Posterior Triangle of Neck

Dr. Skantha KandiahMBA, MSc (NUI),

MB BCh BAO (NUI), LRCP & SISenior Lecturer in Anatomy and Lecturer in Healthcare

ManagementRCSI

Posterior Triangle

Posterior Triangle

• Base: Middle 1/3 of the clavicle

• Roof: Investing layer of deep cervical fascia

• Floor: prevertebral fascia lying on splenius, levator scapulae and scalenus medius

Contents

• Upper trunk of Brachial Plexus• Apex of the lung extends to 2cm above the

middle 1/3 of the clavicle• Lymph nodes• Subclavian artery – at root of neck• Subclavian vein – at root of neck• External Jugular Vein• Spinal part of XI

External Jugular Vein

XI

• Accessory nerve

• Spinal and Cranial parts

• Spinal part accessory nerve – superficial structure in posterior triangle

• 1/3 down the posterior border of SCM to 2/3 down the anterior border of trapezius

XI

XI

• SCM

• Trapezius

• How do you test above muscles?

• Spinal and cranial parts

Other Nerves…..

Cervical Plexus: Muscular Branches

• Anterior primary rami of the upper cervical nerves form the cervical plexus

• ansa cervicalis: C1,2,3 and XII (descendens hypoglossi)

• Ansa cervicalis supplies the strap muscles

• Phrenic nerve: C3,4,5

Cervical Plexus: Cutaneous Branches

• Lesser occipital C2: upper triangle, behind ear

• Great Auricular C2,3: skin over parotid

• Transverse Cervical C2,3: chin to sternum

• Supraclavicular C3,4

Stab Wound to Posterior Triangle

• Upper trunk brachial plexus injury

• What is it called?

• Apex of the lung is here, so what might happen?

• Bleeding from?

Sample Question

• Describe the boundaries and contents of the posterior triangle of the neck. Explain the consequences of a stab injury to the posterior triangle. Give surface markings of any important structures you name.