Unit 1 Muscles of the Thorax

Clavicular head - anterior surface clavicle, medial half

Sternocostal head - anterior surface of sternum, costal cartilages 1-7, 6th rib

pectoralis major (origin)

lateral border of intertubercular sulcus

pectoralis major (insertion)

Medial and Lateral Pectoral Ns

pectoralis major (innervation)

flexion at GH joint, adduction at GH joint, medial rotation at GH joint, flexion of extended arm (clavicular head) at GH joint, extension of flexed arm (sternocostal head) at GH joint

pectoralis major (function)

anterior surface ribs 3-5

pectoralis minor (origin)

coracoid process of scapula

pectoralis minor (insertion)

Medial Pectoral N

pectoralis minor (innervation)

protract/abduct scapula,

depresses lateral angle of scapula

pectoralis minor (function)

rib 1 between bony portion and costal cartilage 1

subclavius (origin)

inferior surface of clavicle

subclavius (insertion)

Nerve to subclavius

subclavius (innervation)

stabilizes sternoclavicular joint by pulling clavicle medially

subclavius (function)

inferior margin of rib above

external intercostal (origin)

superior margin of rib below

external intercostal (insertion)

Intercostal N

external intercostal (innervation)

moves ribs superiorly,

most active during inspiration,

supports intercostal space

external intercostal (function)

lateral edge of costal groove of rib above

internal intercostal (origin)

superior margin of rib below,

deep to attachment of external intercostal

internal intercostal (insertion)

Intercostal N

internal intercostal (innervation)

moves ribs inferiorly,

most active during expiration,

supports intercostal space

internal intercostal (function)

medial edge of costal groove of rib above

innermost intercostal (origin)

internal aspect of superior margin of rib below

innermost intercostal (insertion)

Intercostal N

innermost intercostal (innervation)

acts with internal intercostals

innermost intercostal (function)

internal surface of lower ribs near angle

subcostales (origin)

internal surface of second or third rib below

subcostales (insertion)

Intercostal N

subcostales (innervation)

depress ribs

subcostales (function)

Inferior aspect of deep surface of sternum

-Xiphoid process

-Costal cartilages IV-VII

transversus thoracis (origin)

Inferior margins and internal surface of costal cartilages of 2nd-6th ribs

transversus thoracis (insertion)

Intercostal N

transversus thoracis (innervation)

depress costal cartilages

transversus thoracis (function)

muscle fibers arise from margins of inferior thoracic aperture

respiratory diaphragm (origin)

converge onto central tendon

respiratory diaphragm (insertion)

Phrenic N

respiratory diaphragm (innervation)

respiration

respiratory diaphragm (function)

lateral surfaces upper 8-9 ribs

serratus anterior (origin)

medial border of scapula, on anterior surface

serratus anterior (insertion)

Long thoracic nerve

serratus anterior (innervation)

protract/abduct scapula,

rotate scapula,

fix scapula

serratus anterior (function)

spinous process of C7 to T3,

lower portion ligamentum nuchae,

supraspinous ligament

serratus posterior superior (origin)

upper border ribs 2-5

serratus posterior superior (insertion)

Anterior rami of upper thoracics Ns

serratus posterior superior (innervation)

elevates ribs 2-5

serratus posterior superior (function)

spinous process of T11 to L3,

supraspinous ligament

serratus posterior inferior (origin)

lower border ribs 9-12

serratus posterior inferior (insertion)

anterior rami of lower thoracic Ns

serratus posterior inferior (innervation)

depresses ribs,

prevent lower ribs from elevating when diaphragm contracts

serratus posterior inferior (function)

transverse processes C7-T11

levatores costarum (origin)

rib below vertebra of origin

levatores costarum (insertions)

Posterior rami of spinal nerves

levatores costarum (innervation)

elevate rib

levatores costarum (function)