Module 3 Flashcards Preview

Physiology Module > Module 3 > Flashcards

Flashcards in Module 3 Deck (341)
Loading flashcards...

- sacral reflexes for control of bladder and colon evacuation are suppressed



- impairment or loss of motor and sensory function in the arms, trunk, legs, and pelvic organs

Tetraplegia / Quadriplegia


- impairment of function of the legs and pelvic organs

Paraplegia / Biplegia


- total paralysis of the arm, leg, and trunk on the same side of the body
- does not usually result from spinal cord injuries but from strokes



- polysynaptic reflex useful in testing for spinal shock
- checks anal sphincter contraction in response to squeezing the glans penis
o absence indicates spinal shock
o first reflex to return after spinal shock
- once this reflex has returned, all remaining neurologic deficits are considered permanent

Bulbocavernosus Reflex


- contains motor areas- stimulation will elicit contralateral movements
- displays somatotopic arrangement
- areas of the body that are capable of especially refined and complex movements (i.e. fingers, lips, and tongue) have a disproportionately large area of representation

Cerebral Cortex


- divided into three sub-areas, each of which has its own topographical representation of muscle groups and specific motor functions:

Motor Cortex


- located in precentral gyrus or Brodmann area 4
- responsible for the execution of movement (programmed patterns of motor neurons and voluntary movement)
- is somatotopically organized (motor homunculus)

Primary Motor Cortex


Epileptic events in the primary motor cortex cause __

Jacksonian seizures


- immediately anterior to the lateral portion of the primary motor cortex
- forms a portion of Brodmann area 6
- responsible for generating a plan for movement - transferred to primary motor cortex for execution
- stimulation causes activation of groups of muscles

Premotor Area


- located in the medial portion of Brodmann area 6 just anterior to the lower extremity portion of the precentral gyrus
- stimulation causes activation of bilateral muscle activation (usually upper extremities)
- programs complex motor sequences
- active during mental rehearsal for a movement

Supplementary Motor Area


- motor speech area
- converts simple vocal utterances into whole words and complete sentences

Broca's Area


- controls conjugate eye movement required to shift gaze from one object to another

Frontal Eye Field (Brodmann Area 8)


- enables movement of head correlated with eyes

Head Rotation Area


- when damaged, hand movements are lost (motor apraxia)

Area For Fine Movements Of Hand


- carried by the corticospinal (pyramidal) and extrapyramidal tracts
- also sends numerous collaterals to the basal ganglia, cerebellum and brainstem

Motor Outflow of Cerebral Cortex


- motor areas receive inputs from many sources
o predominant sensory input is from the somatosensory system, which receives its input from the thalamus

- afferent information is also received from the visual system, cerebellum, and basal ganglia
o used to refine movements, particularly to match the force generated in specific muscle groups to an imposed load

Motor Input of Cerebral Cortex


What are the three sub-areas of the motor cortex?

Primary Motor Area- execution of movement
Premotor Area - planning of movement
Supplementary Motor Area - bilateral muscle movement


- originates over a wide area of cortex including both motor and somatosensory areas
- more than 80 per cent of the fibers decussate at the pyramids (cervicomedullary junction)
- predominant pathway for the control of fine skilled manipulative movements of the extremities
- loss of precise hand movements is a hallmark feature of lesions to the corticospinal tract

Corticospinal Tract



- Motor Cortex
- Corona radiata
- Internal capsule
- Cerebral peduncle
- Brainstem
- Cervicomedullary junction*
- Corticospinal tract (A/L)
- Anterior horn cell
- Ventral root
- Peripheral nerve
- Neuromuscular junction
- Muscle


- conveys nerve impulses from the motor cortex to skeletal muscles of the head and neck
- axons of UMNs descend from the cortex into the brain stem, where some decussate and others do not
- provide input to lower motor neurons in the nuclei of cranial nerves III, IV, V, VI, VII, IX, X, XI, and XII
- control voluntary movements of the eyes, tongue and neck, chewing, facial expression and speech

Corticobulbar Tract


- also called Cerebrovascular Disease
- cessation of blood flow to the brain due to:
o ruptured blood vessel that bleeds into the brain
o thrombosis of a vessel, producing local ischemia
- muscles controlled by the damaged areas show a corresponding loss of function
o clumsiness and loss of fine muscle control
o postural movements may not be affected
o hyperreflexia, hypertonia and spasticity occur with extension of involvement



- due to lesions to supplementary and premotor areas
- loss of the ability to prepare for voluntary movement
- ability to execute simple movements is retained



- above the anterior horn cell
- motor neurons that originate in the motor region of the cerebral cortex or the brain stem
- main effector neurons for voluntary movement in layer V of the primary motor cortex (Betz cells)
- UMN pathways (above anterior horn cell) include:
▪ corticospinal tract
▪ corticobulbar tracts
▪ extrapyramidal tracts

Upper Motor Neuron


- below the anterior horn cell
- motor neurons connecting the brainstem and spinal cord to muscle fibers
- bring nerve impulses from the upper motor neurons out to the muscles
- begins at the level of the anterior horn cell in the spinal cord

Lower Motor Neuron


- total loss of motor function associated with an increase in muscle tone
- associated with clasp-knife phenomenon and hyperreflexia

Spastic Paralysis


- total loss of motor function associated with a decrease in muscle tone
- associated with floppiness, areflexia or hyporeflexia

Flaccid Paralysis


- reflex extension of the great toe with flexion of the other toes
- evoked by stroking the lateral sole of the foot
- presence indicates an upper motor neuron lesion

Babinski Reflex


- small, local, involuntary muscle contractions visible under the skin
- arise from spontaneous discharge of a bundle of skeletal muscle fibers
- presence indicates a lower motor neuron lesion



muscle tone: Increased
paralysis: Spastic Paralysis
deep tendon reflex: Hyperreflexia
babinski sign: Present
clonus: Present
fasciculations: Absent
atrophy: Atrophy of Disuse

Upper Motor Neuron (UMN) Lesion