after patient consenting, induction of anathesia Under sterile conditions, and while the patients will be still on the lateral position with the diseased side up after induction of anesthesia, a linear ultrasound transducer (10-12 MHz) will be placed in a sagittal plane over the mid-clavicular region of the thoracic cage. Then counting down ribs till the seventh rib will be identified in the mid-axillar]y line. The following muscles will be identified overlying the sixth rib: the latissimus dorsi (superficial and posterior), teres major (superior) and serratus muscle (deep and inferior). The needle (22-G, 50-mm Touhy needle) will be introduced in-plane with respect to the ultrasound probe targeting the plane deep to the serratus anterior muscle . Under continuous ultrasound guidance, 20 ml of 0.25% bupivacaine will be injected then a catheter will be threaded. A continuous infusion of 5 ml/hr of 0.125% bupivacaine will be then started through the catheter.

with the use of the visual analouge scale (VAS) in the preoperative visit. Where 0 score as no pain and 10 as the worst imaginable pain.