Transcript Document
Posterior Triangle Nainika Menon Borders • Anterior: sternocleidomastoid mm (SCM) – posterior border • Posterior: trapezius mm – anterior border • Base: Middle 1/3 clavicle • Apex: Superior nuchal line (occipital bone) • Roof: Investing layer of fascia • Floor (sup inf): splenius capitis, levator scapulae, posterior/middle/anterior scalene mm (all covered by prevertebral layer of fascia) POSTERIOR TRIANGLE Occipital Triangle Inferior belly of omohyoid Omoclavicular Triangle - (Part of) external jugular vv - Posterior branches (cutaneous) of cervical plexus - 3rd part of subclavian aa - Spinal accessory nn (CN 11) - Part of subclavian vv - Brachial plexus (trunks) - Suprascapular aa - Cervicodorsal trunk - Supraclavicular lymph nodes - Cervical lymph nodes External Jugular vv • Superficial • Retromandibular vv (posterior branch) + Posterior auricular vv = external jugular vv (angle of mandible) • Drains into subclavian vv (not to be confused with: IJV + subclavian vv --> brachiocephalic vv) Spinal Accessory nn (CN 11) • Deep to SCM across posterior triangle over levator scapulae deep to trapezius • Clinical note: can be damaged – Difficulty turning head to side (with resistance) SCM – Shoulders droop/cannot raise and retract shoulder/cannot raise arm above horizontal Trapezius Trapezius • Origin: superior nuchal line/external occipital protuberance + ligamentum nuchae + vertebrae C7-T12 (spinous processes) • Insertion: lateral 1/3 clavicle + acromion + spine of scapula • Innervation: CN 11 • Action: – Superior part (descending) – maintains shoulders – Middle part – retraction of scapula – Inferior part (ascending) – lowers shoulders – Bilaterally extension of neck – Unilaterally lateral flexion to the side that is contracting – General: elevation, retraction, rotation of scapula Arteries • Subclavian aa thyrocervical trunk (2nd branch) cervicodorsal trunk (aka transverse cervical aa) • Cervicodorsal trunk/subclavian aa suprascapular aa • 3rd part of subclavian aa (blood supply to upper limb) – subclavian vv is anteroinferior 0 Lymphatics • Superficial regions of neck superficial cervical lymph nodes inferior deep cervical lymph nodes supraclavicular lymph nodes • Deep cervical lymph nodes run along IJV Cutaneous Branches of Cervical Plexus • Lesser occipital nn (C2) • Great auricular nn (C2,3) • Transverse cervical nn (C2,3) • Supraclavicular nn (C3,4) Thank You! References • Information from: MOORE, Keith L., Anne AGUR, Arthur DALLEY. Essential Clinical Anatomy. 4th ed. Baltimore: Lippincott Williams & Wilkins, 2011 DRAKE, Richard L., A. Wayne VOGL, Adam W. M. MITCHELL. Gray’s Anatomy for Students. 2nd ed. Philadelphia: Churchill Livingstone, 2010 • Images from: DRAKE, Richard L., A. Wayne VOGL, Adam W. M. MITCHELL. Gray’s Anatomy for Students. 2nd ed. Philadelphia: Churchill Livingstone, 2010