Anatomy of the Nervous System week 1

Question 1

What is the central nervous system composed of?

Answer 1

brain and spinal cord

Question 2

What is the peripheral nervous system (PNS) composed of? List specific examples.

Answer 2

All nervous structures outside of the CNS that connect the CNS to the body. Includes, cranial, spinal, autonomic (innervate organs), ganglia, receptor

Question 3

What are ganglia? Give a specific example.

Answer 3

Collections of neurons (both cell bodies and processes) with a common fxn. Example is dorsal root ganglion (aka spinal ganglion)

Question 4

What are cranial nerves? How many of them are there?

Answer 4

1. nerves that emerge from the brain
2. 12

Question 5

How many pairs of spinal nerves are there? How many are there in each region of the spinal cord?

Answer 5

31 total pairs

8 Cervical

12 Thoracic

5 Lumbar

5 Sacral

1 Coccygeal

Question 6

Cervical spinal nerves C1-C7 exit (above/below) their corresponding vertebrae. Cervical spinal nerve 8 exits (above/below) C7.

Answer 6

1. Pairs C1-C7 exit above their corresponding vertebrae
2. The 8th cervical spinal nerve pair exits below C7

Question 7

Spinal nerves emerge from adjacent _____.

Answer 7

pedicles

Question 8

Name the portions of vertebral disks.

Answer 8

Question 9

Spinal nerves are _____ nerves containing ____ and ____ information.

Answer 9

1. mixed
2. sensory (afferent)
3. motor (efferent)

Question 10

Spinal nerves contain both somatic and visceral components. Define these 2 terms.

Answer 10

somatic: pertaining to skin and skeletal muscles
visceral: pertianing to organs (smooth muscle, cardiac muscles, and glands)

Question 11

What are the 4 components of a spinal nerve? (what kind of info do they receive and send and to what portions of the body)

Answer 11

1. general somatic afferents (GSA): sensory info from skin, skeletal muscle, tendon, connective tissue
2. general somatic efferents (GSE): motor info to skeletal muscle
3. general visceral afferents (GVA) : sensory info from organs (e.g stretch of the bladder when it is full)
4. general visceral efferents (GVE): motor info to organs (e.g. to smooth muscle in a blood vessel or to cardiac muscle)

Question 12

Describe the branches of a spinal nerve and what information is contained in each portion.

Answer 12

dorsal: posterior
ventral: anterior

dorsal and ventral rootlets: where axons intially connect to spinal cord

dorsal root: contains only sensory axons. can be GSA or GVA

dorsal root ganglion: collection of cell bodies for sensory axons (GSA and GVA). is located in PNS (bc located outside of spinal cord)

spinal nerve: mixed nerve. contains axons/fibers for sensory and motor neurons. is very short

dorsal ramus: mixed nerve that contains afferent and efferent axons/fibers that innervate deep back muscles and the skin that overlies them

ventral ramus: mixed nerve that contains afferent and efferent axons that innervate everything else in the body (not in the head, which is for CN)

there is no ventral root ganglion! the cell bodies for the ventral root are located in the CNS.

also note that ventral rami, dorsal rami, and spinal nerves are all mixed. where sensory and motor components split is in the dorsal and ventral roots

Question 13

Describe the track neurons innervating deep back muscles and the skin overlying them travel when sending info to and from the spinal cord.

Answer 13

GSA axons travel from the deep back muscles or skin overlying them through the dorsal ramus, through the spinal nerve, through the dorsal root and rootlets into the spinal cord. GSE axons travel from the spinal cord, into ventral rootlets and roots, through the spinal nerve, and through the dorsal ramus to the deep back muscles or skin that overlies them

Question 14

Describe the track neurons innervating all of the body (exlcuding the head, deep back muscles, and skin overlying deep back muscles) travel when sending info to and from the spinal cord.

Answer 14

GSA and GVA axons from the body travel through the ventral ramus into the spinal nerve, dorsal root ganglion, dorsal root and rootlets, and into the spinal cord. GSE and GVE axons travel from the spinal cord, through the ventral rootlets and roots, spinal nerve, and the ventral ramus to the body

Question 15

Describe the track neurons travel in the knee jerk reflex.

Answer 15

Receptors on GSA axons in the muscle spindle travel through the ventral ramus, spinal nerve, dorsal root ganglion, dorsal root and rootlets, and synapse on a single GSE neuron in the spinal cord. GSE axon then travels through the ventral root, spinal nerve, and ventral ramus to synapse on the quadricep muscle causing contraction

Question 16

Spinal nerves can exist as ____ ___ or networks of nerves in ____ formation. Give examples.

Answer 16

1. single nerves: example is intercostal nerves. course along the ribs. each intercostal nerve corresponds to a single spinal level . T10 intercostal nerve is really the
   ventral ramus which branched from the T10 spinal nerve. Dorsal rami innervating deep
   back muscles are also examples
2. plexus: example is brachial plexus. a network of ventral rami in the axilla that redistribute their axons to form other names nerves such as the medial and lateral pectoral nerves

Question 17

What type of information do afferent neurons convey?

Answer 17

touch, temperature, pain, stretch, and proprioception (position sense, spatial awareness)

Question 18

dermatomes

Answer 18

A patch of skin innervated by a single spinal nerve. Regardless of whether spinal nerves remain as single nerves or course through a plexus, spinal nerves maintain this association with a particular patch of skin

Question 19

True or false: Both GVA and GVE components are present in spinal nerves and the dorsal and ventral rami.

Answer 19

True.

Question 20

GVA and GVE components may participate in the formation of ____ ____ which typically course along arteries to reach their target organs (e.g. pulmonary plexus to the lungs and cardiac plexus to the heart)

Answer 20

autonomic plexuses

Question 21

What are cutaneous nerves? What components do they contain?

Answer 21

1. Mixed nerves that innervate the skin as well as smooth muscle, sweat glands, and smooth muscle of vessels in skin
2. contains GSA, GVA, and GVE but no GSE (bc no skeletal muscle in skin)