Muscles of Upper Arm Flashcards
Pectoralis Major
Proximal: Clavicular head- anterior surface of medial 1/2 of clavicle. Sternocostal head- sternum and superior 6 costal cartilages, aponeurosis of external oblique muscle
Distal: lateral lip of intertubercular sulcus
Innervation : Medial and Lateral Pectoral Nerve
Action: adduction and medial rotation of humerus. Draws scapula anteriorly and inferiorly against thoracic wall (bench press)
Pectoralis Minor
Proximal: 3rd to 5th ribs
Distal: Coracoid Process
Innervation: Medial Pectoral Nerve
Action: stabilizes scapula by drawing scapula anteriorly and inferiorly against thoracic wall
Subclavious
Proximal: junction of 1st rib and its costal cartilage
Distal: inferior surface of middle third of clavicle
Innervation: Subclacian Nerve
Action: anchors and depresses Clavicle
Serratus Anterior
Proximal: 1st to 8th ribs
Distal: medial border of Scapula
Innervation: Long Thoracic Nerve
Action: “boxer’s muscle” Protracts scapula drawing it anteriorly/forward
Trapezius
Medial: medial third of superior nuchal line; external occipital protuberance, nuchal ligament; spinous processes of C7-T12 vertebrae
Lateral: lateral 1/3 of clavicle, acromion and spine of scapula
Innervation: Spinal accessory nerve (cranial never XI) and C3, C4 spinal nerve
Action: Descending- elevates “shoulder shrugging” Ascending- depresses
Middle- retracts scapula
Latissimus dorsi
Medial: spinous processes of T6-T12 thoracic vertebrae, thoracolumbar fascia, iliac crest, inferior 3 or 4 ribs
Lateral: floor of intertubercular groove of humerus
Innervation: Thoracodorsal Nerve
Actions: extends, adduction and medial rotation of shoulder joint; raises body towards arm during climbing
Levator Scapulae
Medial: posterior tubercles of transverse processes of C1-C4
Lateral: medial border of scapula superior to root of spine
Innervation: Dorsal Scapular Nerve
Action: elevates scapula
Rhomboids (major and minor)
Medial: spinous processes of C7-T1(minor); spinous processes of T2-T5(major)
Lateral: medial border of scapula
Innervation: Dorsal Scapular Nerve
Action: retract scapula and rotate glenoid cavity inferiorly
Deltoid
Proximal: lateral 1/3 of clavicle, acromion and spine of scapula (insertion of trapezius is and as origin of deltoid)
Distal: deltoid tuberosity
Innervation: Axillary Nerve
Action: flex, medially rotates shoulder joint; extends, laterally rotate and abduction of arm
Supraspinatus
Proximal: supraspinous fossa
Distal: greater tubercle of humerus
Innervation: Suprascapular Nerve
Action: initiates abduction (15°) of arm
Infraspinatus
Proximal: infraspinous fossa of scapula
Distal: greater tubercle of humerus
Innervation: Suprascapular Nerve
Action: laterally rotates shoulder joint
Teres Minor
Proximal: middle part of lateral border of scapula
Distal: greater tubercle of humerus
Innervation: Axillary Nerve
Action: laterally rotates shoulder joint (same as infraspinatus)
Teres Major
Proximal: inferior part of lateral border of scapula
Distal: medial lip of intertubercular sulcus of humerus
Innervation: Lower Subscapular Nerve
Action: medially rotates and adducts the shoulder joint
Subscapularis
Proximal: subscapular fossa of scapula
Distal: lesser tubercle of humerus
Innervation: upper and lower subscapular nerves
Action: medially rotates and adducts shoulder joint
Biceps Brachii
Proximal: short head- coracoid process; long head- supraglenoid tubercle of scapula
Distal: radial tuberosity
Innervation: musculocutaneous nerve
Action: flexes elbow and supinates forearm (opening bottle of wine)
