Back Muscles Diagrams, Functions, and other Details

Every one of us is well familiar with the division of muscles of the back. According to medical science, these muscles are divided into 3 different groups. Superficial, Intermediate, & deep.

  1. Superficial Muscles
  2. Intermediate Muscles
  3. Deep Back Muscles.

Muscles of the Back Diagrams & Functions

Trapezius Muscle of Back

Diagram  
Attachments The Trapezius Muscles starts from the SkullLigamentum NuchaeSpinous Processes of C7-T12 The fibers of Trapezius muscles attached to ClavicleAcromionScapula Spine
Innervation Receiving the messages or moto innervation is from the accessory nerves. From c3 & c4 spinal nerves the Trapezius muscles also receives fibers.
Actions During the abduction of our arm the upper fibers of it rotates and elevates the scapula. The middle fibers actually retract the scapula while the lower one pulls the scapula inferiorly.

Latissimus Dorsi

Diagram
Attachments Latissimus Dorsi as mentioned above has wide origin from Spinous processes of T6-T12Iliac Crest.Thoracolumbar Fascia. Inferior 3 ribs. The fibers of Latissimus Dorsi converges into the tendons of our back which directly attached to the intertubercular sulcus of the humerus.
Innervation Thoracodorsal nerve.
Actions Rotates the upper limb of back. 

Levator Scapulae

Diagram
Attachments Starts from the transverse processes of the C1-C4 spine & went down to the medial border of scapula.
Innervation Dorsal Scapular Nerve.
Actions Perform the functionality of Scapula Elevation.  

Rhomboids

Major Rhomboids

Diagram
Attachments Starts from the Spinal Processes of T2-T5 and directly attaches to the border (medial) of Scapula between the inferior angle and scapula spine.
Innervation Dorsal Scapular Nerve.
Actions Rotates & Retracts the Scapula.   

Minor Rhomboid

Diagram
Attachments Starts from the Spinal processes of the C7-T1 spine & went down to the medial border of scapula at spine of scapula.
Innervation Dorsal Scapular Nerve.
Actions Perform the functionality of Scapula Elevation.  

Serratus Posterior Superior

Diagram
Attachments These muscles start from the lower part of Ligamentum Nuchae.CervicalThoracic Spines from C7 to T3. The fibers of these muscles having direction inferolateral and attached through the ribs 2 to 5.
Innervation Intercostal Nerves.
Actions Assist to Elevate the Rib 2 to 5.   

Serratus Posterior Inferior

Diagram
Attachments Starts from the Thoracic & Lumber Spines (T11 to L3) The fibers of the muscles pass in superolateral direction and attached to the ribs 9 to 12.
Innervation Intercostal Nerves.
Actions Assist to Elevate the Rib 9 to 12.   

Intrinsic Deep Muscles of the Back

Splenius Capitis

Diagram
Attachments These types of muscles start from the lower side of Ligamentum Nuchae. Spinous Processes C7 to T3/4 Vertebrate. The fibers went through and attached to the mastoid process & occipital bone of human skull. 
Innervation Posterior Rami of Spinal Nerves C3 & C4. 
Actions Assist to rotate head to the side.   

Intermediate Intrinsic Back Muscles

Iliocostalis

Diagram
Attachments Originates from the origin of tendinous and directly attached to the cervical transverse processes and costal angle of the ribs.
Innervation Posterior Rami of spinal nerves.
Actions Helps in laterally flex to the vertebral column by acting unilaterally. Also helps to extend the vertebral column & head when act as bilaterally.

You can get more information about muscles: we have shared links below. Follow links to get more information.

Muscles in the Back
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Upper Back Muscles
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Upper Left Back Pain