Muscles of the Back Flashcards
describe the location, attachments and function of the superficial (extrinsic) back muscles.
The superficial back muscles are situated underneath the skin and superficial fascia. They originate from the vertebral column and attach to the bones of the shoulder – the clavicle, scapula and humerus. All these muscles are therefore associated with movements of the upper limb.
name the superficial (extrinsic) back muscles and which lie the most superficially
the trapezius, latissimus dorsi, levator scapulae and the rhomboids.
The trapezius and the latissimus dorsi lie the most superficially, with the trapezius covering the rhomboids and levator scapulae.
what are the actions of the trapezius muscle?
The upper fibres of the trapezius elevates the scapula and rotates it during abduction of the arm. The middle fibres retract the scapula and the lower fibres pull the scapula inferiorly.
what are the actions of the latissimus dorsi?
Extends, adducts and medially rotates the upper limb.
what is the action of the levator scapulae?
elevates the scapula
what are the actions of the rhomboids?
retracts and rotates the scapula
where are the intermediate (extrinsice) back muscles located, what is their function?
The intermediate group contains two muscles – the serratus posterior superior and serratus posterior inferior. These muscles run from the vertebral column to the ribcage, and assist with elevating and depressing the ribs. They are thought to have a slight respiratory function.
what is the action of the serratus posterior superior muscle? what is their innervation?
elevates ribs 2-5
innervated by intercostal nerves
what is the action of the serratus posterior inferior muscle? what is their innervation
depression of ribs 2-5
innervated by intercostal nerves
what are the three intermediate deep (intrinsic) back muscles?
the iliocostalis, longissimus and spinalis. Together these muscles form a column, known as the erector spinae.
what is the function of the erector spinae muscles?
Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.
