Anatomy of Sternocleidomastoid Muscle

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Questions and Answers

Which of the following nerves supplies the skin of the neck?

Posterior rami of C5, 6 & 7

Posterior rami of C2, 3 & 4

Anterior rami of C2, 3 & 4 (correct)

Anterior rami of C5, 6 & 7

Which vein drains into the subclavian vein?

External jugular vein (correct)

Posterior auricular vein

Internal jugular vein

Anterior jugular vein

What is the origin of the platysma muscle?

Sternomastoid muscle

Deep fascia covering the pectoral region (correct)

Superficial fascia of the side of the neck

Clavicle

Which of the following is NOT a tributary of the external jugular vein?

Internal jugular vein Signup and view all the answers

What is the course of the anterior jugular vein?

It descends close to the midline to the suprasternal notch Signup and view all the answers

What forms the jugular arch?

The union of the right and left anterior jugular veins Signup and view all the answers

What is the origin of the sternal head of the sternocleidomastoid muscle?

Superolateral part of the front of the manubrium sterni Signup and view all the answers

What is the action of the sternocleidomastoid muscle when one muscle contracts?

Turns the face to the opposite side Signup and view all the answers

What forms the floor of the posterior triangle?

Semispinalis capitis, splenius capitis, and levator scapulae Signup and view all the answers

What is the nerve supply of the sternocleidomastoid muscle?

All of the above Signup and view all the answers

What is the action of the sternocleidomastoid muscle when both muscles contract together?

Flexes the neck forward Signup and view all the answers

What is the insertion of the sternocleidomastoid muscle?

Both A and B Signup and view all the answers

Which muscle divides the posterior triangle of the neck into two parts?

Omohyoid muscle Signup and view all the answers

What is the name of the larger upper part of the posterior triangle of the neck?

Occipital triangle Signup and view all the answers

What is the name of the nerve found in the posterior triangle of the neck?

All of the above Signup and view all the answers

Which artery is NOT found in the posterior triangle of the neck?

Vertebral artery Signup and view all the answers

What is the location of the occipital lymph nodes in the posterior triangle of the neck?

At the apex of the triangle Signup and view all the answers

Which of the following veins is NOT found in the posterior triangle of the neck?

Internal jugular vein Signup and view all the answers

Study Notes

Posterior Triangle of the Neck

Cutaneous nerves of the neck are supplied by the anterior rami of C2, 3 & 4 through the cutaneous branches of cervical plexus.
Cutaneous branches include lesser occipital (C2), great auricular (C2 & 3), transverse cervical (C2 & 3), and supraclavicular (C3 & 4).

Superficial Veins of the Neck

External jugular vein:
- Begins behind the angle of mandible by the union of posterior auricular and posterior division of posterior facial vein.
- Descends obliquely backwards across the sternomastoid and pierces the deep fascia to end in the subclavian vein.
- Tributaries include posterior auricular vein, posterior division of posterior facial vein, posterior external jugular vein, transverse cervical vein, suprascapular vein, and anterior jugular veins.
Anterior jugular vein:
- Begins below the chin and descends close to midline to the suprasternal notch, where it joins its fellow forming jugular arch.
- Then bends sharply laterally deep to the sternomastoid to drain into the external jugular vein.

Platysma Muscle

Lies in the superficial fascia of the side of the neck.
Origin: From the deep fascia covering the pectoral region.
Insertion: Into the lower border of the mandible.
Nerve supply: Facial nerve (cervical branch).
Action: Depresses the mandible and draws down the angle of the mouth.

Sternocleidomastoid Muscle

Origin:
- Sternal head: from the superolateral part of the front of the manubrium sterni.
- Clavicular head: from the medial 1/3 of the superior surface of the clavicle.
Insertion: Lateral surface of the mastoid process and lateral half of the superior nuchal line.
Nerve supply:
- Spinal accessory (motor).
- Branches from ventral rami of C2,3 (sensory, proprioceptive).
Actions:
- Flexes the neck to the same side and elevates to the opposite side when one muscle contracts.
- Turns the face to the opposite side and tilts the head towards the shoulder.
- Flexes the neck when both muscles contract together.

Posterior Triangle

Boundaries:
- Anterior: posterior border of sternomastoid.
- Posterior: anterior border of trapezius.
- Inferior (base): intermediate of third of the clavicle.
- Apex: meeting of trapezius and sternomastoid.
Roof: formed by skin, superficial fascia, and platysma, and deep fascia.
Floor: formed by semispinalis capitis, splenius capitis, levator scapula, scalenus posterior, and scalenus medius muscles.
Division:
- Subdivided by the inferior belly of omohyoid into occipital triangle and supraclavicular triangle.

Contents of the Posterior Triangle

Nerves:
- Roots and trunks of brachial plexus.
- Branches of cervical plexus.
- Spinal accessory.
Arteries: third part of subclavian, transverse cervical, suprascapular, and occipital.
Veins: subclavian, transverse cervical, suprascapular, and lower part of the external jugular.
Muscles: inferior belly of omohyoid.
Lymph nodes:
- Supraclavicular: along the lower part of the posterior border of the sternomastoid muscle.
- Occipital: at the apex of the triangle.