Trunk Muscle Actions, Innervations, Attachments

shoulder internal rotation ; shoulder adduction

action: Pectoralis Major

clavicular head: anterior surface of medial half of clavicle ; sternocostal head: anterior surface of sternum, superior 6 costal cartilages, aponeurosis of external oblique

proximal attachment: Pectoralis Major

lateral lip of intertubercular groove of humerus

distal attachment: Pectoralis Major

lateral pectoral nerve C5-C7 ; medial pectoral nerve C8-T1

innervation: Pectoralis Major

scapular stabilizatioin by drawing it inferiorly and anteriorly; scapular anterior tilt

action: Pectoralis Minor

ribs 3-5 near costal cartilage

proximal attachment: Pectoralis Minor

coracoid process of the scapula

distal attachment: Pectoralis Minor

medial pectoral nerve C8-T1

innervation: Pectoralis Minor

scapular protraction; scapular upward rotation

action: Serratus Anterior

external surface of the lateral aspect of ribs 1-8

proximal attachment: Serratus Anterior

anterior surface of medial border of scapula

distal attachment: Serratus Anterior

long thoracic nerve C5-C7

innervation: Serratus Anterior

rib elevation during forced inspiration

action: External Intercostal

tubercles of ribs

proximal attachment: External Intercostal

costalcondral joints

distal attachment: External Intercostal

intercostal nerves of that level

innervation: External Intercostal

rib depression during forced expiration

action: Internal Intercostal

angles of ribs

proximal attachment: Internal Intercostal

sternum

distal attachment: Internal Intercostal

intercostal nerves of that level

innervation: Internal Intercostal

rib depression during forced expiration

action: Innermost Intercostal

- angle of rib

proximal attachment: Innermost Intercostal

costalcondral joints

distal attachment: Innermost Intercostal

intercostal nerves of that level

innervation: Innermost Intercostal

rib depression during expiration

action: Transverse Thoracis

posterior surface of lower sternum

proximal attachment: Transverse Thoracis

internal surface of costal cartilages 2-6

distal attachment: Transverse Thoracis

intercostal nerves

innervation: Transverse Thoracis

elevate mandible; weak protrusion

action: Masseter

maxillary process of zygomatic bone and zygomatic arch

proximal attachment: Masseter

ramus of the mandible

distal attachment: Masseter

trigeminal nerve (CN V)

innervation: Masseter

elevate mandible ; retract mandible

action: Temporalis

floor of temporal fossa and deep surface of temporal fascia

proximal attachment: Temporalis

coronoid process and ramus of mandible

distal attachment: Temporalis

trigeminal nerve (CN V)

innervation: Temporalis

protract mandible and depress chin

action bilateral: Lateral Pterygoid

swings jaw toward contralateral side

action: unilateral: Lateral Pterygoid

1: crest of greater wing of sphenoid ; 2:lateral surface of lateral pterygoid plate

proximal attachment: Lateral Pterygoid

condyloid process of mandible ad TMJ capsule

distal attachment: Lateral Pterygoid

trigeminal nerve (CN V)

innervation: Lateral Pterygoid

elevate mandible ; weak protrusion

action: Medial Pterygoid

1: medial surface of lateral pterygoid plate and palatine bone; 2: tuberosity of maxilla

proximal attachment: Medial Pterygoid

ramus of the mandible

distal attachment: Medial Pterygoid

trigeminal nerve (CN V)

innervation: Medial Pterygoid

depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

action: Digastric

anterior belly: anterior mandible ; posterior belly: base of cranium

proximal attachment: Digastric

hyoid bone via fascial sling

distal attachment: Digastric

facial nerve (CN VII) ; trigeminal nerve (CN V)

innervation: Digastric

elevated and retracts hyoid bone

action: Stylohyoid

styloid process

proximal attachment: Stylohyoid

hyoid bone

distal attachment: Stylohyoid

facial nerve (CN VII)

innervation:Stylohyoid

depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

action: Mylohyoid

medial body of mandible

proximal attachment: Mylohyoid

hyoid bone

distal attachment: Mylohyoid

trigeminal nerve (CN V)

innervation: Mylohyoid

depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

action: Geniohyoid

anterior body of mandible

proximal attachment: Geniohyoid

hyoid bone

distal attachment: Geniohyoid

nerve to geniohyoid (C1-C2)

innervation: Geniohyoid

fixes or depresses hyoid bone

action: Omohyoid

scapula

proximal attachment: Omohyoid

hyoid bone

distal attachment: Omohyoid

ansa cervicalis (C1-C3)

innervation: Omohyoid

fixes or depresses hyoid bone

action: Sternohyoid

manubrium of sternum

proximal attachment: Sternohyoid

hyoid bone

distal attachment: Sternohyoid

ansa cervicalis (C1-C3)

innervation: Sternohyoid

fixes or depresses hyoid bone

action: Sternothyroid

manubrium of sternum

proximal attachment: Sternothyroid

thyroid cartilage

distal attachment: Sternothyroid

ansa cervicalis (C2-C3)

innervation: Sternothyroid

fixes or depresses hyoid bone

action: Thyrohyoid

thyroid cartilage

proximal attachment: Thyrohyoid

hyoid bone

distal attachment: Thyrohyoid

C1

innervation: Thyrohyoid

upper cervical extension iwth lower cervical flexion

action bilateral: Sternocleidomastoid

ipsilateral neck flexion with contralateral rotation

action unilateral: Sternocleidomastoid

lateral surface of mastoid process of temporal bone

proximal attachment: Sternocleidomastoid

manubrium and medial portion of clavicle

distal attachment: Sternocleidomastoid

spinal accessory nerve (CN XI) ; anterior rami of C2-C3

innervation: Sternocleidomastoid

neck flexion

action: Anterior Scalene

transverse process of C3-C6

proximal attachment: Anterior Scalene

1st rib

distal attachment: Anterior Scalene

cervical spinal nerve C4-C6

innervation: Anterior Scalene

flexes neck laterally - ipsilateral

action unilateral: Middle Scalene

elevates 1st rib during forced inspiration

action bilateral: Middle Scalene

posterior tubercles of transverse processes of C2-C7

proximal attachment: Middle Scalene

superior surface of 1st rib, posterior to groove for subclavian artery

distal attachment: Middle Scalene

anterior rami of cervical spinal nerves C3-C7

innervation: Middle Scalene

flexes neck laterally - ipsilateral

action unilateral: Posterior Scalene

elevates 2nd rib during forced inspiration

action bilateral: Posterior Scalene

posterior tubercles of transverse processes of C5-C7

proximal attachment: Posterior Scalene

external border of 2nd rib

distal attachment: Posterior Scalene

anterior rami of cervical spinal nerve C7-C8

innervation: Posterior Scalene

neck flexion

action: bilateral: Longus Colli

neck contralateral rotation

action: unilateral: Longus Colli

anterior tubercle of C1, bodies of C1-C3, and TPs of C3-C6

proximal attachment: Longus Colli

bodies of C5-T3 and TPs of C3-C5

distal attachment: Longus Colli