Pectoral Region Anatomy PDF

PECTORAL REGION  BY  Dr Edu Otong Pectoral region  Pectoral region is the region that connects the upper limb to the trunk.  Layers of Pectoral region  1. Skin  2. Superficial fascia with cutaneous nerve and vessels  3. Deep fascia: Pectoral fascia and clavipectoral...

PECTORAL REGION  BY  Dr Edu Otong Pectoral region  Pectoral region is the region that connects the upper limb to the trunk.  Layers of Pectoral region  1. Skin  2. Superficial fascia with cutaneous nerve and vessels  3. Deep fascia: Pectoral fascia and clavipectoral fascia  4. Muscles  5 Nerves  6 vessels Superficial structures of the Pectoral region  Deep to the skin is subcutaneous tissue (superficial fascia) containing fat as well as:  Mammary gland  The cutaneous nerve  supraclavicular nerve  cutaneous branches of inter-costal nerves  The cutaneous vessels Deep fascia of the Pectoral region If no structure (muscle or tendon, for example) intervenes between the skin and the bone, the deep fascia usually attaches to bone. The pectoral fascia invests the pectoralis major and is continuous inferiorly with the fascia of the anterior abdominal wall. The pectoral fascia leaves the lateral border of the pectoralis major and becomes the axillary fascia, which forms the floor of the axilla.  Deep to the pectoral fascia and the pectoralis major, another fascial layer, the clavipectoral fascia, descends from the clavicle, enclosing the subclavius and then the pectoralis minor, becoming continuous inferiorly with the axillary fascia. The part of the clavipectoral fascia between the pectoralis minor and the subclavius, the costocoracoid membrane, is pierced by the lateral pectoral nerve, which primarily supplies the pectoralis major. The part of the clavipectoral fascia inferior to the pectoralis minor, the suspensory ligament of axilla, supports the axillary fascia and pulls it and the skin inferior to it upward during abduction of the arm, forming the axillary fossa.  Clavipectoral fascia is pierced by the following structure:  Lateral pectoral nerve  Acromio-thoracic vessel  Cephalic vein  Lymphatics from the breast draining into apical lymph nodes  The scapulohumeral muscles that cover the scapula and form the bulk of the shoulder are also ensheathed by deep fascia called deltoid fascia. The deltoid fascia invests the deltoid and is continuous with the pectoral fascia anteriorly and the dense infraspinous fascia posteriorly. The muscles that cover the anterior and posterior surfaces of the scapula are covered superficially by deep fascia, which is attached to the margins of the scapula. This arrangement creates osseofibrous subscapular, supraspinous, and infraspinous compartments. Clavipectoral fascia Pectoral region  The pectoral muscles includes:  pectoralis major,  pectoralis minor,  subclavius, and  serratus anterior. Pectoralis Major Origin Clavicular head: anterior surface of medial half of clavicle Sternocostal head: anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle Attachment. Lateral lip of intertubercular sulcus (groove) of humerus Innervation Lateral and medial pectoral nerves; clavicular head (C5, C6 ), sternocostal head (C7, C8, T1) Main Action Adducts and medially rotates humerus; draws scapula anteriorly and inferiorly Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position Pectoralis Minor Origin 3rd-5th ribs near their costal cartilages Attachment: Medial border and superior surface of coracoid process of scapula Innervation: Medial pectoral nerve (C8,T1) Action: Stabilizes scapula by drawing inferiorly and anteriorly against thoracic wall Subclavius Origin Junction of 1st rib and its costal cartilage Attachment: Inferior surface of middle third of clavicle Innervation: Subclavian nerve (C5, C6) Action: Anchors and depresses clavicle Serratus anterior Origin External surfaces of lateral parts of 1st-8th ribs Attachment: Anterior surface of medial border of scapula Innervation: Long thoracic nerve (C5, C6, C7 ) Action: Protracts scapula and holds against thoracic wall; rotates scapula Attachments pectoral muscles Surface Anatomy of Pectoral Regions The large vessels and nerves to the upper limb pass posterior to the convexity in the clavicle. The clavipectoral (deltopectoral) triangle is the slightly depressed area just inferior to the lateral part of the clavicle. The clavipectoral triangle is bounded by the clavicle superiorly, the deltoid laterally, and the clavicular head of pectoralis major medially. When the arm is abducted and then adducted against resistance, the two heads of the pectoralis major are visible and palpable. Testing of Pectoralis Major For testing of clavicular head: keep the arm of the person in abducted position and then ask him to flex the arm against resistance. For testing sterno-costal head: ask the person to adduct his arm against resistance.