A plexus is an axon network of the anterior rami of nerves from different spinal regions, except for thoracic nerves T2 to T12, which form the intercostal nerves.
The first four and partly the fifth cervical spinal nerves in the neck region form the cervical plexus. It innervates the skin and muscles in the head, neck, and shoulders.
The phrenic nerve is a crucial motor nerve of the cervical plexus. It innervates the diaphragm, controlling the breathing movements.
The other two motor nerves in the cervical plexus are the ansa cervicalis, and segmental branches.
Additionally, the cervical plexus has four sensory nerves — the lesser occipital, great auricular, transverse cervical, and supraclavicular.
The brachial plexus is situated partially in the neck and axilla. This provides nerve supply to the shoulder and upper limbs.
The brachial plexus mainly arises from the fifth to eighth cervical nerves and the first thoracic nerve.
Of these brachial nerves, the axillary, musculocutaneous, radial, median, and ulnar are the five significant nerves responsible for most of the shoulder, hand, and finger movements.
Nerve plexuses are networks of interlacing nerves that serve as communication hubs to distribute and organize nerve action across various body regions. The nerve plexuses are organized into the cervical plexus located in the neck region, brachial plexus in the shoulder area, lumbar plexus found in the lower back, sacral plexus situated in the pelvis, and coccygeal plexus located in the coccygeal region.
The Cervical Plexus
The cervical plexus, formed by the anterior rami of the first four cervical spinal nerves (C1-C4), and partially the fifth cervical spinal nerve (C5), is situated in the neck region. This plexus innervates the skin and muscles of the head, neck, and shoulders, facilitating both sensory and motor functions.
Other motor components of the cervical plexus include the ansa cervicalis and segmental branches. The ansa cervicalis innervates some infrahyoid muscles, aiding in swallowing and speech. The segmental branches supply motor fibers to the deep muscles of the neck, contributing to the stability and movement of the head.
The Brachial Plexus
The brachial plexus extends from the neck into the axilla and is formed by the anterior rami of the fifth to eighth cervical nerves (C5-C8) and the first thoracic nerve (T1). This plexus supplies the shoulder and upper limbs, orchestrating a wide range of movements and sensory functions. The brachial plexus gives rise to five significant nerves: