Side Front And Back Of The Neck Anatomy Notes

Side, Front And Back Of The Neck

Question 1. Enumerate the structures present in the superficial fascia of the neck.
Answer.

The superficial fascia of the neck contains:

• Platysma
• Cutaneous nerves
• Superficial veins
• Superficial lymph vessels and lymph nodes

Question 2. Write a short note on the external jugular vein.
Answer.

Formation The external jugular vein is formed on the sternocleidomastoid muscle below and behind the angle of the mandible by the union of the posterior auricular vein and posterior division of the retromandibular vein. It has two valves – one before its termination and another an inch above the middle of the clavicle.

Course It descends obliquely downwards and backwards across the sternocleidomastoid. It pierces the superficial lamina of the investing layer of deep cervical fascia above the clavicle in the region of the subclavian triangle. Here it crosses the third part of the subclavian artery and after piercing a deep lamina of the investing layer of the deep cervical fascia ends in the subclavian vein deep into the clavicle.

Tributaries These are

• Anterior jugular vein
• Transverse cervical vein
• Suprascapular vein

Applied anatomy

• Air embolism: If the external jugular vein is cut an inch above the clavicle, its lumen is held open because its margins are adhered to the deep fascia. As a result, the air is sucked into the lumen of the external jugular vein during inspiration, leading to air embolism that may subsequently cause death.
• The external jugular vein is used by clinicians to measure the external jugular venous pressure and/or pressure in the right atrium.

Question 3. Enumerate the various layers of the deep cervical fascia.
Answer.

The deep cervical fascia consists of the following three layers:

• Investing layer
• pretracheal fascia/layer
• Prevertebral fascia/layer

Question 4. Describe the investing layer of the deep cervical fascia in brief.
Answer.

It surrounds the neck like a collar.

Attachments

Superiorly

• External occipital protuberance
• Superior nuchal line
• Mastoid process
• Base of mandible

Inferiorly

• Spine of scapula
• Acromion process of scapula
• Clavicle
• Manubrium sterni

Read And Learn More: Selective Anatomy Notes And Question And Answers

Anteriorly

• Symphysis menti
• Hyoid bone
• Oblique line of thyroid cartilage

Posteriorly

• Ligamentum nuchae
• Spine of 7th cervical vertebra

Features

• Splits to enclose:
  • Two muscles: Trapezius and sternocleidomastoid
  • Two salivary glands: Parotid and submandibular
  • Two spaces: Suprasternal and supraclavicular
• Forms two pulleys/slings – one each for the intermediate tendon of digastric and omohyoid
• Thickens to form two structures: Stylomandibular ligament and parotid masseteric fascia

Question 5. What is suprasternal space (of Burns)? Give its contents.
Answer.

It is a triangular space above the suprasternal notch enclosed between the two layers of the investing layer of deep cervical fascia.

Contents

• Sternal heads of sternocleidomastoid muscles
• Jugular venous arch
• Interclavicular (‘T’) ligament
• Lymph node (sometimes)

Question 6. Write a short note on pre-tracheal fascia.
Answer. 

The pretracheal fascia is so called because it is a layer of deep cervical fascia that lies in front of trachea.

Attachments

Superiorly

• Hyoid bone in the median plane
• Oblique line of thyroid cartilage
• Cricoid cartilage

Inferiorly:

• It splits to enclose the thyroid gland, i.e. forms a capsule of the thyroid gland and finally blends with the arch of the aorta.
• On either side, it fuses with the front of the carotid sheath.

Functions

• Provides a slippery surface for the free movements of the trachea during deglutition
• Supports the thyroid gland and does not allow it to sink into the mediastinum

Applied anatomy Thyroid swelling moves up and down during swallowing because it is enclosed in the pretracheal fascia, which is attached to the laryngeal skeleton (i.e. cricoid and thyroid cartilages and hyoid bone). Since the larynx moves up and down during swallowing, the thyroid gland also moves up and down during swallowing.

Question 7. Write a short note on prevertebral fascia.
Answer.

It is so called because it lies in front of the cervical part of the vertebral column.

Attachments

Superiorly: The base of the skull.

Inferiorly: Bodies of T3 and T4 vertebra.

Laterally: Merges with posterior lamina of investing layer of the deep cervical fascia enclosing trapezius muscle.

Features to remember

• Forms the fascial carpet of the floor of the posterior triangle.
• Cervical and brachial plexuses of nerves lie deep in it.
• Forms axillary sheath, which extends into the axilla. (Note: The subclavian and axillary veins lie outside the sheath so that they can dilate during increased venous return from the limb.)

Question 8. Write a short note on the carotid sheath.
Answer.

Formation

• It is formed by the condensation of fibroareolar tissue around common and internal carotid arteries and internal jugular vein.
• It extends from the base of the skull to the arch of the aorta.
• Its anterior wall is connected to the pretracheal fascia while its posterior wall is connected to the prevertebral fascia.

Thickness It is thick around common and internal carotid arteries, and thin around the internal jugular vein to allow the free expansion of the vein during increased venous return.

Relations

Anteriorly: Ansa cervicalis is embedded in the wall or sheath.

Posteriorly: The sympathetic trunk is present behind the sheath.

Contents

• Common and internal carotid arteries
• Internal jugular vein
• Vagus nerve

Applied anatomy It is frequently exposed in block dissection of the neck during surgical removal of the deep cervical lymph nodes.

Question 9. Write a short note on cervical lymph nodes.
Answer.

The cervical lymph nodes are divided into two groups: (a) superficial and (b) deep.

Superficial lymph nodes The following groups of superficial lymph nodes are present at the craniocervical junction.

• Submental nodes
• Submandibular lymph nodes
• Preauricular (superficial parotid) nodes
• Retroauricular nodes
• Occipital nodes

Others

• Nodes lying along the facial vein
• Node lying along the anterior jugular vein
• Nodes lying along the external jugular vein

Deep lymph nodes

Groups of lymph nodes lying along the internal jugular vein

• Jugulo-digastric nodes
• Jugulo-omohyoid nodes

Others

• Retropharyngeal
• Prelaryngeal
• Pretracheal and paratracheal

Question 10. Describe the sternocleidomastoid muscle in brief.
Answer.

The sternocleidomastoid muscle is a large superficial muscle of the neck. It lies obliquely on the side of the neck between anterior and posterior triangles. It stands out prominently when the head is turned to the opposite side.

Origin It arises by two heads – sternal and clavicular.

1. Sternal head: By a rounded tendon from the upper part of the anterior surface of the manubrium sterni.
2. Clavicular head: By the musculoaponeurotic fibres from the superior border and anterior surface of the medial one-third of the clavicle.

Insertion By a strong tendon into the lateral surface of the mastoid process and by thick aponeurosis into the lateral half of the superior nuchal line of the occipital bone.

Nerve supply

• Spinal accessory nerve (motor)
• Ventral rami of C2 and C3 (proprioceptive)

Actions

• Tilts the head towards the shoulder on the same side and simultaneously rotates the head in such a way that the face is turned to the opposite side and upwards.
• Both the muscles acting together draw the head forward and downwards, as in lifting/elevating the head from the pillow when lying down on the bed in the supine position.

Applied anatomy

Torticollis: It is a deformity of the neck in which the head is bent to one side and the chin faces towards the opposite side. It occurs due to spasm or contracture of the sternocleidomastoid muscle.

Question 11. Describe the posterior triangle under the following headings:

1. Boundaries,
2. Contents and 
3. Applied anatomy.
   

Answer.

It is a triangle on the side of the neck.

Boundaries

Anterior: Posterior border of sternocleidomastoid.

Posterior: Anterior border of trapezius.

Inferior (or base): Middle one-third of the clavicle.

Apex: Meeting point of sternocleidomastoid and trapezius at the superior nuchal line of the occipital bone.

Floor: It is muscular and formed by the following muscles from above to downwards:

• Semispinalis capital
• Splenius capitis
• Levator scapulae
• Scalenus medius

Roof

• Investing layer of the deep cervical fascia
• Superficial fascia containing platysma

Contents The main contents are

• Roots and trunks of the brachial plexus
• The third part of the subclavian artery
• Subclavian vein
• Spinal accessory nerve
• Occipital artery
• Lymph nodes
• Inferior belly of omohyoid

Applied anatomy

• Pus from the tubercular abscess of the cervical spine may track into the posterior triangle, deep to a prevertebral layer of the deep cervical fascia (i.e. underneath the fascial carpet of the posterior triangle), and may produce swelling.
• Left supraclavicular lymph nodes (Virchow lymph nodes) may be enlarged due to malignancy of the stomach and other abdominal organs.

Question 12. What are the subdivisions of the posterior triangle?
Answer.

The posterior triangle is divided into two parts by an inferior belly of omohyoid:

• A larger upper part is called the occipital triangle because it contains the occipital artery.
• A smaller lower part is called a subclavian triangle because it contains a subclavian artery. It is also called a supraclavicular triangle.

Question 13. Enumerate the structures piercing the roof of the posterior triangle.
Answer.

The roof of the posterior triangle is pierced by the following structures.

Four cutaneous nerves

• Lesser occipital nerve (C2)
• Great auricular nerve (C2 and C3)
• Transverse cervical nerve (C2 and C3)
• Supraclavicular nerves (anterior, middle and posterior; C3 and C4)

One vein External jugular vein

Question 14. Describe the digastric (submandibular) triangle in brief.
Answer.

Boundaries

Anteroinferiorly: Anterior belly of digastric.

Posteroinferiorly: Posterior belly of digastric and stylohyoid.

Superiorly (base)

• Base of mandible
• An imaginary line, joining the angle of the mandible to the mastoid process

Floor: From anterior to posterior, it is formed by three muscles:

• Mylohyoid
• Hyoglossus
• Middle constrictor of the pharynx

Roof: It is formed by:

• Investing layer of the deep fascia enclosing the submandibular gland
• Superficial fascia containing:
  • Cervical branch of the facial nerve
  • Cutaneous branch of the great auricular nerve
  • Common facial vein

Contents

Question 15. Describe the boundaries and contents of the carotid triangle.
Answer.

Boundaries

Anterosuperiorly: Posterior belly of the digastric and the stylohyoid.

Anteroinferiorly: Superior belly of the omohyoid.

Posteriorly: Anterior border of the sternocleidomastoid.

Contents

Arteries

• Common carotid artery
• Internal carotid artery
• The external carotid artery and its first five branches (superior thyroid, lingual, facial, ascending pharyngeal and occipital arteries)

Veins

• Internal jugular vein
• Common facial vein
• Pharyngeal vein
• Lingual vein

Nerves

• Vagus nerve
• Superior laryngeal branch of the vagus nerve, dividing into the external and internal laryngeal nerves
• Spinal accessory nerve running obliquely backwards and downwards over the internal jugular vein
• Hypoglossal nerve running horizontally forward over the external carotid, internal carotid and lingual (loop) arteries
• Ansa cervicalis
• Sympathetic chain

Lymph nodes Deep cervical lymph nodes

Special structures

• Carotid sinus
• Carotid body

Question 16. Write a short note on the ansa cervicalis.
Answer.

The ansa cervicalis is a ‘U’-shaped nerve loop derived from ventral rami of C1, C2 and C3 nerves.

Location

It lies on the anterior wall of the carotid sheath in the carotid triangle.

Roots

• The superior root (limb) is formed by descendants hypoglossal (a branch of the hypoglossal nerve), which contains the fibres of the ventral ramus of the C1 nerve.
• The inferior root (limb) is formed by the descending cervicalis, which contains the fibres of the ventral rami of the C2 and C3 nerves.

Distribution

Superior root → superior belly of omohyoid

Inferior root → sternohyoid, sternothyroid and inferior belly of omohyoid

Question 17. Describe briefly the carotid sinus and carotid body.
Answer.

Carotid sinus

It is a dilatation in the terminal part of the common carotid artery and/or the beginning of the internal carotid artery. It is richly innervated by glossopharyngeal and sympathetic nerves. It functions as a baroreceptor. The pressure on the carotid sinuses (in individuals with carotid sinus hypersensitivity) can lead to slowing of heart rate (bradycardia) and syncope (carotid sinus syndrome).

Carotid body

It is a small, reddish-brown oval body that lies behind the bifurcation of the common carotid artery. It is supplied by glossopharyngeal, vagus, and sympathetic nerves. It acts as a chemoreceptor and responds to O₂ and CO₂ levels, and the pH of the blood.

Question 18. Describe the external carotid artery in brief.
Answer.

Origin and extent

• It is one of the two terminal branches of the common carotid artery.
• It extends from the level of the upper border of the thyroid cartilage to the back of the neck of the mandible, where it terminates by dividing into superficial temporal and maxillary arteries.

Branches

They are eight in number which corresponds to the number of alphabets in the term ‘EXTERNAL’, i.e. 8.

Question 19. Write a short note on the facial artery.
Answer.

Origin and extent

It arises from the anterior aspect of the external carotid artery in the carotid triangle of the neck, just below the level of the tip of the greater cornu of the hyoid bone.

It extends from its site of origin in the neck to the medial angle of the eye in the face, where it terminates by anastomosing with the dorsal nasal artery, a branch of the ophthalmic artery.

Branches

In the neck

• Ascending palatine artery
• Glandular branches to the submandibular gland
• Tonsillar artery
• Submental artery

In the face

• Superior labial artery
• Inferior labial artery
• Lateral nasal branch
• Unnamed muscular branches

Applied anatomy

The pulsations of the facial artery can be felt:

• On the base of the mandible, at the anteroinferior angle of the masseter
• 1.25 cm lateral to the angle of mouth, just lateral to modiolus with index finger put in the oral cavity and thumb placed on the outer aspect of the cheek

Question 20. Describe the boundaries and contents of the muscular triangle.
Answer.

Boundaries

Anteriorly: The anterior median line of the neck.

Posterosuperiorly: Superior belly of omohyoid.

Posteroinferiorly: Anterior border of the sternocleidomastoid.

Contents Infrahyoid (ribbon) muscles:

Question 21. Describe the boundaries and contents of the submental triangle.
Answer.

Boundaries

Lateral (on each side): Anterior belly of digastric.

Base: Body of hyoid bone.

Apex: Symphysis menti.

Floor: Oral diaphragm (formed by mylohyoid muscles).

Roof: Investing layer of deep cervical fascia.

Contents

• Submental lymph nodes (three to four in number)
• Submental veins, which unite to form anterior jugular veins

Question 22. Enumerate the structures in the anterior median line of the neck.
Answer.

From above to downward, these are

• Mylohyoid raphe (a fibrous raphe extending from the symphysis menti to the hyoid bone)
• Body of hyoid bone
• Median thyrohyoid ligament
• The angle of thyroid cartilage (Adam’s apple in males)
• Median cricothyroid ligament
• Cricoid cartilage
• The first ring of the trachea
• Isthmus of the thyroid gland lying on the 2nd, 3rd and 4th tracheal rings
• Infrahyoid veins and thyroid ima artery (sometimes)
• Jugular venous arch connecting two anterior jugular veins

Question 23. Describe the boundaries, contents and applied anatomy of the suboccipital triangle.
Answer.

The suboccipital triangle is an intermuscular triangular space situated deep in the suboccipital region.

Boundaries

Superomedially:

Rectus capitis posterior major supplemented by the rectus capitis posterior minor.

Superolaterally:

Obliquus capitis superior.

Inferiorly

Obliquus capitis inferior.

Floor

• Posterior arch of atlas
• Posterior atlanto-occipital membrane

Roof

• Medially
  • Dense fibrous tissue covered by semispinalis capitis
• Laterally
  • Longissimus capitis
  • Splenius capitis

Contents

• The third part of the vertebral artery
• Dorsal ramus of the 1st cervical nerve (suboccipital nerve)
• Greater occipital nerve (dorsal ramus of C2)
• Suboccipital plexus of veins

Applied anatomy The suboccipital triangle is the

• Site for cisternal puncture
• Site through which neurosurgeons approach the posterior cranial fossa of cranial cavity