Clinical Applied Anatomy Neurons

Nervous System

• enables the body to react to continuous changes in its internal and external environments

• controls and integrates various activities of the body

Central Nervous System

• Brian and Spinal Cord

• Function:

  • integrate incoming and outgoing neural signals

  • control center for higher mental function (like thinking and learning)

Peripheral Nervous System

• Somatic NS

• Autonomic Nervous System (ANS)

  • Parasympathetic

  • sympathetic

Gray Matter

nerve cells bodies and inter-neurons

White matter

long tracts

dorsal root

sensory

dosal root ganglion

sensory nerve cell bodies

ventral root

motor nerves

spinal nerve

mixed motor and sensory

Dorsal Rami

motor and sensory to the back

Ventral Rami

motor and sensory to the limbs

Components of a Typical Spinal nerve

• nerve rootlets —> two nerve roots —> unite to form a spinal nerve —> two rami

venteral root

consists of motor fibers

dorsal root

consists of sensory fibers

spinal nerve

carries both motor and sensory fibers

ventral ramus

supply nerve fibers to anterior and lateral regions of the trunk and the upper and lower limbs

dorsal ramus

supply nerve fibers to synovial joints of the vertebral column, deep muscles of the back, and the overlying skin

Spinal Nerves

• made up of the ventral and dorsal root

• 31 pairs

  • Cervical = 8

  • Thoracic = 12

  • Lumbar = 5

  • Sacral = 5

  • Coccygeal = 1

Peripheral Nerves

• nerves outside the central nervous system

• supplies the organs, limbs, and skin

• carries motor and sensory OR only motor OR only sensory

Autonomic Nervous System

• Parasympathetic = promoting normal function and conserving energy

• Sympathetic = fight or flight

Somatic Nervous System

Composed of somatic parts of the CNS and PNS and provides general sensory and motor interaction to all parts of the body EXEPT —> viscera, smooth muscle, and glands

Somatic Motor

transmit impulses to skeletal muscle

Somatic Sensory

pain, temperature, touch, pressure

Myotomes

• all musculature derived from a given somite and therefore innervated by the same segment nerve

• each skeletal muscle is usually innervated by somatic motor fiber of several spinal nerves

• so, muscle myotomes will often consist of several segments

• grouped by joints movement for clinical testing

C1-2

Head nodding (OA motion)

C2 - 3

Cervical SB and rotation

C3 - 4

shoulder elevation

C5

shoulder abduction, ER, IR, Elbow Flexion

C6

elbow flexion, wrist extension, pronation

C7

elbow extension, wrist flexion

C8

finger and thumb extension and flexion

C8 - T1

hand intrinsic (ventral and dorsal interossei)

L1 - 2 (L3)

Hip flexion

L2 - 3

hip adduction

L3 - 4

knee extension

L4 - 5

ankle dorsiflexion

L5

great toe, extension, hip abductors, medial hamstrings

L5 - S1

ankle inversion, ankle eversion

S1

plantar flexion

Dermatomes

• area of skin innervated by the general sensory fibers of a single spinal nerve

• each spinal nerve carries sensory info from a region of the body

Myotomes Vs. Peripheral Nerve

myotome: musculature derived from a single spinal nerve

Peripheral Nerve: a specific muscle innervated by a peripheral nerve

dermatomes vs. peripheral nerve

dermatomes: area of skin innervated by fibers of a single spinal nerve

peripheral nerve: a specific area of skin innervated by a peripheral nerve

hypoesthesia

diminished sensation

hyperesthesia

heightened snesitivity to sensory stimuli

anesthesia

the complete lack of sensation

paresthesia

abnormal and negative perceived sensation (example: burning, pins and needles, tingling, numbness)

dysesthesia

unpleasant or disagreeable sensation

allodynia

exaggerated or painful response to sensory stimuli that should not be painful