Triangles Of The Neck

Divisions Created By Muscles

Presented By,Arya V Devi

Introduction

It is limited

•This quadrilateral space is divided by the Sternocleidomastoid muscle into two main triangles

•The Sternocleidomastoid muscle passes obliquely upwards and backwards from its site of origin at the clavicle and sternum to its point of insertion on the mastoid process and the occipital bone

•The triangle in front of this muscle is the anterior triangle and the one behind it is the posterior triangle

Anterior TriangleBoundari

esAnterior border of the

SCM muscle

Midline of the neck

Inferior border of the mandible

RoofSkin

Superfacial fascia

Platysma muscle

Investing layer of deep cervical fascia

Posterior triangle

Boundaries

Anteriorly: The Sternocleidomastoid

musc

posteriorly:The Trapezius muscle.

Inferiorly:The Clavicle

The apex: occipital bone

Roof

Skin

Superficial fascia

Platysma muscle

Investing layer of the deep cervical fascia

Floor

Splenius Capitis

Levator scapulae

Posterior scalene

Middle scalene

Anterior scalene

Subdivisions

Anterior Triangle•Digastric/submandibular

•Submental •Muscular •Carotid triangles

Posterior Triangle• Occipital triangle• Subclavian triangle

Anterior Triangle

Contents Of The Anterior Triangle

Vessels• Carotid system• Internal jugular

vein

Nerves• Cranial nerves

7,9,10,11,12• Cervical plexus

Muscles• Suprahyoid

muscles: (digastric , mylohyoid,stylohyoid,geniohyoid )

• Infrahyoid muscles: (sternohyoid,sternothyroid,thyrohyoid, omohyoid )

Submandibular Triangle

Submandibular Triangle

Superiorly•Mastoid & mandiblePosteriorly •Stylohyoid•Posterior belly of digastric

Anteriorly•Anterior belly of digastric

Submandibular Triangle

Roof•Platysma •Facial vein (fv) •Cervical branch of facial nerve (cbf)

Removal of the superficial structures displays the submandibular salivary gland itself.

Contents Of The Submandibular Triangle

Facial

artery

Lingual

nerve

and submandibul

ar ganglion

•The lingual nerve and submandibular duct pass through a gap between the hypoglossal (hg) and mylohyoid (mh) muscles

Submandibul

ar duct Ling

ual arter

y

• The lingual artery passes deep to the hyoglossus muscle

Hypogloss

al nerv

e

Submental TriangleUnpaired triangle

Submental Triangle

Formed by the :Anterior midline of

neckHyoid bone

Anterior belly of digastric muscle

Located between the two anterior

digastric muscles

Structures Submental lymph node-

drain the floor of the mouth.

Mylohyoid muscle (mh) arise from the body of

the hyoid bone and insert into the

mylohyoid line of the inside of the mandible.

Carotid Triangle

Carotid Triangle

Boundaries of the carotid triangle are:

posterior belly of digastric muscle (pbd) superior belly of the omohyoid muscle (so)

anterior border of sternomastoid muscle (st)

Roof: skin

superficial fascia platysma

Carotid TriangleDeepest aspect of the carotid triangle

The muscles, at this level, are the middle and lower pharyngeal constrictors

Floor

Superior laryngeal nerve, a branch of the vagus its 2 terminal branches

Internal laryngeal (ilb--sensory to upper part of the larynx)

External laryngeal (elb--motor to the cricoid muscle)

Structures seen passing through

Contents Of Carotid Triangle

Veins• Common facial

vein • Near by:

• Retromandibular vein

• Posterior auricular vein (pav)

• Facial vein (fv)

• External jugular vein

• Anterior jugular vein

Arteries• Facial• Lingual• Occipital• Common carotid• External carotid• Internal carotid• Superior thyroid

Nerves• Hypoglossal (XII) • C1 root of ansa

cervicalis (C1) • C1 fibers running

with hypoglossal nerve (nerve to thyrohyoid muscle (nth)

• C2-C3 root of ansa cervicalis

• Ansa cervicalis (ac)

Muscular Triangle

Muscular TriangleBoundaries•Mid line of neck •Superior belly of omohyoid •Sternomastoid

The muscles forming and within the triangle•Superficial layer •Sternohyoid (sh) •Superior belly of omohyoid (oh) •Deep layer •Thyroid (th) •Sternothyroid (st)

Strap Muscles

Muscular Triangle

When the strap muscles are reflected, you can see the

thyroid gland with its arteries (superior and inferior thyroid artery)

If the thyroid gland is reflected laterally, the

structures making up the larynx and trachea are seen: thyrohyoid membrane (thm)

thyroid cartilage (Adam's apple)(tc)

cricothyroid membrane and ligament (ctm)

cricoid cartilage (cc) tracheal rings (tr)

Table of MusclesMuscle Origin Insertion Nerve supply

Sternohyoid Sternum Hyoid Ansa

Omohyoid Suprascapular notch Hyoid Ansa

Sternothyroid Below sternohyoid on manubrium

Thyroid cartilage oblique line Ansa

Thyrohyoid Thyroid cartilage oblique line Hyoid C1-C2 (ansa)

Anterior belly digastric Intermediate tendon Inner surface of mandile Trigeminal nerve

Posterior bellyDigastric

Medial aspect of the mastoid process -Intermediate tendon- Facial nerve

Mylohyoid Mylohyoid line of mandible Hyoid bone Trigeminal nerve

Hyoglossus Hyoid bone Lateral side of tongue Hypoglossal

Stylohyoid Styloid process Hyoid Facial nerve

Clinical Considerations

The cricothyroid ligament and membrane are frequently pierced in emergency situations to open the airway.

It has been known that an empty ball-point pen or a hollow stem has been used in the field to save lives, where an air passage has been closed above this region.

Posterior Triangle

Boundaries of Posterior Triangle

Boundaries of Posterior Triangle

Anteriorly •Sternocleidomastoid

Posteriorly •Anterior edge of trapezius

Inferiorly •Middle third of the clavicle

Apex •Between the attachments of sternocleidomastoid and trapezius to the occiput and is often blunted, so that the 'triangle' becomes quadrilateral

Roof •Investing layer of the deep cervical fascia

Floor •Prevertebral fascia overlying splenius capitis, levator scapulae and the scalene muscles

Nerves And Plexuses• Spinal

acessory nerve.

• Branches of Cervical plexus

• Roots and trunks of brachial plexus

Vessels• Subclavian

artery• Transverse

Cervical artery

• Suprascapular artery

• External jugular vein (terminal part)

Lymph Nodes• Occipital• Supraclavi

cular

Muscles• Inferior

belly of Omohyoid muscle

Contents of the posterior triangle

Clinical Significance Of The Posterior Triangle

The Accessory Nerve may be damaged, while taking lymph node biopsy.

The External Jugular Vein is present in a superficial location here and this makes it vulnerable to injury.

Lower and smaller division of the posterior triangle

It corresponds in the living neck with the lower part of a deep, prominent hollow, namely, the greater supraclavicular fossa

Its size varies with the extent of the clavicular attachments of sternocleidomastoid and trapezius and also the level of the inferior belly of omohyoid

Subclavian Triangle

BoundariesBorders•It shares the same boundaries• Except that superiorly it is limited by omohyoid

Floor•The first rib, •Scalenus medius•The first slip of serratus anterior

Roof•Supraclavicular nerves•Platysma•Superficial and deep fasciae•Skin

Contents

The suprascapular

vesselsBrachial plexus Third part of the

subclavian artery

Subclavian veins

The external jugular vein

The nerve to subclavius

The triangle contains some lymph nodes.

Occipital triangleUpper and larger part of the posterior

triangle

BoundariesShares the same borders

Except that inferiorly by the inferior belly of omohyoid

Borders

Semispinalis capitis

Occasionally appears at the apex

Posteriorly

Boundaries Platysma

Superficial and deep fasciae

Skin

Roof

Spleniuscapitis

Levator scapulae

Scaleni medius

Floor

Contents Cutaneous and muscular branches of the

cervical plexusUppermost part of the brachial plexus

Transverse cervical vessels

Spinal accessory nerveSupraclavicular nerves

Lymph nodes

That’s it!!!