Anatomy and Physiology of Speech and Non-Speech Functions

Flashcards: Nerves, Framework for Respiration, Muscles for Inspiration, Muscles for Expiration, and Respiratory Physiology

Motor Unit

Set of muscle fibers that are all innervated by the same motor neurons.

Innervation Ratio

The number of fibers controlled by one neuron.

• In muscles where the innervation ratios are low = very fine motor skills. Each neuron is responsible for only a small increment in force.

• In muscles where the innervation ratios are high = gross motor skills. Each neuron is responsible for a very large increment in force.

Neurons (Actors)

A specialized cell that receives and transmits information through electrical and chemical signals.

Glial Cells (Stage Hands)

Support, protect, and nourish neurons and help them function properly.

Nerve Cell Types: Neurons

• Sensory neurons: usually unipolar and carry sensory information to the CNS.

• Motor neurons: usually multipolar and sends/commands muscles and glands.

• Interneurons: connect and process information between neurons.

• Cortical neurons: many types found in the cerebral cortex.

Nerve Cell Types: Glial

• Astrocytes: support neurons and regulate their environment

• Oligodendrocytes: make myelin in the CNS (central nervous system) - brain/spinal cord.

• Schwann cells: make myelin in the PNS (peripheral nervous system) - nerves outside of the brain/spinal cord.

• Microglia: remove pathogens and damaged cells.

Multipolar Neurons

Neurons with many dendrites and one axon.

• Dendrites: collect information (“reporters”).

• One axon: sends signals away from the cell body.

• Synaptic contacts: connect with many other cells.

• Location: most cell bodies are in the CNS.

Bipolar Neurons

Neurons with two processes extending from opposite ends of the cell body.

• Peripheral process: dendrite - receives sensory information and carries it toward the cell body.

• Central process: axon - carries the signal away from the cell body towards the CNS.

• Structure: one extension comes from each end of the cell body, giving it two processes total.

Neuroglial Cells: Function and Location

• Function: support and protect neurons

• Frequency 40-50 times more glial cells than neurons

• Location: gray and white matter of the brain

Neuroglial Cells: Types and Locations

CNS (brain and spinal cord):

• Astrocytes

• Oligodendroglia

• Microglia

PNS (nerves outside of the CNS):

• Schwann cells

Myelin Sheath

• Insulates axons and prevents electrical signal leakage.

• Speeds up the conduction of electrical impulses

• Made up of lipids and proteins.

• Gives white matter it’s white appearance.

Step 1: Action Potential

An all-or-nothing electrical event where the neurons membrane potential rapidly changes and returns toward resting potential.

• Travels down the axon to the axon terminals.

Step 2: Synaptic Transmission (Neuron —> Muscle)

• The action potential triggers neurotransmitter release.

• Acetylcholine (ACh): the neurotransmitter at the neuromuscular junction.

• ACh crosses the synaptic gap and signals the muscle fiber.

Electrostatic Gradient

Ions move according to electrical attraction and repulsion between charges.

• Opposite attract; like charges repel.

Concentration Gradient

Particles tend to move from an area of higher concentration to an area of lower concentration.

Classification of the Nervous System by Structure

• Central Nervous System (CNS): brain, brain stem, and spinal cord.

• Peripheral Nervous System (PNS): cranial nerves, spinal nerves, and peripheral sensory receptors.

Classification of the Nervous System by Signal Transmission

• Afferent: carries sensory information toward the CNS.

• Efferent: carries signals away from the CNS.

Muscle Spindle

• Detects muscle length and stretching.

• Stretching the muscle spindle typically triggers contraction of muscle.

Golgi Tendon Organ

• Detects force or tension produced by a conducting muscle.

• It’s activity can inhibit muscle contraction and help muscle relax.

Difference Between Muscle Spindles and Golgi Tendon Organs

• Muscle spindle: detects muscle length and stretch.

• Golgi tendon organs: detect muscle tension and force.

Respiration: Skeletal Framework

Function: provides structural support and attachment points for respiratory muscles, helping chest move during breathing.

• Vertebral column

• Ribs and sternum

• Pectoral girdle: scapula and clavicle

• Pelvic girdle

Role of Vertebral Column

• Protects the spinal cord (CNS).

• Supports the trunk, shoulder girdle, and head.

• Provides attachment points for muscles.

Sections of The Vertebral Column

• Cervical: C1-C7 (7 vertebrae) —> 7am = breakfast

• Thoracic: T1-T12 (12 vertebrae) —> 12pm = lunch

• Lumbar: L1-L5 (5 vertebrae) —> 5pm = dinner

• Sacral: S1-S5 (fused together)

• Coccyx: fused vertebrae forming the tailbone

Spinal Nerves and Vertebrae

• Spinal nerves exit through openings between vertebrae.

• Spinal nerves are named according to their spinal region

• EXCEPTION: there are 8 pairs of cervical nerves (C1-C8), but only 7 cervical vertebrae.

Scoliosis

An abnormal curvature of the spine.

• Treatment depends on severity of the curve and skeletal maturity - (physical therapy, occupational therapy, casting, bracing, or surgery).

Myotome

A group of muscles or muscle region supplied by motor fibers from a single spinal nerve root.

• Generally, muscles lower in the body are innervated by lower spinal nerves.

What Is the Major Exception to the General Pattern of Motor Innervation?

The diaphragm is located low in the body but is innervated by C3–C5 through the phrenic nerve.

Dermatome

• An area of skin supplied by sensory fibers from a single spinal nerve root.

• Sensory loss can help identify the location of nerve damage.

How Can Dermatomes Help Identify Nerve Damage?

• Testing sensation in different skin regions can help identify which spinal nerve root may be affected.

• Different sensory patterns can indicate different levels of nerve injury.

What Is the Difference Between a Myotome and a Dermatome?

• Myotome: Muscle region supplied by a motor nerve root.

• Dermatome: Skin region supplied by a sensory nerve root.

Tubercle

A small bony projection or bump.

Facet

A smooth bony surface where bones articulate (connect).

Process

A bony projection or spike.

Foramen

A hole, space, or opening in a bone or structure.

Cervical Vertebrae (C1–C7)

• There are 7 cervical vertebrae.

• Located in the neck.

• C1 is the atlas; C2 is the axis.

Atlas (C1)

• The first cervical vertebra.

• Supports the skull and allows the head to nod.

Axis (C2)

• The second cervical vertebra.

• Allows the head to rotate from side to side.

Cervical Vertebrae (C3–C7)

• The remaining five cervical vertebrae.

• Support the neck and allow neck movement.

Thoracic Vertebrae (T1–T12)

• There are 12 thoracic vertebrae.

• Have large spinous and transverse processes.

• Have costal facets for rib articulation.

Costal Facets

Smooth surfaces on thoracic vertebrae where ribs articulate.

How Do Ribs Articulate With Thoracic Vertebrae?

Ribs connect with costal facets on thoracic vertebral bodies and transverse processes.

Lumbar Vertebrae (L1–L5)

• There are 5 lumbar vertebrae.

• Have larger vertebral bodies to support body weight.

• Have smaller transverse processes than thoracic vertebrae.

How Do Lumbar Vertebrae Differ From Thoracic Vertebrae?

• Lumbar vertebrae have larger bodies and generally smaller transverse processes.

• Thoracic vertebrae have costal facets for rib articulation.

Sacrum

• Forms the base of the vertebral column.

• Connects the spine to the pelvis.

• Transfers body weight to the pelvis and lower limbs.

• Protects sacral spinal nerves.

Coccyx (Tailbone)

• The bottommost part of the vertebral column.

• Provides attachment for muscles, tendons, and ligaments of the pelvic floor.

• Helps support the body while sitting.

What Are the Two Structures at the Base of the Vertebral Column?

Sacrum and coccyx.