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Sunday, December 29, 2013
Thursday, December 26, 2013
Anatomy of nose bones
The nose is the part of the respiratory tract that sits front and center on your face. You use it to breathe air in and to stop and smell the roses.
Anatomy of Nose Bones
Bones of Nose:
The nose has a bony part that’s formed by the bony nasal septum, the nasal bones, and parts of the maxillae, palatine, and frontal bones.
Nasal Bone :
Each human has two nasal bones located in the upper-middle area of the face, between the maxillary bones' frontal processes. They are placed side by side at the middle and upper part of the face, and form, by their junction, “the bridge” of the nose.
Nasal bones are normally small and oblong, but can differ in size and shape in different people.
The function of each nasal bone is to bind together the cartilaginous tissues that form individual nose shapes.
Each nasal bone has two surfaces and four borders :
Surfaces.
The outer surface is concavoconvex from above downward, convex from side to side, and perforated about its center by a foramen, for the transmission of a small vein.
The inner surface is concave from side to side, and is traversed from above downward, by a groove for the passage of a branch of the nasociliary nerve.
Borders.
The superior border is narrow, thick, and serrated for articulation with the nasal notch of the frontal bone.
The inferior border is thin, and gives attachment to the lateral cartilage of the nose; near its middle is a notch which marks the end of the groove just referred to.
The lateral border is serrated, beveled at the expense of the inner surface above, and of the outer below, to articulate with the frontal process of the maxilla.
The medial border, thicker above than below, articulates with its fellow of the opposite side, and is prolonged behind into a vertical crest, which forms part of the nasal septum: this crest articulates, from above downward, with the spine of the frontal, the perpendicular plate of the ethmoid, and the septal cartilage of the nose.
Ossification:
Each bone is ossified from one center, which appears at the beginning of the third month of fetal life in the membrane overlying the front part of the cartilaginous nasal capsule.
Articulations:
The nasal articulates with four bones: two of the cranium, the frontal and ethmoid, and two of the face, the opposite nasal and the maxilla.
Articulation with the frontal is via the serrated superior margin. The thin lateral margin butts against the frontal process of the maxilla. The medial border meets with its fellow from the opposing side and superiorly articulates with a small portion of the perpendicular plate of the ethmoid bone. Inferiorly, the notched margin is continuous with the lateral nasal cartilage.
References :
Anatomy of the Human Body > II. Osteology > 5b. The Facial Bones. 1. The Nasal Bones.
Anatomy Expert - http://www.anatomyexpert.com/structure_detail/7/
Physiology of speech
Physiology of Speech
*The production of speech is a highly complex motor task that involves approximately 100 orofacial, laryngeal, pharyngeal, and respiratory muscles.
* Speech can be defined as waves of air pressure created by airflow pressed out of the lungs and going out through the mouth and nasal cavities. The air passes through the vocal folds (chords) via the path from the lungs through the vocal tract, vibrating them at different frequencies.
*Speech production requires airflow from the lungs (respiration) to be phonated through the vocal folds of the larynx (phonation) and resonated in the vocal cavities shaped by the jaw, soft palate, lips, tongue and other articulators (articulation)such as : The Vocal tract, The Pharynx, The Glottis, The Velum, The Teeth, The Nose and Larynx.
The Articulators
The structures involved in the articulation of speech can be classified into two categories:
• Movable : Lips, Tongue, Soft Palate, Pharynx, Mandible
• Fixed : Incisors, Hard Palate, Aleolar Ridge
Mechanism
Speech sound is a wave of air that originates from complex actions of the human body, supported by three functional units:
- Generation of air pressure
- Regulation of vibration
- Control of resonators
The lung air pressure for speech results from functions of the respiratory system during a prolonged phase of expiration after a short inhalation.
Vibrations of air for voiced sounds are introduced by the vocal folds in the larynx; they are controlled by a set of laryngeal muscles and airflow from the lungs. The oscillation of the vocal folds converts the expiratory air into intermittent airflow pulses that result in a buzzing sound.
The narrow constrictions of the airway along the tract above the larynx also generate transient source sounds; their pressure gives rise to an airstream with turbulence or burst sounds. The resonators are formed in the upper respiratory tract by the pharyngeal, oral, and nasal cavities. These cavities act as resonance chambers to transform the laryngeal buzz or turbulence sounds into the sounds with special linguistic functions. The main articulators are the tongue, lower jaw, lips, and velum. They generate patterned movements to alter the resonance characteristics of the supra-laryngeal airway.
References:
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