Subclavian Artery

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Origin and Termination of Subclavian Artery

There are two subclavian arteries, right and left and they mainly supply upper limb as it continues as axillary artery.They also supplies parts of thorax, neck and brain,

Origin: 

•  Right subclavian artery arieses from the brachiocephalic trunk behind the right sternoclavicular joint.
• Left subclavian artery arises from the arch of aorta in the thorax.

Termination: They terminate at the outer border of 1st rib and continues as axillary arteries.

 Course of Subclavian Artery

Course: The right subclavian artery has only cervical part on the other hand the left subclavian artery has a thoracic part in addition to cervical part.

• The left subclavian artery ascends upwards from the arch of aorta on the mediastinal pleura and grooves the left lung. It enters the neck by passing behind the left sternoclavicular joint.
• The cervical part of both the arteries have similar course. They arche laterally across the anterior surface of the cervical pleura  to the first rib posterior to the scalenus anterior muscle. At the outer border of 1st rib, it  continues as  axillary artery.

Parts of Subclavian Artery

Each artery is divided into three parts by scalenus anterior muscle (diagram above).

1. First part– it extends from the origin to medial border of scalenus anterior.
2. Second part– it is located behind the scalenus anterior muscle.
3. Third part– it extends from the lateral border of scalenus anterior to the outer border of the very first rib. 

Branches of Subclavian artery

It usually gives four branches. All the branches arise from the first part except costocervical branch on right side.

•  From 1st part of subclavian artery
  • Vertebral artery
  • Internal thoracic artery
  • Thyrocervical trunk
  • Costocervical trunk (on left side only)
•  From the 2nd part of subclavian artery
  • Costocervical trunk (only on the right side)

Relations of Subclavian Artery

Relations of 1st Part

Anterior:

• Carotid sheath containing common carotid artery, internal jugular vein and vagus nerve
•  Infrahyoid muscles viz sternothyroid and sternohyoid
• Sternocleidomastoid muscle.
• Thoracic duct  and phrenic nerve (on left side)

 Posterior:

• Apex of the lung covered by the cervical pleura and supra pleural membrane.
• Sympathetic trunk.
• Right recurrent laryngeal nerve (on right side)

Relations of 2nd Part

Anterior:

• Scalenus anterior muscle.
• Phrenic nerve (on right side only).
• Sternocleidomastoid muscle.

Posterior:

• Apex of lung covered by the cervical pleura and suprapleural membrane.
• Lower trunk of brachial plexus and scalenus medius muscle.

Relations of 3rd Part

Anterior:

• Subclavian and external jugular veins.
• Clavicle in the lower part.

Posterior:

• Lower trunk of the brachial plexus and scalenus medius muscle.

Applied Aspect