Superficial Back Muscles

Question 1

Trapezius Muscle (Netters Plate 171)

Answer 1

Origin: Superior nucheal line, external occipital protuberance, nucheal ligament, spinous processes of C7 - T12

Insertion: Lateral 1/3 of clavical, acromion, spine of scapula

Innervation: Motor accessory nerve 11 (Comes down from neck)

Blood supply: Ascending branch of transverse cervical artery

Function: Assists with the rotation of the scapula in order to abduction of humerus above horizontal

Question 2

Latissumus dorsi (Netters Plate 174)

Answer 2

Origin: Spinous proccesses of T7 thru L5, iliac crest, and last three ribs

Insertion: Intertubercular sulcus of humerus

Innervation: Thoracodorsal nerve of the brachial plexus

Blood supply: Thoracodorsal artery

Function: Extension, ADDuction, and medial rotation of the upper limb.

Question 3

Levator Scapulae (Netters Plate 171)

Answer 3

Origin: Posterior tubercles of transverse processes C1 - C4

Insertion: Medial border of scapula

Innervation: Ventral rami of C3-C4 and dorsal scapular nerve

Blood supply: Ascending transverse cervical arteries

Function: Retract, ADDuct, and elevate the scapula

Question 4

Rhomboid major (Netter’s plates 171 & 174)

Answer 4

Origin: Spines of vertebrae T2-T5

Insertion: Medial border of the scapula inferior to the spine of the scapula

Innervation: Dorsal scapular nerve (C5)

Blood supply: Dorsal scapular artery

Function: Retracts, elevates and rotates the scapula inferiorly

Question 5

Rhomboid minor (Netter’s plate 171 & 174)

Answer 5

Origin: Inferior end of the ligamentum nuchae, spines of vertebrae C7 and T1

Insertion: Medial border of the scapula at the root of the spine of the scapula

Innervation: Dorsal scapular nerve (C5)

Blood supply: Dorsal scapular artery

Function: Retracts, elevates and rotates the scapula inferiorly

Question 6

What is the Triangle of Auscultation and what are it’s borders?

Answer 6

The Triangle of Auscultation is a triangular gap formed by the superior horizontal border of the latissimus dorsi, the medial border of the scapula, and the inferolateral border of the trapezius; this is a good place to examine posterior segments of the lungs with a stethoscope.

Question 7

What is the lumbar triangle (Petit’s triangle) and why is it clinically significant?

Answer 7

The lumbar triangle is bordered medially by the latissimus dorsi, laterally by the external abdominal oblique, and inferiorly by the iliac crest. This point is vulnerable to abdominal (lumbar) hernia.

The definition of a hernia is the protrusion of a portion of an organ or tissue through an abnormal opening.