Back Muscles

posterior region of thorax

1. TRAPEZE

Medial Insertion : Superior nuchal line, nuchal ligament, and spinous processes from C7 to T12

Lateral Insertion : Posterior border of clavicle, acromion and spine of scapula

Innervation : Accessory Nerve (XI cranial nerve) and Trapezius nerve (C3 – C4)

Action :

* Fixed in the Spine : Shoulder Elevation, Scapula Adduction, Superior Rotation of the Scapulae and Shoulder Depression

* Fixed on the Scapula :

Unilateral Contraction : Homolateral Tilt and Contralateral Head Rotation

Bilateral Contraction : Head Extension

2. Latissimus dorsi

Medial Insertion : Spinous processes of 6th last thoracic and all lumbar vertebrae, sacral crest, posterior 1/3 of iliac crest, and outer surface of last 4 ribs

Lateral Insertion : Intertubercular Groove

Innervation : Thoracodorsal Nerve (C6 – C8)

Action : Adduction, Extension and Medial Rotation of the Arm. Shoulder Depression

3. RHOMBOID

Medial Insertion : Spinous processes from C7 to T5

Lateral Insertion : Medial border of scapula

Innervation : Dorsal nerve of the scapula (C5)

Action : Inferior adduction and rotation of the scapulae and shoulder elevation

4. SCAPULA LIFTER

Inferior Insertion : Superior angle of scapula

Superior Insertion : Transverse process from atlas to C4

Innervation : Dorsal nerve of the scapula (C5)

Action : Elevation and Adduction of the Scapula. Cervical Spine Tilt and Homolateral Rotation and Head Extension.

5. SERRATILE MINOR POSTEROSUPEROR

Medial Insertion : Spinous processes from C7 to T3

Lateral Insertion : Upper border and outer surface of 2nd to 5th ribs

Innervation : Branches of the first 4 intercostal nerves

Action : Elevation of the first ribs (inspiratory action)

6. SERRATILE MINOR POSTERO-INFERIOR

Medial Insertion : Spinous processes from T11 to L3

Lateral Insertion : Lower edge and outer surface of the last 4 ribs

Innervation : 9th to 12th intercostal nerves

Action : Depression of the last ribs (expiratory action)

Posterior Region of the Neck

1. SPLENIUM OF THE HEAD

Superior Insertion : Lateral 1/3 of superior nuchal line and mastoid process of temporal bone

Inferior Insertion : Spinous processes from C7 to T4

Innervation : Spinal nerves of the corresponding segment

Action : Extension, Tilt and Homolateral Rotation of the Head

2. SPLENIUM OF THE NECK

Superior Insertion : Transverse process of the first 3 cervical vertebrae

Inferior Insertion : Spinous process from T3 to T6

Innervation : Spinal nerves of the corresponding segment

Action : Extension, Tilt and Homolateral Rotation of the Head

3. SEMISPINHAL OF THE HEAD

Superior Insertion : Between the superior and inferior nuchal line

Lower Insertion : Transverse process from T1 to T7 and articular processes from C5 to C7

Innervation : Spinal nerves of the corresponding segment

Action : Head extension and homolateral head tilt

4. SEMISPINHAL OF THE NECK

Superior Insertion : Spinous process from C1 to C7

Lower Insertion : Transverse processes from T1 to T6

Innervation : Spinal nerves (dorsal branches)

Action : Extension and Contralateral Rotation of the Neck

5. SEMISPINALS OF THE THORAX

Superior Insertion : Spinous process C6 to T4

Lower Insertion : Transverse processes from T6 to T10

Innervation : Spinal nerves (dorsal branches)

Action : Extension and Contralateral Rotation of the Neck

Suboccipitals – Suboccipital Trine

1. HEAD MAJOR POSTERIOR RECTUS

Superior Insertion : Inferior nuchal line

Lower Insertion: Spinous process of axis

Innervation : Cervical Plexus (C1)

Action : Head extension and contralateral rotation

two . HEAD MINOR POSTERIOR RECTUS

Superior Insertion : Inferior nuchal line

Inferior Insertion : Tubercle of posterior arch of atlas

Innervation : Cervical Plexus (C1)

Action : Head Extension

3. UPPER OBLIQUE OF THE HEAD

Superior Insertion : Between the superior and inferior nuchal lines

Lower Insertion : Transverse process of the atlas

Innervation : Cervical Plexus (C1)

Action : Extension, Homolateral Tilt, and Contralateral Head Rotation

4. LOWER HEAD OBLIQUE

Superior Insertion : Transverse process of the atlas

Inferior Insertion : Spinous process of axis

Innervation : Cervical Plexus (C2)

Action : Extension and Homolateral Rotation of the Atlas

Vertebral Gutter Muscles – Paravertebrals

SPINE ERECTORS

SPINAL (+ Medial)

Head portion:

Connected to the semispinal of the head

Neck portion :
Origin : Nuchal ligament and spinous processes from C7 to T2
Insertion : Spinous processes C2 to C4

Chest portion :
Origin : Spinous processes T11 to L2
Insertion : Spinous processes of the upper thoracic (ranges from 4 to 8)

Innervation : Spinal nerves (dorsal branches)

Action : Extension of the Spine

LONG BACK (Intermediate)

Head portion :
Superior Insertion : Mastoid Process
Lower Insertion : Transverse processes from T1 to T4 and articular processes from C4 to C7

Neck portion :
Upper Insertion : Transverse processes from C2 to C6
Lower Insertion : Transverse processes from T1 to T4

Chest portion :
Superior Insertion : Transverse processes of thoracic vertebrae and last 10 ribs
Inferior Insertion : Transverse processes of the lumbar vertebrae and lumbocostal aponeurosis

Innervation : Spinal nerves (dorsal branches)

Action : Extension and Homolateral Tilt of the Spine

ILIOCOSTAL (+ Lateral)

Cervical Portion :
Upper Insertion : Transverse processes from C4 to C6
Lower Insertion : Angle of 3rd to 6th ribs

Thoracic Portion :
Superior Insertion : Angle of first 6 ribs and transverse process of C7
Lower Insertion : Angle of the last 6 ribs

Lumbar Portion :
Superior Insertion : Angle of the last 6 ribs
Inferior Insertion : Dorsal surface of sacrum

Innervation : Spinal nerves (dorsal branches)

Action : Extension and Homolateral Tilt of the Spine

ROTATORS

Insertions : Extends from sacrum to C2. Connect the transverse process of one vertebra with the spinous process of the overlying vertebra

Innervation : Spinal nerves of the corresponding segment

Action : Extension and Contralateral Rotation of the Spine

MULTIFIDS

Origin : Dorsum of the sacrum, EIPS, mammillary processes of the lumbar, transverse process of the thoracic and articular processes from C4 to C7

Insertion : Spinous process 3 to 5 vertebrae above

Innervation : Spinal nerves of the corresponding segment

Action : Stabilization and Extension of the Spine

INTERTRANSVERSAL

Superior Insertion : Transverse process of the superior vertebra

Lower Insertion : Transverse process of lower vertebra

Innervation : Spinal nerves of the corresponding segment

Action : Homolateral Tilt of the Spine

INTERSPINALS

Superior Insertion : Spinous process of the superior vertebra

Inferior Insertion : Spinous process of the inferior vertebra

Innervation : Spinal nerves of the corresponding segment

Action : Extension of the Spine

BACK MUSCLES Rear View - Surface Layer

Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.

BACK MUSCLES Rear View - Intermediate Layer

Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.

BACK MUSCLES Rear View - Deep Layer

Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.