Term
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Definition
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PECTORALIS MAJOR
ORIGIN
Clavicular head-medial half clavicle. Sternocostal head-lateral manubrium and sternum, six upper costal cartilages and external oblique aponeurosis |
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INSERTION
Lateral lip of bicipital groove of humerus and anterior lip of deltoid tuberosity |
ACTION
Clavicular head:flexes and adducts arm. Sternal head: adducts and medially rotates arm . Accessory for inspiration |
NERVE
Medial pectoral nerve (from medial cord) and lateral pectoral nerve (from lateral cord) (C6, 7, 8) |
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Term
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Definition
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PECTORALIS MINOR
ORIGIN
3, 4, 5 ribs |
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INSERTION
Medial and upper surface of coracoid process of scapula |
ACTION
Elevates ribs if scapula fixed, protracts scapula (assists serratus anterior) |
NERVE
Medial pectoral nerve (C8, T1) (from medial cord) |
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Term
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Definition
SUBCLAVIUS
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ORIGIN
Costochondral junction of 1st rib
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INSERTION
Subclavian groove on inferior surface of middle third of clavicle |
ACTION
Depresses clavicle and steadies it during shoulder movements |
NERVE
Nerve to subclavius (C5, 6, upper trunk) |
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Term
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Definition
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SCALENUS ANTERIOR
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ORIGIN
Anterior tubercles of transverse processes of C3-6
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INSERTION
Scalene tubercle on superior aspect of 1st rib |
ACTION
Accessory to inspiration. lateral flexion of neck when 1st rib fixed |
NERVE
Anterior primary rami of C5, 6 |
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Term
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Definition
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SCALENUS MEDIUS
ORIGIN
Posterior tubercles of transverse processes of C2-7 |
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INSERTION
Superior aspect of neck of 1st rib |
ACTION
Accessory to inspiration |
NERVE
Anterior primary rami of C3-8 |
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Term
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Definition
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SCALENUS POSTERIOR
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ORIGIN
Posterior tubercles of transverse processes C4-6
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INSERTION
Post/lateral surface of 2nd rib |
ACTION
Accessory to inspiration |
NERVE
Anterior primary rami of C6-8 |
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Term
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Definition
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SERRATUS ANTERIOR
ORIGIN
Upper eight ribs and anterior intercostal membranes from midclavicular line. Lower four interdigitating with external oblique |
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INSERTION
Inner medial border scapula. 1 and 2: upper angle; 3 and 4: length of costal surface ; 5-8: inferior angle |
ACTION
Laterally rotates and protracts scapula |
NERVE
Long thoracic nerve (C5, 6, 7) (from roots) slips from ribs 1 and 2: C5; 3 and 4: C6; 5-8: C7) |
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Term
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Definition
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EXTERNAL INTERCOSTALS
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ORIGIN
Inferior border of ribs as far back as posterior angles
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INSERTION
Superior border of ribs below, passing obliquely downwards and backwards |
ACTION
Fix intercostal spaces during respiration. Aids forced inspiration by elevating ribs |
NERVE
Muscular collateral branches of intercostal nerves |
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Term
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Definition
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INNERMOST INTERCOSTALS
ORIGIN
Internal aspect of ribs above and below |
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INSERTION
Internal aspect of ribs above and below |
ACTION
Fix intercostal spaces during respiration |
NERVE
Muscular collateral branches of intercostal nerve |
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Term
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Definition
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INTERNAL INTERCOSTALS
ORIGIN
Inferior border of ribs as far back as posterior angles |
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INSERTION
Superior border of ribs below , passing obliquely downwards and backwards |
ACTION
Fix intercostal spaces during espiration. Aids forced inspiration by elevating ribs |
NERVE
Muscular collateral branches of intercostal nerves |
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Term
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Definition
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TRANSVERSUS THORACIS
ORIGIN
Lower third of inner aspect of sternum and lower three costosternal junctions |
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INSERTION
Second to sixth costal cartilages |
ACTION
Depresses upper ribs |
NERVE
Muscular collateral branches of intercostal nerves |
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