Harrison's groove
Encyclopedia
Harrison's groove, also known as Harrison's sulcus, is a horizontal line at the lower margin of the thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...

 where the diaphragm
Thoracic diaphragm
In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...

 attaches to the ribs.

It is usually caused by chronic asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

 or obstructive respiratory disease. It may also appear in rickets
Rickets
Rickets is a softening of bones in children due to deficiency or impaired metabolism of vitamin D, magnesium , phosphorus or calcium, potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries...

 because the patients lack the mineralized calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 in their bones necessary to harden them; thus the diaphragm, which is always in tension
Muscle tone
In physiology, medicine, and anatomy, muscle tone is the continuous and passive partial contraction of the muscles, or the muscle’s resistance to passive stretch during resting state. It helps maintain posture, and it declines during REM sleep.-Purpose:Unconscious nerve impulses maintain the...

, pulls the softened bone inward.

It is named after Edward Harrison
Edward Harrison (physician)
Edward Harrison was a British physician who described Harrison's groove. He studied in London under John and William Hunter, and in Edinburgh where he received his doctorate in 1784. He practised in Horncastle, Lincolnshire for 30 years, founding the Horncastle Dispensary and the Lincolnshire...

.
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