Posterior Triangle

of the Neck

Khaleel Alyahya, PhD, MedKing Saud University@khaleelya

TRIANGLES OF THE NECK

The neck is divided into anterior and posterior triangles by the sternocleidomastoid muscle;

Anterior triangle lies in front of the muscle

Posterior triangle lies behind the muscle.

STERNOCLEIDOMASTOID MUSCLE

The sternocleidomastoid orsternomastoid is a strap- likemuscle that descends obliquelyacross the side of the neck.

It originates at the manubrium ofthe sternum (sterno-) and theclavicle (cleido-), and has aninsertion at the mastoid processof the temporal bone of the skull.

BOUNDRIES

Anteriorly: Posterior border of sternomastoid.

Posteriorly: Anterior border of Trapezius.

Base:Middle 1/3 of the clavicle.

Apex:Meeting of Trapezius

& Sternomastoid.

OMOHYOID MUSCLE

Omohyoid muscle has:

Superior belly Intermediate tendon Inferior belly

The inferior belly of omohyoidsubdivides the posterior triangle into: large occipital triangle above. small supraclavicular triangle below.

Roof:

Skin, Superficial fascia

Platysma muscle Cutaneous branches of cervical plexus External jugular vein Investing layer of deep cervical fascia.

Floor:

from below upward: Scalenus medius Levator scapulae Splenius capitis Semispinalis capitis

The muscles of the floor are covered by prevertebral layer of deep cervical fascia.

POSTERIOR TRIANGLE

DEEP FASCIA OF NECK

The deep fascia of the neck is called deep cervical fascia

Parts of Deep Cervical Fascia: Investing layers. Prevertebral layer. Pretracheal layer. Carotid sheath.

INVESTING LAYER OF DEEP CERVICAL FASCIA

PLATYSMA

The platysma can be seenas a sheet of muscle byasking the patient to clenchhis jaw firmly. The muscle extends fromthe body of the mandibledownward over the clavicleonto the anterior thoracicwall.

CONTENT OF POSTERIOR TRIANGLENerves: The main contents are nerves:

The three trunks of the brachial plexus. Four cutaneous branches of cervical plexus.

lesser occipital, great auricular, transverse cervical supraclavicular nerves.

Spinal accessory.

Arteries: 3rd part of subclavian artery. Suprascapular artery. Transverse cervical artery. Occipital artery.

Veins: Subclavian vein. External jugular vein.

Muscle: Inferior belly of omohyoid muscle.

ACCESSORY NERVE (SPINAL PART)11th Cranial Nerve

The spinal part of the accessory

nerve enters the posterior triangle by emerging from beneath the middle of the posterior border of sternomastoid muscle, which it has supplied.

It runs downward and laterally across the posterior triangle on the levator scapulae muscle.

It also supplies the trapezius.

EXTERNAL JUGULAR VIEN

The external jugular veinbegins just behind the angle of the mandible by the union of the posterior auricular vein & the posterior division of the retromandibular vein.

EXTERNAL JUGULAR VIEN

The external jugular vein descendsobliquely superficial to sternomastoidmuscle and, just above the clavicle in theposterior triangle, pierces the deep fasciaand drains into the subclavian vein.

It is the only tributary of the subclavianvein.

It varies considerably in size, and itscourse extends from the angle of themandible to the middle of the clavicle.

THIRD PART OF SUBCLAVIAN ARTERY

The third part of the subclavianartery occupies the lower anteriorangle of the posterior triangle justbehind the sternomastoid muscle.

THIRD PART OF SUBCLAVIAN ARTERY

QUESTION?