Eventually cells from the tissue surrounding the ossicles will experience apoptosis and a new layer of endodermal epithelial will constitute the formation of the tympanic cavity wall. Outer ear
Unlike structures of the inner and middle ear, which develop from pharyngeal pouches, the ear canal originates from the dorsal portion of the first pharyngeal cleft. It is fully expanded by the end of the 18th week of development. The eardrum is made up of three layers (ectoderm, endoderm and connective tissue). The pinna originates as a fusion of six hillocks. The first three hillocks are derived from the lower part of the first pharyngeal arch and form the tragus, crus of the helix, and helix, respectively. The final three hillocks are derived from the upper part of the second pharyngeal arch and form the antihelix, antitragus, and earlobe. The outer ears develop in the lower neck. As the mandible forms they move towards their final position level with the eyes. Clinical significance
Hearing loss
Hearing loss may be either partial or total. This may be a result of injury or damage, congenital disease, or physiological causes. When hearing loss is a result of injury or damage to the outer ear or middle ear, it is known as conductive hearing loss. When deafness is a result of injury or damage to the inner ear, vestibulochoclear nerve, or brain, it is known as sensorineural hearing loss. Causes of conductive hearing loss include an ear canal blocked by ear wax, ossicles that are fixed together or absent, or holes in the eardrum.
Causes
Sometimes there is no obvious explanation for the cause of PGP but usually there is a combination of factors such as:

The pelvic joints moving unevenly. A change in the activity of the muscles in the pelvis, hip, abdomen, back and pelvic floor. A history of pelvic trauma. The position of the baby altering the loading stresses on the pelvic ligaments and joints. Strenuous work. Previous lower back pain. Previous pelvic girdle pain during pregnancy. Hypermobility, genetical ability to stretch joints beyond normal range. An event during the pregnancy or birth that caused injury or strain to the pelvic joints or rupture of the fibrocartilage. The occurrence of PGP is associated with twin pregnancy, first pregnancy and a higher age at first pregnancy. Mechanism
Pregnancy related Pelvic Girdle Pain (PGP) can be either specific (trauma or injury to pelvic joints or genetical i.e. connective tissue disease) and non-specific. PGP disorder is complex and multi-factorial and likely to be also represented by a series of sub-groups driven by pain varying from peripheral or central nervous system,
altered laxity/stiffness of muscles, laxity to injury of tendinous/ligamentous structures to mal-adaptive body mechanics.Pregnancy begins the physiological changes through a pattern of hormonal secretion and signal transduction thus initiating the remodelling of soft tissues, cartilage and ligaments. Over time, the ligaments could be stretched either by injury or excess strain and in turn may cause PGP. Anatomy
The pelvis is the largest bony part of the skeleton and contains three joints: the pubic symphysis, and two sacroiliac joints.