Origin, insertion, action, innervation of neck and thorax muscles

Digastric (anterior belly) origin

from interior surface of mandible at chin

Digastric (anterior belly) insertion

hyoid bone

Digastric (anterior belly) action

depresses mandible, opening mouth, and/or elevates larynx

Digastric (anterior belly) innervation

trigeminal nerve (V), mandibular branch

Sternocliedomastioid origin

clavicular head attaches to sternal end of clavicle, sternal head attaches to manubrium

sternocliedomastoid insertion

mastoid region of skuill and lateral portion of superior nuchal line

sternocleidomastoid action

flex the neck together, bends neck toward opposite shoulder and turns face to opposite side

sternocleidomastoid innervation

accessory nerve (XI) and cervical nspinal nerves (C2 and C3) of cervical plexus

external intercostals origin

inferior border of each rib

external intercostal insertion

superior border of more inferior rib

external intercostal action

elevate ribs

external intercostal innervation

intercostal nerves (branches of thoracic spinal nerves)

internal intercostal origin

superior border of each rib

internal intercostal insertion

inferior border of the more superior rib

internal intercostal action

depress ribs

internal intercostal innervation

intercostal nerves (branches of thoracic spinal nerves)

Transverse abdominis origin

cartilages of ribs 7-12, iliac crest, and thoracolumbar fascia

transverse abdominis insertion

linea alba and pubis

transverse abdominis action

compress abdomen

transverse abdominis innervation

intercostal nerves 5-12, iliohypogastric, anbd ilioinguinal nerves

rectus abdominis origin

superior surface of pubis around symphysis

rectus abdominis insertion

inferior surfaces of cartilages (ribs 5-7) and xiphoid process of sternum

rectus abdominis action

depress ribs, flex vertebral column, and compress abdomen

Rectus abdominis innervation

intercostal nerves (T7-T12)

Pectoralis major origin