Posterior Muscles of the Chest, Back, and Abdomen

What muscle is this?

splenius capitis

splenius capitis origin

nuchal ligament and spinous processes of C7-T4

splenius capitis insertion

occipital bone and mastoid process of temporal bone

splenius capitis action

Acting together (bilaterally), extend head and extend vertebral column; acting singly (unilaterally), laterally flex and/or rotate head to same side as contracting muscle.

splenius capitis innervation

middle cervical spinal nerves

What muscle is this?

splenius cervicis

splenius cervicis origin

spinous processes of T3-T6

splenius cervicis insertion

transverse processes of C1-C2 or C1-C4

splenius cervicis action

Acting together, extend head; acting singly, laterally flex and/or rotate head to same side as contracting muscle.

splenius cervicis innervation

inferior cervical spinal nerves

erector spinae complex

Consists of iliocostalis muscles (lateral), longissimus muscles (intermediate), and spinalis muscles (medial)

What muscle is this?

iliocostalis

iliocostalis origin

ribs 1-12 and iliac crest

iliocostalis insertion

transverse processes of C4-C6

iliocostalis action

acting together, muscles of each region (cervical, thoracic, and lumbar) extend and maintain erect posture of vertebral column of their respective regions; acting singly, laterally flex vertebral column of their respective regions to same side as contracting muscle

iliocostalis innervation

cervical, thoracic, and lumbar spinal nerves

What muscle is this?

longissimus

longissimus origin

articular processes of C4-C7 and transverse processes of T1-T5

longissimus insertion

mastoid process of temporal bone, transverse processes of C2-C6, transverse processes of lumbar vertebrae

longissimus action

Acting together, both longissimus capitis muscles extend head and extend vertebral column; acting singly, rotate head to same side as contracting muscle.

longissimus innervation

Portions of cervical, thoracic, and lumbar spinal nerves

What muscle is this?

spinalis

spinalis origin

nuchal ligament, spinous process of C7, T10-L2

spinalis insertion

occipital bone, spinous process of axis (C2), and spinous process of superior thoracic vertebrae

spinalis action

Acting together, muscles of each region (cervical, thoracic, and lumbar) extend vertebral column of their respective regions and extend head.

spinalis innervation

cervical and thoracic spinal nerves

What muscle is this?

trapezius

trapezius origin

superior nuchal line of occipital bone, ligamentum nuchae, and spines of C7-T12

trapezius insertion

clavicle and acromion and spine of scapula

trapezius action

Superior fibers upward rotate scapula; middle fibers adduct scapula; inferior fibers depress and upward rotate scapula; superior and inferior fibers together rotate scapula upward; stabilizes scapula. RMA: Superior fibers can help extend head.

trapezius innervation

accessory (XI) nerve and cervical spinal nerves C3-C5

What muscle is this?

levator scapulae

levator scapulae origin

transverse processes of C1-C4

levator scapulae insertion

superior vertebral border of scapula

levator scapulae action

elevates scapula and rotates it downward; laterally flexes neck to same side

levator scapulae innervation

dorsal scapular nerve and cervical spinal nerves

What muscle is this?

rhomboid major

rhomboid major origin

spines of T2-T5

rhomboid major insertion

vertebral border of scapula inferior to spine

rhomboid major action

adducts scapula and rotates it downward; stabilizes scapula

rhomboid major innervation

dorsal scapular nerve

What muscle is this?

rhomboid minor

rhomboid minor origin

spines of C7-T1

rhomboid minor insertion

vertebral border of scapula superior to spine

rhomboid minor action

adducts scapula and rotates it downward; stabilizes scapula

rhomboid minor innervation

dorsal scapular nerve

What muscle is this?

latissimus dorsi

latissimus dorsi origin

spines of T7-L5, lumbar vertebrae, crests of sacrum and ilium, ribs 9-12 via thoracolumbar fascia

latissimus dorsi insertion

intertubercular sulcus of humerus

latissimus dorsi action

Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly. RMA: Elevates vertebral column and torso.

latissimus dorsi innervation

thoracodorsal nerve

What muscle is this?

supraspinatus

supraspinatus origin

supraspinous fossa of scapula

supraspinatus insertion

greater tubercle of humerus

supraspinatus action

medially rotates arm at shoulder point

supraspinatus innervation

suprascapular nerve

What muscle is this?

infraspinatus

infraspinatus origin

infraspinous fossa of scapula

infraspinatus insertion

greater tubercle of humerus

infraspinatus action

laterally rotates arm at shoulder joint

infraspinatus innervation

suprascapular nerve

What is this muscle?

subscapularis

subscapularis origin

subscapular fossa of scapula

subscapularis insertion

lesser tubercle of humerus

subscapularis action

medially rotates arm at shoulder point

subscapularis innervation

upper and lower subscapular nerve

What is this muscle

teres major

teres major origin

inferior angle of scapula

teres major insertion

medial lip of intertubercular sulcus of humerus

teres major action

extends arm at shoulder joint and assists in adduction and medial rotation of arm at shoulder point

teres major innervation

lower subscapular nerve

What is this muscle?

teres minor

teres minor origin

inferior lateral border of scapula

teres minor insertion

greater tubercle of humerus

teres minor action

laterally rotates and extends arm at shoulder joint

teres minor innervation

axillary nerve

What muscle is this?

serratus posterior inferior

serratus posterior inferior origin

supraspinal ligament and spinous processes of vertebrae T11-L3

serratus posterior inferior insertion

lower borders of ribs 9-12

serratus posterior inferior action

depression of rib

serratus posterior inferior innervation

intercostal nerves 9-12

What muscle is this?

serratus posterior superior

serratus posterior superior origin

supraspinal ligament, ligamentum nuchae, spinous processes of vertebrae T1-T3, and vertebrae C7

serratus posterior superior insertion

upper borders of ribs 2-5

serratus posterior superior action

elevation of the upper ribs

serratus posterior superior innervation

intercostal nerves 2-5 (T1-T5)