Stellate ganglion (or cervicothoracic ganglion) is a sympathetic ganglion formed by the fusion of the inferior cervical ganglion and the first thoracic ganglion. It exists in 80% of individuals. The stellate ganglion is oval-shaped, measuring 1 inch long and 0.5 inches wide.
The sympathetic innervation for the head and neck regions originates from the thoracic region (T1-6) and ascends to reach the structures in the head and neck.
- Level: C7 vertebra
- Posterior: Transverse process of C7 and the neck of the first rib
- Inferior: Cervical pleura
- Superior: Subclavian artery
- Anterior: Prevertebral lamina of the cervical fascia common carotid artery, subclavian artery, proximal vertebral artery.
Sympathetic chain & ganglia
The sympathetic fibers leave the spinal cord and enter the sympathetic chain where they form ganglia, and extend from the base of the skull to the coccyx. These presynaptic sympathetic fibres synapse in these ganglia, and the postsynaptic branches course along the branches of the arteries associated with each of these ganglia and innervate the head and neck structures.
There are three main cervical ganglia related to specific arteries: the superior, middle and inferior cervical ganglia. In some cases, the middle cervical ganglion is often absent and the inferior cervical ganglion is often fused with the first thoracic ganglion, forming the cervicothoracic ganglion. In other cases, the superior and middle cervical ganglia are connected together.
Superior Cervical Ganglion:
The superior cervical ganglion is located posterior to the carotid artery, and anterior to the C1-4 vertebrae. The post-ganglionic nerves originating from here include:
- Internal carotid nerve – courses along the internal carotid artery, The internal carotid plexus gives off branches that innervate structures in the eye, the pterygopalatine artery, and the internal carotid artery.
External carotid nerve – courses along the common and external carotid arteries and innervates them.
- Pharyngeal plexus – receives branches from the superior cervical ganglion, vagus, and glossopharyngeal nerves.
- Superior cardiac branch – contributes to the cardiac plexus in the thorax.
- Nerves to cranial nerves II, III IV, VI and IX.
- Gray rami communicantes – distributes sympathetic fibres to the anterior rami of C1-C4.
Middle Cervical Ganglion:
Often absent but when present, it is located anteriorly to the inferior thyroid artery and the C6 vertebra. Its postganglionic fibres are:
- Gray rami communicantes – distributes sympathetic fibres to the anterior rami of C5 and C6.
- Thyroid branches – courses along the inferior thyroid artery, innervating the larynx, trachea, pharynx and upper oesophagus.
- Middle cardiac branch – contributes to the cardiac plexus in the thorax.
Inferior Cervical Ganglion:
It is situated anteriorly to the C7 vertebra. In some cases, it is fused with the first thoracic vertebrae, forming the cervicothoracic ganglion. Its post-ganglionic fibres include:
- Gray rami communicantes – distributes sympathetic fibres to the anterior rami of C7, C8, and T1.
- Branches to the subclavian and vertebral arteries
- Inferior cardiac nerve – contributes to the cardiac plexus in the thorax.