Triangles Of Neck

Question 1

What arch forms CN V?

Answer 1

First arch

Question 2

What arch forms CN VII?

Answer 2

Second arch

Question 3

What arch forms CN IX?

Answer 3

Third arch

Question 4

What arch forms CN X?

Answer 4

Fourth/sixth arch

Question 5

What is cervical fascia?

Answer 5

Component of connective tissue forming
sheaths around structures in the neck

• Covers the triangles of the neck

Question 6

Contrast a deep and superficial. Cervical fascia

Answer 6

• Superficial fascia
– Loose, fatty subcutaneous layer (contains the platysma m.)

• Deep fascia

1. Carotid sheath
2. Superficial (investing) layer
3. Middle (pretracheal) layer
   Infrahyoid/muscular fascia (A)
   Visceral fascia
   – Pretracheal fascia (B)
   – Buccopharyngeal fascia (C)
4. Deep (prevertebral) layer

All layers contribute to carotid sheath

Question 7

What is the investing fascia?

Answer 7

Deep to superficial fascia and embedded platysma muscle

Surrounds the neck ‘investing’ around the SCM and trapezius m.

Question 8

What are the boundaries of the posterior triangle?

Answer 8

Boundaries of posterior triangle – trapezius m. (CN XI)
posterior triangle
• Upper fibers- elevate scapula
• Middle fibers- adduct scapula
• Lower fibers- depress scapula

– sternocleidomastoid m. (CN XI)
• Unilateral headrotationto
opposite side

• Bilateral draw head forward
– clavicle

Question 9

What are the boundaries of the anterior triangle?

Answer 9

Boundaries of anterior triangle
– midline
– sternocleidomastoid m. (CN XI)
– mandible

Question 10

What does the Omohyoid muscle do?

Answer 10

Omohyoid (inf. belly)

• subdivides the posterior triangle into occipital and subclavian (supraclavicular) triangles

Question 11

What nerves innervate posterior, anterior and middle scalene?

Answer 11

C3-7

Question 12

What innervates splenus capitus?

Answer 12

(Dorsal ramus)

Question 13

What nerve innervates the levator scapulae?

Answer 13

Dorsal scapular nerve

Question 14

What’s the importance of cervical plexus?

Answer 14

Cervical plexus – ventral rami

of spinal nerves C1-C4

Question 15

What are the cutaneous branches of the posterior triangle?

Answer 15

Cutaneous branches emerging from the posterior triangle

Lesser occipital (C2)
Great auricular (C2,3) 
Transverse cervical (C2,3)
Supraclavicular (C3,4)

Question 16

What are the motor and cutaneous areas of the cervical plexus?

Answer 16

Formed by ventral rami of cervical spinal nerves C1-C4

Motor - to infrahyoid and prevertebral muscles of the neck and diaphragm (phrenic n.)

Cutaneous - areas of head, neck, shoulder upper chest, and central part of diaphragm (phrenic n.)

Question 17

What is the path of the hypoglossal nerve?

Answer 17

Path of the nerve:
• exits the skull through hypoglossal canal and descends medial to ICA and IJV
• passes between ICA and IJV and hooks around occipital a.
• passes deep to digastric and stylohyoid mm.
• disappears deep to mylohyoid m. on its way to tongue

Question 18

What does the hypoglossal nerve innervate?

Answer 18

C1 fibers piggyback along hypoglossal n. to geniohyoid and thyrohyoid mm.
All other infrahyoid muscles are innervated by the ansa cervicalis (C1-C3)

Question 19

What spinal level innervate the nerve to thyrohyoid?

Answer 19

C1

Question 20

What are the contents of the carotid sheath?

Answer 20

Contents of the carotid sheath:

Internal jugular v. (IJV)
Common carotid a. (CCA)
Vagus nerves

Question 21

What are the contents of the posterior sheath?

Answer 21

Carotid sheath:
Internal jugular v. (IJV)
Common carotid a. (CCA)
Vagus nerves

Inferior thyroid artery

Thyrocervical trunk

Phrenic nerve-

Phrenic n. (C3,4,5)
* On top of anterior scalene muscle

Transverse cervical artery
1. superficial branch
2. deep (descending) branch
Maybe absent if it came off directly from subclavian as the dorsal scapular artery

Structures emerging through the scalene gap (triangle) formed by ant. & mid. scalene muscles:

 - Brachial plexus trunks (C5-T1) 
 - Subclavian a.

Question 22

What does NOT pass through the scalene gap?

Answer 22

Subclavian v.

Question 23

What is the anterior triangle divided into?

Answer 23

Subdivided by digastric and
omohyoid mm. into:
1. submental triangle
2. digastric (submandibular) triangle
3. carotid triangle
4. muscular triangle

Question 24

What is the vasculature from the internal and external carotid artery?

Answer 24

Internal carotid a. (ICA):
No branches until inside skull

External carotid a. (ECA):

1. sup. thyroid artery
2. ascending pharyngeal a.
3. lingual a.
4. facial a.
5. occipital a.
6. post. auricular a.
7. maxillary a.
8. superficial temporal a.

Question 25

What is the Carotid sinus?

Answer 25

Carotid sinus dilated portion at the proximal part of ICA • Contains baroreceptors to monitor blood pressure • Innervated by branches of CN IX

Question 26

What is the carotid body?

Answer 26

``` Carotid body small cluster of cells near carotid sinus • Contains chemoreceptors to monitor blood chemistry (i.e. O2, pH) • Innervated by branches of CN IX and X ```

Question 27

What is the thyroid gland?

Answer 27

2 lobes connected by isthmus (anterior to 2nd and 3rd tracheal cartilages) Pyramidal lobe (if present) – along the path of thyroglossal duct

Question 28

What is the arterial supply of the thyroid gland?

Answer 28

• superior thyroid (from ECA) • inferior thyroid (from thyrocervical trunk) • thyroid ima – (variable presence)

Question 29

Whaat is the venous drainage of the thyroid gland?

Answer 29

- Venous drainage • superior thyroid (into IJV) • middle thyroid (into IJV) • inferior thyroid (into brachiocephalic vein)

Question 30

Where does the recurrent pharyngeal nerve course in relation to the thyroid gland?

Answer 30

The recurrent laryngeal nerve courses posterior to the thyroid gland in the tracheoesophageal groove

Question 31

What are the contents of the carotid sheath?

Answer 31

Fascial tube extending from the base of the skull to thorax contents: • CCA (ICA) • IJV • Vagus n. (CN X) • (CN IX, XI, XII – in the uppermost part of sheath for part of their course)

Question 32

What are the relationships of the carotid sheath?

Answer 32

Relationships: – Phrenic n. lies posterior on top of anterior scalene (covered by prevertebral fascia) – Sympathetic chain lies posteromedial to sheath (in front of prevertebral fascia) – Inside the sheath the IJV is usually large and more superficial (anterior or lateral) to the CCA – Vagus n. is usually found posterior to, and between CCA/IJV

Question 33

What are the collar lymph nodes?

Answer 33

``` Collar nodes (superficial): • occipital • mastoid (posterior auricular) • parotid (pre-auricular) • submandibular • submental ``` - afferents drain superficial structures of face, scalp, and head - form a collar around the neck and efferents drain mainly to the deep cervical nodes (along IJV)

Question 34

What are the superficial cervical nodes?

Answer 34

Superficial cervical nodes - organized into anterior group (along anterior jugular v.) and posterolateral group (along EJV) - afferents drain superficial structures of the neck – efferents drain to the deep cervical nodes

Question 35

Describe the deep cervical lymph nodes

Answer 35

Deep cervical nodes: - Receive most of the lymph from head and neck - located in a vertical chain along the IJV - afferents drain superficial cervical nodes and various other outlying nodes including: prelaryngeal, pretracheal, paratracheal, retropharyngeal, infrahyoid - efferents eventually form R & L jugular trunks and drain to right lymphatic duct or thoracic duct - often divided into superior and inferior groups where the omohyoid tendon crosses IJV 1. Jugulo-digastric (tonsilar) node – large prominent node draining tonsillar region 2. Jugulo-omohyoid node – large prominent node draining the tongue