Lecture 2-Dermatomes, Myotomes, Spinal Nerves

Question 1

Describe the initial embryological development of a dermomyotome

• Mesodermal derivatives
  - Intermediate mesoderm-what structures are derived from this?

Answer 1

• Kidney

- Gonads

Question 2

Describe the initial embryological development of a dermomyotome
-Mesodermal derivatives-Chordamesoderm-what structure is derived from this and what does it form?

Answer 2

-Notochord-forms the nucleus pulposus in intervertebral disk (between vertebra)

Question 3

Describe the initial embryological development of a dermomyotome
-Mesodermal derivatives-Paraxial mesoderm-what is derived from this?

Answer 3

• Head

- Somite

Question 4

Describe the initial embryological development of a dermomyotome

• Mesodermal derivatives-Paraxial mesoderm
  - Somites-what is derived from this?

Answer 4

• Sclerotome (cartilage)
• Myotome (skeletal muscle)
• Dermatome (epidermis)

Question 5

Describe the initial embryological development of a dermomyotome

• Mesodermal derivatives-Paraxial mesoderm
  - Somites-Function of cells of the sclerotome?

Answer 5

Cells of the sclerotome condense around the notochord and form the vertebrae

Question 6

Describe the initial embryological development of a dermomyotome
-Mesodermal derivatives-Lateral mesoderm-what is derived from this?

Answer 6

• Splanchnic (circulatory system) and viscera
• Somatic (body cavity)
• Extra-embryonic

Question 7

Describe the major components of spinal nerves

??–>spinal nerve–>??

Answer 7

Root–>spinal nerve–>ramus

Question 8

Describe the major components of spinal nerves

-Spinal nerve–>ramus?

Answer 8

• Dorsal ramus

- Ventral ramus

Question 9

Describe the major components of spinal nerves

-Spinal nerve–>dorsal ramus-Goes to?

Answer 9

Epaxial muscles

Question 10

Epaxial

Answer 10

• Cells migrating posterior

- Making intrinsic muscles of the back and associated dermis

Question 11

Describe the initial embryological development of a dermomyotome
-Mesodermal derivatives?

Answer 11

• Intermediate mesoderm
• Chordamesoderm
• Paraxial mesoderm
• Lateral Mesoderm

Question 12

Describe the major components of spinal nerves

-Spinal nerve–>ventral ramus-Goes to?

Answer 12

Hypaxial muscles

Question 13

Hypaxial

Answer 13

• Anterior migrating cells

- Make muscles of limbs and trunk and associated dermis

Question 15

Describe the major components of spinal nerves

-Spinal nerve–>ventral ramus-Cutaneous nerve forms?

Answer 15

Dermatome

Question 16

Describe the major components of spinal nerves

-Spinal nerve–>ventral ramus-Motor nerve forms?

Answer 16

Myotome

Question 17

Compare and contrast a myotome with a dermatome

-Myotome?

Answer 17

• All the muscles that are innervated by a single EFFERENT anterior root
• Most muscles are composed of more than one myotome

Question 18

Compare and contrast a myotome with a dermatome

-Dermatome?

Answer 18

-The area of skin supplied with AFFERENT (sensory) fibers by a single posterior spinal root

Question 19

Describe differences between innervation maps of skin and muscle relative to dermatome and myotome maps

Answer 19

???

Question 20

Contrast segmental innervation with innervation via plexus formation

Answer 20

???

Question 21

What is a spinal nerve plexus?

Answer 21

When multiple nerves combine into one peripheral nerve

Question 22

Identify the major spinal nerve plexuses.

Answer 22

• Cervical plexus
• Brachial plexus
• Lumbar plexus
• Lumbosacral plexus

Question 23

-In what week of gestation do limb buds appear? What are the segments corresponding to the upper and lower limb buds?

Answer 23

-Limb buds appear in week

Question 24

Name the major terminal branches of the brachial plexus.

-Acronym?

Answer 24

Acronym-RUMMMM

• Radial nerve (C5-T1)
• Ulnar nerve (C8-T1)
• Musculocutaneous nerve (C5-C7)
• Median nerve (C6-T1)
• Medial brachial cutaneous nerve (C8-T2)
• Medial antebrachial cutaneous nerve (C8-T11)

Question 25

Name the major terminal branches of the lumbosacral plexus.

-Acronym?

Answer 25

Acronym-FLOPS

• Femoral nerve (L2-L4)
• Lateral femoral cutaneous nerve (L2-L3)
• Obturator nerve (L2-L4)
• Posterior femoral cutaneous nerve (S1-S3)
• Sciatic nerve (L4-S3)