Posterior Triangle Of Neck

Posterior Triangle Of Neck


TRIANGLES OF NECK

  • Anterolateral aspect (side) of neck is divided by sternocleidomastoid muscle into anterior triangle in front of the muscle & posterior triangle, behind the muscle.

POSTERIOR TRIANGLE OF NECK

  • Posterior triangle is situated behind sternocleidomastoid muscle.
  • Anterior border is formed by posterior border of sternocleidomastoid.
  • Posterior border is formed by anterior margin of trapezius.
  • Base is formed by superior surface of middle third of clavicle.
  • Apex lies on superior nuchal line at junction of trapezius & sternocleidomastoid.
  • Roof is formed by investing layer of deep cervical fascia, skin & superficial fascia.
  • Floor is formed by prevertebral layer of deep cervical fascia covering following muscles: splenius capitis, levator scapulae, scalenus medius & semispinalis capitis.
  • Posterior triangle is subdivided into an larger upper occipital triangle & smaller lower supraclavicular (subclavian) triangle by inferior belly of omohyoid.

CONTENTS OF THE POSTERIOR TRIANGLE

CONTENTS

OCCIPITAL TRIANGLE

SUBCLAVIAN TRIANGLE

NERVES

  1. Spinal accessory nerve

  2. Four cutaneous branches of cervical plexus:

  • Lesser Occipital (C2)
  • Great auricular (C2, C3)
  • Anterior cutaneous nerve of neck (C2, C3)
  • Supraclavicular nerves (C3, C4)

  3. Muscular branches

  • Two small branches to the levator scapulae (C3, C4)
  • Two small branches to the trapezius (C3, C4)
  • Nerve to rhomboideus (proprioceptive) (C5)

  4. C5, C6 roots of the brachial plexus

  1. Three trunks of brachial plexus
  2. Nerve to serratus anterior (long thoracic C5, C6, C7)
  3. Nerve to subclavius (C5,C6)
  4. Suprascapular nerve (C5,C6)

VESSELS

  1. Transverse cervical artery & vein
  2. Occipital artery
  1. Third part of subclavian artery & subclavian vein
  2. Suprascapular ratery & vein
  3. Lower part of external jugular vein

LYMPH NODES

  • Along the posterior border of the sternocleidomastoid nodes more in the lower part-the supraclavicular nodes & a few at the upper angle- the occipital nodes.
  • A few members of the supraclavicular chain.
 Spinal accessory nerve (XI cranial nerve) runs along the levator scapulae to supply trapezius.
  • Because it lies close to the roof, the nerve may be damaged by a lacerating injury or during incision & drainage of abscess in posterior triangle causing paralysis of trapezius which results in drooping of shoulder & difficulty in overhead abduction & diffficulty in shrugging of shoulder.
SUBOCCIPITAL TRIANGLE
  • Lies more deeply in upper part of back of neck just below the occipital bone.
  • It is bounded by:
  1. Superomedially: rectus capitis posterior major & minor
  2. Superolaterally: Obliques capitis superior
  3. Inferolaterally: Obliques capitis inferior
  • Floor is formed by posterior atlantooccipital membrane & posterior arch of atlas.
  • Its contents are:
  1. 3rd part of vertebral artery
  2. suboccipital nerve (dorsal ramus of C1)
  3. Suboccipital venous plexus.
Exam Question
 
  • The omohyoid muscle is an important landmark in both the anterior and posterior triangles of the neck.
  • Base of the posterior triangle of neck is formed by superior surface of middle third of clavicle.
  • Superficial incision on posterior triangle of neck leads to difficulty in shrugging of shoulder.
  • Contents of Suboccipital triangle are:
  1. 3rd part of vertebral artery
  2. suboccipital nerve (dorsal ramus of C1)
  3. Suboccipital venous plexus.
Don’t Forget to Solve all the previous Year Question asked on Posterior Triangle Of Neck

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