APPLIED SURGICAL ANATOMY OF TRIANGLES OF HEAD &NECK

PRESENTED BY ABHISHEK MOTIMATH

TRIANGLES OF NECK

ANTERIOR TRIANGLE: 1.SUBMENTAL TRIANGLE2.SUBMANDIBULAR/DIGASTRIC TRIANGLE3.MUSCULAR TRIANGLE4.CAROTID TRIANGLE

POSTERIOR TRIANGLES

• 1. OCCIPITAL TRIANGLE

• 2.SUBCLAVIAN TRIANGLE

BACK OF NECK TRIANGLE

1.Suboccipital triangle

Anterior Triangle

Posterior Triangle of the Neck

The Neck

• Connects the head to the trunk• Conduit for blood vessels, nerves, and hollow

organs• All of these complicated structures are packed

in a very narrow area that allows for a great deal of mobility for the head as it moves relative to the ground

FASCIA OF NECK

Superficial fascia:- Connective tissue below dermis- Completely surrounds neck -thin and hard to demonstrate- Contains Platysma & Superficial veins

Deep Cervical Fascia• Form the boundaries of compartments• Fascial spaces can communicate infection or

fluid to other regions of the body• Used as a guide to surgical dissection• Allow the neck structures to glide past one

another• Supports the thyroid, lymph nodes and blood

vessels

Deep Cervical Fascia

Deep Cervical Fascia

Deep Cervical Fascial Spaces• Retropharyngeal - b/n prevertebral and

buccopharyngeal• Pretracheal - b/n infrahyoids and trachea• Lateral pharyngeal - lat to pharynx and

communicate with RP and SM spaces• Submandibular - below tongue

– deep portion above mylohyoid– superficial portion below mylohyoid

Anterior Triangle of the Neck

ANTERIOR TRIANGLE - • Sub mental triangle--formed by the anterior

belly of the digastric, hyoid, and midline • Submandibular triangle--formed by the

mandible, posterior belly of the digastric, and anterior belly of the digastric

• Carotid triangle--formed by the superior belly of the omohyoid, SCM, and posterior belly of the Digastric

• Muscular triangle--formed by the midline, superior belly of the omohyoid, and SCM

Muscular Triangle

Contents of MUSCULAR TRIANGLE

• No significant structure is present• Beneath its floor lie thyroid

glands,larynx,trachea,esophagus• Infrahyoid muscle are present in this triangle

• Infrahyoid muscles are arranged in two layers;• Superficial –sternohyoid and omohyoid• Deep-sternothyroid and thyrohyoid

Submental Triangle

Contents of submental triangle

• Submental lymph nodes;3 or 4 in no. situated in the superficial fascia below the chin and drains the lymph from the central part of lower lip,adjoining gums,floor of the mouth and tip of tongue

• Commencement of ant. Jugular vein

DIGASTRIC TRIANGLE

Contents of digastric triangleSuperficial part of submandibular gland ;Facial vein and submandibular lymph nodes lie

superficial to the glandsFacial artery;

• A part of hypoglossal nerve• Lower part of parotid gland ,overlapping the

posterior belly • ECA• Carotid sheath

CAROTID TRIANGLE

CONTENTS OF CAROTID TRIANGLE

• Arteries; CCA and its two terminal branches internal and external .

• In the carotid triangle the INT CAROTID is posterolateral while EXT CAROTID is anteromedial

• CCA and INT CAROTID artery do not give any branches in this triangle

CONTENTS OF CAROTID TRIANGLE

NERVES PRESENT IN THE CAROTID TRIANGLE

• Portion of spinal part of accessory nerve• Loop of hypoglossalA) Descendens hypoglossi ;supplies the sup. Belly of

omohyoidB) Nerve to the thyrohyoid• Vagus nerve; passes downward within carotid sheath

between IJV laterally and carotid system of arteries medially In fact vagus is not a content of this triangle as it

overlapped by SCM

VEINS PRESENT IN THE CAROTID TRIANGLE

• Internal jugular vein; extends from the base of skull to the root of neck and collects blood from the brain ,superficial part of the face and neck

• Also present are the tributaries of IJV such as sup. Thyroid, lingual ,common facial, pharyngeal,and sometimes occipital veins

BRANCHES OF VAGUS NERVE IN THE NECK

• Pharyngeal• Superior laryngeal• Branch to the carotid sinus and body• Sup. And inf. Cervical cardiac • Right recurrent laryngeal nerve

CAROTID SHEATH

It is a tubular thickly matted fascial condensation extend from the base of skull to the root of neck.

The inferior parts contain several important structures 1) CCA medially2) IJV laterally3) Vagus nerve posteriorly4) Ansa cervicalis5) Deep Cervical lymph nodes lie along the carotid

sheath and IJV6) Cervical part of sympathetic trunk runs posterior

BRANCHES OF EXTERNAL CAROTID ARTERY IN CAROTID TRIANGLE

• Superior thyroid artery• Lingual artery• Facial artery • occipital artery• Ascending pharyngeal

artery

Pulse of carotid triangle by placing the digits in the triangle and compressing the artery slightly against transverse process of the cervical vertebra

Carotids sinus ; dilatation of the proximal part of ICA ;acts as baroreceptor

Carotid body ;receives rich nerve supply from the glossopharyngeal ,vagus, sympathetic nerves and it act as chemoreceptor

Potato tumor of neck is produced by the enlargement of the carotid body. Tumor moves transversely ,shows transmitted pulsation and is often associated with slow pulse and attacks of fainting due to pressure on the carotid sinus

APPLIED ANATOMY OF CAROTID TRIANGLE

• Vagus nerve and recurrent laryngeal nerves are in risk to damage during surgery in this triangle. Damage to this nerve may produce alteration in the voice

• When surgery of tongue is to be done and one need to ligate lingual artery then 1st part of the artery present in this triangle is ligated

• Blind clamping of IJV –not done coz vagus and hypoglossal nerve are in vicinity

• Carotid sheath-can be marked out by a line joining the sternoclavicular joint to a point midway between the tip of the mastoid process and the angle of mandible

• Carotid triangle provides an important surgical approach-

[1]carotid arterial system

[2]internal jugular vein

[3]vagus and hypoglossal nerve

[4]cervical sympathetic trunk • Carotid sinus hypersensitivity-pressure on one or both

carotid sinuses results in excessive slowing of heart rate, a fall in blood pressure and cerebral ischemia

• Arteriosclerosis of internal carotid artery-extensive arteriosclerosis of ICA in the neck can result in visual impairment and blindness in the eye on the side of lesion or even motor paralysis and sensory loss on the opposite side of body

• Air embolism –serious complication of a lacerated wall of the IJV coz the wall of this vein contains little smooth muscle

• During neck dissection Lower end of internal jugular vein is approached first by dividing the SCM because it is the main vein draining the primary tumor. the carotid sheath is opened to expose the IJV and it is important to identify the length of at least 2cm to facilitate ligation making sure that vagus nerve is not included.the danger of tearing of IJV is not blood loss but air embolism

• Upper end of IJV is important because we have to ligate it during neck dissection .this can be identified by dividing SCM .the position can be located by palpation of transverse portion of atlas over which it lies .

• Here hypoglossal nerve is to be identified and preserved and can be done as it runs across the ECA ,lingual and facial.

Upper end of internal jugular vein

• When ever there is a need to cut omohyoid muscle then it is to be cut through the tendon and at this point transverse cervical artery n vein is encountered and is to be ligated

• Phrenic nerve and brachial plexus is to be protected, they run behind prevertebral fascia and is safe as long as this fascia is not breached during surgery

Posterior Triangle of the Neck

OCCIPITAL TRIANGLEBOUNDARIES: • Front; post. Border of SCM• Behind; anterior border of trapeezius

muscle• Below; inf. Belly of omohyoid• Floor; formed from above downward by ;• 1)semispinalis capitis muscle• 2)splenius capitis• 3)levator scapulae• 4)scalenus medius and posterior

Contents of occipital triangleFour cutaneous branches of the

cervical plexus• 1st;lesser occipital nerve(c2)• 2nd;great auricular nerve(c2,c3)• 3rd;transverse cervical nerve(c2,c3)• 4th ;Supraclavicular nerve(c3,c4)• UPPER TRUNK OF BRACHIAL PLEXUS; by c5,c6 roots

peeps in occipital triangle between scalenus medius and inferior belly of omohyoid

CONTENTS OF OCCIPITAL TRIANGLE

• spinal part of accessory nerve;

• 3rd and 4th cervical nerve

• dorsal scapular nerve ;supply rhomboid muscle• occipital artery• transverse cervical artery and vein

Preservation of Spinal accessory nerve

• Whenever we do surgery in the posterior triangle then we have to keep in mind that this nerve runs in the roof and not floor and hence can be damaged during elevation of flap itself. How to identify this nerve;

• 1.nerve exit point which is called ERB’S POINT which is 1cm above point where great auricular nerve winds around SCM on its way to supply parotid gland

SUPRACLAVICULAR TRIANGLE

Contents of supraclavicular triangle

[1]nerves-

(a)three trunks of brachial plexus

(b)nerve to serratus anterior

(c)Nerve to subclavius

(d)Suprascapular nerve

[2]vessels-

(a)Third part of subclavian artery and subclavian vien

(b)Suprascapular artery and vein

(c)Commencement of transverse cervical artery

(d)Lower part of external jugular vein

[3]lymph nodes-

(a)Few members of supraclavicular chains

CONTENTS OF POSTERIOR TRIANGLEOCCIPITALARTERY

GREATAURICULAR N.

LESSEROCCIPITAL N.

ACCESSORY N.

SUPRACLAVICULAR NERVES

TRANSVERSECERVICAL NERVE

EXTERNALJUGULAR VEIN

• ERB’S POINT- Area of the upper trunk of brachial plexus which is most exposed to shearing force. Here c5 and c6 roots unite to form the upper trunk ,which gives off two branches ,nerve to subclavius and suprascapular nerve.

• ERB’S-DUCHENNE PARALYSIS: commonest type of injury occurring at birth and produced by excessive stretching of upper trunk at the ERB’S point from the pressure of forceps used during delivery .the resulting paralysis involves the following muscle supplied by nerve c5,c6;deltoid,supraspinatus,infraspinatus,biceps,brachilis,and brachioradialis.in the affected limb arm hang by the side and is rotated medially.

Applied part of posterior triangle

• KLUMPKE’S PARALYSIS: takes place due to injury of c8 and TI nerves ,before or after formation of lower trunk. the paralysis affect the intrinsic muscle of the hand ,flexor of the digits producing ‘claw hand’ .may be caused by pressure of a cervical rib .sometimes sagging of the shoulder girdle due to weakness and fatigue of muscle allows compression of the lower trunk against scalenus anterior muscle .this is called ‘scalenus anterior syndrome’

• INJURY TO THE LONG THORACIC NERVE: sometimes observed in porter who have to carry heavy load on shoulder .the resulting paralysis of serratus anterior is manifested by backward projection of scapula when the arm is held forward ,by the unopposed action of rhomboid muscle. this appearance is called ‘WINGING OF SCAPULA’

• Palpation and compression of the subclavian artery in patient with upper limb hemorrhage-can be stopped by exerting strong pressure downward and backward on the third part of subclavian artery against the upper surface of first rib

• Pleura and lung injuries in the root of the neck-cervical dome of the pleura and the apex of the lung extend upto the root of the neck on each side and lie behind subclavian artery so penetrating wound above the medial end of the clavicle may involve the apex of the lung

• Brachial plexus nerve block-can easily be obtained by closing the distal part of axillary sheath in axilla with finger pressure ,inserting a syringe needle into the proximal part of the sheath and then injecting the local anaesthetic

• Most common swelling in the posterior triangle due to enlargement of the supraclavicular lymph nodes which are commonly enlarged in tuberculosis, Hodgkin’s disease, and in malignant growth of the breast,arm,or chest

• Left supraclavicular node or Virchow or scalene nodes involve in malignant growth of distant organ so they are therefore known as signal nodes

• Torticollis or wry neck in which head is bent to one side and chin points to the other side results from spasm or contraction of SCM ,trapezius supplied by spinal accessory nerve

• Second part of subclavian artery may get compressed by the scalene anterior muscle resulting in decreased blood supply to the upper limb

• Cervical rib may compress the subclavian artery resulting in diminished radial pulse or obliterated on turning the patient’s head upward and to the affected side after a deep breath [Adson’s test]

• Dysphagia caused by compression of eosophagus by an abnormal subclavian artery is called Dysphagia lusoria

• Blalock’s operation for fallot’s tetra logy ,the right subclavian artery is anastomosed end to side to short circuit the pulmonary stenosis

SUB OCCIPITAL TRIANGLE

Contents of sub occipital triangle

• THIRD PART OF VERTEBRAL ARTERY; Here the artery gives muscular branches to supply the sub occipital muscles and meningeal branches to the posterior cranial fossa

• FIRST CERVICAL NERVE(SUBOCCIPITAL NERVE);supply the muscle of surrounding area

• SUB OCCIPITAL VENOUS PLEXUS; in and around the sub occipital triangle and collects blood from the neighbouring muscle

Structures related to this triangle• Greater occipital nerve; thickest cutaneous nerve

of the body curls around obliquus capitis inferior .it pierces the trapezius muscle and supply the posterior part of scalp up to the vertex.

• Third occipital nerve; Ascends medial to the greater occipital nerve to supply the back of neck up to the external occipital protuberance

• Occipital artery; Descending branch of this artery here maintain collateral circulation after ligation of ECA or subclavian artery

Applied anatomy

• Cisternal puncture is often employed through the sub occipital region to collect CSF from the cisterna magna.the needle pierces the posterior atlanto occipital membrane at a depth of about 4-5 cm (as indicated by sudden loss of resistance ) and enters cisterna puncture

various midline swelling in anterior triangle -

(from above downward)• Ludwig's angina• Enlarged sub mental lymph nodes• Sublingual dermoid• Thyroglossal cyst• Sub hyoid bursitis• Retrosternal goiter• Thymic swelling

Lateral swellings in the neck

• In the submandibular triangle-

1.Enlarged lymph node2.Enlargement of submandibular

gland3.Deep or plunging ranula4.Extension of growth from the jaw5.sjogren’s syndrome

IN THE CAROTID TRIANGLE

• Carotid body tumor• Branchial cyst• Aneurysm of carotid artery• Thyroid swelling• Laryngocele• Lymph node swelling

IN THE POSTERIOR TRIANGLE

• Enlarged supraclavicular nodes• Cystic hygroma• Pharyngeal pouch• Subclavian aneurysm• Cervical rib• Lipoma• Cold abscess

Important neck masses 1.Congenital neck massesLymphangiomas-occur in infants and

children ,tending to be more common in submandibular and supraclavicular region.

Midline dermoid-present as solid or cystic masses in the midline of the neck between the suprasternal notch and sub mental region. Treatment is complete excision

• Thyroglossal duct cysts-most common midline neck cyst ,mostly painless and moves on swallowing or protruding the tongue with mean age 5 years. Treatment is by excision

• Thyroglossal duct carcinoma-may be suspected if the cyst is hard and irregular or recently undergoes changes

• Branchial cyst-2/3 of this is present on left and 1/3 on right side is affected.2/3 lies anterior to the upper third SCM,1/3 in middle and lower neck ,parotid, and the posterior triangle region. Treatment is surgical excision

• Branchial fistula –external opening is at the external border of the SCM ,at the junction of the middle and lower thirds and internal opening on the anterior aspect of tonsillar fossa.TRACT runs below the stylohyoid muscle and posterior belly of Digastric above the hypoglossal nerve

• Haemangiomas-most common benign tumors of infancy and is present most often within the masseter and trapezius muscle

Acquired neck masses• Ranulas-cystic mass in the floor of the mouth

or tongue .plunging ranula result from the extravasattion of mucus below the mylohyoid muscle and present as painless ,non mobile neck swelling

• Laryngoceles –arise within the saccule of the laryngeal ventricle.manual compression may result in the escape of gases and fluid into the airway (BRYCE’S SIGN)

• Pharyngeal pouches are also seen

Infective neck masses• Para pharyngeal abscess –more common in

adults and is complication of tonsillectomy or tonsillitis or extraction of third molar or due to the extension of infection from the petrous part of temporal bone .neck swelling is maximal at the posterior midthird of sternocliedomastoid muscle's/t is I/D the space being opened from a point medial to the mandible to the clavicle

• Ludwigs angina-source of infection in 80% cases is dental while in remaining 20% cases it is soft tissues and tonsillar infection

• AIDS-head and neck manifestation are seen• Toxoplasmosis-caused by toxoplasmosis Gondi• Actinomycosis-• Infectious mononucleosis• Brucellosis-• Tuberculous cervical lymphadenitis-long

standing lymphdenopathy due to tuberculosis ,usually the deep jugular chain ,although the posterior triangles nodes can also be affected

• Neoplastic region of oral cavity• Acute lymphadenitis

REFERENCE• TEXTBOOK OF ANATOMY: B.D.CHAURASIA• GRAY’S ANATOMY• TEXTBOOK OF ANATOMY: A.K.DUTTA• ATLAS OF HUMAN ANATOMY : FRANK NETTER