Prevertebral Muscles

Prevertebral Muscles

1. Anterior Vertebral Muscles

   • Lie directly posterior to the retropharyngeal space and medial to the neuromuscular plane of the cervical and brachial plexuses and subclavian artery.
     • • Longus Colli
         • Origin: Anterior tubercle of C1 vertebra (atlas); bodies of C1-C3 and transverse processes of C3-C6 vertebrae
           • Insertion: Bodies of C5-T3 vertebrae; transverse processes of C3-C5
             • Action: Flexes neck with rotation (torsion) to opposite side if acting unilaterally
               • Nerve; Anterior rami of C2-C6 spinal nerves
       • Longus Capitis
         • Origin: Basilar part of occipital bone
           • Insertion: Anterior tubercles of C3-C6 transverse processes
             • Action: Flex head
               • Nerve: Anterior rami of C1-C3 spinal nerves
     • • Rectus Capitis Anterior
         • Origin: Base of cranium, just anterior to occipital condyle
           • Insertion: Anterior surface of lateral mass of atlas (C1 vertebra)
             • Action: Flex head
               • Nerve: Branches from loop between C1 and C2 spinal nerves
     • • Anterior Scalenes
         • Origin: Transverse processes of C3-C6 vertebrae
           • Insertion: 1st rib
             • Action: Flex head
               • Nerve: Cervical spinal nerves C4-C6

2. Lateral Vertebral Muscles

   • Lie posterior to the neurovascular plane and all of them except for rectus capitis lateralis form the floor of the lateral cervical region.
     • • Rectus Capitis Lateralis
         • Origin: Jugular process of occipital bone
           • Insertion: Transverse process of atlas (C1 vertebra)
             • Action: Flexes head and helps stabilize it
               • Nerve: Branches from loop between C1 and C2 spinal nerves
     • • Splenius Capitis
         • Origin: inferior half of nuchal ligament and spinous processes of superior six thoracic vertebrae
           • Insertion: Lateral aspect of mastoid process and lateral third of superior nuchal line
             • Action: Laterally flexes and rotates head and neck to same side
               • Nerve: Posterior rami of middle cervical spinal nerves
       • Levator Scapulae
         • Origin: Posterior tubercles of transverse processes C2-C6 vertebrae
           • Insertion: Superior part of medial border of scapula
             • Action: Downward rotation of scapula and tilts its glenoid cavity inferiorly by rotating scapula
     • • Middle Scalenes
         • Origin: Posterior tubercles of transverse processes of C5-C7 vertebrae
           • Insertion: Superior surface of 1st rib; posterior to groove for subclavian artery
             • Action: Flexes neck laterally; elevates 1st rib during forced inspiration
               • Nerve: Anterior rami of cervical spinal nerves
       • Posterior Scalenes
         • Origin: Posterior tubercles of transverse processes of C5-C7 vertebrae
           • Insertion: External border of 2nd rib
             • Action: Flexes neck laterally; elevates 2nd rib during forced inspiration
               • Nerve: Anterior rami of cervical spinal nerves C7 and C8

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