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Anatomy 2201 > Spinal Cord and Plexuses (Ch. 16) > Flashcards

Spinal Cord and Plexuses (Ch. 16) Flashcards

1
Q

What is the spinal cord a part of (CNS or PNS)?

A

CNS

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2
Q

What are fxns of the spinal cord?

A

Sensory and motor innervation of body
Two-way conduction pathway for signals between body and brain
Major center for reflexes

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3
Q

Where does the Spinal Cord travel?

A

Extends from foramen magnum (occipital bone) to level of L1 or L2 (lumbar vertebrae)

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4
Q

How many pairs of spinal nerves are there (part of PNS)?

A

31 pairs of spinal nerves

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5
Q

What are the 2 enlargements of the spinal cord? Why do they exist?

A

Cervical and Lumbar enlargements for nerves supplying upper and lower limbs

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6
Q

What is the inferior end of the actual spinal cord?

A

Conus Medullaris

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7
Q

The nerve roots at the inferior end of the vertebral canal is called the ______ _______?

A

Cauda Equina

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8
Q

What is the Filum Terminale?

A

A long filament the extends past Conus Medullaris and attaches to coccyx

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9
Q

What protects the spinal cord?

A

Bone, meninges, and CSF

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10
Q

What is the Epidural Space?

A

Filled with fat and veins

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11
Q

Are the subdural space, arachnoid mater, subarachnoid space, and pia mater the same in the spinal cord as the brain?

A

Yes

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12
Q

What are the Denticulate Ligaments?

A

Anchor spinal cord to dura mater

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13
Q

Where is an Epidural Nerve Block inserted? Why? What is it used for?

A

Needle between L4 and L5 vertebrae permits injection of anesthesia into epidural space without risk of damage to spinal cord. The Cauda Equina gets “pushed” out of the way if necessary.

Epidural. Commonly used during childbirth

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14
Q

Spinal Cord Gray Matter

A

Gray matter forms an “H,” surrounded by white matter

Gray commissure is composed of unmyelinated axons crossing from one side of the CNS to the other

Central canal is the central cavity (hollow) of the spinal cord

Dorsal (posterior) arms of H are dorsal horns

Ventral (anterior) arms are ventral horns

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15
Q

Anterior (Ventral) and Posterior (Dorsal) Roots

A

Dorsal horns receive info from sensory neurons (cell bodies located in dorsal root ganglia)

Signal from sensory neurons reach spinal cord via dorsal roots.

Ventral horns send out info to skeletal muscle. Signals going out to motor neurons travel via ventral roots

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16
Q

Spinal Nerves

A

Dorsal and Ventral roots merge to form spinal nerve

Spinal nerve has BOTH sensory and motor axons

Exits vertebral column at intervertebral foramina

Immediately splits into dorsal and ventral rami

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17
Q

Dorsal (Posterior) and Ventral (Anterior) Rami

A

Ventral and Dorsal Rami carry both sensory and motor fibers

Ventral rami innervate most of the body, including trunk and limbs. Dorsal rami innervate small portion of the back

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18
Q

Reflexes

A

Very simple neuron chain

Basic structural plan of NS

Reflexes EXCLUDE brain; rapid, automatic, unlearned motor response to stimulus

Can be somatic (hot stove) or visceral (vomiting)

Signal comes in and synapses at interneurons. Interneurons stimulate and inhibit as appropriate

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19
Q

What are Dermatomes?

A

Area of skin supplied by a single spinal nerve. All spinal nerves EXCEPT C1

Numbness can pinpoint spinal cord injuries

20
Q

What is Referred Pain?

A

(Dermatomes)

When pain from an organ is mistakenly referred to dermatome.
ex: Appendicitis starts as pain in T10 dermatome

21
Q

Nerve Plexuses

A

A network of nerves…formed by VENTRAL rami only

All spinal nerves except T2-T12 branch and rejoin

Each muscle in a limb receives its nerve supply from more than one spinal nerve…damage to one spinal nerve cannot completely paralyze any limb muscle

22
Q

What are the 4 nerve plexuses?

A
  1. Cervical plexus (C1-C5)
  2. Brachial plexus (C5-T1)
  3. Lumbar plexus (L1-L4)
  4. Sacral plexus (L4-S4)
23
Q

Cervical Plexus

A

Ventral rami of first 4 cervical nerves

Most branches are cutaneous sensory. Some motor to anterior neck

Phrenic Nerve receives fibers from C3, C4, and C5; innervates diaphragm for respiration

24
Q

Brachial Plexus

A

Partly in neck, partly in axilla

Gives rise to most nerves of the upper limb.

Mixing of ventral rami of C5-C8 and most of the ventral ramus of T1

Main components:
–ventral rami, trunks, divisions, cords, terminal branches

25
Q

Brachial Plexus: Number of roots, trunks, divisions; Anterior and Posterior Divisions

A

5 roots give rise to 3 trunks which branch into 2 divisions

Anterior Division: nerves that innervate anterior compartment muscles of upper limb and skin

Posterior Division: nerves that serve posterior compartment and skin

26
Q

Brachial Plexus: C5-T1

A

Roots: C5-T1
Trunks: upper, middle, lower
Anterior Divisions (cords): lateral and medial
–lateral (from upper trunk) –> supplies musculocutaneous nerve
–medial (from lower trunk) –> supplies medial and ulnar nerves

Posterior Division (from middle trunk): supplies radial nerve and axillary nerve

27
Q

What are the terminal branches of the Brachial Plexus?

A 
Axillary Nerve
Radial Nerve
Musculocutaneous Nerve
Median Nerve
Ulnar Nerve
28
Q

Musculocutaneous Nerve

A

brachial plexus

Sensory innervation: skin sensation for lateral arm
Motor innervation: anterior compartment of arm

29
Q

Ulnar Nerve

A

brachial plexus

aka “funny bone” nerve

Sensory Innervation: skin of medial hand, medial side of digit 4, all of digit 5
Motor Innervation: flexors and intrinsic hand muscles

30
Q

Median Nerve

A

brachial plexus

Sensory Innervation: skin of lateral palm and digits 1-3 and lateral side of digit 4
Motor innervation: anterior compartment of forearm (w/ ulnar); intrinsic muscle of lateral palm, muscles that oppose the thumb

31
Q

Median Nerve Lesion

A

aka Carpal Tunnel Syndrome

Affects motor nerve to thenar muscles
Pain/numbness in lateral palm
From compression of nerve near hand

32
Q

Axillary Nerve

A

brachial plexus

Sensory Innervation: shoulder joint and skin on part of deltoid
Motor innervation: Teres Minor and Deltoid

33
Q

Radial Nerve

A

brachial plexus

Sensory Innervation: skin over dorso-lateral arm, forearm, and hand
Motor Innervation: posterior compartment of arm and forearm (extensors)

34
Q

Lumbar Plexuses

A

Ventral Rami: branches into Iliohypogastric, Ilioinguinal, Genitofemoral, and Obturator

Anterior Division

Posterior Divison: branches into Lateral Femoral Cutaneous and Femoral

35
Q

Femoral Nerve

A

lumbar plexus

Sensory Innervation: skin of antero-medial thigh; skin of medial foot
Motor Innervation: muscles of anterior thigh (thigh flexors, leg extensors [ex: quadriceps femoris])

36
Q

Phrenic Nerve

A

cervical plexus

Phrenic Nerve receives fibers from C3, C4, and C5; innervates diaphragm for respiration

“C3, C4, C5 keep the diaphragm alive”

37
Q

Obturator Nerve

A

lumbar plexus

Sensory Innervation: skin of medial thigh
Motor Innervation: muscles of medial thigh

*Adductor Magnus innervated by both Obturator and Tibial Nerves

38
Q

Sacral Plexus: Sciatic Nerve

A

Tibial Nerve and Common Fibular Nerve together in common sheath = “Sciatic Nerve”

Longest and thickest nerve of body. Senses all of lower limb except anterior/medial thigh

39
Q

Sacral Plexus: L4-S4; Anterior Division

A

Ventral Rami: L4-S4
Anterior Division: Tibial and Pudendal
Posterior Division

40
Q

Tibial Nerve

A

Anterior compartment of sacral plexus

Sensory Innervation: skin of postero-lateral leg, skin of sole of foot (subdivides into plantar nerves)
Motor Innervation: muscles of posterior thigh and muscles of posterior leg
–plus Adductor Magnus (w/ Obturator N.) and Biceps Femoris (w/ Common Fibular N.)

41
Q

Sacral Plexus: L4-S4; Posterior Division

A

Ventral Rami: L4-S4
Posterior Division: Common Fibular, Superior Gluteal, Lumbosacral Trunk, Inferior Gluteal
Anterior Compartment

42
Q

Common Fibular Nerve

A

Posterior compartment of sacral plexus

Sensory Innervation: skin of anterolateral leg, skin on dorsum of foot
Motor Innervation: muscles of anterior leg (deep fibular), muscles of lateral leg (superficial fibular)
–Common Fibular N. also innervates Biceps Femoris (w/ Tibial N.)

43
Q

Fibular Nerve Lesion

A

Foot-Drop

Fibular Nerve = Peroneal Nerve

44
Q

What is the longest and thickest nerve of the body?

A

Sciatic Nerve

45
Q

The Sciatic Nerve serves all of the lower limb except _____?

A

Anterior/medial thigh

Anatomy 2201 (33 decks)

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