CSD 3423 A&P Study Guide (Topics 1-3 + Terminology)

Define: hearing mechanism

A sensory system that helps us listen and understand speech and sounds, and helps maintain balance.

Define: function of the ear

A sensory organ that helps us perceive (hear) sound energy and body movement (compare: eye = light energy, touch = mechanical energy).

Basic classification of the hearing mechanism

Divided into the peripheral auditory system (outer, middle, inner ear) and the central auditory system (auditory pathway + auditory cortex).

3 parts of the peripheral auditory system

Outer ear, middle ear, and inner ear.

2 parts of the central auditory system

The central auditory pathway (multiple nuclei/stations: cochlear nucleus, SOC, LL, IC, MGB) and the auditory cortex (in the temporal lobe).

Basic function of the peripheral auditory system

Registers sound and does basic analysis of it (pitch, loudness, duration/rhythm), and registers/analyzes body movement (up-down, front-back, head rotation).

Basic function of the central auditory system

Conducts advanced analysis of sound (location, meaning) and helps coordinate body movement and maintain balance.

Primary form of energy in the outer ear

Acoustic energy.

Primary form of energy in the middle ear

Mechanical (vibrational) energy.

Primary form of energy in the inner ear

Hydraulic/electric energy - specifically hydrodynamic in the cochlea.

Primary form of energy in the VIIIth (auditory) nerve

Electrochemical energy.

Primary form of energy in the auditory brainstem

Electrochemical energy.

Primary form of energy in the brain (central auditory mechanism)

Electrochemical energy.

By what month of gestation is the inner ear fully formed?

By the 5th fetal month (the inner ear develops from the inside out, with the first trimester critical for development).

Human audible frequency range

Approximately 20 Hz to 20,000 Hz.

Period of the Zygote - timing and what happens

Begins when the egg is fertilized in the fallopian tube; a period of rapid cell division; ends about 2 weeks later when the zygote implants in the uterine wall.

Period of the Embryo - timing and what happens

From 3 to 8 weeks after conception; body parts are formed; the embryo rests in the amnion filled with amniotic fluid, joined to the placenta by the umbilical cord.

Period of the Fetus - timing and what happens

From 9 weeks after conception to birth; increase in size and body systems begin to function.

Age of viability

22 to 28 weeks gestation.

3 general risk factors in prenatal development

1. Nutrition (adequate food, protein, vitamins, minerals)

2. stress (decreases oxygen to the fetus and weakens the mother's immune system)

3. mother's age (neither too young nor too old).

Define: teratogen

A drug or other substance capable of interfering with the development of a fetus, causing birth defects; teratogens are not universally harmful - they harm particular structures at a particular point in development.

Define: anoxia

Lack of oxygen (at birth); often leads to surgical removal of the fetus (C-section).

Define: very low birthweight baby

A baby born weighing less than 1500 grams (3 lb 4 oz); only about 1.5% of babies born are this small.

2 major causes of very low birthweight

Premature birth (less than 37 weeks) and intrauterine growth restriction (also: problems with the placenta, poor maternal health, birth defects).

Problems very low birthweight babies have (list several)

Low oxygen levels at birth, inability to maintain body temperature, difficulty feeding/gaining weight, infection, breathing problems (e.g. respiratory distress syndrome), neurological problems (bleeding in the brain), gastrointestinal problems, and sudden infant death syndrome (SIDS).

4 long-term problems of very low birthweight babies

Cerebral palsy, blindness, hearing loss, and intellectual disability

APGAR - what it assesses and when

A newborn health score given at 1 and 5 minutes after birth (an additional score at 10 minutes if there are problems); assesses Activity/muscle tone, Pulse, Grimace/reflex irritability, Appearance/skin color, and Respiration.

APGAR score interpretation

7-10 is normal; 4-7 might require some resuscitative measures; 3 and below requires immediate resuscitation.

Cartilaginous vs. bony breakdown of the external auditory canal (EAC)

Lateral 1/3 is cartilage; medial 2/3 is bone.

Conveyor belt shedding

A self-cleaning process of the external auditory canal; a normal process of the outer 1/3 of the EAC.

Concha - dimensions and resonance

10 to 20 mm in diameter, volume about 2.5 cm3; the concha effect produces a 4000-5000 Hz resonance; it is the acoustically most important part of the outer ear; has two parts, the cavum concha and cymba concha.

How does the pinna help with sound localization?

The pinna and head provide directionality cues (horizontal plane) that depend on wavelength of sound, diameter of the head, and the head shadow effect; diffraction/bending occurs above ~1500 Hz, and front-to-back cues come from sounds behind the head being reduced for 3000-6000 Hz.

External auditory meatus - definition and diameter

The opening to the external auditory canal; diameter is about 5 to 7 mm.

External auditory canal (EAC) - average adult diameter

About 7 mm.

External auditory canal (EAC) - average length

23 to 30 mm (longer at the bottom, shorter at the top).

External auditory canal (EAC) - resonant frequency and boost

Resonance of about 2,600 to 3,500 Hz; ear canal resonance provides roughly a 10 dB boost around 3000 Hz.

External auditory canal (EAC) - outer 1/3 contents

Quasi-independent pieces of cartilage, cerumenous glands, sebaceous (fat) glands, apocrine glands, and hair lining (pointing up and out).

External auditory canal (EAC) - medial 2/3 characteristics

Osseous (bony), with only a thin skin covering; described as a cylinder of temporal bone at the base of the skull; the tympanic portion forms the anterior/inferior walls and the lower part of the posterior wall (squamous and mastoid portions).

Isthmus of the external auditory canal

The osseous-cartilaginous junction - the point where the outer 1/3 (cartilage) meets the inner 2/3 (bone).

Functions of the external auditory canal

Efficient sound transmission to the tympanic membrane (with ear canal resonance boosting ~10 dB around 3000 Hz); protects the tympanic membrane and inner ear from injury, extreme temperatures, and foreign bodies; and is self-cleansing.

Tragus - definition

A small triangular protrusion on the anterior portion of the pinna; Greek for "goat's beard"; when closed off it can cut out sound.

Helix and antihelix

Helix = the outer rim of the pinna; antihelix = the elevation running close to the center of the pinna.

Squamous epithelium of the EAC - thickness

Bony skin is about 0.2 mm thick; cartilage skin is about 0.5 to 1.0 mm thick.

Apopilosebaceous unit

A hair follicle plus an erector pili muscle, an apocrine (or eccrine) gland, and sebaceous glands.

Anatomical position terms: Ventral

toward the front/belly side

Anatomical position terms: Dorsal

toward the back side

Anatomical position terms: Anterior

toward the front

Anatomical position terms: Posterior

toward the back

Anatomical position terms: Rostral

toward the head/nose end

Anatomical position terms: Caudal

toward the tail end

Anatomical position terms: Superior

above/upper

Anatomical position terms:Inferior

below/lower

Anatomical position terms: Superficial

near the surface

Anatomical position terms: Deep

farther from the surface.

Anatomical position terms: External

outside

Anatomical position terms: Internal

inside

Anatomical position terms: Medial

toward the midline

Anatomical position terms: Lateral

away from the midline (toward the side)

Anatomical position terms: Proximal

closer to the point of attachment/trunk

Anatomical position terms: Distal

farther from the point of attachment/trunk.

Anatomical position terms: Prone

lying face down

Anatomical position terms: Supine

lying face up.

Anatomical position terms: Ipsilateral

on the same side

Anatomical position terms: Contralateral

on the opposite side.

Planes of the body: Sagittal

divides the body into left and right portions

Planes of the body: Mid-Sagittal

a sagittal cut exactly at the midline, giving equal left and right halves.

Planes of the body: Coronal (Frontal)

Divides the body into front (anterior) and back (posterior) portions.

Planes of the body: Transverse (Horizontal)

Divides the body into upper (superior) and lower (inferior) portions.

Prefix: A-

Without.

Prefix: Ecto-

Outside, outer.

Prefix: Endo-

Inside, inner.

Prefix: Epi-

Over, upon.

Prefix: Hemi-

Half.

Prefix: In-

In, into.

Prefix: Infra-

Below, under.

Prefix: Meso-

Middle.

Prefix: Peri-

Around.

Prefix: Post-

After, behind.

Prefix: Pre-

Before, in front of.

Prefix: Semi-

Half.

Prefix: Sub-

Under.

Prefix: Super-

Above, over.

Prefix: Supra-

Above, over.

Prefix: Trans-

Across, over.

Prefix: Ex-

Out from, out of.

Prefix: Micro-

Small.

Prefix (pathology): Hyper-

Above, excessive, more than normal.

Prefix (pathology): Dis-

To undo, free from.

Prefix (pathology): Dys-

Bad, painful, difficult.

Combining form: Cardi/o

Heart.

Combining form: Acr/o

Extremities.

Combining form: Rhin/o

Nose.

Combining form: Ot/o

Ear.

Combining form: Laryng/o

Larynx.

Combining form: Ophthalm/o

Eye.

Combining form: Cephal/o

Head.

Combining form: Encephal/o

Brain.

Combining form: Nephr/o

Kidney.

Combining form: Dactyl/o

Finger.

Suffix: -algia

Pain.