Back muscles

Question 1

Trapezius muscle
origin,
insertion,
innervation and action

Answer 1

origin: Base of skull down and T12 spinous process

insertion: the pectoral girdle
i. Superior (descending) – inserts onto lateral part of clavicle
ii. Intermediate – lateral parts of the scapular spine scapular retraction (adduction)
iii. Inferior (ascending) - medial parts of the scapula spine

action:
i. Pectoral girdle will be elevated
ii. Scapula will be retracted (adduction) – pull toward midline
1. Inferior angle will rotate laterally, (left rotation clockwise)
2. Superior Rotation of the (right rotation counterclockwise)
iii. Used for abduction

innervation: Spinal component of the Cranial Accessory Nerve (CN XI)

Question 2

latissimus dorsi

Answer 2

Origin:
i. Begins at the inferior angle of the scapula (superior border)
ii. Midline T7 – below

Insertion:
proximal humerus. Crosses the proximal end of the humerus

action on the shoulder:
extend, rotate, adduct

Innervation: of the brachial plexus

Thoracodorsal nerve innervates the latissimus dorsi

Question 3

triangle of auscultation
borders

Answer 3

c. Trapezius forms the medial boundary
d. The medial edge of the scapula is the lateral boundary
e. Superior border of the latissimus dorsi is the inferior boundary
f. Inferior to the trapezius & latissimus dorsi are cutaneous branches of dorsal primary rami which sensory nerves from the skin
g. Used to listen to lung sounds
h. Can be physically expanded to allow access & thinner body wall

Question 4

levator scapula

Answer 4

Origin: from cervical vertebrae (transverse processes)
Inserts: to the medial border of the scapula
Superior to the scapular spine
action: Elevates the scapula

Question 5

Rhomboid minor

Answer 5

Inserts: onto scapula at the spine
Origin: from spinous processes of inferior cervical and upper thoracic vertebrae
Action: is to retract (adduct) the scapula
Innervated: by brachial plexus