Spinal Nerves

Question 1

What is rami communicans?

Answer 1

Branch from anterior ramus-> Contain visceral motor/autonomic neurons of the sympathetic nervous system

-> not a mixed nerve

Question 2

How are the 31 pairs of spinal nn. & plexuses arrange?

Answer 2

8 pairs of cervical nerves

12 pairs of thoracic nerves

5 pairs of lumbar

5 pairs of sacral

1 pair of coccygeal

Question 3

The _______ intervenes the the skin of the neck and portions of the head, chest and shoulders. Also intervenes the muscles of the neck includinfg the infrahyoid and scalene muscles

A) cervical plexus

B) sacral plexus

C) lumbar plexus

D) brachial plexus

Answer 3

A) cervical plexus

Question 4

The _______ provide motor and sensory innervations to the upper limb

A) cervical plexus

B) sacral plexus

C) lumbar plexus

D) brachial plexus

Answer 4

D) brachial plexus

Question 5

The _______ provide motor and sensory innervations to the lower limb (abs, quad, adductors)

A) cervical plexus

B) sacral plexus

C) lumbar plexus

D) brachial plexus

Answer 5

C) lumbar plexus

Question 6

The _______ provide motor and sensory innervations to the lower limb (glutes, hip joint, hamstrings)

A) cervical plexus

B) sacral plexus

C) lumbar plexus

D) brachial plexus

Answer 6

B) sacral plexus

Question 7

What plexus are these nerves from?
What structure is supplied by each nerve?

A) phrenic nerve

B) ulnar nerve

C) median nerve

D) musculocutneous nerve

E) radial nerve

Answer 7

A) cervical plexus-> the diaphragm

All the rest are brachial plexus

B) motor: triceps, brachialradialis, extensors of forearm and digits
Sensory: POSTERIOR arm, forearm, thumb, & 2nd,3rd digit, lateral 4th digit

C) wrist flexors, sensory to anterior thumb and anterior 2,3,4 digits

D) biceps brachii, coracobrachiallis, & brachialis muscles
—> sensory lateral forearm

E) motor to certain forearm flexors and most intrinsic hand muscles
Sensory to fifth and 4th digit

Question 8

The speed of an action potential is greatly dependent on the ______ & _______ of myelin sheath

Answer 8

Diameter & thickness

Large diameter= fastest-> proprioceptive, touch

Small diameter= slower-> pain, temperature

Question 9

What is dermatomes

Answer 9

Skin mapped according to spinal nerve supplying somatic sensation

Helps to identify source of referred pain