Posterior triangle of neck

Clinical importanceContent

Boundaries

P.T.N.

Topic to be

discuss today

introduction

References

Introduction• The posterior triangle of the

neck is an area of the body frequently visited by regional anesthesiologists, acute and chronic pain physicians, surgeons of all disciplines, and diagnosticians.

• lateral aspect of the neck in direct continuity with the upper limb.

• It has two division-• 1. occipital triangle• 2. supraclaviular triangle

boundaries

Muscles forming floor and border of P.T.N.

Content Arteries in P.T.N.

Arteries

External Jugular vein

Nerve

• A variety of nerves pass through or are within the posterior triangle. These include the accessory nerve [XI],

• branches of the cervical plexus, • components forming the brachial plexus,

Cervical plexus

Skin over manubrium

Skin over upper half of deltoid muscle

Intercostal space till first rib

Skin of neck till first rib Largest ascending br. Skin over pinna, parotid gl.

Medial part of pinna up to scalp

• Muscular branches of cervical plexus– Are given off segmentally to

prevertebral vessels (longus capitis, longus colli and scalenes)

– The fibres from the branch of C1 are carried to superior root of ansa cervicalis and nerves to thyrohyoid and geniohyoid

– Branches from C2 and C3 are to the sternocleidomastoid, while branches from C3 and C4 are to the trapezius

– The inferior root of ansa cervicalis is formed by union of a branch each from C2 and C3

Brachial plexus

• The trunks cross the base of the posterior triangle.

• Several branches of the brachial plexus may be visible in the posterior triangle.

• These include the: • dorsal scapular nerve to the

rhomboid muscles; • long thoracic nerve to the

serratus anterior muscle;• nerve to the subclavius muscle; • suprascapular nerve to the

supraspinatus and infraspinatus muscles.

• Right EJV is examined to access the venous pressure.

• Most common swelling in the p.t.n. is due to enlargement of supraclavicular lymph node. While doing biopsy of the lymph node one must careful in preserving the accessory nerve which may get entangled with the lymph node.

Applied aspect

• Supraclavicular lymph node are commonly enlarged in tuberculosis, Hodgkin’s disease and in malignant growth of breast chest and arm.

• Block dissection of the neck for malignant disease is the removal of cervical lymph node along with other structure involved in the growth. This procedure doesnot endanger those nerve of the p.t. which lie deep to the prevertebral fascia.

• Cervical Rib may compress the subclavian artery. In these cases the radial pulse is diminished or obliterated on turning the patients head upwards and to the affected side after a deep breath (ADSON’S TEST).

• Dysphasia lusoria- is caused by compression of the oesophagus by an abnormal subclavian artery.

• Second part of the subclavian artery may get pressed by the scalenus anterior muscle, resulting in decreased blood supply to the upper limb.

• Selective neck dissection for posterior scalp and upper posterolateral neck cutaneous malignancies: selective neck dissection II-V, postauricular, suboccipital, or posterolateral neck dissection.

• Level V– Refers to posterior triangle

group of nodes– Drains the other lymphatic

regions in the neck– Level Va:

• Superior to inf belly of omohyoid

• Contains the chain of nodes along the accessory nerve, which drain the nasopharynx

– Level Vb:• Inferior to inf belly of

omohyoid• Contains nodes related to the

thyrocervical trunk which drains the thyroid gland

Scalena Anticus Syndrome: Within the posterior triangle of neck, the subclavian artery and the branchial plexus are found between the sclaneous

anterior and scalenus medius muscles. If the interval between these muscles is narrowed, the plexus and artery gets compressed – thoracic inlet syndrome or scalene anticus syndrome.

This results in pain along the upper limb especially along the medial border of the upper limb and muscle atrophy may be found. Subclavian artery compression causes ischemia of upper limb.

Erb’s Point

C5 root, C6 root, nerve to subclavius and suprascapular nerve

meet at a point – Erb’s point. Injury to this point is Erb’s paralysis or upper arm type of brachial plexus injury in the upper trunk.

S/s paralysis of deltoid, biceps brachii, brachialis and

brachioradialis. The arm is adducted, forearm is pronated, fingers

are flexed – PORTER RECEVING TIPS POSITION.

Suprasternal Space

Along the lower part of the root of post triangle the fascia splits to

enclose the space, supraclavicular space.

This space encloses external jugular vein, supraclavicular nerves,

lymphatic. Near the lower part of midline of neck, the fascia splits

to enclose a space called SUPRASTERNAL SPACE (SPACE OF BURNS).

Jugular Venous Pressure

External jugular vein is examined to assess the venous pressure, the atrial pressure is reflected because there are no valves in the entire course. Normally the veins may be full on lying down but they collapse on reclining at 45 degrees. If they remain full even at 45 degrees and erect posture, it suggests increased venous pressure which is commonly observed in congestive cardiac failure and cardiac tamponade.

Cervical Masses

LATERAL NECK MASSES: Branchial cleft anomalies Cystic hygroma Hemangioma Lipoma Neurilemmoma Carotid body tumor Salivary gland (parotid) - Adenoma - Warthin tumor Others - Thyroid or parathyroid - Adenoma - Sebaceous cysts - Myomas

References

• Hollinshead book for head and neck anatomy 2nd edition

• Grays anatomy for dental student.• Human anatomy by b.d.chaurasia.• Applied sonoanatomy of the posterior

triangle of the neck Int J Shoulder Surg. 2010 Jul-Sep; 4(3): 63–74.

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