Anatomy and Physiology: Lab 10 Brain, Spinal Cord, Peripheral Nerves & Motor Nervous System (lecture)

Sensory and Motor Innervation of Phrenic Nerve

Diaphram

Anatomical marker of Phrenic Nerve?

Lateral to heart

What nerves make up the Brachial Plexus?

• musculocutaneous

• median

• ulnar

• radial

• axillary

What nerves make up the Lumbar Plexus?

• Femoral

• Obturator

What nerves make up the Sacral Plexus?

• Sciatic

  *Tibial

  *Common Fibular

Sensory and Motor Innervation of Musculocutaneous Nerve

Sensory: lateral forearm
Motor: all anterior arm muscles; forearm flexion, forearm supination

Anatomical marker of Musculocutaneous Nerve

pierces coracobrachialis

stays in upper arm

lateral-most nerve in the “M”

Sensory and Motor Innervation of Median nerve

Sensory: lateral palm, anterior digits 1-3

Motor: anterior forearm muscles (NOT Flexor Carpi Ulnaris), Thenar muscle

What is the anatomical marker for the Median Nerve?

innervates anterior forearm

innervates thenar muscle

middle nerve of the “M”

Sensory and Motor Innervation of Ulnar nerve

Sensory: Digits 4-5

Motor: Flexor Carpi Ulnaris; flex wrist, adduct/abduct fingers

What is the anatomical marker of the Ulnar nerve?

• innervates medial forearm

• innervates hypothenar

• innervates flexor carpi ulnaris

• most medial nerve of the “M”

Sensory and Motor Innervation of Radial nerve

Sensory: Posterior arm and forearm, back of hand, posterior digits 1-3

Motor: all posterior arm and forearm muscles

What is the anatomical marker of the Radial nerve?

• all posterior arm muscles (extends length of entire arm)

• lateral part of the “Y”

Sensory and Motor Innervation of Axillary nerve

Sensory: upper, lateral arm

Motor: Deltoid and Teres Minor

What is the anatomical marker for the axillary nerve?

• STAYS within armpit

• innervates deltoid and teres minor

• medial part of the “Y”

Sensory and Motor Innervation of Femoral nerve

Sensory: anterior thigh, medial leg, foot

Motor: anterior thigh muscles; extend knee, flex hip

What is the anatomical marker of the the Femoral nerve?

• innervates inguinal ligament

• all anterior thigh muscles

• medial leg all the way down the foot

Sensory and Motor Innervation of Obturator nerve

Sensory: Upper, medial thigh

Motor: Medial thigh muscles

What is the anatomical marker of the Obturator nerve?

• innervates inner thigh (addductors: gracilis, aductor longus, pectineus)

• on top of adductor brevis

Sensory and Motor Innervation of Sciatic nerve

• Sensory: NONE

• Motor: Posterior thigh muscles

What is the anatomical marker of the Sciatic nerve?

• no motor or sensory innervation!!

• controls Tibial and common Fibular nerve

Sensory and Motor Innervation of Tibial nerve

Sensory: Heel, plantar foot

Motor: all posterior leg muscles; plantar flexion, inversion, flex digits

What is the anatomical marker for the Tibial nerve?

posterior thigh, hamstrings, calves, bottom of foot

Sensory and Motor Innervation of Common Fibular

Sensory: bit of skin between toes 1 and 2, lateral leg, dorsal foot

Motor: all anterior and lateral leg muscles, dorsiflexion

What is the anatomical marker for the Common Fibular muscle?

• parallel to tibial nerve

• wraps around the lower leg to the front

What are spinal nerves?

• exits thru intervertebral foramen

• mixed motor and sensory (two way street)

• branch into ventral and dorsal ramus (like highway exists)

How many pairs of spinal nerves are there?

• 8 cervical

• 12 Thoracic

• 5 Lumbar

• 5 Sacral

• 1 Coccygeal

How are spinal nerves named?

Cervical: nerve named for vertebra below; C5 nerve is between C4 and C5 (C8 nerve is between C7 and T1)

Everything else: nerve names for the vertebra above; T6 nerve is between T6-T7 vertebra

What are ganglia?

cell bodes in the PNS. Can be sensory or autonomic (no motor!)

What are the divisions of the Peripheral nervous system?

Autonomic nervous system

• sympathetic (homeostasis during stress/emergency; fight or flight)

• parasympathetic (rest and digest; homeostasis during rest)

somatic nervous system

• sensory afferent

• motor efferent

What is Bell’s Palsy?

• paralyze facial nerve (CN 7)

• one side of the face droops (there is one facial nerve for each half of the face and usually only one is damaged)

• some cases are idiopathic

• most cases follow viral infections

What are characteristics of somatic motor pathways?

• consciously controlled

• signals come from CNS and move to skeletal muscles, to move those muscles

• descending pathway

What are the types of neurons utilized in somatic/descending pathways?

• upper motor neuron (UMN) go from the brain down the spinal cord

• lower motor neuron (LMN) go from spinal cord up to the brain

What are the types of somatic/descending motor pathways?

• Direct: conscious skeletal muscle movement; UMN communicates directly with LMN (no interneuron)

• Indirect: reflex like knee jerk; interneurons used between UMN and LMN

What are the steps to a direct/pyramidal pathway?

1.) primary motor cortex in the brain connects to UMN

2.) UMN synapses with LMN in the anterior horn of the vertebra

3.) LMN connects to skeletal muscle

What are the types of direct/ pyramidal pathways?

• lateral corticospinal tract

  • innervates limbs

  • decussate at midline at the medulla (goes from L to R side…L side of the brain controls the R side of the body)

• anterior corticospinal tract

  • innervates axial skeletal muscles

  • posture, stability

  • decussate (cross midline) at spinal cord (L to R)

• corticobulbar tract

  • innervates face and neck

  • doesn’t go thru spinal cord; cranial nerves instead

  • decussate UMN to LMN at brainstem

What are the characteristics of Indirect/extrapyramidal pathways?

• modifies somatic motor pathways

• more than one UMN

What are the types of indirect pathways?

• Rubrospinal tract:

  • precise movements

  • moves hand way from hot stove

• Reticulospinal tract:

  • posture, balance

  • goes from midbrain to spinal cord

• Tectospinal tract:

  • looking in the direction of sound or light

• Vestibulospinal tract:

  • coordinates head and body position when we are sitting, standing or walking

  • works together with direct pathways

Preganglionic and Postganglionic neurons

Preganglionic neurons are PNS presynaptic neurons. They are the first LMN. Postganglionic neurons are PNS postsynaptic neurons. They are the second LMN connected to the first LMN through a ganglion.

What are the types of acetylcholine (cholinergic) receptors?

• Nicotinic: found in parasympathetic and sympathetic NS. Causes excitation

• Muscarinic: cell response by G protein. Excitatory OR inhibitory (??)

Ach receptors are found in the sympathetic AND parasympathetic systems

What are the types of norepinephrine/epinephrine (adrenergic) recepts?

alpha (excitatory)

• a₁: constricts blood vessels, dilates eyes

• a₂: CNS, sedation, stops insulin secretion in pancreas

beta

• b₁: hear rate increase

• b₂: blood vessels dilate (increase blood flow)

What are the categories of reflexes?

• Intrinsic/ learned: born with the reflex vs. learned

• somatic/ visceral: skeletal muscles vs. smooth/ cardial

• Monosynaptic/Polysnaptic

• Ipsilateral/ Contralateral