Unit 2: Anatomy and physiology of speech mechanism

Fill in the blanks:

1. The ______________________ in the temporal lobe is responsible for understanding language and organizing words.
2. The basic unit of the nervous system that transmits nerve signals is the ______________________.
3. Tiny air sacs in the lungs where gas exchange occurs are called ______________________.
4. The ______________________ is the primary muscle that contracts and moves downward during inspiration.
5. The ______________________ cartilage is the largest, shield-shaped cartilage of the larynx, often called the Adam’s apple.
6. The only complete ring of cartilage in the airway is the ______________________ cartilage.
7. The space between the true vocal folds is known as the ______________________ (or rima glottidis).
8. The ______________________ is the main muscle responsible for controlling lip movements.
9. A ______________________ occurs when the palatal bones fail to fuse properly during development.
10. The vertical groove located above the upper lip is called the ______________________.

Answers:

1. Wernicke’s area
2. Neuron
3. Alveoli
4. Diaphragm
5. Thyroid
6. Cricoid
7. Glottis
8. Orbicularis oris
9. Cleft palate
10. Philtrum

Tick the correct option:

1. Which lobe of the brain contains the Broca’s area, responsible for motor commands for speech?

a) Temporal

b) Parietal

c) Frontal

d) Occipital

2. What is the approximate vital capacity (maximum breathing capacity) of an adult human?

a) 500 ml

b) 1 liter

c) 2 liters

d) 4 liters

3. Which cartilage is leaf-shaped and protects the airway during swallowing?

a) Cricoid

b) Epiglottis

c) Arytenoid

d) Thyroid

4. The “pitch” of a person’s voice primarily depends on:

a) Frequency of vocal fold vibration

b) Amount of airflow

c) Shape of the lips

d) Size of the lungs

5. Which muscle is the ONLY one responsible for opening (abducting) the vocal folds?

a) Lateral cricoarytenoid

b) Posterior cricoarytenoid

c) Cricothyroid

d) Vocalis

6. The resonatory system (vocal tract) consists of which three structures?

a) Pharynx, oral cavity, nasal cavity

b) Larynx, trachea, lungs

c) Lips, tongue, teeth

d) Brain, nerves, muscles

7. Which extrinsic tongue muscle is responsible for protruding the tongue?

a) Styloglossus

b) Hyoglossus

c) Genioglossus

d) Palatoglossus

8. What is the normal rate of speech for a fluent adult speaker?

a) 10-50 words/min

b) 80-180 words/min

c) 200-300 words/min

d) 500 words/min

9. The reddish color of the soft palate and lips is primarily due to:

a) Pigmentation

b) Mucus

c) Thin skin

d) Rich blood supply

10. Which structure acts as a “door” to control airflow between the oral and nasal cavities?

a) Hard palate

b) Velopharyngeal port

c) Epiglottis

d) Glottis

Answers:

1. Frontal
2. 4 liters
3. Epiglottis
4. Frequency of vocal fold vibration
5. Posterior cricoarytenoid
6. Pharynx, oral cavity, nasal cavity
7. Geninoglossus
8. 80-180 words/min
9. Rich blood supply
10. Velopharyngeal port

True or False:

1. Speech is considered an “overlaid function” because the organs involved have primary biological roles like breathing and eating. (True)
2. In speech breathing, the duration of inspiration and expiration is equal. (False)
3. The larynx is generally positioned higher in the necks of women and children than in men. (True)
4. The vocal folds contain many mucous glands to keep themselves lubricated. (False)
5. The intrinsic muscles of the larynx move the larynx as a whole up and down the neck. (False)
6. The left hemisphere of the brain is typically dominant for language in most individuals. (True)
7. The hard palate consists of both bone and muscle. (False)
8. If the velopharyngeal port is open, air passes through the nose, creating nasal sounds. (True)
9. Adult males have a sharper thyroid angle (90°) compared to adult females (120°). (True)
10. The tongue is an entirely muscular organ with no skeletal attachments. (False)

Answers:

1. True
2. False
3. True
4. False
5. False
6. True
7. False
8. True
9. Trye
10. False

Very short answer type questions:

1. What is the function of Reinke’s space?
2. Define “Vital Capacity.”
3. What are the two main divisions of the Nervous System?
4. Which cranial nerve pair is primarily responsible for the larynx?
5. What is the “Adam’s Apple”?
6. What is the primary role of the intrinsic muscles of the tongue?
7. Name the four lobes of the brain.
8. What is the “transfer function” of the vocal tract?
9. How many teeth does a normal adult have?
10. What is the function of the saccule in the larynx?

Answers:

1. It is the superficial layer of the lamina propria in the vocal folds, essential for vibration.
2. The maximum amount of air a person can expel from the lungs after a maximum inhalation.
3. The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
4. The Vagus nerve (10th cranial nerve).
5. The laryngeal prominence formed by the sharp angle of the thyroid cartilage.
6. To allow flexibility and precise changes in the tongue’s shape.
7. Frontal, Temporal, Parietal, and Occipital.
8. The process where the vocal tract acts as a filter to modify the sound produced by the larynx.
9. 32 teeth.
10. It contains mucous glands that lubricate the vocal folds.

Short answer type questions:

1. Describe the difference between quiet breathing and speech breathing.
2. Explain the role of Wernicke’s and Broca’s areas in communication.
3. What is the “Signet Ring” cartilage, and why is it unique?
4. List the three parameters of voice and what they depend on.
5. How does the infant larynx differ from the adult larynx?
6. Describe the structure of the hard palate.
7. Explain the function of the Velopharyngeal (VP) Port during speech.
8. What are the biological vs. non-biological functions of the larynx?
9. What are intrinsic vs. extrinsic laryngeal muscles?
10. Explain how the tongue acts as a “filter” in speech.

Answers:

1. In quiet breathing, inspiration and expiration are roughly equal in duration. In speech breathing, inspiration is very short and quick, while expiration is significantly prolonged to provide a steady stream of air for speaking.
2. Wernicke’s area (temporal lobe) is for language comprehension and word selection. Broca’s area (frontal lobe) is for programming the motor movements required to physically produce speech.
3. The cricoid cartilage is shaped like a signet ring (narrow in front, broad in back). It is unique because it is the only complete, closed circle of cartilage in the entire respiratory tract.
4. Pitch: Depends on the frequency of vocal fold vibration. Loudness: Depends on the force and volume of the pulmonary airflow. Quality: Depends on the complexity of the vibration and resonance.
5. The infant larynx is 1/3 the size, positioned higher in the neck, more flexible/less fibrous, and the epiglottis is often omega-shaped rather than leaf-shaped.
6. It is a bony structure formed by the palatine processes of the maxilla and the horizontal plates of the palatine bones, covered by a mucous membrane.
7. The VP port acts as a valve. For oral sounds, the soft palate raises to close the port, directing air through the mouth. For nasal sounds (/m/, /n/), the soft palate lowers to open the port, allowing air into the nasal cavity.
8. Biological: Protecting the airway from food/liquid and building subglottic pressure for lifting or coughing. Non-biological: Sound production for speech and singing.
9. Intrinsic muscles have both attachments within the larynx and move the cartilages (controlling the vocal folds). Extrinsic muscles have one attachment outside the larynx and move the entire larynx up or down.
10. The tongue changes position to alter the shape and volume of the oral cavity. This changes the resonance frequencies, filtering the voice into different vowel and consonant sounds.

Long answer type questions:

1. Discuss the “Speech Chain” and the coordinated functioning of the four systems involved in speaking.
2. Provide a detailed anatomical description of the thyroid and cricoid cartilages.
3. Describe the internal anatomy of the larynx, including the true and false vocal folds and the laryngeal ventricle.
4. Analyze the role of the tongue in speech production, including its extrinsic and intrinsic muscle functions.
5. Explain the process of voice production (phonation) and the three main parameters of voice.
6. Discuss the anatomy and physiology of the soft palate (velum) in relation to speech and swallowing.
7. Detail the Nervous System’s control over speech, including the role of the brain, cranial nerves, and the structure of a neuron.

Answers:

1. Speech is a complex motor activity requiring the synchronized functioning of four primary systems, all governed by a central “commander.” The Nervous System: Acting as the coordinator, the brain (specifically Wernicke’s and Broca’s areas) plans the message and sends motor commands through nerves to the rest of the body. The Respiratory System: Acting as the “pump” or energy source, it provides controlled expiratory airflow. Speech is produced using modified air from the lungs, requiring an air pressure of about 5–8 cm of $H_2O$. The Phonatory System: The larynx acts as the “vibrator.” As air passes through, the vocal folds vibrate to produce a basic sound known as voice (phonation). Articulatory & Resonatory Systems: These act as the “filters.” The pharynx, oral cavity, and nasal cavity (the vocal tract) modify the raw sound into distinct, meaningful speech sounds through the movement of the tongue, lips, and palate.
2. These two cartilages form the main structural framework of the larynx. Thyroid Cartilage: The largest laryngeal cartilage, it is shield-shaped and made of two flat plates (laminae) that meet at a midline. The angle of this junction is approximately 90° in males (forming the Adam’s apple) and 120° in females. It features superior and inferior horns (cornu) that help connect it to the hyoid bone and cricoid cartilage. Cricoid Cartilage: Located immediately below the thyroid, it is the only complete ring of cartilage in the airway. It is shaped like a signet ring, with a narrow anterior arch and a broad posterior lamina. It articulates with the thyroid and arytenoid cartilages, allowing for the rotational movements necessary to change the pitch of the voice.
3. The laryngeal cavity is divided into three sections by two sets of horizontal folds: Vestibular Folds (False Vocal Cords): These are the upper, thicker folds. They are primarily protective and do not vibrate during normal voice production. Vocal Folds (True Vocal Cords): These are the lower, thinner, white folds. They consist of five layers: the epithelium, three layers of lamina propria (including Reinke’s space), and the vocalis muscle. They are responsible for sound production. Laryngeal Ventricle: This is the recess or space located between the false and true vocal folds. It leads to the saccule, which contains mucous glands that lubricate the vocal folds for smooth vibration. The Glottis: This is the variable opening between the true vocal folds, which changes shape during breathing and phonation.
4. The tongue is the primary organ of taste and the most versatile articulator in speech. It is a muscular “box” that changes the shape of the oral cavity to filter sound. Intrinsic Muscles: These muscles (Superior/Inferior Longitudinal, Transverse, Vertical) are located entirely within the tongue. They allow the tongue to change its internal shape—flattening, narrowing, or curling the tip—which is essential for precise speech sounds. Extrinsic Muscles: These muscles (Genioglossus, Hyoglossus, etc.) attach the tongue to the skull, hyoid, and jaw. They are responsible for moving the tongue as a whole—protruding it, retracting it, or elevating it. Filter Function: By moving to different “places of articulation” (like the palate or teeth), the tongue creates different resonant chambers that result in different speech sounds, such as /d/ versus /g/.
5. Voice production (phonation) is defined as the modification of the pulmonary air stream. The Process: During expiration for speech, the vocal folds continuously open and close (vibration). This breaks the continuous airflow into small puffs or bursts of air, creating sound. The Three Parameters: Pitch: Depends on the frequency (number) of vocal fold vibrations. Faster vibrations create a higher pitch. Loudness: Depends on the force or amount of expiratory airflow. Quality: Refers to the clarity or pleasantness of the sound, determined by how the sound is resonated in the vocal tract.
6. The soft palate is a muscular extension of the hard palate that acts as a valve between the oral and nasal cavities. In Speech: The velum raises (closing the Velopharyngeal Port) for oral sounds to ensure air escapes through the mouth. It lowers for nasal sounds (like /m/ and /n/) to allow air into the nasal cavity. In Swallowing: During swallowing, the velum and uvula move upward to seal the nasopharynx, preventing food and liquid from entering the nasal cavity. Structure: It consists of muscles like the Levator Veli Palatini (which raises it) and the Tensor Veli Palatini (which tenses it), along with the uvula at its posterior end.
7. The nervous system is the central commander that plans and executes the act of speaking. The Brain: The temporal lobe (Wernicke’s area) understands language and selects words. The frontal lobe (Broca’s area) converts these into motor plans. Transmission: Motor commands are sent via neurons—the basic units of the system. Signals travel down axons covered in myelin (which allows speeds up to 200 mph) to reach the muscles. Cranial Nerves: There are 12 pairs of cranial nerves. Specifically, the Vagus nerve provides the sensory and motor supply to the larynx, ensuring the vocal folds open and close as needed. Sensory Feedback: Sensory nerves carry information from the tongue and skin back to the brain, allowing the speaker to monitor and correct their own speech in real-time.