How Do Superficial Human Back Muscles work?

Human back muscles are divided into three groups. The intrinsic or deep muscles are those muscles that merge with the vertebral column. The second group is the superficial muscles associated with shoulder and neck movements. The final group is the intermediate muscles which help with the thoracic cage movement.

Let’s drive in this article through superficial human back muscles and know more about how do muscles work? how does the muscular system works in the back? and how to work back muscles?

– Superficial group contains these muscles:

• Trapezius
• Latissimus dorsi
• Rhomboid major
• Rhomboid minor
• Rhomboid minor
• Levator scapulae

Trapizus

Shape	Large triangular superficial human back muscle that looks like a trapezoid and spans across the dorsum of the neck and shoulders.
Origin and attachment	derives from the skull, nuchal ligament and the spinous processes of C7 to T12.  the trapezius muscle attached to the lateral 1/3 of the clavicle, acromion and the spine of scapula.
Innervation	The motor innervation is originated from the spinal accessory nerve (cranial nerve XI). The sensory innervation is originated from the spinal nerves C3-C4.
Actions	The upper fibers of trapezius can raise and rotate the scapula during the arm abduction and extend the neck. The middle fibers retract the spine of scapula. The lower fibers help the upper fibers in rotating the scapula spine.
Functions	According to the different trapezius heads: Superior head – elevation, rotation during abduction of the arm Middle head – adductionInferior head – depression, rotation during adduction of the armAll three heads work together to aid in mainly postural attributes, remaining the spinal column erect when the person is standing.

Latissimus Dorsi

Shape	Broad, flat muscle that spans a wide area from the lower back
Origin and attachment	Originates from the spinous processes of T6-T12, iliac crest, thoracolumbar fascia and the inferior three ribs. The fibers converge into a tendon that attaches to the intertubercular humerus groove.
Innervation	Thoracodorsal nerve supplies motor and sensory innervation, which derives fibers from spinal roots C6-C8.
Actions	Extends, retracts and rotates the upper limb
Functions	Effective shoulder extensor and adductor Aids in internal rotation of the humerus Researcher reported about Latissimus Dorsi human back muscle during deep inspiration and with forceful respiratory functions such as coughing and sneezing.

 

Rhomboids

Rhomboids human back muscles are a collective group of two muscles formed by the rhomboid major and minor. The rhomboid minor is located superiorly to the major. 

Shape	Rhomboid major: is a quadrangular, broad and thin strap-like muscle that connects the scapula to the spinous processes of the spine. It is located inferior to the rhomboid minor. Rhomboid minor: is a cylindrical, narrow and thin strap-like muscle that connects the scapula to the spinous processes of the spine. It is smaller and more superiorly located than the adjacent rhomboid major.
Origin and attachment	Rhomboid major: derives from the spinous processes of T2-T5 vertebrae and inserts on the medial border of the scapula, between the scapula spine and inferior to the rhomboid minor. Rhomboid minor: drives from the spinous processes of C7-T1 vertebrae and inserts on the medial border of the scapula, at the level of the spine of scapula.
Innervation	Both rhomboids human back muscles receive innervation from the dorsal scapular nerve of the C5 nerve root.
Actions	Both rhomboids elevate, retract rotate the spine of scapula
Functions	important in upper limb movement and stabilization of the shoulder through articulation with the trunk

Levator Scapulae

Shape	small strap-like muscle. It starts from the neck and descends to attach to the scapula.
Origin and attachment	Originates from the transverse processes of the C1-C4 vertebrae and insert on the scapula medial border of the scapula.
Innervation	Receives innervation derived from the dorsal scapular nerve of the C5 nerve root.
Actions	Elevates the scapula.
Functions	Levator scapula human back muscle assists in neck extension, ipsilateral rotation, and lateral flexion

References:

https://teachmeanatomy.info/back/muscles/superficial/

https://www.ncbi.nlm.nih.gov/books/NBK518994/#article-30528.s3

Written by Dr.Shaimaa Khaled