Back Structures and Innervations

trapezius insertion

posterior aspect of lateral one third of clavicle, acromion, and spine of scapula

trapezius action

elevates, depresses, retracts, and upwardly rotates the pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints; extends and laterally flexes head and neck

trapezius innervation

accessory nerve, anterior rami of third of fourth cervical nerves

latissimus dorsi insertion

floor of intertubercular sulcus of humerus

latissimus dorsi action

adducts, medially rotates, and extends arm at glenohumeral (shoulder) joint

latissimus dorsi action

thoracodorsal nerve (C6-C8)

external oblique insertion

anterior superior iliac spine, anterior half of iliac crest, pubic crest, pubic tubercle, linea alba

external oblique action

flexes, laterally flexes, and rotates trunk; compresses and provides structural support to adjacent abdominal structures

external oblique innervation

anterior rami of seventh to twelfth thoracic nerves

splenius capitis insertion

mastoid process of temporal bone; lateral one third of superior nuchal line of occipital bone

splenius captitis action

rotates and extends head

splenius capitis innervation

posterior rami of second and third cervical nerves

splenius cervicis insertion

transverse processes of C1-C3 vertebrae

splenius cervicis action

extends, rotates, and laterally flexes the neck at cervical vertebral joints

splenius cervicis innervation

posterior rami of lower cervical nerves

levator scapulae insertion

superior angle of scapula, medial border of scapula superior to spine of scapula

levator scapulae action

elevates and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints; extends and laterally flexes neck at cervical vertebral joints

levator scapulae innervation

anterior rami of third and fourth cervical nerves, dorsal scapular nerve (C5)

rhomboid minor insertion

medial border of scapula adjacent to spine of scapula

rhomboid minor action

retracts and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints

rhomboid minor innervation

dorsal scapular nerve (C4-C5)

rhomboid major insertion

medial border of scapula inferior to spine of scapula

rhomboid major action

retracts and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints

rhomboid major innervation

dorsal scapular nerve (C4-C5)

serratus posterior superior insertion

external surfaces of second and fifth ribs

serratus posterior superior action

elevates ribs at their costovertebral joints

serratus posterior superior innervation

anterior rami of second and fifth thoracic nerves

serratus posterior inferior insertion

external surfaces of ninth to twelfth ribs

serratus posterior inferior action

depresses ribs at their costovertebral joints

serratus posterior inferior innervation

anterior rami of ninth to twelfth thoracic nerves

iliocostalis lumborum insertion

transverse processes of L1-L4 vertebrae; angles of fifth to tenth ribs

Iliocostalis Lumborum action

extends and laterally flexes trunk

Iliocostalis Lumborum innervation

lateral branches of posterior rami of thoracic and lumbar nerves

Longissimus Thoracis insertion

transverse processes of lumbar and thoracic vertebrae, and second to twelfth ribs

Longissimus Thoracis action

extends and laterally flexes trunk

Longissimus Thoracis Innervation

lateral branches of posterior rami of thoracic and lumbar nerves

Spinalis Thoracis insertion

spinous processes of T2-T8 vertebrae

Spinalis Thoracis action

extends and laterally flexes trunk

Spinalis Thoracis innervation

posterior rami of thoracic and upper lumbar nerves

Semispinalis Cervicis insertion

spinous processes of C2-C5 vertebrae

Semispinalis Cervicis action

extends and rotates the neck at cervical vertebral joints

Semispinalis Cervicis innervation

medial branches of posterior rami of lower cervical and upper thoracic nerves

Semispinalis Thoracis insertion

spinous process of C6-T4 vertebrae

Spinalis Thoracis action

extends and rotates the trunk

Semispinalis Thoracis innervation

medial branches of posterior rami of thoracic nerves

Semispinalis Capitis insertion

area located between superior and inferior nuchal lines of occipital bones

Semispinalis Capitis action

extends and rotates the head

Semispinalis Captiis innervation

greater occipital (C2) and third cervical nerves