Ontogenetic Development Auditory system development

Vocabulary flashcards covering ontogeny, embryology, and key components and timeline of auditory system development from the lecture notes.

The series of steps that leads to a mature state; a fertilized ovum develops into billions of cells forming a functional organism.

Ontogeny

The formation and development of an embryo; stages include fertilization, cleavage, blastulation, implantation, and embryonic disc.

Embryogenesis

The study of embryonic development; closely related to ontogeny.

Embryology

Development of form and shape in an organism, including tissue growth and cellular differentiation.

Morphogenesis

The stage when the embryo forms a blastula, a hollow ball of cells, after cleavage.

Blastulation

The union of sperm and egg that forms a zygote.

Fertilization

A rapid series of cell divisions following fertilization, without growth.

Cleavage

Attachment of the embryo to the uterine wall.

Implantation

An early embryonic structure from which tissues and organs develop.

Embryonic disc

Embryonic head and neck structures that contribute to facial features and related structures.

Pharyngeal arches

The spiral-shaped organ in the inner ear that converts sound into neural signals.

Cochlea

The part of the ear containing the cochlea and vestibular apparatus responsible for hearing and balance.

Inner ear

The three tiny middle-ear bones (malleus, incus, stapes) that transmit sound to the inner ear.

Ossicles

The eardrum; a thin membrane separating the outer ear from the middle ear.

Tympanic membrane

The air-filled cavity containing the ossicles that transmit sound.

Middle ear

The external part of the ear, including the pinna and ear canal.

Outer ear

Specialized sensory cells in the cochlea that transduce vibrations into neural impulses.

Hair cells

The early embryonic structure that develops into the brain and spinal cord.

Neural tube

Formation of a myelin sheath around neurons, increasing the speed of nerve conduction.

Myelination

Formation of synapses between neurons, creating neural networks.

Synaptogenesis

The fetus begins to hear external sounds around 22–23 weeks post conception; sounds are muffled by maternal tissues.

Fetal hearing onset (22–23 weeks)

Around 26 weeks, the fetus may respond to sounds with changes in heartbeat, breathing, or movement.

Fetal response at 26 weeks

By 32–35 weeks, the middle ear cavity, outer ear canal, and outer ear are formed, ready to hear at birth.

Ear formation by 32–35 weeks

Hearing continues to develop, typically maturing around 14–15 years; newborns may remember sounds heard in utero and distinguish the mother’s voice.

Birth and beyond