Dermatomes And Myotomes Of The Upper Limb

Question 1

What do somites differentiate into?

Answer 1

Sclerotome
Dermatomyotome

Question 2

What does a sclerotome form?

Answer 2

Vertebrae and ribs

Question 3

What does dermatomyotome form?

Answer 3

Muscle and dermis of skin

Question 4

What does skin and muscle derived from a single dermatomyotome have in common?

Answer 4

Spinal nerve supply

Question 5

What is a myotome?

Answer 5

Group of muscles supplied by a single spinal nerve

Question 6

What is a Dermatome?

Answer 6

Area of skin supplied by a single spinal nerve

Question 7

What is a spinal nerve made up of?

Answer 7

Both sensory and motor axons

Question 8

Where are spinal nerves found?

Answer 8

Intervertebral Foramen

Question 9

Where do the C1-C7 cervical nerves emerge with respect to their associated vertebrae?

Answer 9

Above their vertebrae

Question 10

Where does the C8 spinal nerve exit the spinal canal?

Answer 10

Between C7 and T1
Below C7 above T1

Question 11

Where do the T1-L5 spinal nerves exit with respect to their corresponding vertebrae?

Answer 11

Below their vertebrae

Question 12

Where do the S1-S4 spinal nerves exit?

Answer 12

Via 4 pairs of sacral foramina

Question 13

Where does the S5 and Co1 spinal nerves exit?

Answer 13

Via sacral hiatus posteriorly

Question 14

What are the names of the bones where the C1 spinal nerve emerges between?

Answer 14

Occipital bone and atlas (C1)

Question 15

What do spinal nerves branch into once they’ve emerged from the spinal cord?

Answer 15

Posterior/dorsal ramus
Anterior/ventral ramus

Question 16

What part of the body do the anterior/ventral rami supply?

Answer 16

Muscles and skin of upper and lower limbs
Lateral and ventral trunk (Front and sides)

Question 17

What part of the body do the posterior/dorsal rami supply?

Answer 17

Deep muscles and skin of dorsal trunk

Question 18

There is a junction between C4 and T2, how do the C5-T1 nerve roots supply the upper limbs?

Answer 18

Via the Brachial plexus

Question 19

What spinal nerve roots make up the Brachial plexus?

Answer 19

C5-T1

Question 20

Where is the C4 Dermatome?

Answer 20

Top of chest spans towards shoulders

Question 21

Where is the C5 dermatome?

Answer 21

RADIAL ASPECT (Lateral portion of arm when in anatomical position)
From the shoulder, stops just before elbow joint

Question 22

Where is the C6 Dermatome?

Answer 22

Cross elbow joint from arm to forearm
RADIAL aspect (Lateral aspect) of forearm and supplies THUMB and INDEX finger

Question 23

Where is the C7 dermatome?

Answer 23

The MIDDLE FINGER
C7 to heaven

Question 24

Where is the C8 dermatome?

Answer 24

RING and LITTLE finger
Moves slightly onto ULNAR aspect of forearm

Question 25

Where is the T1 Dermatome?

Answer 25

ULNAR aspect of the forearm just past the elbow joint/cubital fossa

Question 26

Where is the T2 Dermatome?

Answer 26

ULNAR aspect of the arm and the UPPER chest

Question 27

What is the name of the structure where rearrangement of the ventral rami of spinal nerves occur producing peripheral nerves?

Answer 27

Plexuses

Question 28

What often makes up a peripheral nerve?

Answer 28

Axons from several spinal nerves Axons from one spinal nerve can enter multiple peripheral nerves

Question 29

What peripheral nerves does C6 supply?

Answer 29

Musculocutaneous nerve Axillary Radial nerve Median nerve

Question 30

What are the spinal nerve roots supplying the musuculocutaneus nerve?

Answer 30

C5, C6 and (C7) C7 has very little contribution

Question 31

What is special about the C5 fibres that supply the musculocutaneous nerve?

Answer 31

They are all motor fibres No sensory input from C5

Question 32

What are peripheral nerve territories?

Answer 32

Areas of skin supplied by the peripheral nerves They are NOT the same as Dermatome

Question 33

What plexus is responsible for peripheral nerve formation in the upper limbs?

Answer 33

Brachial plexus

Question 34

What plexus is responsible for peripheral nerve formation in the lower limbs?

Answer 34

Lumbosacral plexus

Question 35

What spinal nerves make up the femoral nerve? (Lumbosacral plexus)

Answer 35

L2, L3, L4

Question 36

What are the 2 major branches of the femoral nerve?

Answer 36

Anterior femoral cutaneous nerve Saphenous nerve

Question 37

Where does the saphenous nerve cover?

Answer 37

Medial leg below the knee

Question 38

Where does the anterior Femoral cutaneous nerve cover?

Answer 38

Knee and anterior thigh

Question 39

What are the 5 spinal nerve roots that supply the upper limbs via the brachial plexus?

Answer 39

C5 C6 C7 C8 T1

Question 40

What is the function of the C5 myotome?

Answer 40

Shoulder ABduction Shoulder external rotation

Question 41

What is the function of the C6 myotome?

Answer 41

Elbow Flexion Wrist extension Supination (Neutral position then turn palm to the ceiling)

Question 42

What is the function of the C7 myotome?

Answer 42

Elbow extension Wrist Flexion Pronation (opposite of supination)

Question 43

What is the function of the C8 myotome?

Answer 43

Finger Flexion Finger extension

Question 44

What is the function of the T1 myotome?

Answer 44

Finger ABduction Finger ADduction