Unit 3 Slide 1 Quiz #1 Slides 1-29

[blank_start]Striated[blank_end] muscles are made up of many [blank_start]fibers[blank_end] which are made up of many [blank_start]muscle cells.[blank_end]

A large mass of muscles is made up of [blank_start]extrafusal fibers[blank_end].

Fibers contain two types of protein, [blank_start]actin[blank_end] and [blank_start]myosin[blank_end].

Actin is a [blank_start]thin[blank_end] filament, and myosin is a [blank_start]thick[blank_end] filament.

Muscles are attached to [blank_start]bones[blank_end] with [blank_start]tendons[blank_end].

Muscles are made up of [blank_start]muscle fibers[blank_end], which are made up of [blank_start]myofibrils[blank_end], which are made up of [blank_start]sacromeres[blank_end].

Proteins [blank_start]contract[blank_end] when stimulated and cause the muscle to [blank_start]shorten[blank_end].

[blank_start]Striated[blank_end] muscles are named after their [blank_start]striped[blank_end] appearance. They work in [blank_start]pairs[blank_end] with a [blank_start]reciprocal[blank_end] muscle, for example the biceps and triceps.

Each muscle cell is either [blank_start]contracted[blank_end] or not, and [blank_start]number[blank_end] of muscle cells [blank_start]contracted[blank_end] determines [blank_start]tone[blank_end].

Normally muscle is neither completely [blank_start]flaccid[blank_end] nor completely [blank_start]contracted[blank_end].

The basic element of the motor unit system consists of [blank_start]lower motor neuron[blank_end], [blank_start]extrafusal muscle fiber[blank_end] cells, and the [blank_start]neuromuscular junction[blank_end].

The basic element of the motor system is the [blank_start]motor unit[blank_end].

A [blank_start]lower[blank_end] motor neuron, or an [blank_start]alpha[blank_end] motor neuron, can innervate many [blank_start]extrafusal[blank_end] muscle fibers.

The neuromuscular junction is the connection between the [blank_start]LMN[blank_end] and the [blank_start]motor end plate[blank_end].

Motor units with [blank_start]fewer[blank_end] fibers cells tend to control more [blank_start]fine-grained[blank_end] muscle movements than movements with [blank_start]more[blank_end] fiber cells.

Alpha motor neurons are large [blank_start]multipolar[blank_end] neurons that innervate [blank_start]skeletal[blank_end] muscle.

[blank_start]Somas[blank_end] (cell bodies) are in the ventral [blank_start]horn[blank_end] of the [blank_start]brain stem[blank_end] and [blank_start]spinal cord[blank_end], axons extend through the ventral [blank_start]horn[blank_end] and [blank_start]root[blank_end].

A neuromuscular junction is the meeting of an [blank_start]axon terminal[blank_end] and a [blank_start]muscle cell.[blank_end]

The junction works like a [blank_start]synapse[blank_end] between nerves, with the transmitter [blank_start]acetylcholine[blank_end].

The [blank_start]prefrontal cortex[blank_end], (BA [blank_start]9[blank_end] & [blank_start]10[blank_end]) controls higher order control of motor functioning (planning, organization, and logic)

The frontal [blank_start]eye fields[blank_end] (BA 8) are responsible for [blank_start]voluntary[blank_end] [blank_start]eye[blank_end] movement.

Broca's Area (BA 44 & 45) is responsible for generating [blank_start]motor programs[blank_end] used for [blank_start]production of speech[blank_end].

The primary motor area (BA [blank_start]4[blank_end]) is [blank_start]anterior[blank_end] to the central sulcus.

The primary motor area is directly involved in the production of [blank_start]voluntary movement[blank_end]. It demonstrates [blank_start]somatotopic[blank_end] organization, where each hemisphere demonstrates [blank_start]contralateral[blank_end] control.

The [blank_start]primary motor cortex[blank_end] is the beginning of the [blank_start]pyramidal pathway[blank_end]. The neurons are arranged in [blank_start]columns[blank_end] that control a small group of [blank_start]syergistic[blank_end] muscles.

The pyramidal system [blank_start]directly[blank_end] controls [blank_start]voluntary[blank_end] movement, but the extrapyramidal system [blank_start]indirectly[blank_end] controls [blank_start]voluntary[blank_end] and [blank_start]involuntary[blank_end] movement.

Mysthenia gravis involves motor problems with the [blank_start]post-synaptic receptors[blank_end]. Lambert-Eaton involves issues with the [blank_start]pre-synaptic channels[blank_end].

The columns are then arranged in [blank_start]clusters[blank_end] that control [blank_start]larger groups[blank_end] of muscles.

The pyramidal system is named for the large pyramidal ([blank_start]Betz[blank_end]) cells. It is responsible for [blank_start]direct control[blank_end] of volitional movement. It is made up of two major tracts, [blank_start]corticospinal[blank_end] and [blank_start]corticonuclear[blank_end].

Betz cells are located primarily within the [blank_start]motor strip[blank_end] ([blank_start]pre-central gyrus[blank_end])

The motor system is a [blank_start]two[blank_end] neuron chain that links the cerebral cortex to the skeletal muscles via one of the two [blank_start]pyramidal pathways.[blank_end]

The upper motor neuron is entirely within the [blank_start]CNS[blank_end] and the lower motor neuron goes from the [blank_start]CNS[blank_end] to the muscle.

The [blank_start]corticonuclear[blank_end] [blank_start]pathway[blank_end] include voluntary pathways for movement of all speech and swallowing muscles, except respiration.

It begins at the [blank_start]bilateral motor cortices[blank_end] and terminates at the [blank_start]motor nuclei[blank_end] of cranial nerves in the [blank_start]brainstem[blank_end].

Exceptions to the bilateral innervation include the [blank_start]tongue[blank_end] (intermediate) and the [blank_start]trapezius[blank_end] and [blank_start]lower[blank_end] face (unilateral).

Upper motor neurons are also known as [blank_start]first order[blank_end] neurons. LMN are also known as [blank_start]second order[blank_end] motor neurons, and make up the [blank_start]final common pathway[blank_end].

LMN receive input from many [blank_start]pathways[blank_end] in addition to the UMN.