Week 1 Notes: Foundations of Speech and Hearing - Anatomy and Physiology

Anatomy and Physiology

• Anatomy: definition — the study of the structure of organisms and the relations of their parts.
• Physiology: definition — the study of functions of living organisms or their parts.
• Source: Hoit, J.D., Weismer, G., & Story, B. (2022). Foundations of Speech and Hearing: Anatomy and Physiology, 2nd Edition, Plural Publishing, Inc.

Speech and Hearing Subsystems

• Speech subsystems:
  • Velopharyngeal-nasal
  • Pharyngeal-oral
  • Laryngeal
  • Respiratory
• Hearing subsystems:
  • Outer ear
  • Middle ear
  • Inner ear

Basic Anatomy Position and Directions

• Basic anatomical position involves four elements: $4$ elements
  • body standing erect
  • facing observer
  • arms at side
  • palms facing forward
• Direction note: the terms ventral and dorsal have different meanings when applied to the upper part of the brain

Prone, Supine, and Planes

• Prone: lying face down
• Supine: lying face up
• Posterior: toward the back of a part
• Planes (principal reference orientations):
  • Sagittal plane: $ext{divides the body into left and right sections}$
  • Coronal (Frontal) plane: ext{divides the body into front & back sections}
  • Superior: upper point
  • Inferior: lower point
  • Anterior: toward the front of a part
  • Posterior: toward the back of a part
  • Lateral: away from the midline
  • Medial: toward the midline
• Directions note: ventral/dorsal terminology is context-dependent

Anatomical Planes

• Coronal (Frontal) plane: front vs back
• Sagittal plane: left vs right
• Median plane: equal left and right sections
• Transverse (Horizontal, Axial) plane: upper vs lower

Anatomical Planes of Section (Overview)

• The three common planes: Horizontal (Transverse), Coronal, Sagittal
• Reference image: NEUROANATOMY 2e, Figure 2.5
• Note: These planes are used to describe locations in neuroanatomy

Coronal, Sagittal, and Horizontal Views

• MR images of the corpus callosum shown from different views:
  • Coronal view
  • Sagittal view
  • Horizontal view

Directional Terms (Expanded)

• Superior: the upper point
• Inferior: the lower point
• Anterior: toward the front of a part
• Posterior: toward the back of a part
• Proximal: closer to the trunk or attached end
• Distal: further from the trunk or attached end
• Adduct: to draw toward midline
• Abduct: to draw away from midline
• Dorsal: pertaining to the back
• Ventral: pertaining to the belly
• Medial: toward the midline
• Lateral: away from the midline

Superficial and Deep; Cranial, Rostral, Caudal; External and Internal

• Superficial: toward the surface
• Deep: away from the surface
• Cranial: toward the head
• Rostral: toward the nose or beak
• Caudal: toward the tail
• External: toward the outer surface
• Internal: toward the inner surface (synonymous with deep)

Examples of Directional Terms in Practice

• The brain was sectioned along the coronal plane to examine structures in the frontal and occipital lobes.
• The tumor was best visualized on the transverse MRI scan at the level of the ventricles.
• The fingers are distal to the elbow.
• The occipital lobe is posterior to the frontal lobe.
• The navel (belly button) is on the ventral surface of the body.
• The spinal cord is located on the dorsal side of the body.

Quick Quiz (Practice Prompts)

• My skin is deep or superficial relative to my muscles.
• My nose is superior or inferior to my chin.
• The anatomical position of the thumb is lateral or medial to the pinky finger.
• The fingers are distal or proximal to the wrist, which is distal or proximal to the shoulder.
• The image shown is sagittal or coronal plane?

Units of the Human Body

• Cell: the fundamental structure and functional component of a living organism
• Cells form tissues, tissues form organs, and organs form organ systems (e.g., nervous, muscular, cardiovascular, respiratory, digestive)

Cells

• Every cell has:
  • A cell membrane (outer covering)
  • Cytoplasm (fluid inside the cell)
  • A nucleus (except red blood cells)
  • Organelles (e.g., mitochondria, ribosomes)

Neuron

• A neuron is a specialized nerve cell and the basic unit of nervous tissue
• Function: sends and receives electrical signals
• All neurons are cells, but not all cells are neurons

Basic Neuron Structure

• Cell Body (Soma): contains the nucleus; main office
• Dendrites: receive messages from other neurons (like ears or branches)
• Axon: sends messages away to other cells (like a wire or tail)
• Myelin Sheath: covers the axon to speed up messages (insulation on a wire / paved highway)
• Axon Terminals: pass the message to the next neuron (like hands passing notes)
• Schwann cell: forms the myelin sheath in the peripheral nervous system
• Node of Ranvier: gaps in the myelin sheath that speed transmission
• There are different types of neurons: classify by shape (structure):
  • Unipolar: one process that includes both axon and dendrite
  • Bipolar: two processes (one axon, one dendrite)
  • Multipolar: more than two processes (one axon and two or more dendrites)

Tissues

• Types of tissue: Epithelial, Connective, Muscle, Nerve
• Epithelial tissue:
  • Protection: layers protect underlying tissues from wear and tear
  • Absorption: layers aid absorption of fluids and nutrients
  • Secretion: epithelial cells produce fluids such as mucus, perspiration, and enzymes
  • Stratified squamous epithelium: covers the anterior part of the vocal folds

Connective Tissue (CT)

• CT connects and binds structures; supports the body; maintains bodily integrity
• Composed of extracellular matrix (ECM): collagen fibers, elastin fibers, reticular fibers
• Main fiber types:
  • Collagen fibers
  • Elastic fibers
  • Reticular fibers

Types of Connective Tissue

• Loose
• Dense
• Cartilage (rigid):
  • Hyaline cartilage (most laryngeal cartilages except the epiglottis)
  • Fibrous cartilage (e.g., vertebrae)
  • Elastic cartilage (epiglottis, external ear)
• Bones: bone cells, collagen fibers, and ground substance
• Dense/Compact vs. Spongy (cancellous)
• Vascular CT: blood and lymph tissues

Muscle Tissue

• Groups of muscle fibers are bundled into fascicles
• Types of muscle tissue:
  • Striated (skeletal) muscles: connected to the skeleton; voluntary control
  • Smooth muscles: involuntary; controlled by the autonomic nervous system; found in walls of blood vessels, airways, esophagus, and organs
  • Cardiac muscle: found in the heart

Movements and Forces

• Movements involve over >100 skeletal muscles
• Contraction types:
  • Isometric
  • Concentric
  • Eccentric

Motor Unit and Spoken Communication

• Motor unit = nerve and its associated muscle fibers
• Stages of Spoken Communication: overview listed (no detailed content provided in this transcript)

Practical and Real-World Relevance

• Understanding anatomy/physiology underpins assessment and treatment in speech-language pathology
• Planes and directional terms are essential for locating structures in imaging and during clinical exams
• Knowledge of tissue types and muscle physiology informs speech production mechanics and intervention strategies

References

• Foundations of Speech and Hearing: Anatomy and Physiology (2nd ed.) by Hoit, Weismer, Story, Plural Publishing, 2022