Thorax Muscles Flashcards
Serratus Anterior Origin
Upper eight ribs and ant intercostal membranes from midclavicular line. Lower four interdigitating with external oblique
Serratus Anterior Insertion
Inner med border scapula. 1 and 2: upper angle; 3 and 4: length of costal surface ; 5-8: inf angle
Serratus Anterior Action
Lat rotates protracts scapula
Serratus Anterior Innervation
Long thoracic Nerve (C5, 6, 7) (from roots) slips from ribs 1 and 2: C5; 3 and 4: C6; 5-8: C7)
Diaphragm Origin
Vertebral:crura from bodies of L1, 2 (left), L1-3(right). Costal: med and lat arcuate ligs, inner aspect of lower six ribs . Sternal: two slips from post aspect of xiphoid
Diaphragm Insertion
Trefoil central tendon
Diaphragm Action
Inspiration and assists in raising intra-abdominal pressure
Diaphragm Innervation
Phrenic N (motor) (C3, 4, 5). Sensory: phrenic, intercostals(6-12) and upper two lumbar N roots
External Intercostals Origin
Inf border of ribs as far back as post angles
External Intercostals Insertion
Sup border of ribs below, passing obliquely downwards and backwards
External Intercostals Action
Fix intercostal spaces during respiration. Aids forced inspiration by elevating ribs
External Intercostals Innervation
Muscular collateral brs of intercostal Ns
Innermost Intercostals Origin
Int aspect of ribs above and below
Innermost Intercostals Insertion
Int aspect of ribs above and below
Innermost Intercostals Action
Fix intercostal spaces during respiration
Innermost Intercostals Innervation
Muscular collateral brs of intercostal Ns
Internal Intercostals Origin
Inf border of ribs as far back as post angles
Internal Intercostals Insertion
Sup border of ribs below , passing obliquely downwards and backwards
Internal Intercostals Action
Fix intercostal spaces during expiration. Aids forced inspiration by elevating ribs
Internal Intercostals Innervation
Muscular collateral brs of intercostal Ns
Levatores Costarum Origin
Transverse processes C7 to T11
Levatores Costarum Insertion
Post surface and angle of rib below
Levatores Costarum Action
Elevates ribs
Levatores Costarum Innervation
Muscular collateral brs of intercostal Ns
Pectoralis Major Origin
Clavicular head-med half clavicle. Sternocostal head -lat manubrium and sternum, six upper costal cartilages and ext oblique aponeurosis
Pectoralis Major Insertion
Lat lip of bicipital groove of humerus and ant lip of deltoid tuberosity
Pectoralis Major Action
Clavicular head:flexes and adducts arm. Sternal head: adducts and med rotates arm . Accessory for inspiration
Pectoralis Major Innervation
Med pectoral nn(from med cord) and lat pectoral nn (from lat cord) (C6, 7, 8)
Pectoralis Minor Origin
3, 4,5 ribs
Pectoralis Minor Insertion
Med and upper surface of coracoid process of scapula
Pectoralis Minor Action
Elevates ribs if scapula fixed, protracts scapula (assists serratus ant )
Pectoralis Minor Innervation
Med pectoral N (C8, T1) (from med cord)
Serratus Posterior Inferior Origin
Spinous processes and supraspinous ligs of T11-L2
Serratus Posterior Inferior Insertion
Post aspect of ribs 9-12
Serratus Posterior Inferior Action
Assists forced expiration
Serratus Posterior Inferior Innervation
Ant primary rami (T9-12)
Serratus Posterior Superior Origin
Spinous processes and supraspinous ligs of C7-T2
Serratus Posterior Superior Insertion
Post aspect of ribs 2-5
Serratus Posterior Superior Action
Assists forced inspiration
Serratus Posterior Superior Innervation
Ant primary rami (T2-5)
Subcostals Origin
Int post aspects of lower six ribs
Subcostals Insertion
Int aspects of ribs two to three levels below
Subcostals Action
Depresses lower ribs
Subcostals Innervation
Muscular collateral brs of intercostal Ns
Transversus Thoracis Origin
Lower third of inner aspect of sternum and lower three costosternal junctions
Transversus Thoracis Insertion
Second to sixth costal cartilages
Transversus Thoracis Action
Depresses upper ribs
Transversus Thoracis Innervation
Muscular collateral brs of intercostal Ns
