HEAD AND NECK ANATOMY

Question 1

Platysma origin and insertion points

Answer 1

Origin: pectoralis major and deltoid
Fibres cross the clavicle, meet in the midline and fuse with muscles of the face
Insertion: inferior portion of mandible

Question 2

Layers of deep cervical fascia

Answer 2

• investing layer of deep cervical fascia
• pre tracheal fascia
• pre vertebral fascia
• carotid sheath

Question 3

Layers we go through in a tracheostomy

Answer 3

Skin
Subcutaneous fat
Superficial cervical fascia with platysma
Investing layer of deep cervical fascia
Sternohyoid
Sternothyroid
Pre tracheal fascia
Thyroid isthmus
Trachea

Question 4

What makes up the superficial cervical fascia?

Answer 4

Superficial cervical fascia lies between the dermis and deep cervical fascia

made of superficial vessels, lymph nodes, neurovascular supply to the skin, platysma, fat

Question 5

Pathway of investing layer of deep cervical fascia

Answer 5

from posterior aspect of ligamentum nuchae:
- splits to enclose trapezius
- then reforms to create roof of posterior triangle
- then splits to enclose SCM
- then fuses to one sheet to form roof of anterior triangle

• splits @ lower body of mandible to enclose submandibular gland
  > superficial: attaches to lower body of mandible
  > deep: attaches to mylohyoid line
• splits @ angle of mandible
  > superficial: passes superficially to parotid gland, blends with epimysium of masseteric muscle to form parotidomasseteric fascia (unyielding fascia, causes pain when stretched)
  > deep: passes medial to parotid, thickens to form stylomandibular ligament

Question 6

What outlines the retropharyngeal space?

Answer 6

located between the buccopharyngeal fascia (posterior aspect of the visceral pretracheal fascia) and the prevertebral fascia.
laterally it is bordered by the carotid sheath

extends from base of skull to posterior mediastinum

Question 7

Features of deep neck space infections

Answer 7

Features of deep neck space infection:
Pain, swelling of the neck
Odynophagia, dysphagia, trismus and dyspnea
Fever and chills

Examination:
Submandibular space infection : swelling of overlying soft tissue. Firm induration of bilateral floor of mouth (Ludwig’s angina)&raquo_space; *can cause posterior and superior displacement of tongue causing airway compromise
Parapharyngeal space infection : medial displacement of tonsil, and lateral pharyngeal wall
Retropharyngeal space infection: pharyngeal bulge on ipslateral side

Question 8

Complications of deep neck space infections

Answer 8

A) Internal jugular vein thrombophlebitis (Lemierre syndrome)
> shaking chills, spiking fevers, tender swelling @ angle of jaw/along SCM
> septic emboli can affect lungs, MSK, liver
- Tend to resolve with prolonged abx and do not need surgical intervention (ligation and resection of vein)
- Anticoagulation; controversial but recommended in cases of septic emboli/thrombus progression

B) Mediastinitis  - > downward extension of infection within retropharyngeal space, danger space, prevertebral or pretracheal space > increasing chest pain or dyspnea > chest XR or CT scan can show widened mediastinum/pneumomediastinum > transthoracic drainage is necessary when infection has spread below carina

C) Carotid artery erosion > from common, internal or external carotid branches > suspect if: recurrent small hemorrhages from throat/ear, hematoma of surrounding neck tissues, protracted clinical course, presence of blood clots at time of I&D  > if detected, aggressive treatment warranted by gaining control of vessel with repair and ligation

D) Meningitis

E) Cavernous sinus thrombosis

Question 9

What does the carotid sheath contain?

Answer 9

Internal jugular vein
carotid artery (common and internal)
vagus nerve
ansa cervicalis (embedded within anterior wall of sheath)
lymph nodes
escaping from the upper part of the carotid sheath - glossopharyngeal (IX), superial laryngeal branch of vagus (X), spinal accessory (XI) and hypoglossal (XII) nerves

Question 10

What is the ansa cervicalis?

Answer 10

a loop formed by muscular branches of cervical spinal nerves C1-3.
it is situated within the carotid sheath

they innervate 3 of 4 infrahyoid muscles:
- sternohyoid
- sternothyroid
- omohyoid
(thyrohyoid muscle is innervated by C1 through a separate branch)

Question 11

Branches of external carotid artery?

Answer 11

Some anatomists like freaking out poor medical students

Superior thyroid artery
Ascending pharyngeal artery
Lingual artery
Facial artery
Occipital artery
Posterior auricular artery
Maxillary artery
Superficial temporal artery

Question 12

Which structures lie @ the C6 vertebral level

Answer 12

Cricoid cartilage
Larynx becomes trachea
Pharynx become esophagus
Vertebral artery enters the foramen transversarium of C6 vertebrae
Inferior thyroid artery and midde thyroid veins cross to thyroid gland
Middle cervical sympathetic ganglion
Carotid tubercle of Chassaignac
- paired anterior tubercles of the transverse processes of the sixth cervical vertebrae
- compress carotid artery against this for SVT
- stellate ganglion block in anaes
Superior belly of omohyoid crosses the carotid sheath

Question 13

@ level C4

Answer 13

common carotid bifurcates into int and ext carotid
upper thyroid cartilage