Back Muscles

Question 1

Serratus Posterior Inferior

Answer 1

Innervation: Ventral Rami of Lower Thoracic Nerves (Intercostals)
Blood Supply: Posterior Intercostal Arteries
Action: Depresses Ribs

Question 2

Serratus Posterior Superior

Answer 2

Innervation: Ventral Rami of Upper Thoracic Nerves (intercostals)
Blood Supply: Posterior Intercostal Arteries
Action: Elevates Ribs

Question 3

Erector Spinae Group

Iliocostalis, longissimus, Spinalis

Answer 3

Innervation: Dorsal Rami
Blood Supply:
-Cervical: Occipital, deep cervical, & Vertebral
-Thoracic: Dorsal of Post. Intercostal, subcostal and
lumbar
-Sacral: Dorsal of Lateral sacral Nerves
Action: Extend and laterally bend the spine

Question 4

Splenius Capitis

Answer 4

Innervation: Dorsal Rami
Blood Supply: Descending branches of Occipital Art. & Deep cervical artery.
Action: Extend head & laterally bends and rotates head to the same side

Question 5

Obliquus Capitis Inferior

Answer 5

Innervation: Sub. Occipital Nerve (C1)
Blood Supply: Vertebral Artery & Descending Branch of occipital
Action: Rotates atlas to turn face to the same side.

Question 6

Obliquus Capitis Superior

Answer 6

Innervation: Sub. Occipital Nerve (C1)
Blood Supply:Vertebral Artery & Descending Branch of occipital
Action: Extends and Bends Head Laterally

Question 7

Rectus Capitis Posterior Major

Answer 7

Innervation: Sub. Occipital Nerve (C1)
Blood Supply:Vertebral Artery & Descending Branch of occipital
Action: Extends and Rotates head to same side

Question 8

Rectus Capitis Posterior Minor

Answer 8

Innervation: Sub. Occipital Nerve (C1)
Blood Supply:Vertebral Artery & Descending Branch of occipital
Action: Extends Head

Question 9

Latissimus Dorsi

Answer 9

Innervation: Thoracodorsal Nerve
Blood Supply: Thoracodorsal artery, dorsal
perforating branches of 9th, 10th,
and 11th posterior intercostal,
subcostal, and first three lumbar
arteries
Action: “Swimming”- Extends, adducts, and medially rotates humerus

Question 10

Levator Scapulae

Answer 10

Innervation: Ventral rami of C3–C4 and dorsal
scapular nerve
Blood Supply: Dorsal scapular artery , transverse
cervical artery, ascending cervical
artery
Action: Elevates scapula medially so inferiorly
rotates glenoid cavity

Question 11

Rhomboid Major

Answer 11

Innervation: Dorsal scapular nerve
Blood Supply: Dorsal scapular artery OR deep
branch of transverse cervical artery,
dorsal perforating branches of the
upper five or six posterior intercostal
arteries
Action: Fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity

Question 12

Rhomboid Minor

Answer 12

Innervation: Dorsal scapular nerve
Blood Supply: Dorsal scapular artery OR deep
branch of transverse cervical artery,
dorsal perforating branches of the
upper five or six posterior intercostal
arteries
Action: Fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity

Question 13

Trapezius

Answer 13

Innervation: Accessory nerve (CN XI)
Blood Supply: Transverse cervical artery, dorsal perforating branches of posterior intercostal arteries
Action: Elevates, retracts, and rotates scapula; lower fibers depress scapula

Question 14

Transversospinalis

Answer 14

Innervation: Dorsal rami of each region
Blood Supply: Occipital, deep cervical, and vertebral arteries.
Action: Stabilizes spine