Sternomastoid Region and Posterior Triangle of Neck

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Sternomastoid Region and Posterior Triangle of
Neck
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• The anterior and posterior cervical triangles are
  interconnected through the substernomastoid
  space. This space includes the following
  structures
• deep cervical lymph nodes
• digastric node
• omohyoid node
• ansa cervicalis (ac)
• carotid sheath (cs)
• internal jugular vein and tributaries(ij)
• common carotid artery and its (cc) bifurcation
• external carotid artery
• occipital branch (oc)
• internal carotid artery
• vagus nerve (v)

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• Boundaries of Posterior Triangle
• anterior--sternomastoid
• posterior--trapezius
• inferior--middle third of clavicle

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• Roof of Posterior Triangle
• skin
• superficial fascia
• platysma inferiorly

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• Structures Superficial to Sternomastoid
• external jugular vein (blue)
• superficial cervical lymph nodes (green)
• lesser occipital nerve (lc)
• great auricular nerve (ga)
• transverse cervical nerve (tc)
• supraclavicular nerves (sc)
• spinal accessory nerve (sa)

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• Muscles of the Floor of the Posterior Triangle
• splenius capitis (sc)
• levator scapulae (ls)
• scalenus posterior (sp)
• scalenus medius (sm)
• scalenus anterior (sa)
• inferior belly of omohyoid (io)

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• Structures Near the Root of the Neck
• brachial plexus (bp)
• subclavian artery (sca)
• subclavian vein (sv)
• Note the brachial plexus and subclavian artery
  pass between the scalenus anterior (sa) and
  medius (sm) muscles. The subclavian vein passes
  anterior to the scalenus anterior muscle.

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• Other Structures in Posterior Triangle
• spinal accessory (sa)
• brachial plexus (bp)
• transverse cervical artery (tc)
• suprascapular artery (ss)

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Table of Muscles