BMS 202: Pectoral Region and Scapula

Scapula

• Has 3 angles: lateral, superior, and inferior
• Has 3 borders: superior, medial, and lateral
• Has 2 surfaces: anterior (ventral) and posterior (dorsal)
• Features: Acromion process, Coracoid process, and Glenoid cavity (fossa)

Surfaces of Scapula

• Ventral surface: smooth (subscapular fossa)
• Dorsal surface: shows the spine with supraspinous fossa above and infraspinous fossa below

Humerus

• Upper end: has 3 parts - Head, Greater tuberosity, and Lesser tuberosity (appears from anterior only)
• Just below the head is the anatomical neck
• Between the upper end and the shaft is the surgical neck
• Extending to the shaft between the two tuberosities is the bicipital groove

Pectoral Region

• Definition: region of the front of the chest
• Layers: Skin, Superficial fascia containing Mammary gland, Deep fascia (pectoral fascia), and Pectoral muscles

Pectoralis Major

• Origin: Clavicular head (ant surface of med ½ of clavicle) and Sternocostal head (front of sternum & Upper 6 costal cartilages)
• Insertion: lateral lip of bicipital groove
• Nerve supply: Medial and lateral pectoral nerves
• Action: Flexion, Adduction, and Medial rotation of arm

Pectoralis Minor

• Origin: Outer surface of 3,4,5 ribs
• Insertion: Coracoid process
• Nerve supply: Medial pectoral nerves
• Action: Protraction and Depression of scapula

Subclavius

• Origin: Upper surface of 1st rib at costochondral junction
• Insertion: Groove at lower surface of middle 1/3 of clavicle
• Nerve supply: Nerve to subclavius
• Action: Steady the clavicle by preventing excessive movement at shoulder girdle

Clavipectoral Fascia

• Part of pectoral fascia deep to pectoralis major
• Between subclavius and pectoralis minor
• Attachments: Above (split to enclose subclavius), Med (1st and 2nd costal cartilages), Lat (coracoid process), and Below (split to enclose pectoralis minor and continues as suspensory ligament of axilla)

Structures Piercing Clavipectoral Fascia

• Thoraco-acromial artery
• Lateral pectoral nerve
• Cephalic vein
• Infralavicular lymph vessels

Serratus Anterior

• Origin: Outer surface of the upper 8 ribs
• Insertion: Front of medial border of scapula
• Nerve supply: Long thoracic nerve
• Action: 1. Protraction of scapula, 2. Upward rotation of scapula (Move arm above head) (abduction > 90º) together with trapezius
• Paralysis of serratus ant due to injury of long thoracic nerve (during mastectomy) leads to Winging of Scapula

Identify and describe the pectoral region, muscles, and scapula structure, including attachments, nerve supply, and actions. Learn about the parts of the scapula, including its angles and borders.