Ansa subclavia

Ansa subclavia (also known as Vieussens' ring or Vieussens' ansa) is a nerve loop in the human anatomy that is part of the sympathetic nervous system. It is named after the French anatomist Raymond de Vieussens who first described it in the 17th century.

Anatomy

The ansa subclavia is located in the superior thoracic aperture, near the root of the neck. It is formed by fibers from the cervical ganglia and the first thoracic ganglion. The loop is connected to the stellate ganglion, which is a fusion of the inferior cervical ganglion and the first thoracic ganglion.

The ansa subclavia gives off branches to the thyroid gland, thymus gland, and the heart. These branches are part of the sympathetic innervation of these organs.

Function

The ansa subclavia is part of the sympathetic nervous system, which is responsible for the body's 'fight or flight' response. It plays a role in regulating heart rate and blood pressure, as well as other functions related to stress response.

The branches of the ansa subclavia that innervate the heart contribute to the regulation of heart rate and force of contraction. The branches to the thyroid and thymus glands are involved in the regulation of metabolism and immune response, respectively.

Clinical significance

Due to its location and the vital organs it innervates, damage to the ansa subclavia can have serious consequences. Conditions such as Horner's syndrome and thoracic outlet syndrome can result from damage to this nerve loop.

Horner's syndrome can occur if the ansa subclavia is damaged, leading to symptoms such as drooping of the eyelid (ptosis), constriction of the pupil (miosis), and absence of sweating (anhidrosis) on the affected side of the face.

Thoracic outlet syndrome can also be caused by compression of the ansa subclavia, leading to symptoms such as pain, numbness, and weakness in the arm and hand.

See also

• Sympathetic nervous system
• Cervical ganglia
• Stellate ganglion
• Horner's syndrome
• Thoracic outlet syndrome