triangles of the neck ppt year 1
TRANSCRIPT
TRIANGLES OF THE NECK
• The side of the neck presents a somewhat quadrilateral outline .
• It is limited above by the lower border of the body of the mandible ,and an imaginary line drawn from the angle of the mandible to the mastoid process.
• Below ,it is limited by the upper border of the clavicle.
• Medially ,by the midline of the neck.
• Posteriorly , by the anterior border of the Trapezius muscle .
Quadrilateral outline in the neck
The Sternocleidomastoid muscle
• 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 and posterior triangles
Anterior Triangle
Posterior triangle
Posterior triangle
• This is formed by :
• The Sternocleidomastoid musc.,anteriorly.
• The Trapezius muscle, posteriorly.
• The Clavicle ,inferiorly.
• The apex of the triangle is formed by the occipital bone.
The ROOF of the posterior triangle is formed by:
• Skin
• Superficial fascia
• Platysma muscle
• Investing layer of the deep cervical fascia
The FLOOR of the triangle is formed by the following muscles from above downwards:
Splenius Capitis
Levator scapulae
Posterior scalene
Middle scalene
Anterior scalene
Subdivisions of the posterior triangle
• The posterior triangle is further divided into two smaller triangles by the Inferior belly of the Omohyoid muscle .
• These are the : Supraclavicular
triangle Occipital triangle
Supraclavicular triangle
• It is formed by the
Inferior belly of the Omohyoid ,
the Clavicle ,
Sternocleidomastoid muscle.
The Occipital triangle
• The Occipital triangle is formed by the
Inferior belly of the Omohyoid
The Trapezius muscle Sternocleidomastoid muscle.
CONTENTS OF THE POSTERIOR TRIANGLE
• NERVES and PLEXUSES:
• Spinal acessory nerve.
• Branches of Cervical plexus
• Roots and trunks of brachial plexus.
Contents of the posterior triangle
• VESSELS:
• Subclavian artery
• Transverse Cervical artery
• Suprascapular artery
• External jugular vein (terminal part)
LYMPH NODES:
• Occipital
• Supraclavicular
MUSCLES:
• Inferior belly of Omohyoid muscle
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.
THE ANTERIOR
TRIANGLE
ANTERIOR TRIANGLE
• BOUNDARIES: Anterior border of the SCM muscle midline of the neck inferior border of the mandible• ROOF:• Skin • Superfacial fascia and platysma muscle• Investing layer of deep cervical fascia
SUBDIVISIONS OF ANTERIOR TRIANGLE
SUBDIVISIONS OF THE ANTERIOR TRIANGLE
• The anterior triangle is divided into four smaller triangles:
1. SUBMENTAL TRIANGLE
2. SUBMANDIBULAR TRIANGLE
3. CAROTID TRIANGLE
4. MUSCULAR TRIANGLE
SUBMENTAL TRIANGLE
• Formed by the :
anterior midline of neck
hyoid bone
anterior belly of digastric muscle
SUBMANDIBULAR TRIANGLE
• Formed by:Inferior border
of the mandible
Anterior belly of the digastric muscle
Posterior belly of the digastric muscle
CAROTID TRIANGLE
• FORMED BY:
Superior belly of the Omohyoid
muscle
Sternocleidomastoid muscle
Posterior belly of the digastric muscle
MUSCULAR TRIANGLE
• Formed by:
midline of the neck
superior belly of the Omohyoid
sternocleidomastoid muscle
Contents of the anterior triangle
CONTENTS OF THE ANTERIOR TRIANGLE
• VESSELS:
carotid system(CCA,ICA, ECA)
Internal Jugular vein
• NERVES:
Cranial nerves 7,9,10,11,12
Cervical plexus
• MUSCLES:
Suprahyoid muscles: (Digastric , Mylohyoid,Stylohyoid,Geniohyoid )These elevate the hyoid bone , and the floor of the mouth ,and depress the mandible .
Infrahyoid muscles : (Sternohyoid,Sternothyroid,Thyrohyoid, Omohyoid )
These depress the hyoid bone and the larynx.
That’s it!