Muscles of the back

Question 1

List the extrinsic muscles of the back.

Answer 1

1. Trapezius
2. Latissimus dorsi
3. Rhomboid major
4. Rhomboid minor
5. Levator scapulae
6. Serratus posterior

Question 2

What is the innervation, function and arterial blood supply of the trapezius muscle?

Answer 2

• Accessory nerve
• Transverse cervical artery
• Elevation of scapula and rotation during abduction of the arm.

Question 3

What is the innervation, function and arterial blood supply of the latissimus dorsi muscle?

Answer 3

• Thoraco-dorsal nerve
• Thoraco dorsal artery
• Extends, adducts and medially rotates the upper limb.

Question 4

What is the innervation, function and arterial blood supply of the levator scapulae muscle?

Answer 4

• Cervical rami C3-4 and C5 = dorsal scapula nerve
• Dorsal scapular artery
• Elevates the scapular

Question 5

What is the innervation, function and arterial blood supply of the rhomboids?

Answer 5

• Dorsal scapular nerve
• Dorsal scapular arteries
• Retracts and rotates the scapula.

Question 6

What is the innervation, function and arterial blood supply of the serratus posterior muscle?

Answer 6

1. Serratus posterior superior:
   - Intercostal nerves
   - Posterior intercostal arteries
   - Elevates ribs 2-5.
2. Serratus posterior inferior:
   - Intercostal nerves
   - Posterior intercostal arteries, subcostal artery and upper lumbar arteries.
   - Depresses ribs 9-12

Question 7

List the intrinsic muscles of the back.

Answer 7

1. Spinotransversalis:
   - Splenius capitis
   - Splenius cervicis
2. Erector spinae:
   - Ileocostalis
   - Longissimus
   - Spinalis
3. Tranversospinalis:
   - Semisplinalis
   - Multifudus
   - Rotatores

Question 8

What is the innervation and function of the Splenius capitis?

Answer 8

• Posterior rami of spinal nerves C3 and C4.
• Rotate head to the same side.

Question 9

What is the innervation and function of the Splenius cervicis?

Answer 9

• Posterior rami of the lower cervical spinal nerves
• Muscular branches of the occipital artery from the external carotid artery.
• Rotate head to the same side.

Question 10

What is the innervation and function of the Ileocostalis?

Answer 10

• Posterior rami of the spinal nerves.
• Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.

Question 11

What is the innervation and function of the Longissimus?

Answer 11

• Posterior rami of the spinal nerves.
• Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.

Question 12

What is the innervation and function of the Spinalis?

Answer 12

• Posterior rami of the spinal nerves.
• Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.

Question 13

What is the innervation and function of the semispinalis?

Answer 13

• Posterior rami of the spinal nerves.
• Extends and contra-laterally rotates the head and vertebral column.

Question 14

What is the innervation and function of the Multifudus?

Answer 14

• Posterior rami of the spinal nerves.
• Stabilises the vertebral column.

Question 15

What is the innervation and function of the Rotatores?

Answer 15

• Posterior rami of the spinal nerves.
• Stabilises the vertebral column, and has a proprioceptive function.