becomes possible in flexed elbow by the action of biceps brachii. Sensory Loss Sensory loss on small area of skin over the posterior surface of the lower part of the arm. Sensory loss along narrow strip on the back of the forearm.

13. B) Injury of radial nerve in the radial/spiral groove In radial groove, the radial nerve may be injured due to: Midshaft fracture of humerus Inadvertently wrongly placed i.m. injection Direct pressure on radial nerve by a drunkard falling asleep with his one arm over the back of the chair (saturday night paralysis).

14. Injuries of median nerve The lesions of median nerve may occur at the following 4 sites: a) at elbow b) at mid forearm c) at wrist (distal forearm) d) in the carpal tunnel

15. a) Injury of the median nerve at the elbow : At elbow the median nerve can be injured due to: Supracondylar fracture of humerus , Application of tight tourniquet during venepuncture , and Entrapment of nerve between 2 heads of pronator tere or under the fibrous arch connecting the 2 heads of flexor digitorum superficialis .

16. Characteristic clinical features in such cases will beas follows: Benediction type of deformity of the hand : When patient tries to make fist, the index and middle fingers remain straight, due to paralysis of both superficial and deep flexors (FDS and FDP) of these fingers leading to loss of flexion at PIP and DIP joints. The ring and little finger can be kept in flexed position due to intact nerve supply of medial half of the FDP.

17. Ape thumb deformity : In this type of deformity, thenar eminence is flattened and thumb lies adducted, due to paralysis of muscles of thenar eminence and normal adductor pollicis, respectively. Loss of sensation in lateral half of the palm and lateral three and a half digits and also on the dorsal aspects of the same digits.

18. b) Injury of the median nerve at the midforearm The injury of median nerve at midforearm results in pointing index finger, due to paralysis of radial head of FDS muscle that continues as tendon of index finger.

19. Injury in the carpal tunnel/carpal tunnel syndrome The median nerve is injured in the carpal tunnel due to its compression and produces a clinical condition called carpal tunnel syndrome. The carpal tunnel is formed by anterior concavity of carpus and flexor retinaculum. The tunnel is tightly packed with nine long flexor tendons of fingers and thumb with their surrounding synovial sheaths and median nerve.

20. The median nerve gets compressed in the tunnel due to its narrowing following a number of pathological conditions such as: a) Tenosynovitis of flexor tendons (idiopathic) b) Myxoedema (deficiency of thyroxine) c) Retention of fluid in pregnancy d) Fracture dislocation of luna te bone and e) Osteoarthritis of the wrist .

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