The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus. The median nerve originates from the lateral and medial cords of the brachial plexus, and has contributions from ventral roots of C5-C7 (lateral cord) and C8 and T1 (medial cord).The median nerve is the only nerve that passes through the carpal tunnel. Carpal tunnel syndrome is the disability that results from the median nerve being pressed in the carpal tunnel. Structure
The median nerve arises from the branches from lateral and medial cords of the brachial plexus, courses through the anterior part of arm, forearm, and hand, and terminates by supplying the muscles of the hand. Arm
After receiving inputs from both the lateral and medial cords of the brachial plexus, the median nerve enters the arm from the axilla at the inferior margin of the teres major muscle. It then passes vertically down and courses lateral to the brachial artery between biceps brachii (above) and brachialis (below). At first, it is lateral to the artery and lies anterior to the shoulder joint; it then crosses anteriorly to run medial to the artery in the distal arm and into the cubital fossa. Inside the cubital fossa, the median nerve passes medial to the brachial artery. The median nerve gives off an articular branch to the elbow joint. A branch to pronator teres muscle arise from the median nerve immediately above the elbow joint.
Weill–Marchesani syndrome is a rare genetic disorder characterized by short stature; an unusually short, broad head (brachycephaly) and other facial abnormalities; hand defects, including unusually short fingers (brachydactyly); and distinctive eye (ocular) abnormalities. It was named after ophthalmologists Georges Weill (1866–1952) and Oswald Marchesani (1900–1952) who first described it in 1932 and 1939, respectively. The eye manifestations typically include unusually small, round lenses of the eyes (microspherophakia), which may be prone to dislocating (ectopia lentis), as well as other ocular defects. Due to such abnormalities, affected individuals may have varying degrees of visual impairment, ranging from nearsightedness myopia to blindness. Weill–Marchesani syndrome may have autosomal recessive inheritance involving the ADAMTS10 gene,  or autosomal dominant inheritance involving the FBN1 gene. In some cases there is no association with either of these genes. Diagnosis
Diagnosis is made when several characteristic clinical signs are observed. There is no single test to confirm the presence of Weill–Marchesani syndrome. Exploring family history or examining other family members may prove helpful in confirming this diagnosis. Treatment
Eye surgery has been documented to help those with ocular diseases, such as some forms of glaucoma. Prognosis
However, long term medical management of glaucoma has not proven to be successful for patients with Weill–Marchesani syndrome. Physical therapy and orthopedic treatments are generally prescribed for problems stemming from mobility from this connective tissue disorder. However, this disorder has no cure, and generally, treatments are given to improve quality of life. See also
ADAMTS17
LTBP2

References
External links

GeneReviews/NCBI/NIH/UW entry on Weill-Marchesani Syndrome