Anatomy of the neck part 2

Question 1

Where does the bifurcation of the common carotids occur

Answer 1

The superior part of each common carotid artery and its division into external and internal carotid arteries occurs in the carotid triangle (Fig. 8.166), which is a subdivision of the anterior triangle of the neck

Question 2

Describe the carotid sinus

Answer 2

At the bifurcation, the common carotid artery and the beginning of the internal carotid artery are dilated. This dilation is the carotid sinus (Fig. 8.167) and contains receptors that monitor changes in blood pressure and are innervated by a branch of the glossopharyngeal nerve [IX].

Question 3

Describe the carotid body

Answer 3

Another accumulation of receptors in the area of the bifurcation is responsible for detecting changes in blood chemistry, primarily oxygen content. This is the carotid body and is innervated by branches from both the glossopharyngeal [IX] and vagus [X] nerves.

Question 4

Summarise the internal carotid arteries

Answer 4

After its origin, the internal carotid artery ascends toward the base of the skull (Fig. 8.167). It gives off no branches in the neck and enters the cranial cavity through the carotid canal in the petrous part of the temporal bone.
The internal carotid arteries supply the cerebral hemispheres, the eyes and the contents of the orbits, and the forehead.

Question 5

Summarise the external carotid arteries

Answer 5

The external carotid arteries begin giving off branches immediately after the bifurcation of the common carotid arteries

Question 6

What does the internal jugular vein drain; describe its basic appearance and where it exits the skull

Answer 6

Collecting blood from the skull, brain, superficial face, and parts of the neck, the internal jugular vein begins as a dilated continuation of the sigmoid sinus, which is a dural venous sinus. This initial dilated part is referred to as the superior bulb of jugular vein and receives another dural venous sinus (the inferior petrosal sinus) soon after it is formed. It exits the skull through the jugular foramen associated with the glossopharyngeal [IX], vagus [X], and accessory [XI] nerves, and enters the carotid sheath.

Question 7

Describe the passage of the internal jugular vein

Answer 7

The internal jugular vein traverses the neck within the carotid sheath, initially posterior to the internal carotid artery, but passes to a more lateral position farther down. It remains lateral to the common carotid artery through the rest of the neck with the vagus nerve [X] posterior and partially between the two vessels.
The paired internal jugular veins join with the subclavian veins posterior to the sternal end of the clavicle to form the right and left brachiocephalic veins

Question 8

List some tributaries of the internal jugular vein

Answer 8

Tributaries to each internal jugular vein include the inferior petrosal sinus, and the facial, lingual, pharyngeal, occipital, superior thyroid, and middle thyroid veins.

Question 9

Describe the importance of the jugular venous pulse

Answer 9

The jugular venous pulse is an important clinical sign that enables the physician to assess the venous pressure and waveform and is a reflection of the functioning of the right side of the heart

Question 10

Which cranial nerves pass through the anterior triangle

Answer 10

The cranial nerves in these categories include the facial [VII], glossopharyngeal [IX], vagus [X], accessory [XI], and hypoglossal [XII

Question 11

Branches of which spinal nerve pass through the anterior triangle

Answer 11

Branches of spinal nerves in these categories include the transverse cervical nerve from the cervical plexus and the upper and lower roots of the ansa cervicalis.

Question 12

Describe the facial nerve in the anterior triangle

Answer 12

After emerging from the stylomastoid foramen, the facial nerve [VII] gives off branches that innervate two muscles associated with the anterior triangle of the neck:
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the posterior belly of the digastric, and
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the stylohyoid.
The facial nerve [VII] also innervates the platysma muscle that overlies the anterior triangle and part of the posterior triangle of the neck.

Question 13

Describe the passage of the glossopharyngeal nerve

Answer 13

It begins its descent between the internal carotid artery and the internal jugular vein, lying deep to the styloid process and the muscles associated with the styloid process. As the glossopharyngeal nerve [IX] completes its descent, it passes forward between the internal and external carotid arteries, and curves around the lateral border of the stylopharyngeus muscle (Fig. 8.168). At this point, it continues in an anterior direction, deep to the hyoglossus muscle, to reach the base of the tongue and the area of the palatine tonsil.

Question 14

What does the glossopharyngeal nerve innervate in the anterior triangle

Answer 14

As the glossopharyngeal nerve [IX] passes through the area of the anterior triangle of the neck it innervates the stylopharyngeus muscle, sends a branch to the carotid sinus, and supplies sensory branches to the pharynx.

Question 15

Describe the basic course of the vagus nerve

Answer 15

The vagus nerve [X] exits the cranial cavity through the jugular foramen between the glossopharyngeal [IX] and accessory [XI] nerves.
Outside the skull the vagus nerve [X] enters the carotid sheath and descends through the neck enclosed in this structure medial to the internal jugular vein and posterior to the internal carotid and common carotid arteries

Question 16

Describe the branches of the vagus nerve in the anterior triangle

Answer 16

Branches of the vagus nerve [X] as it passes through the anterior triangle of the neck include a motor branch to the pharynx, a branch to the carotid body, the superior laryngeal nerve (which divides into external and internal laryngeal branches), and possibly a cardiac branch.

Question 17

Describe the basic course of the accessory nerve

Answer 17

The accessory nerve [XI] is the most posterior of the three cranial nerves exiting the cranial cavity through the jugular foramen. It begins its descent medial to the internal jugular vein, emerging from between the internal jugular vein and internal carotid artery to cross the lateral surface of the internal jugular vein as it passes downward and backward to disappear either into or beneath the anterior border of the sternocleidomastoid muscle

Question 18

Does the accessory nerve give off any branches in the anterior triangle

Answer 18

The accessory nerve gives off no branches as it passes through the anterior triangle of the neck.

BUT it does innervate the sternocleidomastoid and trapezius muscle

Question 19

How would you test the function of the accessory nerve

Answer 19

Ask the patient to shrug their shoulders and hold it there

Question 20

Where does the accessory nerve exit the skull?

Answer 20

The accessory nerve begins in the upper spinal cord and ascends to enter the skull through the foramen magnum
The accessory nerve then leaves via the jugular foramen

Question 21

Describe the basic course of the hypoglossal nerve

Answer 21

The hypoglossal nerve [XII] leaves the cranial cavity through the hypoglossal canal and is medial to the internal jugular vein and internal carotid artery immediately outside the skull. As it descends, it passes outward between the internal jugular vein and internal carotid artery (Fig. 8.171). At this point it passes forward, hooking around the occipital artery, across the lateral surfaces of the internal and external carotid arteries and the lingual artery, and then continues deep to the posterior belly of the digastric and stylohyoid muscles. It passes over the surface of the hyoglossus muscle and disappears deep to the mylohyoid muscle.

Question 22

Are there any branches of the hypoglossal nerve in the anterior triangle

Answer 22

The hypoglossal nerve [XII] leaves the cranial cavity through the hypoglossal canal and is medial to the internal jugular vein and internal carotid artery immediately outside the skull. As it descends, it passes outward between the internal jugular vein and internal carotid artery (Fig. 8.171). At this point it passes forward, hooking around the occipital artery, across the lateral surfaces of the internal and external carotid arteries and the lingual artery, and then continues deep to the posterior belly of the digastric and stylohyoid muscles. It passes over the surface of the hyoglossus muscle and disappears deep to the mylohyoid muscle.

Question 23

Describe the transverse cervical nerve

Answer 23

Branch of cervical plexus arising from the anterior rami of C2-3.
It emerges deep to the posterior border of the sternocleidomastoid, near the middle of the muscle, and loops around the muscle to cross its anterior surface in a transverse direction.
It continues across the neck and provides cutaneous innervation to this area.

Question 24

Describe the ansa cervicalis

Answer 24

A loop of nerve fibres from C1-C3 that innervate the ‘strap muscles’ in the anterior triangle of the neck.
It begins as branches of the cervical nerve C1 join the hypoglossal nerve soon after it leaves the skull.
Superior and inferior roots innervate the superior and inferior bellies of the omohyoid muscle respectively.

Question 25

Describe the anatomical location of the oesophagus

Answer 25

The oesophagus is part of the G.I system and has a short course in the lower neck. It begins at C6, where it is continuous with the pharynx above and courses inferiorly to pass through the thoracic inlet. It lies directly anterior to the vertebral column.

Question 26

Describe the anatomical location of the trachea

Answer 26

Part of lower airway and, like the oesophagus, begins at C6, where it is continuous with the larynx above. The larynx lies directly anterior to the oesophagus and passes inferiorly in the midline to enter the thorax.

Question 27

Describe the anatomical location of the pharynx and larynx

Answer 27

Pharynx- common pathway for air and food, and it connects respiratory and digestive compartments in the head with similar compartments in the lower neck
The larynx is the upper end of the lower airway. It is continuous with the trachea below and the pharynx poster superiorly.

Question 28

Describe the basic structure of the thyroid gland

Answer 28

The thyroid gland is anterior in the neck below and lateral to the thyroid cartilage. It consists of two lateral lobes (which cover the anterolateral surfaces of the trachea, the cricoid cartilage, and the lower part of the thyroid cartilage) with an isthmus that connects the lateral lobes and crosses the anterior surfaces of the second and third tracheal cartilages.

Question 29

Describe the anatomical location of the thyroid gland

Answer 29

Lying deep to the sternohyoid, sternothyroid, and omohyoid muscles, the thyroid gland is in the visceral compartment of the neck. This compartment also includes the pharynx, trachea, and esophagus and is surrounded by the pretracheal layers of fascia.

Question 30

Describe the key features of the parathyroid glands

Answer 30

The parathyroid glands are two pairs of small, ovoid, yellowish structures on the deep surface of the lateral lobes of the thyroid gland. They are designated as the superior and inferior parathyroid glands. However, their position is quite variable and they may be anywhere from the carotid bifurcation superiorly to the mediastinum inferiorly.

Question 31

Out of the triangles which constitute the anterior triangle of the neck, which is the only unpaired triangle?

Answer 31

the submental triangle.

Question 32

What is the function of the trapezius

Answer 32

To elevate the shoulders

Question 33

What are the muscles of the anterior triangle mainly associated with

Answer 33

Moving mandible. hyoid and larynx (or stabilising these structures during swallowing)

Question 34

What is the posterior triangle mainly filled with

Answer 34

Nerves and vessels on their way down to the neck and the limbs

Question 35

Where is the posterior triangle found

Answer 35

The posterior triangle of the neck is on the lateral aspect of the neck in direct continuity with the upper limb

Question 36

Describe the borders of the posterior triangle

Answer 36

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anteriorly by the posterior edge of the sternocleidomastoid muscle,

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posteriorly by the anterior edge of the trapezius muscle,

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basally by the middle one-third of the clavicle, and

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apically by the occipital bone just posterior to the mastoid process where the attachments of the trapezius and sternocleidomastoid come together.

Question 37

What are the key structures found in the posterior triangle

Answer 37

External jugular vein
Subclavian artery
Subclavian vein
Trunks of the brachial plexus
Phrenic nerve
Vagus nerve
Spinal accessory nerve

Question 38

What layer of fascia is found at the roof of the posterior triangle

Answer 38

The roof of the posterior triangle consists of an investing layer of cervical fascia that surrounds the sternocleidomastoid and trapezius muscles as it passes through the region.

Question 39

What fascia is found at the floor of the posterior triangle

Answer 39

The muscular floor of the posterior triangle is covered by the prevertebral layer of cervical fascia; and from superior to inferior consists of the splenius capitis, levator scapulae, and the posterior, middle, and anterior scalene muscles.

Question 40

Describe the origin and insertion of the trapezius

Answer 40

Origin: Superior nuchal line; external occipital protuberance; ligamentum nuchae; spinous processes of vertebrae CVII to TXII

Insertion: Lateral one-third of clavicle; acromion; spine of scapula

Question 41

Describe the innervation and function of the trapezius

Answer 41

Motor—accessory nerve [XI]; proprioception—C3 and C4

Assists in rotating the scapula during abduction of humerus above horizontal;
upper fibers—elevate,
middle fibers—adduct,
lower fibers—depress scapula

Question 42

Describe the origins and insertions of the sternocleidomastoid

Answer 42

Sternal head:
origin- Upper part of anterior surface of manubrium of sternum

insertion- Lateral one-half of superior nuchal line

clavicular head:
origin- Superior surface of medial one-third of clavicle

insertion - Lateral surface of mastoid process

Question 43

Describe the innervation and function of the sternocleidomastoid

Answer 43

Accessory nerve [XI] and branches from anterior rami of C2 to C3 (C4)

Individually—will tilt head toward shoulder on same side rotating head to turn face to opposite side; acting together, draw head forward

Question 44

List the muscles found in the posterior triangle

Answer 44

Trapezius
Sternocleidomastoid
Splenius capitis
Levator scapulae
Posterior scalene
Middle scalene
Anterior scalene
Omohyoid

Question 45

Describe the superior and inferior bellies of the omohyoid

Answer 45

The superior belly is in the anterior triangle.

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The inferior belly crosses the posterior triangle, subdividing it into a small, omoclavicular or subclavian triangle inferiorly and a much larger occipital triangle superiorly.

Question 46

Describe the formation of the external jugular vein

Answer 46

One of the most superficial structures passing through the posterior triangle of the neck is the external jugular vein (Fig. 8.181). This large vein forms near the angle of the mandible, when the posterior branch of the retromandibular and posterior auricular veins join, and descends through the neck in the superficial fascia.

Question 47

Outline the basic course of the external jugular vein

Answer 47

After crossing the sternocleidomastoid muscle, the external jugular vein enters the posterior triangle and continues its vertical descent.

In the lower part of the posterior triangle, the external jugular vein pierces the investing layer of cervical fascia and ends in the subclavian vein.

Question 48

What are the tributaries of the external jugular vein

Answer 48

Tributaries to the external jugular vein while it traverses the posterior triangle of the neck include the transverse cervical, suprascapular, and anterior jugular veins.

Question 49

Which part of the subclavian artery is found in the posterior triangle of the neck

Answer 49

Several arteries are found within the boundaries of the posterior triangle of the neck. The largest is the third part of the subclavian artery as it crosses the base of the posterior triangle

Question 50

Describe the first part of the subclavian artery

Answer 50

The first part of the subclavian artery ascends to the medial border of the anterior scalene muscle from either the brachiocephalic trunk on the right side or directly from the arch of the aorta on the left side. It has numerous branches.

Question 51

Describe the second part of the subclavian artery

Answer 51

The second part of the subclavian artery passes laterally between the anterior and middle scalene muscles, and one branch may arise from it.

Question 52

Describe the third part of the subclavian artery

Answer 52

The third part of the subclavian artery emerges from between the anterior and middle scalene muscles to cross the base of the posterior triangle. It extends from the lateral border of the anterior scalene muscle to the lateral border of rib I where it becomes the axillary artery and continues into the upper limb.

Question 53

Describe the branches of the first two parts of the subclavian arteries

Answer 53

first part
vertebral artery: courses cranially to supply the posterior cerebral circulation
internal thoracic artery: courses caudally
thyrocervical trunk: very short trunk that soon divides into 4 branches
second part
costocervical trunk: courses cranially before bifurcating

Question 54

Which branch may arise from the third part of the subclavian artery

Answer 54

A single branch (the dorsal scapular artery) may arise from the third part of the subclavian artery. This branch passes posterolaterally to reach the superior angle of the scapula where it descends along the medial border of the scapula posterior to the rhomboid muscles.