Trunk and Thorax Muscles

internal intercostals - function

move ribs inferiorly for expiration

internal intercostals - innervation

intercostal nerves (T1-T11)

internal intercostals - origin

lateral edge of costal groove of superior rib

internal intercostals - insertion

superior margin of inferior rib

external intercostals - function

move ribs superiorly for inspiration

external intercostals - innervation

intercostal nerves (T1-T11)

external intercostals - origin

inferior margin of superior rib

external intercostals - insertion

superior margin of inferior rib

serratus anterior - function

upward rotation and protraction of scapula

stabilization of medial border of scapula (against thoracic wall)

serratus anterior - innervation

long thoracic nerve (C5, C6, C7)

serratus anterior - origin

lateral surfaces of ribs 1-8 or 9

serratus anterior - insertion

medial border of scapula (costal surface)

serratus posterior superior - function

elevation of ribs 2-5

serratus posterior superior - innervation

ventral rami of T2-T5

serratus posterior superior - origin

ligamentum nuchae

spinous processes of C7-T3

supraspinous ligaments

serratus posterior superior - insertion

upper border of ribs 2-5

serratus posterior inferior - function

depression of ribs 9-12

serratus posterior inferior - innervation

ventral rami of T9-T12

serratus posterior inferior - origin

spinous processes of T11-L3

supraspinous ligaments

serratus posterior inferior - insertion

lower border of ribs 9-12

pectoralis major - function

flexion, adduction, and internal rotation of shoulder

pectoralis major - innervation

medial and lateral pectoral nerves

pectoralis major - origin

medial half of clavicle

anterior surface of sternum

costal cartilage of ribs 1-7

fascia of external oblique

pectoralis major - insertion

intertubercular sulcus of humerus (lateral lip)

pectoralis minor - function

depression and protraction of scapula

pectoralis minor - innervation

medial pectoral nerve

pectoralis minor - origin

anterior surface of ribs 3-5

pectoralis minor - insertion

coracoid process of scapula

subclavius - function

depression of clavicle

stabilization of SC joint (pull clavicle medially)

subclavius - innervation

nerve to subclavius

subclavius - origin

junction between rib and costal cartilage of rib 1

subclavius - insertion

groove on inferior clavicle

latissimus dorsi - function

extension, adduction, and internal rotation of shoulder

latissimus dorsi - innervation

thoracodorsal nerve (C6, C7, C8)

latissimus dorsi - origin

ribs 10-12

spinous processes of T7-L5

iliac crest

sacrum

latissimus dorsi - insertion

intertubercular sulcus of humerus (floor)

quadratus lumborum - function

depression and stabilization of rib 12

lateral flexion of trunk (ipsilateral)

quadratus lumborum - innervation

ventral rami of T12-L4

quadratus lumborum - origin

transverse processes of L5

iliolumbar ligament

iliac crest

quadratus lumborum - insertion

transverse processes of L1-L4

inferior border of rib 12