Triangles of the

Neck

Sanjaya AdikariDepartment of Anatomy

Boundaries of the neck

Spinous process of C7

Acromian

Compartments of the neck

Neck has 4 major compartments

• Vertebral compartment

– Cervical vertebrae and associated muscles

• Visceral compartment

– Parts of respiratory and digestive tracts, important glands (thyroid, parathyroid and thymus)

• Two vascular compartments

– Contains major blood vessels and vagus nerve

Compartments of the neck

Cervical fascia

SuperficialContains platysma muscle, cutaneous nerves, superficial veins and superficial LNs

Deep

Deep cervical fascia

Consists of 4 parts

• Investing layer

– Encircles the neck completely

• Pretrachial fascia

– Encircles the visceral compartment

• Prevertebral fascia

– Encircles the vertebral compartment

• Carotid sheaths

– Enclose the two vascular compartments

Clavicle

Manubrium

Acromian & spine

L. nuchae

E.O. protuberance & s. nuchal line

Investing layer• Splits to

enclose the

parotid gl.

• Superficial

layer forms

parotid

fascia &

attached to

zygomatic

arch

MandibleMastoid p.

Clavicle

Manubrium

Acromian & spine

L. nuchae

E.O. protuberance & s. nuchal line

Investing layer

MandibleMastoid p.

Stylomandibular ligament

• Deep layer forms stylomandibular ligament between styloid process & angle of mandible

Prevertebral fascia

• Lies in front of prevertebral muscles

• Extends from skull base to T4 body getting attached to anterior longitudinal ligament

• Extends around the subclavian artery and brachial plexus and becomes axillary sheath

• Phrenic nerve lies behind

• Sympathetic trunk lies in front

• Cutaneus branches of Cx plexus pierce it

Pretrachial fascia

Carotid sheath

Anterior

Vagus nerve

Triangles of the neck

Posterior triangle - contents• External jugular

vein after piercing the investing layer.

• Accessory nerve

• Branches of Cx plexus– Lesser occipital

– Great auricular

– Transverse cervical

– Supraclavicular

Floor of the posterior triangle

• Prevertebral

fascia lying on

the muscles

• Semispinalis

capitis

• Splenius

capitis

• Levator

scapulae

• Scalenus

medius

• Scalenus

anterior

Anterior triangles of the neck

Anterior triangle of the neck

• Suprahyoid muscles

– Digastric: poterior belly by facial N. & anterior

belly by nerve to mylohyoid

– Stylohyoid: by facial nerve

– Mylohyoid: by nerve to mylohyoid, a branch of

inferior alveolar nerve (mandibular division)

– Geniohyoid: by C1 through hypoglossal nerve

Anterior triangle….

• Infrahyoid muscles

– Sternohyoid

– Omohyoid

– Thyrohyoid

– Sternothyroid

These are depressors of the larynx. Supplied by

ansa cervicalis (C1-C3)

Carotid triangle

• Tip of the greater horn of hyoid is an important reference point

• Note the relationships of hypoglossal nerve

Root of the neck

• All structures

that pass

between the

head and

thorax or upper

limb and thorax

must pass

through the

root of the neck

Subclavian Artery

• 1st part of subclavian artery– Vetebral A– Internal thoracic

A– Thyrocervical

trunk• 2nd part of

subclavian artery– Costocervical

trunk• 3rd part of

subclavian artery– Dorsal scapular

A

Thoracic duct in the neck

• Join the

junction

between the

left

subclavian

and internal

jugular veins