Back Muscles

Splenius Capitis

Extends the head and neck; rotates and laterally flexes the head to the same side.

Origin of Splenius Capitis

Nuchal ligament and spinous processes of C7-T3 (or T4).

Insertion of Splenius Capitis

Mastoid process of the temporal bone and the lateral third of the superior nuchal line of the occipital bone.

Splenius Cervicis

Extends the cervical spine; laterally flexes and rotates the neck to the same side.

Origin of Splenius Cervicis

Spinous processes of T3-T6.

Insertion of Splenius Cervicis

Transverse processes of C1-C3 (C4).

Semispinalis Capitis

Extends the head and neck; rotates the head to the opposite side.

Origin of Semispinalis Capitis

Transverse processes of C7-T6 (sometimes T7-T12).

Insertion of Semispinalis Capitis

Between the superior and inferior nuchal lines of the occipital bone.

Semispinalis Cervicis

Extends the cervical spine; rotates the cervical spine to the opposite side.

Origin of Semispinalis Cervicis

Transverse processes of T1-T5 (or T6).

Insertion of Semispinalis Cervicis

Spinous processes of C2-C5.

Deltoid

Flexes and medially rotates the arm; abducts the arm; extends and laterally rotates the arm.

Origin of Deltoid

Lateral third of the clavicle, acromion, and spine of the scapula.

Insertion of Deltoid

Deltoid tuberosity of the humerus.

Trapezius

Elevates, retracts, and rotates the scapula.

Origin of Trapezius

Occipital bone, nuchal ligament, and spinous processes of C7-T12.

Insertion of Trapezius

Lateral third of the clavicle, acromion, and spine of the scapula.

Teres Major

Adducts, extends, and medially rotates the arm at the shoulder joint.

Origin of Teres Major

Dorsal surface of the inferior angle of the scapula.

Insertion of Teres Major

Medial lip of the intertubercular groove of the humerus.

Teres Minor

Laterally rotates the arm at the shoulder joint; helps stabilize the shoulder joint.

Origin of Teres Minor

Lateral border of the scapula.

Insertion of Teres Minor

Greater tubercle of the humerus (below the infraspinatus insertion).

Rhomboid Major

Retracts (adducts) and elevates the scapula; helps rotate the scapula downward.

Origin of Rhomboid Major

Spinous processes of T2-T5.

Insertion of Rhomboid Major

Medial (vertebral) border of the scapula, below the spine of the scapula.

Rhomboid Minor

Retracts (adducts) and elevates the scapula; helps rotate the scapula downward.

Origin of Rhomboid Minor

Nuchal ligament and spinous processes of C7 and T1.

Insertion of Rhomboid Minor

Medial border of the scapula, at the level of the spine of the scapula.

Levator Scapulae

Elevates the scapula; downwardly rotates the scapula; laterally flexes the neck.

Origin of Levator Scapulae

Transverse processes of C1-C4.

Insertion of Levator Scapulae

Superior (medial) border of the scapula.

Latissimus Dorsi

Extends, adducts, and medially rotates the arm at the shoulder joint.

Origin of Latissimus Dorsi

Spinous processes of T7-T12, lumbar vertebrae, sacrum, iliac crest, and lower three or four ribs.

Insertion of Latissimus Dorsi

Intertubercular groove of the humerus (anterior surface).

Serratus Posterior Superior

Elevates the upper ribs (helps with inspiration during breathing).

Origin of Serratus Posterior Superior

Spinous processes of C7-T3 and nuchal ligament.

Insertion of Serratus Posterior Superior

Superior borders of ribs 2-5.

Serratus Posterior Inferior

Depresses the lower ribs (helps with forced expiration during breathing).

Origin of Serratus Posterior Inferior

Spinous processes of T11-L2.

Insertion of Serratus Posterior Inferior

Inferior borders of ribs 9-12.

Supraspinatus

Abducts the arm at the shoulder joint (first 15 degrees); helps stabilize the shoulder joint.

Origin of Supraspinatus

Supraspinous fossa of the scapula.

Insertion of Supraspinatus

Greater tubercle of the humerus (superior facet).

Infraspinatus

Laterally rotates the arm at the shoulder joint; stabilizes the shoulder joint.

Origin of Infraspinatus

Infraspinous fossa of the scapula.

Insertion of Infraspinatus

Greater tubercle of the humerus (middle facet).

Subscapularis

Medially rotates the arm at the shoulder joint; adducts the arm; helps stabilize the shoulder joint.

Origin of Subscapularis

Subscapular fossa of the scapula.

Insertion of Subscapularis

Lesser tubercle of the humerus.

Spinalis

Extends the vertebral column (spine); laterally flexes the vertebral column to the same side.

Origin of Spinalis

Spinous processes of the upper lumbar and lower thoracic vertebrae.

Insertion of Spinalis

Spinous processes of the upper thoracic vertebrae and cervical vertebrae (C2, C3).

Longissimus

Extends the vertebral column (spine); laterally flexes the vertebral column to the same side.

Origin of Longissimus

Transverse processes of the lumbar, thoracic, and cervical vertebrae.

Insertion of Longissimus

Ribs between the tubercles and angles, transverse processes of thoracic and cervical vertebrae, and mastoid process of the temporal bone (for the longissimus capitis).

Iliocostalis

Extends the vertebral column (spine); laterally flexes the vertebral column to the same side.

Origin of Iliocostalis

Iliac crest, sacrum, and the spinous processes of the lumbar vertebrae.

Insertion of Iliocostalis

Angles of the ribs and the transverse processes of cervical vertebrae (C4-C6).