Nerve Supply of the Body Wall

Question 1

What are the 4 main directional terms?

Answer 1

• lateral/medial
• proximal/distal
• cranial/claudal
• posterior/anterior = anterior/ventral

Question 2

What are spinal nerves part of?

Answer 2

PNS not CNS

Question 3

What is the foramen?

Answer 3

an opening where spinal nerves can protrude

Question 4

What are the 5 major parts of a typical vertebra?

Answer 4

• vertebral arch
• articular processes
• pedicle
• laminae
• vertebral body

Question 5

What are the 31 pairs of spinal nerves?

Answer 5

• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

Question 6

Which nerves supply the body wall?

Answer 6

the 12 thoracic spinal nerves and the first lumbar spinal nerve

Question 7

What is within each spinal segment?

Answer 7

2 pairs of roots

Question 8

What does the fissure determine?

Answer 8

the way that the spinal body is facing (dorsal or ventral)

Question 9

What is white and grey matter?

Answer 9

• white = myelinated axon
• grey = collections of cell bodies

Question 10

Where is the afferent (sensory) nerve and what does it do?

Answer 10

dorsal/posterior and senses the surroundings

Question 11

Where is the efferent (motor) nerve and what does it do?

Answer 11

ventral/anterior and is the reaction to the muscle (motor function)

Question 12

What does DAVE stand for?

Answer 12

Dorsal Afferent Ventral Efferent

Question 13

What are the spinal nerves a combination of?

Answer 13

the anterior and posterior roots

Question 14

What are the 3 layers of the meninges?

Answer 14

• dura mater (outer layer, most durable)
• arachnoid mater (middle layer that contains the fluid that cushions the brain)
• pia mater (innermost layer, contains blood vessels)

Question 15

What does each of the 12 thoracic nerves emerge from?

Answer 15

an intervertebral foramen that splits to form the dorsal and ventral rami

Question 16

What do the dorsal and ventral rami contain?

Answer 16

motor and sensory fibres

Question 17

Where does a spinal nerve collect sensory information from and where does it deliver?

Answer 17

• collects from peripheral structures
• delivers to sensory nuclei in the thoracic or superior lumbar segments of the spinal cord

Question 18

What is the area of innervation called?

Answer 18

the rami communicantes

Question 19

Why does the spinal ganglion bulge?

Answer 19

it is full of cell bodies (grey matter)

Question 20

What does the sympathetic nerve carry?

Answer 20

sensory information from the visceral organs

Question 21

What does the anterior ramus contain?

Answer 21

sensory information from the ventrolateral body surface, structures in the body wall and the limbs

Question 22

What does the posterior ramus contain?

Answer 22

sensory information from the skin and skeletal muscles of the back

Question 23

What does the posterior root of the spinal nerve do?

Answer 23

carry sensory information to the spinal cord

Question 24

Where do motor commands originate?

Answer 24

in motor nuclei of the thoracic or superior lumbar segments of the spinal cord

Question 25

What do motor commands mostly execute?

Answer 25

muscle reflexes

Question 26

What does the anterior root contain?

Answer 26

axons of somatic motor and visceral motor neuron

Question 27

What is the white ramus communicantes?

Answer 27

the first branch from the spinal nerve that carries the visceral motor fibres to the nearby sympathetic ganglion

Question 28

Where are white rami found?

Answer 28

only between T1 and L2

Question 29

What does the grey ramus communicantes contain?

Answer 29

postganglionic fibres that innervate glands and smooth muscles in the body wall or limbs

Question 30

Where are the cell bodies within the motor neuron?

Answer 30

the anterior horn of the spinal cord

Question 31

Where is the lower motor neuron?

Answer 31

in the ventral horn of the spinal cord

Question 32

What do the preganglionic sympathetic fibres do?

Answer 32

travel out of the spinal cord and connect with the sympathetic trunk via rami communicantes before synapsing

Question 33

Which sympathetic fibres are myelinated and unmyelinated respectively?

Answer 33

- myelinated = presynaptic, white fibres - unmeymlinated = postsynaptic, grey fibres

Question 34

Where are the postganglionic sympathetic fibres distributed after rejoining the spinal nerve?

Answer 34

the body wall via the dorsal and ventral rami of the spinal nerve

Question 35

What is the paravertebral ganglion?

Answer 35

the area that joins the post and presynaptic fibres

Question 36

What do sympathetic fibres supply via nerves to the skin?

Answer 36

- blood vessels - sweat glands - arrectores pilorum

Question 37

What do the dorsal/posterior rami supply?

Answer 37

muscles, bones, joints and skin of the back

Question 38

What does each ventral/anterior rami supply?

Answer 38

the skin, muscles and serous membranes of the thoracic and abdominal walls (some ventral rami also supply the upper and lower limbs)

Question 39

What is a dermatome?

Answer 39

a segment of skin innervated by a specific spinal nerve

Question 40

What are the centre parts and boundary of dermatomes innervated by respectively?

Answer 40

- centre parts = single spinal nerve - boundary = many nerves working together

Question 41

Give examples of dermatome pathological conditions

Answer 41

- shingles - pain in the left shoulder during a heart attack

Question 42

How and where does shingles occur?

Answer 42

at a specific dermatome around the abdomen and travels to the skin retrogradely from the DRG

Question 43

What are the ventral rami of the first 11 thoracic spinal nerves called?

Answer 43

intercostal nerves

Question 44

What are the typical intercostal nerves?

Answer 44

T4, T5, T6

Question 45

What do the 1st to 3rd ventral rami do?

Answer 45

give branches to the upper limb as well as to the thoracic wall (important for referred pain from the heart)

Question 46

What are the thoracoabdominal nerves?

Answer 46

T7 - T11

Question 47

What is the subcostal nerve?

Answer 47

T12

Question 48

What do the typical intercostal nerves supply?

Answer 48

the thoracic wall including the intercostal muscles

Question 49

What is the function of the intercostal muscles?

Answer 49

to increase thoracic diameter during inspiration

Question 50

Where do the intercostal muscles lie?

Answer 50

on the pleura and between the innermost and internal intercostal muscles

Question 51

What does each intercostal nerve give off at the angle of the rib?

Answer 51

a lateral cutaneous branch, which supplies the skin and subcutaneous tissue of the thorax

Question 52

What is the thorax and what is it made up of?

Answer 52

the chest and is made up of the thoracic wall, its superficial structures (breast, muscles, and skin), and the thoracic cavity

Question 53

What happens to the thorax at the end of the intercostal space medial to vessels?

Answer 53

it turns forward as the anterior cutaneous branch

Question 54

Where are the thoracoabdominal nerves located?

Answer 54

between the transversus and internal oblique muscles and continue behind the rectus abdominus muscle

Question 55

What are the functions of the thoracoabdominal muscles?

Answer 55

- flexion, lateral flexion and rotation of trunk - forced expiration - to increase intra-abdominal pressure during micturition, defecation and parturition

Question 56

What do the thoracoabdominal nerves supply?

Answer 56

muscles of the thoracic and anterior abdominal walls e.g. intercostal, transverses and rectus abdominis, external and internal obliques

Question 57

What would a vertical incision along the linea semilunaris do?

Answer 57

denervate (cut off nerve supply) the rectus abdominus

Question 58

What does each thoracoabdominal nerve supply and how?

Answer 58

a band of skin by means of its lateral and anterior cutaneous branches

Question 59

What do the thoracoabdominal nerves give sensory twigs to?

Answer 59

the adjacent diaphragm, pleura, and peritoneum

Question 60

What are the iliohypogastric and ilioinguinal nerves derived from?

Answer 60

the first lumbar nerve (L1)

Question 61

What do the iliohypogastric and ilioinguinal nerves innervate respectively?

Answer 61

- iliohypogastric = muscle and skin of abdominal region - ilioinguinal = transverse abdominis and internal obliques

Question 62

What is the inguinal region?

Answer 62

the lower portion of the anterior abdominal wall, located superior to the thigh, lateral to the pubic tubercle, and inferomedial to the anterior superior iliac spine

Question 63

What is referred pain?

Answer 63

pain from the internal organs and the body wall that is felt elsewhere and shares the same subsequent pathway up to the brain i.e. cross-talk