Triangles of Neck &

Temporo-mandibular joint

Triangles of the neck• Anatomists use the term triangles of the neck to describe the divisions created by the

major muscles in the region.

• The side of the neck presents a somewhat quadrilateral outline, limited, above, by the

lower border of the body of the mandible, and an imaginary line extending from the

angle of the mandible to the mastiod process; below, by the upper border of the clavicle;

in front, by the middle line of the neck; behind, by the anterior margin of the trapezius.

• This space is subdivided into two large triangles by sternocleidomastoid, which passes

obliquely across the neck, from the sternum and clavicle below, to the mastiod process

and occipital bone above.

• The triangular space in front of this muscle is called the Anterior Triangle Of The Neck;

and that behind it, the Posterior Triangle Of The Neck.

Triangles of neck

• Consists of anterior and posterior• Anterior triangles of neck:

– Digastric– Submental– Carotid– Muscular

Triangles of neck

• Posterior triangles of neck– Occipital – Supraclavicular

Anterior triangles of neck

– Digastric– Submental– Carotid– Muscular

Digastric triangle

• Also known as submandibular triangle• Superiorly(base);base of mandible & line

joining the angle of mandible to mastoid process

• anteroinferiorly; anterior belly of digastric m.• Posteroinferiorly;posterior belly of digastric m.

& stylohyoid m.

Digastric triangle

• Roof; the skin, superficial fascia, platysma and deep fascia, which contain branches of the facial and transverse cutaneous cervical nerves

• Floor;mylohyoid & hyoglossus

Digastric triangle

• Contents• Anterior part:lymph nodes,submental

artery,mylohyoid vessels and facial vein & submandibular salivary gland

• Posterior part :external carotid a. ,parotid gland,styloid process, styloglossus, stylopharyngeus and the glossopharyngeal nerve & internal carotid a. ,internal jugular vein

Applied anatomy of digastric triangle

• Infection in submandibular region is limited to a triangular region.

• Posteriorly;hyoid bone and anterolaterally on each side by halves of mandibular base

• Because the layer of deep fascia is attached to these bones.

• Triangular swelling= Ludwig’s Angina• The swelling may push tongue upwards

Submental triangle

• Its apex is at the chin, • Its base is the body of the hyoid bone • and its floor is formed by both mylohyoid

muscles.• It contains lymph nodes and small veins that

unite to form the anterior jugular vein

Muscular triangle

• Anteriorly by the median line of the neck from the hyoid bone to the sternum,

• Inferoposteriorly by the anterior margin of sternocleidomastoid,

• Posterosuperiorly by the superior belly of omohyoid.

• The triangle contains omohyoid, sternohyoid, sternothyroid and thyrohyoid

Carotid triangle

A. Coverings and boundaries• It is bounded:

Posteriorly : by the sternocleidomastoideus

Inferiorly : by the superior belly of the omohyoideus

Superiorly : by the stylohyoideus

Posterior : belly of the digastricus.

• B. Covered By : the integument, superficial fascia, Platysma

and deep fascia; ramifying in which are branches of the facial and cutaneous cervical nerves.

C. Floor • is formed by parts of the : Thyrohyoideus, hyoglosus, and the

constrictores pharyngis medius and inferior.

THE POSTERIOR TRIANGLES

The posterior triangles from its :

A. BoundariesB. RootC. FloorD. Content E. Applied anatomy

A. Boundaries

• Posterior : anterior border of trapezius

• Base : middle 3rd of clavicle

• Apex : meeting point of sternocleidomastoid

& trapezius at superior nuchal line.

B. Roof a. Skin

b. Superficial facia

c. Investing layer of deep cervical facia

d. Roof is pierced by :

1. Nerves :

i. Lesser occipital

ii. Great auricle

iii. Transverse cutaneous nerves of neck

iv. Supraclavicular nerves

2. Veins : external jugular veins and its tributaries.

3. Lypmh vessels

1. external jugular vein (blue)

2. superficial cervical lymph nodes (green)

3. lesser occipital nerve (lc)

4. great auricular nerve (ga)

5. transverse cervical nerve (tc)

6. supraclavicular nerves (sc)

7. spinal accessory nerve (sa)

C. Floor

• Mainly form by 2nd layer of muscle of neck (above

downward)

1. Splenius capitis.

2. Levator scapulae.

3. Occasionally by semispinalis capitis at apex.

4. Scaleneus medius.

5. Scaleneus posterior.

6. Muscular floor is carpeted by preverterbral facia.

splenius capitis (sc) levator scapulae (ls) scalenus posterior (sp) scalenus medius (sm) scalenus anterior (sa) inferior belly of omohyoid (io)

• The spinal accessory nerve and the lymph nodes are the true contents of the posterior triangle and all others are behind or in front of the facial floor.a. Muscle : inferior belly of omohyoidb. Nerves :

1. Accessory nerves2. Root, trunks of brachial plexus and their branches :

i. Nerves to rhomboideusii. Nerves tomserratus anterioriii. Nerves to subclaviusiv. Suprascapular nerve

D. Content

3. Cervical nerves :

i. Greater occipital nerve emerges from the apex to pass on the scalp.

ii. Great auricle nerveiii. Lesser occipital nerveiv. Transverse cervical nerve of neckv. Supraclavicular nerve

• 3rd and 4th cervical nerves supplying trapezius

4. Arteries

i. Occipital artery emerges from apex

ii. 3rd part of subclavian artery and branches of subclavian artery

a. Suprascapular branches of thyrocervical trunk 1st

b. Transverses cervical part of subclavian

• Transverse cervical artery divides into acending and descending branch anterior

border of sternocleidomastoid.

iii. Veins : external jugular veins and its tributaries. Subclavian vein is

lower down and not include in the triangle.

iv. Lymph nodes :

a. Supraclavicular lymph nodes are present along the posterior border of

sternomastiod.

b. Occipital lypmh nodes

APPLIED ANATOMY

1) Left supraclavicular (Virchow’s) lymph nodes are enlarge in

malignancy of testis, stomach and other abdominal organs.

2) The pressure in the external jugular vein can be recorded in the

recumbent position. It is increased in right sided heart failure

and in the obstruction of the superior vena cava.

3) The retropharyngeal abscess maybe expressed in the lower

part of posterior triangle.

Temporomandibular Joint

By:Norafzalila bt Zainol

Temporomandibular joint (TMJs)- The mandible forms the skeleton of the lower

jaw,which is movable because it articulates with the cranial base at the temporomandibular joint.

- It is modified hinge type of synovial joint.- Joint capsule of TMJ is loose.- Fibrous layer of the capsule attach to the margin

of articula, area of temporal bone and around neck of mandible.

- Articular surface is the condyle of mandible, articular tubercle of temporal bone, mandibular fossa.

- TMJ has 2 synovial membrane:»superior synovial membrane (lines the fibrous

layer of the capsule superior to the articular disc)»inferior synovial membrane (lines the fibrous layer

of the capsule inferior to the articular disc)- Articular disc:»it divide TMJ into 2 separate compartments;

superior comp. (gliding movement of protrusion and retrusion), and inferior comp. (hinge movement of depression and elevation)

- Thick part of the joint capsule forms:

»intrinsic lateral ligament (strengthens the TMJ laterally)

»postglenoid tubercle (prevent posterior dislocation of the joint)

- Enstrinsic ligament and the lateral ligament connect the mandible to the cranium.

- Stylomandibular ligament which is actually thickening of the fibrous capsule of the parotid gland, runs from the styloid process to the angle of the mandible (it does not contribute to the strength of the joint)

- Sphenomandibular ligament runs from the spine of sphenoid to lingua of the mandible (primary passive support of mandible, although the tonus of the muscle of mastication usually bears the mandibles weight)

- However the ligament does serves as a “swinging hinge” for the mandible, serving both as a fulcrum and as a check ligament for the movements of the mandible at TMJs

Movements Muscles

Elevation (close mouth) Temporal masseter, and medial pterygoid

Depression (open mouth) Lateral pterygoid and suprahyoid and infrahyoid muscles

Protrusion (protrude chin) Lateral pterygoid, masseter, and medial pterygoid

Retrusion (retrude chin) Temporal nad masseter

Lateral movement (grinding and chewing) Temporal of same side, pterygoids of opposite side, and masseter

Movement of mandible at the TMJs and the muscles (or forces)producing them:

- To enable more than a small amount of depression of the mandible-that is to open the mouth wider than just to separate the upper and lower teeth- the head of mandibular and articular disc must move anteriorly on the articular surface until the head lies inferior to the articular tubercle (a movement referred to as “translation” by dentists)

- If this anterior gliding occurs unilaterally, the head of the contralateral mandible rotates (pivots) on the inferior surface of the articular disc, permitting simple side-to-side chewing or grinding movements over a small range

- During protrusion and retrusion of the mandible, the head and the articular disc slide anteriorly and posteriorly on the articular surface of the temporal bone, with both sides moving together

- TMJ movements are produced chiefly by the muscles of mastication:

»temporal m.»masseter m.»medial pterygoid m. »lateral pterygoid m.

-Information-

- Upper head of lateral pterygoid m. is active during retraction movement produced by the posterior fibers of temporal m.

(retraction=retrusion)(protraction=protrusion)*commonly used for anterior and posterior

movement of the shoulder- Traction is applied to the articular disc so that it

is not pushed posteriorly ahead of the retraction mandible

- Actually,depression of the mandible is produced by gravity

- Suprahyoid and infrahyoid muscle are strap-like m. On each side of yhe neck that are primarily larynx, respectively - for example during swallowing.

- Indirectly they can also help depress the mandible, especially when opening the mouth suddenly or against resistance.

- The platysma can be similarly used

Applied Anatomy

- Dislocation of the TMJ- Arthritis of the TMJ