Lamina externa is a term used in anatomy to describe the outermost layer of certain structures. The spelling of this term can be explained using the International Phonetic Alphabet (IPA). The first word, "lamina," is spelled /ləˈmiːnə/ in IPA, with the stress on the second syllable. The second word, "externa," is spelled /ɛkˈstɜːnə/ in IPA, with the stress on the first syllable. Overall, the spelling of "lamina externa" can be challenging due to the diverse range of vowel sounds and variable stress patterns present in each word.
The term "lamina externa" refers to a specific anatomical structure commonly found in various organisms. Derived from Latin roots, "lamina" translates to "sheet" or "plate," while "externa" means "external" or "outer." In anatomy, "lamina externa" represents the outer layer or sheet-like component of a structure, often seen in tissues or organs.
In specific anatomical contexts, "lamina externa" is commonly mentioned in relation to the eyes. It refers to the outermost layer of the lamina cribrosa, a sieve-like structure located at the back of the eye. The lamina externa is composed of collagen fibers and is responsible for maintaining the structural integrity of the optic nerve. It functions as a supportive layer that protects the optic nerve fibers as they exit the eye towards the brain.
Aside from ocular anatomy, the term "lamina externa" can be applied to other structures, such as the cell membranes. In this context, it refers to the outermost layer or the external boundary of the cell membrane. The lamina externa of the cell membrane acts as a protective barrier, controlling the movement of molecules in and out of the cell, maintaining cell shape, and providing stability to the cell.
In summary, "lamina externa" refers to the outer layer or sheet-like structure found in various anatomical contexts, notably in ocular anatomy as the outer layer of the lamina cribrosa, and in cell biology as the outermost layer of the cell membrane. Its primary functions include structural support, protection, and maintaining the integrity of the respective structures.
The outer table of the skull, the outer compact layer of the cranial bones.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word lamina is derived from the Latin word lamina meaning a thin plate or layer. Externa is also derived from Latin, where it means outer or external. So, lamina externa translates to external layer or outer plate.