Anatomy of the neck part 3

Question 1

What two triangles can the posterior triangle be split into

Answer 1

occipital triangle

omoclavicular or subclavian triangle separated by the inferior belly of the omohyoid bone

Question 2

Describe the course of the subclavian artery

Answer 2

The subclavian vein is a continuation of the axillary vein and begins at the lateral border of rib I. As it crosses the base of the posterior triangle, the external jugular, and, possibly, the suprascapular and transverse cervical veins enter it (Fig. 8.181). It ends by joining with the internal jugular vein to form the brachiocephalic vein near the sternoclavicular joint. In the posterior triangle it is anterior to, and slightly lower than, the subclavian artery and passes anterior to the anterior scalene muscle.

Question 3

Describe the transverse cervical and suprascapular veins

Answer 3

Transverse cervical and suprascapular veins travel with each of the similarly named arteries. These veins become tributaries to either the external jugular vein or the initial part of the subclavian vein.

Question 4

Summarise the nerves found in the posterior triangle

Answer 4

A variety of nerves pass through or are within the posterior triangle. These include the accessory nerve [XI], branches of the cervical plexus, components forming the brachial plexus, and branches of the brachial plexus.

Question 5

Outline the course of the accessory nerve

Answer 5

The accessory nerve [XI] exits the cranial cavity through the jugular foramen. It descends through the neck in a posterior direction, to reach the anterior border of the sternocleidomastoid muscle. Passing either deep to or through and innervating the sternocleidomastoid muscle, the accessory nerve [XI] continues to descend and enters the posterior triangle (Fig. 8.183). It crosses the posterior triangle, still in an obliquely downward direction, within the investing layer of cervical fascia as this fascia crosses between the sternocleidomastoid and trapezius muscles. When the accessory nerve [XI] reaches the anterior border of the trapezius muscle, it continues on the deep surface of the trapezius and innervates it.

Question 6

What makes the accesory nerve particuarly suceptible to injury

Answer 6

Its superficial location in the neck

Question 7

What is the cervical plexus formed by

Answer 7

The cervical plexus is formed by the anterior rami of cervical nerves C1 to C4

Question 8

Where does the cervical plexus form and what does it consist of

Answer 8

The cervical plexus forms in the substance of the muscles making up the floor of the posterior triangle within the prevertebral layer of cervical fascia, and consists of:

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muscular (or deep) branches, and

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cutaneous (or superficial) branches.

The cutaneous branches are visible in the posterior triangle emerging from beneath the posterior border of the sternocleidomastoid muscle

Question 9

What does the phrenic nerve innervate

Answer 9

Muscular (deep) branches of the cervical plexus distribute to several groups of muscles. A major branch is the phrenic nerve, which supplies the diaphragm with both sensory and motor innervation

Question 10

Describe the passage of the phrenic nerve

Answer 10

It arises from the anterior rami of cervical nerves C3 to C5. Hooking around the upper lateral border of the anterior scalene muscle, the nerve continues inferiorly across the anterior surface of the anterior scalene within the prevertebral fascia to enter the thorax (Fig. 8.185). As the nerve descends in the neck, it is “pinned” to the anterior scalene muscle by the transverse cervical and suprascapular arteries.

Question 11

List the muscles innervated by the cervical plexus

Answer 11

Several muscular branches of the cervical plexus supply prevertebral and lateral vertebral muscles, including the rectus capitis anterior, rectus capitis lateralis, longus colli, and longus capitis

Question 12

What other important structure does the cervical plexus contribute to and what does the structure innervate

Answer 12

The cervical plexus also contributes to the formation of the superior and inferior roots of the ansa cervicalis (Fig. 8.184). This loop of nerves receives contributions from the anterior rami of the cervical nerves C1 to C3 and innervates the infrahyoid muscles.

Question 13

Where are the cutaneous branches of the cervical plexus visible

Answer 13

Cutaneous (superficial) branches of the cervical plexus are visible in the posterior triangle as they pass outward from the posterior border of the sternocleidomastoid muscle

Question 14

What are the cutaneous branches of the cervical plexus

Answer 14

The lesser occipital nerve
The great auricular nerve
The transverse cervical nerve
The supraclavicular nerves

Question 15

What is the brachial plexus formed from

Answer 15

The brachial plexus forms from the anterior rami of cervical nerves C5 to C8 and thoracic nerve T1. The contributions of each of these nerves, which are between the anterior and middle scalene muscles, are the roots of the brachial plexus.

Question 16

What do these roots form

Answer 16

As the roots emerge from between these muscles, they form the next component of the brachial plexus (the trunks) as follows:

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the anterior rami of C5 and C6 form the upper trunk,

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the anterior ramus of C7 forms the middle trunk,

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the anterior rami of C8 and T1 form the lower trunk.

Question 17

Where do these trunks cross and what are their important branches

Answer 17

The trunks cross the base of the posterior triangle (see Fig. 8.182). Several branches of the brachial plexus may be visible in the posterior triangle (see Fig. 7.54 on pg. 741). These include the:

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dorsal scapular nerve to the rhomboid muscles,

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long thoracic nerve to the serratus anterior muscle,

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nerve to the subclavius muscle, and

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suprascapular nerve to the supraspinatus and infraspinatus muscles.

Question 18

What is meant by the root of the neck and what is it bounded by

Answer 18

The root of the neck (Fig. 8.186) is the area immediately superior to the superior thoracic aperture and axillary inlets. It is bounded by:

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the top of the manubrium of the sternum and superior margin of the clavicle anteriorly, and

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the top of the thoracic vertebra TI and the superior margin of the scapula to the coracoid process posteriorly.

Question 19

Describe the projection of the thoracic cavity into the root of the neck

Answer 19

This consists of an upward projection of the pleural cavity, on both sides, and includes the cervical part of the parietal pleura (cupula), and the apical part of the superior lobe of each lung.

Anteriorly, the pleural cavity extends above the top of the manubrium of the sternum and superior border of rib I, while posteriorly, due to the downward slope of the superior thoracic aperture, the pleural cavity remains below the top of vertebra TI.

Question 20

Describe the passage of the right subclavian artery

Answer 20

The right subclavian artery begins posterior to the sternoclavicular joint as one of two terminal branches of the brachiocephalic trunk. It arches superiorly and laterally to pass anterior to the extension of the pleural cavity in the root of the neck and posterior to the anterior scalene muscle. Continuing laterally across rib I, it becomes the axillary artery as it crosses its lateral border.

Question 21

What divides the subclavian artery into 3 parts

Answer 21

The anterior scalene muscle

Question 22

Describe the 3 parts of the subclavian artery

Answer 22

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The first part extends from the origin of the artery to the anterior scalene muscle.

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The second part is the part of the artery posterior to the anterior scalene muscle.

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The third part is the part lateral to the anterior scalene muscle before the artery reaches the lateral border of rib I.

Question 23

What do the branches of the right and left subclavian artery arise from

Answer 23

All branches from the right and left subclavian arteries arise from the first part of the artery, except in the case of one branch (the costocervical trunk) on the right side (Fig. 8.187). The branches include the vertebral artery, the thyrocervical trunk, the internal thoracic artery, and the costocervical trunk.

Question 24

Describe the course of the vertebral artery

Answer 24

The vertebral artery is the first branch of the subclavian artery as it enters the root of the neck (Fig. 8.187). A large branch, arising from the first part of the subclavian artery medial to the anterior scalene muscle, it ascends and enters the foramen in the transverse process of vertebra CVI. Continuing to pass superiorly, the vertebral artery passes through the foramina of vertebrae CV to CI. At the superior border of vertebra CI, the artery turns medially and crosses the posterior arch of vertebra CI. From here it passes through the foramen magnum to enter the posterior cranial fossa.

Question 25

Describe the course of the subclavian veins in the neck

Answer 25

The subclavian veins begin at the lateral margin of rib I as continuations of the axillary veins. Passing medially on each side, just anterior to the anterior scalene muscles, each subclavian vein is joined by the internal jugular vein to form the brachiocephalic veins.

The only tributary to each subclavian vein is an external jugular vein.

The veins accompanying the numerous arteries in this region empty into other veins.

Question 26

How does the phrenic nerve continue to enter the diaphragm

Answer 26

Leaving the lower edge of the anterior scalene muscle each phrenic nerve passes between the subclavian vein and artery to enter the thorax and continue to the diaphragm.

Question 27

Summarise the passage of the vagus nerve in the neck

Answer 27

The vagus nerves [X] descend through the neck within the carotid sheath, posterior to and just between the common carotid artery and the internal jugular vein.

In the lower part of the neck, the vagus nerves [X] give off cardiac branches, which continue downward and medially, passing posterior to the subclavian arteries to disappear into the thorax.

In the root of the neck, each vagus nerve [X] passes anterior to the subclavian artery and posterior to the subclavian vein as it enters the thorax

Question 28

Where does the right recurrent laryngeal nerve emerge

Answer 28

The right recurrent laryngeal nerve is a branch of the right vagus nerve [X] as it reaches the lower edge of the first part of the subclavian artery in the root of the neck. It passes around the subclavian artery and upward and medially in a groove between the trachea and the esophagus as it heads to the larynx.

Question 29

Where does the left recurrent laryngeal nerve emerge

Answer 29

The left recurrent laryngeal nerve is a branch of the left vagus nerve [X] as it crosses the arch of the aorta in the superior mediastinum. It passes below and behind the arch of the aorta and ascends beside the trachea to the larynx

Question 30

Ultimately, where are the right and left recurrent laryngeal nerves visible

Answer 30

The right and left recurrent laryngeal nerves are visible as they originate in (the right recurrent laryngeal nerve), or pass through (the left recurrent laryngeal nerve), the root of the neck.

Question 31

Describe recurrent laryngeal nerve palsy

Answer 31

Damage to either the right or left recurrent laryngeal nerve may lead initially to a hoarse voice and finally to an inability to speak. Recurrent laryngeal nerve palsy can occur from disruption of the nerves anywhere along their course. Furthermore, interruption of the vagus nerves before the division of the recurrent laryngeal nerves can also produce vocal symptoms.

Lung cancer in the apex of the right lung can affect the right recurrent laryngeal nerve, whereas cancers that infiltrate into the area between the pulmonary artery and aorta, an area known clinically as the “aortopulmonary window,” can affect the left recurrent laryngeal nerve. Thyroid surgery also can traumatize the recurrent laryngeal nerves.

Question 32

Describe the components of the sympathetic nervous system found in the neck

Answer 32

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the cervical part of the sympathetic trunk,

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the ganglia associated with the cervical part of the sympathetic trunk, and

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cardiac nerves branching from the cervical part of the sympathetic trunk.

Question 33

Describe the cervical part of the sympathetic trunk

Answer 33

The cervical part of the sympathetic trunk is anterior to the longus colli and longus capitis muscles, and posterior to the common carotid artery in the carotid sheath and the internal carotid artery. It is connected to each cervical spinal nerve by a gray ramus communicans (Fig. 8.190). There are no white rami communicantes in the cervical region.

Question 34

Describe the cervical ganglion

Answer 34

Three ganglia are usually described along the course of the sympathetic trunk in the cervical region, and in these ganglia ascending preganglionic sympathetic fibers from upper thoracic spinal cord levels synapse with postganglionic sympathetic fibers. The postganglionic sympathetic fibers are distributed in branches from these ganglia.

Superior cervical ganglion
Middle cervical ganglion
Inferior cervical ganglion

Question 35

Summarise the course of the lymphatic duct

Answer 35

the thoracic aorta on the left,

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the azygos vein on the right, and

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the esophagus anteriorly.

At about the level of thoracic vertebra TV the thoracic duct passes to the left and continues to ascend just to the left of the esophagus. It passes through the superior mediastinum and enters the root of the neck to the left of the esophagus (Fig. 8.191). Arching laterally, it passes posterior to the carotid sheath and turns inferiorly in front of the thyrocervical trunk, the phrenic nerve, and the vertebral artery.

Question 36

What may the lymphatic duct be joined by as it enters the venous system

Answer 36

The thoracic duct terminates in the junction between the left internal jugular and the left subclavian veins (Fig. 8.191). Near its junction with the venous system it is joined by:

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the left jugular trunk, which drains lymph from the left side of the head and neck,

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the left subclavian trunk, which drains lymph from the left upper limb, and

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occasionally, the left bronchomediastinal trunk, which drains lymph from the left half of the thoracic structures and upper intercostal spaces

same on right side

Question 37

Describe the variability in how the lympahtic ducts enter the venous system

Answer 37

There is variability in how these trunks enter the veins. They may combine into a single right lymphatic duct to enter the venous system or enter as three separate trunks.

Question 38

Summarise the lymphatics in the neck

Answer 38

A description of the organization of the lymphatic system in the neck becomes a summary of the lymphatic system in the head and neck. It is impossible to separate the two regions. The components of this system include superficial nodes around the head, superficial cervical nodes along the external jugular vein, and deep cervical nodes forming a chain along the internal jugular vein

Question 39

Describe the basic pattern of lymphatic drainage

Answer 39

The basic pattern of drainage is for superficial lymphatic vessels to drain to the superficial nodes. Some of these drain to the superficial cervical nodes on their way to the deep cervical nodes and others drain directly to the deep cervical nodes.

Question 40

What are the superificial lymph nodes primarily responsible for

Answer 40

Five groups of superficial lymph nodes form a ring around the head and are primarily responsible for the lymphatic drainage of the face and scalp. Their pattern of drainage is very similar to the area of distribution of the arteries near their location.

Question 41

List the superficial lymph nodes starting posteriorly

Answer 41

occipital
mastoid (posterior auricular nodes)
pre-auricular and parotid nodes
submandibular nodes
submental nodes

Question 42

Describe the occipital nodes

Answer 42

occipital nodes near the attachment of the trapezius muscle to the skull and associated with the occipital artery—lymphatic drainage is from the posterior scalp and neck;

Question 43

Describe the mastoid nodes

Answer 43

posterior to the ear near the attachment of the sternocleidomastoid muscle and associated with the posterior auricular artery—lymphatic drainage is from the posterolateral half of the scalp;

Question 44

Describe the parotid nodes

Answer 44

anterior to the ear and associated with the superficial temporal and transverse facial arteries—lymphatic drainage is from the anterior surface of the auricle, the anterolateral scalp, the upper half of the face, the eyelids, and the cheeks;

Question 45

Describe the submandibular nodes

Answer 45

inferior to the body of the mandible and associated with the facial artery—lymphatic drainage is from structures along the path of the facial artery as high as the forehead, as well as the gingivae, the teeth, and the tongue;

Question 46

Describe the submental nodes

Answer 46

submental nodes inferior and posterior to the chin—lymphatic drainage is from the center part of the lower lip, the chin, the floor of the mouth, the tip of the tongue, and the lower incisor teeth.

Question 47

Describe the pattern of drainage from the superficial lymphatic nodes

Answer 47

Lymphatic flow from these superficial lymph nodes passes in several directions:

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Drainage from the occipital and mastoid nodes passes to the superficial cervical nodes along the external jugular vein- which may then pass to the deep cervical nodes

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Drainage from the pre-auricular and parotid nodes, the submandibular nodes, and the submental nodes passes to the deep cervical nodes.

Question 48

Summarise the superficial cervical lymph nodes

Answer 48

The superficial cervical nodes are a collection of lymph nodes along the external jugular vein on the superficial surface of the sternocleidomastoid muscle (Fig. 8.193). They primarily receive lymphatic drainage from the posterior and posterolateral regions of the scalp through the occipital and mastoid nodes, and send lymphatic vessels in the direction of the deep cervical nodes.

Question 49

Describe the deep cervical lymph nodes

Answer 49

The deep cervical nodes are a collection of lymph nodes that form a chain along the internal jugular vein (Fig. 8.193). They are divided into upper and lower groups where the intermediate tendon of the omohyoid muscle crosses the common carotid artery and the internal jugular vein.

Question 50

Describe the pattern of flow of lymphatic drainage from the deep cervical lymph nodes

Answer 50

The deep cervical nodes eventually receive all lymphatic drainage from the head and neck either directly or through regional groups of nodes.

From the deep cervical nodes, lymphatic vessels form the right and left jugular trunks, which empty into the right lymphatic duct on the right side or the thoracic duct on the left side.

Question 51

What could enlargements of the neck lymph nodes represent

Answer 51

Enlargement of the neck lymph nodes (cervical lymphadenopathy) is a common manifestation of disease processes that occur in the head and neck. It is also a common manifestation of diffuse diseases of the body, which include lymphoma, sarcoidosis, and certain types of viral infection such as glandular fever and human immunodeficiency virus (HIV) infection.

Question 52

Discuss clinical examination of the neck lymph nodes and highlight its importance

Answer 52

Evaluation of cervical lymph nodes is extremely important in determining the nature and etiology of the primary disease process that has produced nodal enlargement.

Clinical evaluation includes a general health assessment, particularly relating to symptoms from the head and neck. Examination of the nodes themselves often gives the clinician a clue as to the nature of the pathological process.

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Soft, tender, and inflamed lymph nodes suggest an acute inflammatory process, which is most likely to be infective.

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Firm multinodular large-volume rubbery nodes often suggest a diagnosis of lymphoma.

Examination should also include careful assessment of other nodal regions, including the supraclavicular fossae, the axillae, the retroperitoneum, and the inguinal regions.

Further examination may include digestive tract endoscopy, chest radiography, and body CT scanning.