Prevertebral Neck Muscles: Rectus Capitis

Prevertebral Muscles of the Neck

• These muscles are relatively weak flexors.
• Located in front of the vertebral column, extending from the skull to the superior mediastinum
• Covered anteriorly by the strong prevertebral fascia
• This fascia provides a slippery surface, allowing the pharynx and esophagus to glide freely during neck movements and swallowing.

Rectus Capitis Anterior

• Extends from the lateral mass of the atlas to the front of the foramen magnum.
• Supplied by the anterior ramus of C1 as it passes forward lateral to the atlanto-occipital joint.
• Assists in flexion and lateral flexion of the head.

Rectus Capitis Lateralis

• Lies edge to edge with the rectus capitis anterior.
• Extends from the lateral mass of the atlas to the jugular process of the occipital bone.
• Supplied by the anterior ramus of C1 as it passes forward lateral to the atlanto-occipital joint.
• Assists in flexion and lateral flexion of the head.

Longus Capitis

• Attaches via four slender tendons to the anterior tubercles of cervical vertebrae C3-C6, aligning with the tendons of the scalenus anterior.
• Inserts into the basiocciput, with the two muscles lying side by side in front of the foramen magnum near the pharyngeal tubercle.
• These muscles bulge slightly into the upper part of the nasopharynx.
• Segmentally supplied by anterior rami of the upper four cervical nerves.
• Function: flexes the skull and upper neck, but weakly due to assistance from gravity and the sternocleidomastoids.

Longus Colli

• Extends from the anterior tubercle of the atlas into the superior mediastinum.
• Consists of upper, lower, and central fibers.
• Upper fibers connect the anterior tubercle of the atlas to the anterior tubercles of the transverse processes of C3-C5 vertebrae.
• Lower fibers connect the bodies of T1-T3 vertebrae with the anterior tubercles on the transverse processes of C5 and C6 vertebrae.
• The lateral border of the lower part, along with the medial border of scalenus anterior, forms a pyramidal space with the carotid tubercle (of Chassaignac) at its apex and the first part of the subclavian artery at its base.
• The vertebral artery and cervical sympathetic trunk (including the stellate ganglion) lie within this space.
• Central fibers connect the bodies of C2-C4 vertebrae with the remaining cervical and upper three thoracic vertebrae.
• Segmentally supplied by anterior rami of the spinal nerves.
• Functions as a flexor of the neck, but its action is weak due to assistance from gravity and the sternocleidomastoids.

Cervical Sympathetic Trunk

• Ascends from the thorax across the neck of the first rib, medial to the highest intercostal vein.
• Runs medial to the vertebral artery and lies in front of the prevertebral fascia, attached by loose areolar tissue.
• Ends at the superior cervical ganglion.
• Located behind the carotid sheath, just medial to the vagus nerve.

Superior Cervical Ganglion

• Contains about 1 million cell bodies.
• Approximately 3 cm long, lying in front of the lateral mass of the atlas and axis.

Middle Cervical Ganglion

• A small and inconstant ganglion.
• Lies on the trunk medial to the carotid tubercle (C6 vertebra) and in front of the vertebral artery.

Inferior Cervical Ganglion

• Located behind the commencement of the vertebral artery.
• Often fused with the first thoracic ganglion to form the stellate ganglion (cervicothoracic ganglion)
• May measure up to 1 cm by 0.5 cm.
• Lies in front of the neck of the first rib.
• The ansa subclavia connects the middle ganglion to the inferior ganglion (or stellate ganglion), passing in front of the subclavian artery.

Ganglia Branches

• No white rami enter the ganglia from the cervical nerves; all fibers ascend from the thoracic part of the trunk.
• Branches are somatically and viscerally distributed.
• Somatic branches: grey rami pass to all eight cervical nerves
• The superior ganglion sends grey rami to the first four cervical nerves (cervical plexus).
• The middle ganglion sends grey rami to the next two cervical nerves (C5 and C6).
• The inferior ganglion sends grey rami to the last two cervical nerves (C7 and C8) which supply the brachial plexus for distribution in the upper limb.

Visceral Branches

• A branch from each ganglion goes to the cardiac plexus.
• The branch from the upper left ganglion runs to the superficial part, while the other two left and all three right ganglionic branches go to the deep part.
• All six cardiac branches pass through the neck behind the common carotid artery and usually the subclavian artery, reaching the superior mediastinum.

Vascular Branches

• The superior ganglion gives branches to the internal and external carotid arteries.
• The internal carotid nerve accompanies the internal carotid artery into the skull.
• Fibers forming the internal carotid plexus are distributed to the pterygopalatine ganglion and the eyeball, including the motor supply of the dilator pupillae of the iris.
• The plexus on the external carotid artery accompanies all branches of the vessel and supplies sympathetic fibers to the pharyngeal plexus, submandibular, and otic ganglia.

Arterial Sympathetic Supply

• The middle cervical ganglion gives branches to the subclavian and inferior thyroid arteries.
• The latter supplies the lower larynx, trachea, hypopharynx, and upper esophagus (visceral only).
• The inferior cervical ganglion gives a large branch to the vertebral artery (vertebral plexus), which runs with all its branches but supplies NO viscera.
• Interruption of the cervical sympathetic pathway leads to Horner's syndrome.

Overview of prevertebral neck muscles including rectus capitis anterior, rectus capitis lateralis and longus capitis. These muscles, located in front of the vertebral column, aid in flexion and lateral flexion of the head. They are covered by prevertebral fascia, facilitating smooth movement during neck motions and swallowing.