Unit 1 Posterior Muscles origin, inserations, actions and innervations

origin, inserations, actions and innervations for unit 1 posterior muscles

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.

Splenius Capitis Origin

Ligamentum nuchae 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.

Serratus Posterior Superior Origin

Nuchal ligament, spinous processes of vertebrae C7-T3

Serratus Posterior Superior Insertion

Superior borders of ribs 2-5

Serratus Posterior Superior Action

Elevates ribs

Serratus Posterior Superior innervation

2nd-5th Intercostal nerves

Serratus Posterior Inferior Origin

Spinous processes of vertebrae T11-L2

Serratus Posterior Inferior Insertion

Inferior borders of ribs 9-12

Serratus Posterior Inferior Action

Depresses ribs/ Draws ribs inferoposteriorly

Serratus Posterior Inferior Innervation

 Anterior rami of spinal nerves T9-T12 (a.k.a. 9th-11th Intercostal nerves + subcostal nerve)

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

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 C3–C5.

Rhomboid minor Origin

Spines of C7–T1

Rhomboid minor Insertion

Vertebral border of scapula superior to spine

Rhomboid minor Action

Elevates and adducts scapula and rotates it downward; stabilizes scapula

Rhomboid minor innervation

Dorsal scapular nerve.

Rhomboid major Origin

Spines of T2–T5

Rhomboid major Insertion

Vertebral border of scapula inferior to spine

Rhomboid major Action

Elevates and adducts scapula and rotates it downward; stabilizes scapula

Rhomboid major Innervation

Dorsal scapular nerve.

Supraspinatus Origin

Supraspinous fossa of scapula.

Supraspinatus Insertion

Greater tubercle of humerus.

Supraspinatus Action

Assists deltoid muscle in abducting arm at shoulder joint

Supraspinatus Innervation

Suprascapular nerve.

Subscapularis Origin

Subscapular fossa of scapula.

Subscapularis Insertion

Lesser tubercle of humerus.

Subscapularis Action

Medially rotates arm at shoulder joint.

Subscapularis Innervation

Upper and lower subscapular nerve.

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.

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 joint.

Teres major Innervation

Lower subscapular nerve

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.

Erector Spinae Complex

Iliocostalis Origin

ribs 1-12, and iliac crest

Erector Spinae Complex

Iliocostalis Insertion

Transverse processes of C4-C6, and ribs 1-12

Erector Spinae Complex

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.

Erector Spinae Complex

Iliocostalis Innervation

Cervical, thoracic, and lumbar spinal nerves

Erector Spinae Complex

Longissimus Origin

articular processes of C4-C7, and transverse processes of T1-T5 and transverse processes of lumbar vertebrae

Erector Spinae Complex

Longissimus Insertion

mastoid process of temporal bone, and transverse processes of C2-C6 and transverse processes all thoracic and superior lumbar vertebrae

Erector Spinae Complex

Longissimus Action

As a group, the longissimus muscles function to extend the head and the vertebral column. They can also rotate the head and flex the vertebral column laterally when contracted only on one side. 

Erector Spinae Complex

Longissimus Innervation

Portions of cervical, thoracic, and lumbar spinal nerves

Erector Spinae Complex

Spinalis Origin

nuchal ligament (ligamentum nuchae), spinous processes of C7, T10-L2

Erector Spinae Complex

Spinalis Insertion

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

Erector Spinae Complex

Spinalis Action

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

Erector Spinae Complex

Spinalis Innervation

Cervical and thoracic spinal nerve