Neck: surface anatomy, fascias, spaces, triangles.

Question 1

What are the 6 deep fascial layers? whats the superficial layer?

Answer 1

Superficial fascia: contains the platysma muscle
Deep Fascial Layers:
1. deep investing fascia (cervical fascia): surrounds SCM
2. infrahyoid fascia: surrounds hyoid
3. pretrachial fascia: surrounds trachea
4. buccopharyngeal fascia: between trachea and esophagus
5. prevertebral fascia
6: alar fascia

Question 2

platysma m.

Answer 2

located in superficial fascial layer
O: superficial fascia of pec major/deltoid
I: inferior margin of mandible, skin of lower portion of face
A: draws corner of mouth down; depresses mandible, elevates skin of chest
N: cervical branch of facial n (CN VII )

Question 3

Deep investing fascia

Answer 3

1st layer of deep fascia

• surrounds entire neck
• provides roof for anterior and posterior triangles
• surrounds trapezius and SCM

Attachments:

• superior: ex. occ. protuberance, nuchal line, mastoid process inferior mandible
• posterior: ex. occ. prot, spinous processes of CV1-7 via nuchal ligament
• inferior: spinous process of CV7, spine of scapula, acromion, clvicle and manubrium

Question 4

suprasternal space

Answer 4

occurs when surfaces of investing fascia and SCM don’t fuse anteriorly and inferiorly
- not clinically very significant, small space that normally fills with fat

Question 5

infrahyoid fascia

Answer 5

2nd layer of deep fascia: begins at hyoid bone and thyroid cartilage

1. superficial layer: invests sternohyoid and omohyoid muscles, attached to posterior surface of manubrium - creates a sling for omohoid
2. deep layer: invests sternothroid and thyrohyoid muscles, attaches to manubrium

• both laminae of fascia fuse inferiorly with the adventitia of brachiocephalic vv. fibrous pericardium and laterally with carotid sheath

Question 6

cervical visceral fascia

Answer 6

pretracheal and buccopharyngeal fascia

- these encircle the visceral structures of neck: pharynx, esophagus, larynx, trachea, throid gland

Question 7

pre-tracheal fascia

Answer 7

third fascial layer
- located anterior to the larynx and trachea, attached to hyoid superiorly, encloses the thyroid gland, blends laterally with buccopharyngeal fascia, fuses with pericardium inferiorly

Question 8

buccopharyngeal fascia

Answer 8

4th deep layer
- attaches superiorly to base of skull, covers buccinator and pharyngeal constrictor muscles, fuses laterally with pre-tracheal fascia, fuses with adventitia of esophagus inferiorly

Question 9

pre-vertebral fascia

Answer 9

5th deep layer

• encircles vertebral column
• continuous with nuchal fascia posteriorly
• superiorly attaches to base of skull anterior and lateral to vertebral column
• anteriorly covers the pre-vertebral musculature and extends inferiorly to posterior mediastium (forms alar)
• laterally: forms floor of posterior cervical triangle, covers scalenes, levator scpulae, splenius and semispinalis mm.
• posterior: nuchal portion: inferiorly fuses with thoracolumbar fascia of deep back

Question 10

alar fascia

Answer 10

6th deep layer: from anterior pre-vertebral fascia
- attaches to midline of buccopharyngeal fascia, bilaterally blends with carotid sheath, inferiorly blends with adventitia of esophagus

Question 11

carotid sheath

Answer 11

neurovascular component of deep fascia: surrounds common and internal carotid aa, internal jugular v. and vagus n.
*** all deep fascias of neck communicate with and help form the carotid sheath - infections of the pretracheal, retrovisceral and danger spaces can invade the carotid sheath, causing aortitis

Question 12

pretracheal or visceral space

Answer 12

located b/w infrahyoid fascia and pre-tracheal fascia

• extends from infrahyoid mm. to thyroid cartilage above and to pericardium below
• ** infections here can dissect into superior mediastinum leading to inflammation of brachiocephalic vv. aorta and pericardium

Question 13

retropharyngeal spaces

Answer 13

located b/w buccopharyngeal and prevertebral and alar fascia

• extend from base of skull to posterior mediastinum
• closed laterally by carotid sheath

Question 14

Retrovesicle space

Answer 14

smaller more anterior space located between buccopharyngeal and alar facia

Question 15

“Danger space”

Answer 15

larger, more psoterior space between pre-vertebral and alar/buccopharyngeal fascias extending from base of skull to diaphragm

*** infections here can lead to retropharyngeal abscess which can lead to dysphagia and dysarthria and can dissect into posterior aspect of superior and posterior mediastinum

Question 16

chronic tonsillitis

Answer 16

can lead to mediastinal absess, leading to inflammation of esophagus as far distally as diaphragm

Question 17

sternocleidomastoid

Answer 17

O: sternal head at manubrium (ant surface)
clavicular head: superior surface
I: mastoid process, superior nuchal line
A: unilaterally: rotates head toward side opposite while elevating chin
bilaterally: flexes head; limits extension of atlanto-occipital joint
N: spinal accessory n (CN XI) and cervical spinal nn. C2, C3

Question 18

Torticollis

Answer 18

“wry neck”

- congenital shortening of SCM placing patients head in sidebent position opposite affected muscle

Question 19

posterior triangle

Answer 19

posterior: trapezius
anterior: SCM
inferior: clavicle

subdivided by passage of inferior omohyoid m.

1. occipital triangle: larger, more superior triangle bounded by trapezius, SCM and Omo
2. Omoclavicular: or (supraclavicular triangle), smaller inferior triangle, bounded by SCM, Omo and clavicle

Question 20

anterior triangle

Answer 20

posterior: SCM
superior: angle of mandible
mid-sagitally: invisible line

subdivided by pasage of superior omohyoid m. and digastric

1. digastric triangle
2. submental triangle
3. carotid triangle
4. muscular triangle

Question 21

digastric/submandibular triangle

Answer 21

superior: inferior margin of mandible
inferior: two bellies of digastric m.

Question 22

submental triangle

Answer 22

laterally: two oppsogin anterior bellies of digastric muscles
inferior: hyoid bone

Question 23

carotid triangle

Answer 23

• most important: contains bifurcation of carotid and CN XII
  superior: posterior belly of digastric
  anterior: superior belly of omohyoid
  posterior: SCM

Question 24

muscular triangle

Answer 24

posterior/superior: superior omohyoid
posterior/inferior: SCM
anterior: midline of neck

Question 25

external jugular veins

Answer 25

formed by union posterior division of retromandibular and the posterior auricular vv. at the angle of the mandible.
- descends superficial to SCM, pierces investing fascia and terminates in subclavian. v.

Question 26

what are four tributaries to external jugular v?

Answer 26

posterior external jugular v.
transverse cervical v.
suprascapular v.
anterior jugular v.

Question 27

what can laceration of external jugular vv. cause?

Answer 27

can lead to air embolism due to negative intrathoracic pressure which sucks air though open vein.
- will hear a bruit upon auscultation of thoracic wall, cyanosis of mucous membranes, reduced blood through the right atrium due to accumulated air, dyspnea.

Question 28

anterior jugular v.

Answer 28

paired, right and left
- formed from small vv. in submental and submandibular regions, coalesce at the level of the hyoid bone to form the anterior jugular vein.
descends from hyoid bone to anterior triangle, joins the external jugular v. via the jugular venous arch.

Question 29

how does the internal jugular v. communicate with the anterior jugular system?

Answer 29

via the common facial vein and the communicating vein

Question 30

what happens if you block the internal jugular v. at its origin

Answer 30

internal jugular vein is the most important venous drainage for the brain and skull, if blocked the emissary vv. and opthalmic vv. with drain through the scalp and connect with the retromandibular and facial vv.
- thus the retromandibular and facial vv. will allow blood to return to the heart without increasing intracranial bp.

Question 31

greater occipital n.

Answer 31

C2
- pierces the semispinalis capitis and trapezius and ascends to innervate the skin over the vertex and the posterolateral area of the skull

Question 32

what happens with C1 dorsal rami?

Answer 32

has no dorsal root in 50% of individuals

- when present it has reduced dorsal ganglion, and its cutaneous distribution is covered by C2

Question 33

what forms cervical plexus?

Answer 33

ventral rami of C1-C4

Question 34

what four nerves emerge from beneath the posterior border of the SCM in the posterior triangle?

Answer 34

1. lesser occipital, C2,3
2. great auricular C2,3
3. transver cervical n. C2,3
4. supraclavicular C3,4

Question 35

Lesser occipital nerve

Answer 35

C2,3

ascends the posterior border of SCM to innervate the medial surface of ear as well as skin behind ear

Question 36

great auricular nerve

Answer 36

C2,3
ascends the lateral surface of the upper half of hte SCM toward the angle of the mandible
- parallels the external jugular v.
- branches off to mandibleand mastoid process

Question 37

transverse cervical n

Answer 37

C2,3
crosses SCM inferior to great auricular n.
- pierces platysma to innervate skin of anterior triangle

Question 38

supraclavicular nn.

Answer 38

C3,4- descends from exit point in the posterior triangle, provides three branches

1. median supraclavicular nn: provides branches to base of neck, upper sternum and sternoclav. joint
2. intermediate supraclavicular nn: cross clavicle to innervate pec major
3. lateral supraclaviular: goes to AC joint and supplies cutaneous innervation to shoulder

Question 39

what are the superficial cervical nodes?

Answer 39

submental, submandibular, external jugular and anterior jugular nodes
–> they drain to the deep cervical lymph nodes that parallel the IJV

• general rule: lymphatic drainage from superficial structures of head and neck drain via superficial cervical nodes to deep cervical nodes which also receive lymph from deeper areas of ace, head and viscera of neck