General Nerves

Question 1

Define a plexus

Answer 1

Plexus = intertwining network of neural tissue from multiple sources

Question 2

Describe the spinal cord + nerves from it

Answer 2

• Runs from cervical region to conus medullaris (L1-2 level)
• after this = formed spinal nerves (Cauda Equina) that exit via intervertebral foramen or ant. sacral foramina
  N.B there are 8 cervical nerves as C1 arises through space between occipital bone and 1st cervical vertebrae (nerve between C7+T1 = C8)

Question 3

Peripheral spinal nerves emerging from spinal cord

Answer 3

Ventral (anterior) roots:
- motor info from anterior horn to effector cells
(Polio myelitis switches of anterior horns at some locations - no motor supply from these areas)

Dorsal (posterior) roots:

• sensory info to spinal cord (dorsal root ganglia contain sensory cell bodies)
• 1st order neurons receive info from receptor and transmit to CNS

Question 4

Define dermatomes

Answer 4

Dermatomes = skin supplied by single spinal nerve or spinal cord level

Question 5

What are the Outlets from the pelvis

Answer 5

1. Inguinal tunnel (under inguinal ligament) - femoral nerve
2. Greater sciatic foramen (under ilium above sacrospinous and sacrotuberous ligaments) - sciatic nerve + gluteal nerves
3. Obturator Canal (between pubis and ischium) - obturator nerve

Question 6

What are the major branches of the lumbo-sacral plexus

Answer 6

> Femoral nerve (with sensory branch - saphenous nerve)
Obturator nerve
Superior Gluteal Nerve
Inferior Gluteal Nerve
Sciatic nerve ( splits into tibial [splits into medial and plantar nerves] and common peroneal nerve [splits into superficial and deep])
*There are also other branches to individual muscles and areas of skin