Textbook

1. Cardiovascular system

2. Pulmonary system

3. Neuromuscular system

3.1 Central nervous system

3.2 Anatomy and function of spinal cord

3.3 Peripheral nervous system

3.4 Stroke deficits and recovery

3.5 Traumatic brain injury

3.6 Spinal cord injury

3.7 Neurodegenerative disorders and epilepsy

3.8 Peripheral nervous system conditions

3.9 Other neurological conditions

3.10 Interventions for neurological conditions

3.11 Vestibular system

4. Pediatrics

5. Musculoskeletal system

6. Other systems

7. Non-systems

Wrapping up

3.1 Central nervous system

Achievable NPTE-PTA

3. Neuromuscular system

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Central nervous system

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Upper motor neuron units

Definitions

Upper motor neuron units: A network of neurons whose cell bodies originate in the cerebral cortex and brainstem. Their axons descend through the spinal cord and synapse with lower motor neurons. Damage to upper motor neuron units produces weakness, hyperreflexia, and hypertonia, typically without muscle atrophy or fasciculations.
Lower motor neuron units: A network of neurons whose cell bodies lie in the spinal cord and brainstem motor nuclei, with axons that travel directly to the muscles they innervate. Damage to lower motor neuron units produces weakness, hyporeflexia or areflexia, and hypotonia, along with muscle atrophy and fasciculations.

Because the two lesions share weakness but differ on every other sign, it helps to line them up on the same rows rather than memorize two separate paragraphs.

The following table compares upper and lower motor neuron lesions on reflexes, muscle tone, atrophy, and fasciculations.

Sign	Upper motor neuron lesion	Lower motor neuron lesion
Reflexes	Hyperreflexia (increased)	Hyporeflexia or areflexia (decreased or absent)
Muscle tone	Hypertonia (increased)	Hypotonia (decreased)
Muscle atrophy	Absent	Present
Fasciculations	Absent	Present

The cerebral cortex and brainstem structures where upper motor neurons originate are described next.

Anatomy of the brain

The brain is divided into two hemispheres, separated externally by the longitudinal fissure and connected internally by the corpus callosum
- Right hemisphere
  - Spatial awareness
  - Emotional processing
  - Facial recognition
  - Creativity
  - Abstract thought
  - Controls the left side of the body
- Left hemisphere
  - Language
  - Logic and reasoning
  - Analytical thinking
  - Controls the right side of the body

The brain is divided into four lobes with distinct characteristics that work collectively to assist function:
- Frontal lobe
  - Executive function
  - Voluntary movement
  - Problem solving
  - Learning
  - Behavior
  - Impulse control
  - Personality
  - Social behavior
  - Expressive language (Broca’s area)
- Parietal lobe
  - Awareness of somatic sense - touch, pain, temperature, pressure, vibration
  - Processing somatic sensation - analyzing, recognizing, and developing memory of somatic sense
  - Spatial and body awareness
  - Coordination of visual, auditory, and somatosensory stimuli
- Temporal lobe
  - Hearing
  - Receptive language (Wernicke’s area)
  - Memory
    - Declarative: memory regarding names of people, places, or things
    - Procedural (not a temporal lobe function - relies mainly on the basal ganglia and cerebellum): memory of how to perform activities such as brushing teeth, putting on makeup, etc.
- Occipital lobe
  - Awareness of visual stimuli
  - Processing of visual stimuli
The cerebellum and brainstem are separate brain structures (not lobes), with their own distinct functions:
- Cerebellum
  - Motor learning
  - Coordinate movement
  - Balance and equilibrium
  - Proprioception sense
  - Maintain posture
- Brainstem
  - Ascending and descending tracts are located in the brainstem
  - Heart rate and respiration rate
  - Sleep and wake cycles
  - Digestion
  - Body temperature
  - Vomiting
  - Swallowing

Other important brain structures

Thalamus
- Receives sensory information from the body
- Sends these signals to the appropriate areas of the cerebral cortex for further processing
- Helps coordinate movements by sending signals to the motor cortex
- Assists with memory processing
Hypothalamus
- Maintains homeostasis within the body by regulation of hormones and autonomic functions, including body temperature (the body’s thermostat), hunger, and thirst
Basal ganglia
- Initiation of movements
- Assists with maintaining posture and muscle tone
- Assists with controlling voluntary movements

Protective layers of brain

Diagram of the brain's protective layers, including the skull and meninges — Brain protective layers

External layers (scalp and skull)

Definitions

Scalp: The outermost skin, fat, and muscular tissue covering the head.
Skull bone: A hard, bony container that shields the brain from direct physical hits.
Periosteum: A thin, strong membrane covering the outside of the skull bone.

The meninges (protective membranes)

Definitions

Dura mater: The tough, thick, and leathery outermost membrane attached directly to the inner skull.
Arachnoid mater: The delicate, middle, web-like membrane. Below it lies the subarachnoid space filled with cerebrospinal fluid that cushions the brain from shocks.
Pia mater: The very tender and thin innermost membrane that hugs the soft outer folds of the brain.

Arterial circulation of the brain

Circle of Willis

A network of arteries that provides blood supply to the brain
Major arteries
- Anterior cerebral artery (ACA)
  - Supplies frontal, prefrontal, and supplementary motor cortex, as well as circulation to primary motor and sensory cortex
  - Injury to the ACA can cause hemiparesis with weakness of the lower extremity > upper extremity, with sparing of face, apraxia, abulia, akinetic mutism, and urinary incontinence
- Anterior communicating artery
  - The blood supply that connects the left and right ACA
  - Injury to the anterior communicating artery can cause visual disturbances, memory deficits, cognitive impairment, severe headache, altered mental status, and impaired executive function
- Middle cerebral artery
  - Blood supply to the frontal, temporal, parietal, and deeper structures
  - Injury to the middle cerebral artery can cause hemiparesis with weakness of the upper extremity > lower extremity, aphasia (the MCA supplies both Broca’s area and Wernicke’s area, so aphasia follows when the dominant hemisphere is involved), and neglect (when the non-dominant hemisphere is involved)
- Internal carotid artery
  - Provides oxygenation to the brain
  - Injury can lead to blurred vision, confusion, memory loss, hemiparesis, or sudden death
- Posterior cerebral artery
  - Supplies blood to the occipital and temporal lobes
  - Injury can cause visual field loss, visual impairment, headache, confusion, and memory impairment
- Posterior communicating artery
  - Connects the internal carotid artery to the posterior cerebral artery
  - Injury can cause visual field loss, ptosis, diplopia, headache, confusion, memory impairment, hemiparesis

PTA scope of practice: The PTA collects data and recognizes and communicates changes in a patient’s status to the supervising PT; evaluating the patient, interpreting findings, and changing the plan of care remain the PT’s responsibility. These arterial patterns help the PTA recognize a new or worsening sign, such as increasing weakness, new aphasia, or neglect, and report it to the supervising PT immediately (activating emergency services when stroke signs appear suddenly); localizing the lesion is not the PTA’s role. Supervision and delegation rules are covered in PTA responsibilities, research, and ADA.

Other important arteries of the brain

Basilar artery
- Supplies: Brainstem, occipital lobe, cerebellum, thalamus, medial temporal lobes
- Functions: Supports autonomic regulation
- Injury signs: Hemiparesis or quadriparesis, facial paralysis, dizziness, headache, dysarthria
- Involvement: Combines with vertebral artery → vertebrobasilar system → damage to both can cause locked-in syndrome
Vertebral artery
- Supplies: Brain and spinal cord
- Origin and branches: arises from the subclavian artery; the two vertebral arteries join to form the basilar artery; the posterior inferior cerebellar artery and the anterior spinal artery are branches of the vertebral artery
- Injury signs: Headache, neck pain, dysarthria, dysphagia, impaired coordination, sensory/motor deficits to the face and body
- Involvement: Joins basilar artery → vertebrobasilar system → dual injury may result in locked-in syndrome
Posterior inferior cerebellar artery (PICA)
- Supplies blood flow to the medulla, fourth ventricle, and cerebellum
- Occlusion causes Wallenberg syndrome (lateral medullary syndrome)
- Injury can cause diplopia, ptosis, facial pain, vertigo, slurred speech, hoarseness, balance deficits, and sensory deficits on the same-side face and the contralateral body

Definitions

Locked-in syndrome: Paralysis of all voluntary muscles, with only eye movement remaining intact. The individual remains conscious but is unable to speak or move.

Upper vs. lower motor neuron lesions

Both cause weakness, but differ on other signs
UMN: hyperreflexia, hypertonia, no atrophy/fasciculations
LMN: hyporeflexia/areflexia, hypotonia, atrophy and fasciculations present

Cerebral hemispheres

Right hemisphere: spatial awareness, emotion, facial recognition, creativity; controls left body side
Left hemisphere: language, logic, analytical thinking; controls right body side
Connected by corpus callosum, separated by longitudinal fissure

Brain lobes

Frontal: executive function, voluntary movement, personality, Broca’s area (expressive language)
Parietal: somatic sensation, spatial/body awareness, sensory integration
Temporal: hearing, Wernicke’s area (receptive language), declarative memory (procedural memory relies on basal ganglia/cerebellum instead)
Occipital: visual awareness and processing

Cerebellum, brainstem, and key subcortical structures

Cerebellum: motor learning, coordination, balance, proprioception, posture
Brainstem: houses ascending/descending tracts; controls HR, respiration, sleep-wake, digestion, temperature, vomiting, swallowing
Thalamus: sensory relay station, aids motor coordination and memory
Hypothalamus: homeostasis (temperature, hunger, thirst, hormones)
Basal ganglia: movement initiation, posture, muscle tone, voluntary movement control

Protective layers of the brain

External: scalp, skull bone, periosteum
Meninges (outer to inner): dura mater (tough, attached to skull), arachnoid mater (web-like, subarachnoid space with CSF cushions brain), pia mater (thin, hugs brain surface)

Circle of Willis arteries and stroke patterns

ACA: frontal/motor cortex; injury → leg > arm weakness, face spared, apraxia, abulia, urinary incontinence
Anterior communicating artery: connects L/R ACA; injury → visual/memory/cognitive deficits, severe headache
MCA: frontal/temporal/parietal; injury → arm > leg weakness, aphasia (dominant side), neglect (non-dominant side)
Internal carotid artery: main brain oxygen supply; injury → vision changes, confusion, hemiparesis, possible sudden death
Posterior cerebral artery: occipital/temporal lobes; injury → visual field loss, confusion, memory impairment
Posterior communicating artery: links carotid to PCA; injury → visual loss, ptosis, diplopia, hemiparesis

PTA role in vascular findings

PTA observes/reports new or worsening signs (weakness, aphasia, neglect) to supervising PT
Not responsible for localizing lesions or changing plan of care
Activate emergency services for sudden stroke signs

Other key brain arteries

Basilar artery: supplies brainstem/cerebellum/thalamus; injury → quadriparesis, facial paralysis, dysarthria; combines with vertebral artery (vertebrobasilar system) — dual damage can cause locked-in syndrome
Vertebral artery: supplies brain/spinal cord; injury → dysphagia, seizures, sensory/motor deficits
PICA: supplies medulla/cerebellum; occlusion causes Wallenberg (lateral medullary) syndrome with diplopia, vertigo, crossed sensory deficits
Locked-in syndrome: full paralysis except eye movement, consciousness intact

Next | 3.2 Anatomy and function of spinal cord

Central nervous system

Upper motor neuron units

Definitions

Upper motor neuron units: A network of neurons whose cell bodies originate in the cerebral cortex and brainstem. Their axons descend through the spinal cord and synapse with lower motor neurons. Damage to upper motor neuron units produces weakness, hyperreflexia, and hypertonia, typically without muscle atrophy or fasciculations.
Lower motor neuron units: A network of neurons whose cell bodies lie in the spinal cord and brainstem motor nuclei, with axons that travel directly to the muscles they innervate. Damage to lower motor neuron units produces weakness, hyporeflexia or areflexia, and hypotonia, along with muscle atrophy and fasciculations.

Because the two lesions share weakness but differ on every other sign, it helps to line them up on the same rows rather than memorize two separate paragraphs.

The following table compares upper and lower motor neuron lesions on reflexes, muscle tone, atrophy, and fasciculations.

Sign	Upper motor neuron lesion	Lower motor neuron lesion
Reflexes	Hyperreflexia (increased)	Hyporeflexia or areflexia (decreased or absent)
Muscle tone	Hypertonia (increased)	Hypotonia (decreased)
Muscle atrophy	Absent	Present
Fasciculations	Absent	Present

The cerebral cortex and brainstem structures where upper motor neurons originate are described next.