muscles of back

Neck 1st layer

Consists of trapezius and latissimus dorsi

Neck 2nd layer

Comprises of splenius muscles, levator scapulae, rhomboideus major and minor, serratus posterior inferior muscle

Neck 3rd layer

Comprises of erector spinae

Neck 4th layer

Multifidus, rotatones, interspinales, intertransversii and suboccipitial muscles

Superficial muscles

Associsated with the shoulder girdle

Intermediate muscles

Invovled with respiration

Deep muscles

Belonging to the vertebral column

Trapezius

Is a large flat triangular muscle that extends over the back of the neck and thorax; middle fiber are directed horizontally into the acromion and the upper border of the spine of the scapula; lowest fibers are directed upwards ans laterally and are inserted on the medial end of the spine of the scapula

Trapezius

Suspends from the shoulder from the skull and vertebral column; upper fibers elevate the scapula; middle fibers pull the scapula medially; lower fibers pull the medial border of the scapula downward

Latissimus dorsi

It is a large flat triangular muscle that extends over the lumbar region and the lower part of the thorax

Latissimus dorsi

It extends adducts and medially rotates the arm

Teres minor

Origin: lateral scapula border; insertion: greater tubercle of the humerus

Teres minor

As performing the same action of a minor muscle, the infraspinatus

Teres major

As performing the same action of a major muscle the latissimus dorsi

Levator scapulae

Raises the scapulae upwards and braces the shoulder backwards

Rhomboid minor

Origin: lower part of ligament nuchae; insertion: medial border of scapula to the spine; pulls the scapula medially

Rhomboid major

Origin: 2nd to 5th thoracic spines; Insertion: Medial border of scapula opposite to the infraspinatus fossa; pulls the scapula medially

Erector spinae

Is the true muscle of the back, it splits into 3 colums

Iliocostalis

Lateral column of the erector spinae

Longissimus

Middle column of the erector spinae

Spinalis

Medial column of erector spinae

Muscles of 4th layer of the back

Multifidus; rotatores; interspinales; suboccipital muscles

Rotatores

This is the deepest group of the muscles of the back 4th layer

Muscles of the back 4th layer

Well developed in the thoracic region