A Brief Overview of Voice Anatomy
The anatomy of voice involves the entire body: abdomen, back, ribs, lungs, pharynx, oral cavity, diaphragm, nasal cavity, brain, nerves, et. al. You might call it an embodied activity. Consequently our voice mechanism requires multiple systems to produce speech acts.
- Cognitive System (brain and nervous system) – the thought
- Respiratory System (diaphragm, lungs, ribs, abdominal and chest muscles) – the breath
- Vibratory System (larynx et. al.) – the voice
- Resonating System (pharynx, oral and nasal cavities) – its timbre
The Vibratory System
The larynx-–our voice box–is essential to voice production though people living without a larynx can use an electrolarynx or learn to manipulate their esophagus (esophageal speech/voice). It is composed of four basic anatomic units:
- skeleton (thyroid cartilage, cricoid cartilage, and two arytenoid cartilages)
- intrinsic muscles (the vocalis muscles–which are part of the thyroarytenoid muscle–extend on each side from the arytenoid cartilage to the inside of the thyroid cartilage just below and behind the Adam’s Apple, forming the vocal folds or vocal cords, which are your voice source or oscillator). The space between the vocal cords is called the glottis or the rima glottidis. The intrinsic muscles alter the position, shape, and tension of the vocal folds to produce adduction and abduction–bringing together or moving apart the vocal cords creating the oscillations that produce sound. These muscles are innervated by one of the two recuurent laryngeal nerves, with one exception, thecricothyroid muscle, which is innervated by the superior laryngeal nerve on each side and is necessary for volume projection and pitch control. The “false vocal cords” are located above the vocal folds.)
- extrinsic muscles (move the larynx superiorly and inferiorly–up and down–elevating and depressing the larynx to make sound. The extrinsic muscles are comprised of the stylopharyngeus or pharynx muscle and the suprahyoid and infrahyoid groups.
- mucosa (oral mucous membrane consists of the stratified squamous epithelium and the lamina propria–its connective tissue)
And it looks like this:
The Respiratory System
The respiratory system engages the infraglottic vocal tract during voice production. It is the power source of the voice using the abdominal and chest muscles, ribs, lungs and diaphragm to project voice.
The Resonating System
The resonating system uses the supraglottic vocal tract, which consists of the pharynx, tongue, palate, oral and nasal cavities. These are the modifiers and articulators that form sound–or phonation–into words and allow speakers to modulate their timbre (vocal quality).
The Cognitive System
The cognitive system is pretty complicated, but from what we know about the brain, most language processing takes place in the cerebral cortex. And, from what we know about the neural structures involved in the brain’s language processing system, it involves two main association areas (but is by no means limited to these two areas). These two areas are located in the dominant hemisphere (the left hemisphere for most people):
- Wernicke’s area (the area between the auditory and visual cortexes–near the back of the brain–where receptive speech takes place. Its main function is the comprehension of language and the ability to communicate coherent ideas. People dealing with receptive aphasia can produce fluent speech but what they produce lacks coherence and they often have difficulty understanding others. In other words, they can reproduce clear speech but this speech lacks coherent meaning.
- Broca’s area (closer to the front of the brain, Broca’s area is in close proximity to the motor cortex and the neural system connected to the larynx, tongue and mouth and is responsible for the motor production of speech. People dealing with expressive aphasia have difficulty producing fluent speech, although they can still understand language. In other words, they maintain cognitive function but have a hard time reproducing speech. This type of non-fluent aphasia is characterized by the omission of small words and is often accompanied by anger and frustration because they are aware of their language disorder.
Truthfully, my knowledge about the brain is limited…at a humor conference at UNC, two years ago. It was awkward and amazing.