Neuroanatomy

What is the Central Nervous System?

the body’s control center

What is the Peripheral Nervous System?

the body’s communication network

The CNS includes what structures?

the brain and spinal cord

What structures are included in the PNS?

all other nerves outside of the brain and spinal cord. cranial nn, spinal nn, and ganglia

What are the functions of the CNS?

to process and interpret signals and sends instructions to the body

What are the functions of the PNS?

to carry information to and from the CNS

What are the two divisions of the PNS?

Sensory (afferent) and Motor (efferent)

What does the sensory (afferent) division do?

bring information like pain, temprature, and joint position toward the CNS

What does the motor (efferent) division do?

sends motor commands from the CNS to the muscles and glands

The somatic nervous system is apart of which division of the PNS?

motor (efferent) division

The autonomic nervous system is apart of which division of the PNS?

motor (efferent) division

What is the function of the somatic nervous system?

it controls voluntary movements (skeletal muscles)

What is the function of the autonomic nervous system?

it controls involuntary (automatic) body functions like heart rate, digestion, sweating

How many pairs of cranial nn. are there and how many arise from the brain

12 pairs with 11 arising from the brain

How many pairs of spinal nn. are there and where do they arise from?

31 pairs all arising from the spinal cord

What are the spinal nn. ?

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccyx

Where does a spinal n. orginate?

from the spinal cord

What happens at the spinal cord in the formation of a spinal n.

the spinal cord splits into two roots, the posterior(dorsal) root and the anterior (ventral) root

Function of the posterior (dorsal) root?

carries sensory (afferent) information from the body towards the spinal cord

has a dorsal root ganglia

Function of the anterior (ventral) root?

carries motor (efferent) information from the CNS to the muscles and glands

True or False. The posterior (dorsal) root and the anterior (ventral) root merge together to form a spinal n.

true

What happens when the spinal n. splits?

It forms the posterior (dorsal) primary rami and the anterior (ventral) primary rami

What does the posterior (dorsal) primary rami do?

it supplies the intrinsic back muscles and skin

What does the anterior (ventral) primary rami do?

it supplies the limbs and trunk and forms the brachial and lumbar plexus

Dermatome

an area of skin supplied by sensory fibers from a single spinal n.

What do dermatomes asses during a neuro exam?

sensation; what a patient can feel

key indicators to assess dermatomes?

numbness/tingling(paresthesia), pain/altered sensation traveling down the extremity (radicular symptoms), sensory changes between sides, MOI involving the spine

Myotome

a group of muscles supplied by motor fibers from a single spinal n.

What do myotomes asses during a neuro exam?

muscle weakness

key indicators to assess myotomes?

unexplained weakness, loss of function not matching injury, decreased strength along a nerve root, reflex changes

Radiculopathy (Nerve Root Injury)

spinal n. is irritated/compressed near where it exits the spinal cord at the intervertebral foramen.

What is the difference between the CNS and PNS in relation to nerve injuries?

The spinal cord is part of the CNS; nerve roots and peripheral nerves are part of the PNS.

A patient has weakness and sensory changes below the level of injury affecting multiple areas of the body. What structure may be injured?

the spinal cord

A patient has weakness and sensory loss that follows the distribution of one named nerve (ex: median nerve). What is likely involved?

a peripheral nerve injury

What symptoms are expected with a nerve root injury?

Dermatome sensory changes + myotome weakness + possible reflex changes.

An athlete has neck pain, pain radiating down the arm, numbness in the thumb, and weak wrist extension. What is suspected?

C6 radiculopathy (nerve root injury)

An athlete has numbness in the pinky and ring finger after hitting their elbow. What structure may be injured?

Ulnar n. (peripheral nerve injury)

An athlete has a cervical injury and now has weakness in both arms and legs. What should be suspected?

spinal cord injury

A patient has weakness with ankle dorsiflexion. Which type of assessment helps determine if a nerve root is involved?

Myotome testing (L4/L5)

C4 dermatome

upper trapezius

C5 dermatome

lateral arm

C6 dermatome

lateral forearm, thumb, and index finger

C7 dermatome

middle & ring finger

C8 dermatome

5th digit & medial forearm

T1 dermatome

medial arm to axilla

T2 dermatome

axilla to middle of chest

T3 dermatome

above nipple; 3rd + 4th interspace

T4 dermatome

nipple line; 4th + 5th interspace

T5 dermatome

below nipple

T6 dermatome

xiphoid process

T10 dermatome

navel

T12 dermatome

pubis

L1 dermatome

inguinal region

L2 dermatome

medial thigh

L3 dermatome

medial knee

L4 dermatome

medial ankle & g. toe

L5 dermatome

dorsum of foot

S1 dermatome

lateral foot

S2 dermatome

postereomedial thigh

C4, CNXI myotome

shoulder elevation

C5 myotome

shoulder abduction

C5-C6 myotome

elbow flexion

C6-C7 myotome

elbow extension

C6-C7 myotome

wrist extension

C6-C7 myotome

wrist flexion

C7-C8 myotome

Finger Flexion/Extension

T1 myotome

Finger Abduction/Adduction

L1-L2 myotome

Hip flexion

L3-L4 myotome

knee extension

L4-L5 myotome

ankle dorsiflexion

L5-S1 myotome

G. toe extension

L5-S1 myotome

ankle eversion

S1-S2 myotome

ankle plantarflexion

S1-S2 myotome

knee flexion

5/5 Normal:

moves through full ROM, against gravity, and w/ full resistance

4/5 Good:

moves through full ROM against moderate pressure

3/5 Fair:

moves through full ROM against gravity

2/5 Poor:

moves through full ROM with gravity eliminated

1/5 Trace:

cannot produce movement, but muscle contraction palpable

0/5 Gone:

no contraction felt