Embryonic Anatomy and External Features

Vocabulary flashcards identifying and defining the major external anatomical structures and landmarks of the developing embryo.

Pharyngeal arches

A series of segmental tissue swellings on the ventrolateral aspect of the embryonic head and neck that give rise to structures of the face, jaws, and neck.

Otic placode

A localized thickening of surface ectoderm situated dorsally on the embryonic head that invaginates to develop into the internal ear.

Lens disc

A cranial ectodermal thickening on the anterolateral aspect of the embryonic head that gives rise to the crystalline lens of the eye.

Pericardial swelling

A prominent bulge on the ventral surface of the embryo located inferior to the pharyngeal arches, created by the underlying developing heart.

Upper limb bud

An outgrowth on the ventrolateral body wall in the lower cervical and upper trunk region that gives rise to the upper limb.

Connecting stalk

A band of extraembryonic tissue extending from the caudal region of the embryo that connects it to the placenta and forms the umbilical cord.

Somites

Paired, segmented blocks of paraxial mesoderm arranged sequentially along both sides of the neural tube that give rise to vertebrae, ribs, skeletal muscle, and dermis.

Lower limb bud

An outgrowth on the ventrolateral body wall in the lumbar and sacral region of the embryo that gives rise to the lower limb.