The thyrocervical trunk and vertebral arteries are branches from the first portion of the subclavian artery. The suprascapular, transverse cervical, and inferior thyroid arteries are the main branches from the thyrocervical trunk while the ascending cervical artery most often branches from the inferior thyroid artery. There is great variation in the branching pattern of the thyrocervical trunk including about 3% of cases in which the vertebral takes origin from the thyrocervical trunk.

The vertebral artery is one of the more important of the subclavian branches. Along with the internal carotid, it provides the major blood supply to the brain. The vertebral and ascending cervical arteries supply the cervical spinal cord with blood, with the vertebral being the primary source of arterial blood.

The photographs are of a male cadaver in whom the pattern of branching from the first part of the subclavian artery is rare and very unusual. In this cadaver, the vertebral artery was small and branched from the thyrocervical trunk. The ascending cervical artery was large, had numerous branches, and arose from the thyrocervical trunk. These branches can be seen entering the intervertebral foramen in the cervical portion of the vertebral column, in all likelihood to supply blood to the cervical spinal cord. This pattern of branching occurs in less than 1% of cases and supports the view that the ascending cervical artery assists the vertebral artery in supplying the cervical portion of the spinal cord.

Figure 1

Figure 1 shows the root of the neck of a male cadaver. The branches from the subclavian artery (3) include a small vertebral artery (5) and a short thyrocervical trunk (2). The transverse cervical artery (4) is large. Two relatively large branches from the thyrocervical turnk appear to course in a superior direction to enter the intervertebral foramen of the cervical region of the vertebral column. These branches represent anomalous ascending cervical arteries. Also shown is the common carotid artery (1). TC = Thyroid Cartilage;
CC = Cricoid Cartilage.

Figure 2

Figure 2 is a close up view of the root of the neck in the same cadaver as shown in Figure 1. The C5, C6 and C7 (#'s 5, 6 and 7 respectively) roots of the brachial plexus (BP) can be seen. The small vertebral artery (V) can be seen branching from the thyrocervical trunk. The white arrow indicates the points of branching of the ascending cervical arteries from the thyrocervical trunk and enterinng the cervical intervertebral foramenia.