Origin: Vertebral spines from T7 to the sacrum, posterior third of the iliac crest, lower 3 or 4 ribs, sometimes from the inferior angle of the scapula

Insertion: Floor of the intertubercular groove

Innervation: Thoracodorsal nerve (C7, C8) from the posterior cord of the brachial plexus

Action: Extends and rotates the arm medially, along with adduction of the arm

Origin: Dorsal surface of the inferior angle of the scapula

Insertion: The medial lip of the intertubercular groove of the humerus

Innervation: Lower subscapular nerve (C5-C7)

Action: Brings the arm towards the body, extends the shoulder joint and rotates the arm inward.

Origin: Lateral border and adjacent posterior surface of the scapula

Insertion: Inferior facet of the greater tuberosity (or tubercle) of the humerus

Innervation: Axillary nerve (C5, C6)

Action:

External Rotation: Primarily produces external rotation of the shoulder joint, along with the infraspinatus

Shoulder Stability: Helps to hold the humeral head in the glenoid cavity, preventing dislocation

Modulates Deltoid Action: Prevents the humeral head from sliding upward during abduction (raising the arm)

Adduction and Abduction: Contributes to arm adduction and abduction

Origin: Infraspinous fossa of the scapula

Insertion: Middle facet of the greater tuberosity of the humerus

Innervation: Suprascapular nerve

Action: External rotator of the shoulder joint and helps stabilize the glenohumeral joint

Origin: Medial third of the superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of vertebrae C7-T12

Insertion: Lateral third of the clavicle, medial side of the acromion and the upper crest of the scapular spine, tubercle of the scapular spine

Innervation: Motor: spinal accessory (XI), proprioception: C3-C4

Action: Elevates and depresses the scapula (depending on which part of the muscle contracts); rotates the scapula superiorly; retracts scapula

Origin: Spines of vertebrae T2-T5

Insertion: Medial border of the scapula inferior to the spine of the scapula

Innervation: Dorsal scapular nerve (C5)

Action: Retracts, elevates and rotates the scapula inferiorly

Origin: Inferior end of the ligamentum nuchae, spines of vertebrae C7 and T1

Insertion: Medial border of the scapula at the root of the spine of the scapula

Innervation: Dorsal scapular nerve (C5)

Action: Retracts, elevates and rotates the scapula inferiorly

Origin: Thoracolumbar fascia, spines of vertebrae T11-T12 and L1-L2

Insertion: Ribs 9-12, lateral to the angles

Innervation: Branches of the ventral primary rami of spinal nerves T9-T12

Action: Pulls down lower ribs

Origin: Posterior part of the iliac crest and the iliolumbar ligament

Insertion: Transverse processes of lumbar vertebrae 1-4 and the 12th rib

Innervation: Subcostal nerve and ventral primary rami of spinal nerves L1-L4

Action: Laterally bends the trunk, fixes the 12th rib

Origin: Iliac crest and sacrum

Insertion: Angles of the ribs

Innervation: Dorsal primary rami of spinal nerves C4-S5

Action: Extends and laterally bends the trunk and neck

Origin: Transverse process at inferior vertebral levels

Insertion: Transverse process at superior vertebral levels and mastoid process

Innervation: Dorsal primary rami of spinal nerves C1-S1

Action: Extends and laterally bends the trunk, neck and head

Origin: Spinous processes at inferior vertebral levels

Insertion: Spinous processes at superior vertebral levels and base of the skull

Innervation: Dorsal primary rami of spinal nerves C2-L3

Action: Extends and laterally bends trunk and neck

Origin: Bodies and transverse processes of lumbar vertebrae

Insertion: Lesser trochanter of femur (with iliacus) via iliopsoas tendon

Innervation: Branches of the ventral primary rami of spinal nerves L2-L4

Action: Flexes the thigh; flexes & laterally bends the lumbar vertebral column

Origin: Iliac fossa and iliac crest; ala of sacrum

Insertion: Lesser trochanter of the femur

Innervation: Femoral nerve

Action: Flexes the thigh; if the thigh is fixed it flexes the pelvis on the thigh