| Term | Definition |
| Prefrontal Cortex | -Most anterior part of cortex
-respons 4 manipulating discrete & skilled volun movements thru planning & innervation of muscles
-Important in learning new motor task (i.e. child learning to tie shoes)
-Site of sequencing, reasoning, thinking, planning |
| Signs of prefrontal Cortex lesion | Difficulty with sequencing and planning |
| Premotor Cortex | -Gives rise to 30% of Motor Fibers
-Info from thalamus, cerebellum, basal ganglia
-Has some skilled patterns which are well learned or have become AUTOMATIC (like tying shoes after you've already learned) |
| Signs of premotor Cortex lesion | -Lesions here show problems w/ automatic motor task like brushing teeth and tying shoes.
-Lesion(s) in the here in the left hemisphere (often extending into Broccas area) are often associated with verbal apraxia |
| Primary Motor Cortex | -Initiation of movement
-30% of motor fibers
-2% of the motor fibers are from Betz Cells which are large to support long axons
-Two major tracts come from here:
Corticospinal tract and Corticobulbar tract |
| Corticospinal tract | -Voluntary Movements
-Comes from upper two thirds of primary motor cortex, premotor cortex and sensory cortex
-Goes through Corona Radiata to Internal Capsule and Pes Pedunculi in the Midbrain and then to the spinal cord |
| Corticobulbar tract | -Responsible for the movement Facial and Associated Muscles (tongue, larynx)
–These fibers project to cranial nerve nuclei which give rise to cranial nerves in brainstem)
-Comes from the inferior 1/3 of the motor cortex and adjacent to corona radiata |
| Primary Sensory Cortex | -Gives rise to the last 40% of motor projections
-Project through motor cortex with modulation of sensory information |
| Supplementary Motor Area | -From upper two thirds of primary motor cortex, premotor cortex and sensory cortex
-Goes through Corona Radiata to Internal Capsule and Pes Pedunculi in the Midbrain and then to the spinal cord |
| Lesions in corticospinal tract result in | -symptom of spastic hemiplegia |
| Lesions in corticobulbar fibers result in | -symptom of paralysis of facial, lingual, palatal and laryngeal muscles.
-Lesion to bilateral nuclie result in less paralysis |
| Upper Motor Neuron Lesion | -Flaccid paralysis followed by spastic hemiplegia (aka. Hyper contracted)
-Increased Muscle Tone
- + Babinski Sign test (toes fan out)
-Hyperreflexias
-Loss of Abdominal Reflexes
-Alternating Hemiplegia (Occurs with lesions in the brainstem) |
| Lower motor neuron Lesion | -Eliminates function of the motor unit, if spinal nerve cut off no more info going to muscles for movement
-weakness of muscles & reduces tendon reflexes
-Muscle tone is flaccid
-Seen in muscular dystrophy & myasthenia gravis
-Absent/reduced Babinski |
