Localization Flashcards
Upper Motor Neuron Lesion
Location: Descending from brain (cortex) to spinal cord (synapse 1 at cell body of anterior horn)
- weakness: Extensors of upper extremities; Flexors of lower extremities
- spastic paralysis: Especially Flexors of upper extremities, and Extensors of LE
- increased reflexes
- increased tone
- difficulties with fine motor control
- positive Babinski reflex
- positive clasp knife spasticity
Lower Motor Neuron Lesion
Location: PNS (leaving the spinal cord to synapse at the NMJ)
- weakness: follows distribution of the motor unit
- atrophy
- fasciculations: simultaneous discharge of whole motor unit
- Fibrillations: spontaneous contraction of a single muscle fiber
- decreased reflexes and tone
- flaccid paralysis
Primary Sensory Cortex
- Post-Central Gyrus (Parietal Lobe)
- Brodmann areas 3, 1 and 2
Primary Motor Cortex
- Pre-Central Gyrus (Frontal Lobe)
- Brodmann area 4
Lateral Corticospinal Tract
Function: Descending voluntary movement of contralateral limbs
1st Order Neuron: Motor cortex descends through the internal capsule, then decussates at the CAUDAL/LOWER MEDULLA (PYRAMIDAL DECUSSATION); descends contra laterally
Synapse 1: Cell body of the anterior horn
2nd Order Neuron: leaves spinal cord
Synpase 2: NMJ
Bell’s Palsy vs. LMN Lesion vs. UMN Lesion
Bell’s Palsy: Complete destruction of Cranial Nerve VII: The whole face loses tone
LMN Lesion: Ipsilateral paralysis of upper and lower face
UMN Lesion: Lesion occurs between the motor cortex and the facial nucleus
- Only CONTRALATERAL paralysis of LOWER FACE
- Forehead is spared due to bilateral UMN innervation
Myotomes
- Diaphragm
- Deltoid
- Tricep
- the muscles that are innervated by specific spinal cord roots
- Diaphragm: C3, C4 and C5
- Deltoid: C5
- Tricep: C7
Dermatomes
- Thumb, Digits 1&2
- Medial Hand
- Big toe
- Heel
- sensory areas that tell you what segment of the spinal cord is effected
- Thumb, Digits 1&2: C6
- Medial Hand/pinky: C8
- Big toe: L5
- Lateral foot/Heel: S1
Deep Tendon Reflexes
- Biceps
- Triceps
- Biceps: C5
- Triceps: C7
Pronator Drift Test
- Hold arms out and close eyes
- Positive test: One arm drifts down and pronates; indicates UMN Cortical Spinal Tract Lesion
Dorsal Column/Medial Lemniscal Pathway
Function: Ascending
- Pressure
- Vibration
- Fine Touch
- Propioception
1st Order Neuron: Cell body in Dorsal Root Ganglion enters spinal cord and ascends ipsilaterally in Dorsal Column
Synapse 1: Medulla (Ipsilateral Nucleus cuneatus or gracilis)
2nd Order neuron: Decussates in medulla, ascends contralaterally to the medial lemniscus
Synpase 2: VPL Thalamus
3rd Order: Sensory Cortex
Spinothalamic Tract
Lateral: Pain & Temperature
Anterior: Crude Touch & Pressure
1st Order: Sensory nerve endings/Cell body in Dorsal root ganglion enters the spinal cord
Synapse 1: Ipsilateral gray matter in spinal cord
2nd Order: Decussation at anterior white commissure, ascending contra laterally
Synapse 2: VPL Thalamus
3rd Order: Sensory Cortex
VPL (ventroposterior lateral) nucleus
receives sensory information from your body
VPM – ventroposterior medial nucleus
receives sensory information from your face
- Is more Superior to the VPL; facial sensory information crosses at level above High Pons
LGN (Lateral geniculate nucleus)
receives visual/optical information
medial geniculate nucleus:
receives hearing
Frontal Lobe
- motor control
- executive functions (initiating, planning, self-check, ability to pay attention)
- Broca’s area (in dominant hemisphere): Motor speech
Lesion:
- IPSILATERAL GAZE
- Aphasia if in dominant (usually left) hemis
- inattention
- contralateral weakness
- perseveration: repetition of words or phrases
Parietal Lobe
- the sensory lobe.
- Position in space, proprioception, having a sense of direction, sensory command
Lesion:
- Hemineglect (Contralateral): Lesion in non-dominant (usually right) side
- anesthesia
- thermalgesia
- apraxia
- graphasthesia
- asterognosia
Temporal Lobe
- Primary Auditory cortex
- Wernicke’s Area (dominant hemisphere): receptive language
- Memory (episodic-lifetime, academic-semantic)
Lesion:
- central deafness
- receptive aphasia
- amnesia
Occipital Lobe
- Principal visual cortex (BRODMANN AREA 17)
Lesion:
- dyslexia
- contralateral hemianopia
- impaired recognition of colors
Fasciculus Cuneatus
Dorsal column pathway for upper body and upper extremities
Fasciculus Gracilis
Dorsal column pathway for lower body and lower extremities
Brown-Sequard Syndrome
Hemisection of spinal cord:
- Ipsilateral UMN signs/Corticospinal tract
- Ipsilateral dorsal column damage (tactile, vibration, propioception sense)
- Contralateral spinal thalamic damage (Pain & temp)
Syringomyelia
- Syrinx at central spinal cord epands and damages the anterior white commissure of the spinothalamic tract
- Results in bilateral, CAPE-LIKE distribution loss of pain and temperature sensation
- Usually at level of C8-T1
Sensory Symptoms at level of Brainstem / Thalamus
Lesion at Thalamus: all sensory modalities are affected contra laterally
Lesion above High Pons:
- Contralateral sensory deficits for face/arms/legs
Lesion Below Mid Pons:
- Ipsilateral sensory deficits of face (sensory fibers have not yet crossed)
- Contralateral sensory deficits of arms/legs
Anterior Cerebral Artery
- Perfuse the motor and sensory cortex of the LOWER LIMBS
Middle Cerebral Artery
- Perfuses the Motor and sensory cortex of the UPPER LIMB and FACE
- Pefuses the temporal (Wernicke’s area) and frontal lobe (Broca’s area)
Internal Carotid Artery
- gives distribution of both the ACA and MCA, feeding the motor/sensory cortex of both upper and lower limbs
- Paresis
= WEAKNESS
- Plegia
= PARALYSIS
Location of Cranial Nerve Nuclei in Brainstem
From Cranial to Caudal:
- Mesencephalon: CNs 3 and 4
- Middle Pons: CN 5
- Pontomedullary junction: CNs 6, 7, 8
- Upper medulla: CNs 9 and 10
- Lower medulla: CN12
Location of Long Tracts in Brainstem
Ventral to Dorsal:
- Pyramidal (motor): ventral
- Medial lemniscus (Propiosensory): central
- Spinocerebellar: dorsolateral
- Spinothalamic: Lateral
- Medial longitudinal fascicle: centrodorsal
- Sympathetic tract: dorsolateral
Oculosympathetic Pathway
An Uncrossed Pathway:
- Primary: Hypothalamus
- Secondary: Intermediolateral column of spinal cord (T1 level)
- Tertiary: Superior cervical (sympathetic) ganglion to the pupil, eylids and face
Horner’s Syndrome
- Associated with lesion of spianl cord above T1
- Sympathectomy of face: PAM is Horny: (everything is ipsilateral)
1. Ptosis: slight dropping of eyelid
2. Anhidrosis: absence of sweating and flushing
3. Miosis: Pupil constriction
Referred Pain
- Pain felt at a distance
- Usually PROXIMAL
- NOT ASSOCIATED WITH DERMATOMES
Upper lumbar area: pain refers to flank, groin, or anterior thigh
Lower lumbar area: pain refers to buttocks and posterior thigh
Radicular Pain
- problem associated with spinal nerve root (e.g., impingement)
- DISTAL PAIN
- DERMATOMAL
- with positive straight leg raise sign
Most Sensitive Test to Diagnose Radiculopathy
Electromyography (EMG): inlcudes nerve conduction studies
- localizes lesion to the root, plexus or nerve
- shows extent of nerve root involvement
Cauda Equina Syndrome
- Loss of function of at least 2 of 18 nerve roots from L2 and below
- deficits are BILATERAL but ASYMMETRIC
- Presents with lower back pain radiating to legs, weakness, sensory loss, bladder/sphincter paralysis
