PECTORAL REGION **The superficial fascia: *Contains: 1. Cutaneous nerves and vessels. 2. The breast (the mammary gland). Cutaneous nerves: a. Supraclavicular nerves: * They are branches from the cervical plexus (C3,4) . * They are arranged as anterior (medial), intermediate and posterior (lateral) nerves. * They supply the skin over the upper half of the deltoid muscle and the front of the thoracic wall down to the level of the 2nd costal cartilage (sternal angle). b. Anterior cutaneous nerves: * They are the terminal branches of the intercostal nerves (ventral rami of T2-T6). * They pierce the pectoralis major muscle & the deep fascia close to the sternum and divide into short medial & long lateral branches to supply the skin from the midsternal line to the midclavicular line. c. Lateral cutaneous nerves: * They are branches of the intercostal nerves (T3-T6). * They pierce the intercostal muscles and divide into anterior and posterior branches which appear between the digitations of serratus anterior muscle. * They supply the skin on the side of the thoracic wall. *N.B.: The lateral cutaneous • branch of the 2nd intercostal nerve is called the intercostobrachial nerve. It supplies the skin of the floor of the axilla and the medial side of the upper arm. *Cutaneous arteries: Include: • 1. Perforating branches of the • internal thoracic artery. 2. Lateral branches of the • posterior intercostal arteries. 3. Superior thoracic, • thoracoacromial & lateral thoracic arteries (from axillary artery). **The deep fascia (Pectoral fascia) * This is a thin membrane that invests the pectoralis major muscle. *Attachments: *Superiorly: to the clavicle. *Inferiorly: continuous laterally with the axillary fascia and medially with the fibrous sheath of the rectus abdominis. *Medially: to the front of the sternum. *Laterally: continuous with fascia that covers the deltoid muscle (shoulder). **The Clavipectoral fascia: *Definition: A strong sheet of fibrous tissue, that lies deep to the clavicular head of pectoralis major muscle, filling the gap between the subclavius and pectoralis minor muscles and covering the axillary vessels and nerves. *Attachments: * Superiorly: It splits to enclose the subclavius muscle and is attached to the lips of the subclavius groove. * Inferiorly: It splits to ensheath the pectoralis minor muscle. The two layers fuse at the lower border of pectoralis minor and continue as the suspensory ligament of the axilla which fuses with the axillary fascia. * Medially: It blends with fascia over the first two intercostal spaces and is attached to the 1st rib medial to subclavius. * Laterally: it is thick and dense and is attached to the coracoid process. *N.B.: Between the 1st rib and coracoid process the fascia often thickens to form a band known as the costocoracoid ligament or membrane. Functions of the clavipectoral fascia: 1. It protects the contents of the axilla. 2. The suspensory ligament raises the skin of the floor of the axilla when the clavicle is elevated and thus it maintains the hollow of the axilla. **Structures piercing the clavipectoral fascia: 1. Thoracoacromial artery and vein. 2. Cephalic vein to terminate into the axillary vein. 3. Lateral pectoral nerve. 4. Lymph vessels. Functions of the clavipectoral fascia: 1. It protects the contents of the axilla. 2. The suspensory ligament raises the skin of the floor of the axilla when the clavicle is elevated and thus it maintains the hollow of the axilla. Pectoralis Major A. Clavicular Head: From anterior surface of medial ½ of the clavicle. B. Sternocostal Head: From: a. corresponding ½ of anterior surface of sternum. b. 2nd to 6th costal cartilages. c. Aponeurosis of ext. oblique muscle of anterior abdominal wall. Insertion By flat bilaminar tendon into the lateral lip of bicipital groove. * Anterior lamina is formed of clavicular & upper sternal fibers. Posterior lamina is from of lower costal and • abdominal fibers.* Both laminae are continuous inferiorly. Nerve supply • Medial Pectoral nerve Lateral Pectoral nerve Action 1. The whole muscle adducts &medially rotates the shoulder joint. It also brings the extended arm to the resting position. 2. The clavicular head flexes the shoulder joint. 3. The Sternocostal head brings the flexed arm to the resting position 4. When insertion is fixed, the muscle draws the trunk upwards towards the upper limb, as in climbing. 1. Superficial to it: Breast & pectoral fascia. 2. It shares in the formation of the anterior wall of the axilla. 3. Its upper border is separated from deltoid muscle by the deltopectoral groove. This groove contains: a. cephalic vein. b. deltoid branch of Thoracoacromial artery. c. deltopectoral L.Ns. 2. Pectoralis Minor O/3rd, 4th & 5th ribs (just lateral to costal cartilages). I/Upper surface and medial border of coracoid process. A/Protraction & depression of the scapula (or shoulder girdle). N.B.: Both pectoralis minor and pectoralis major muscles assist in deep forced inspiration. R/ 1.It divides the axillary artery into 3 parts. 2. Its upper border is related to clavipectoral fascia & Thoracoacromial artery. 3. Its lower border is related to lateral thoracic vessels. 3. Subclavius ORIGIN :Junction of 1st rib and its costal cartilage (1st costochondral junction). INSERTION:Groove of subclavius in the inferior surface of the middle third of the clavicle. Nerve to subclavius. ACTION:It steadies the clavicle during movements of shoulder girdle.