Superficial Back Muscles Exam Study Guide
Three groups: superficial, intermediate and deep
- Superficial – responsible for moving the shoulder.
- Intermediate – responsible for moving the thoracic cage.
- Deep – responsible for moving the vertebral column.
The deep muscles are intrinsic muscles because embryologically they develop in the back. The
superficial and intermediate muscles are extrinsic muscles because they do not develop in the
back.
The superficial back muscles lie under the skin, as well as under the superficial fascia. Their
origin comes from the vertebral column. They attach to the bones located in the shoulder –
clavicle, scapula and humerus. These muscles are responsible for moving the upper limb of the
body.
The muscles that make up the superficial back muscles are the latissimus dorsi, levator scapulae
and rhomboids. The most superficial are the trapezius and the latissimus dorsi. The trapezius
covers both the rhomboids and the levator scapulae.
Trapezius muscle - flat, triangular in shape, broad. Its origin comes from the skull, ligamentum
nuchae and spinous processes of the cerebral vertebrae 7 through thoracic vertebrae 12. The
trapezius fibres attach to the scapula, clavicle and the acromion. It is innervated by the accessory
nerve (motor) and receives proprioceptor fibres from the spinal nerves C3 and C4. The actions of
the trapezius muscle are elevation of the scapula and rotation during abduction of the arm per-
formed by the upper fibres. It also retracts the scapula with the middle fibres and pulls the
scapula inferiorly with its lower fibres.
Latissimus Dorsi - its origin is in the lower back, where it covers a vast area. It is attached to the
spinous processes T6-T12, thoracolumbar fascia, iliac crest and the three inferior ribs. Its fibres
come together to make up a tendon, which attaches to the intertubercular sulcus of the humerus.
The latissimus dorsi originates from the lower part of the back, where it covers a wide area.
Latissumus dorsi is innervated by the thoracodorsal nerve. Its actions are to extend, adduct and
medially rotate the upper limbs.
Three groups: superficial, intermediate and deep
- Superficial – responsible for moving the shoulder.
- Intermediate – responsible for moving the thoracic cage.
- Deep – responsible for moving the vertebral column.
The deep muscles are intrinsic muscles because embryologically they develop in the back. The
superficial and intermediate muscles are extrinsic muscles because they do not develop in the
back.
The superficial back muscles lie under the skin, as well as under the superficial fascia. Their
origin comes from the vertebral column. They attach to the bones located in the shoulder –
clavicle, scapula and humerus. These muscles are responsible for moving the upper limb of the
body.
The muscles that make up the superficial back muscles are the latissimus dorsi, levator scapulae
and rhomboids. The most superficial are the trapezius and the latissimus dorsi. The trapezius
covers both the rhomboids and the levator scapulae.
Trapezius muscle - flat, triangular in shape, broad. Its origin comes from the skull, ligamentum
nuchae and spinous processes of the cerebral vertebrae 7 through thoracic vertebrae 12. The
trapezius fibres attach to the scapula, clavicle and the acromion. It is innervated by the accessory
nerve (motor) and receives proprioceptor fibres from the spinal nerves C3 and C4. The actions of
the trapezius muscle are elevation of the scapula and rotation during abduction of the arm per-
formed by the upper fibres. It also retracts the scapula with the middle fibres and pulls the
scapula inferiorly with its lower fibres.
Latissimus Dorsi - its origin is in the lower back, where it covers a vast area. It is attached to the
spinous processes T6-T12, thoracolumbar fascia, iliac crest and the three inferior ribs. Its fibres
come together to make up a tendon, which attaches to the intertubercular sulcus of the humerus.
The latissimus dorsi originates from the lower part of the back, where it covers a wide area.
Latissumus dorsi is innervated by the thoracodorsal nerve. Its actions are to extend, adduct and
medially rotate the upper limbs.
