Posterior and anterior triangles of the neck

Question 1

What are the 3 types of articular ligaments of the vertebral column?

Answer 1

Articular ligaments = support stability during movement of the vertebral column.
1. Interspinous = connects each spinous process inferiorly
2. Supraspinous = connects each spinous process posteriorly
3. Ligamentum flavum = connects adjacent laminae of each vertebra

Question 2

What is the ligamentum nuchae?

Answer 2

Thickening of the supraspinous ligaments in cervical regions of the neck

Question 3

What is the superficial fascia of the neck?

Answer 3

• Contains cutaneous nerves, superficial veins, superficial lymph nodes
• Contains platysma (inserts lower border of the mandible) and adipose tissue

Question 4

What are the 3 layers of deep cervical fascia of the neck?

Answer 4

Investing layer = keeps everything contained, sits directly beneath the superficial fascia, has attachment to spinous process on cervical vertebrae
Pretracheal layer = encloses the trachea, oesophagus and thyroid gland
Prevertebral layer = compartmentalises cervical vertebrae and deep neck muscles

Question 5

What is the carotid sheath?

Answer 5

Takes contribution from each of the 3 layers of deep fascia. Contains internal jugular vein, common carotid artery, vagus nerve (CN X)

Question 6

What is the sternocleidomastoid muscle?

Answer 6

2 heads = sternal and clavicular, inserts onto mastoid process
Innervation = Spinal accessory nerve (CN X) and C2/C3 ventral rami
Action = extend head and flex cervical region of vertebral column. Contraction of one muscle turns the head to the opposite side

Question 7

What are the boundaries of the posterior triangle ?

Answer 7

Base = middle 1/3 clavicle
Anterior = posterior boarder of sternocleidomastoid
Posterior = anterior boarder of upper fibres of trapezius
Apex = occipital bone
Roof = investing cervical fascia

Question 8

Importance of the omohyoid muscle.

Answer 8

split into 2 bellies by a tendon. Inferior belly crosses posterior triangle. Then travels underneath SCM to enter anterior triangle.

Question 9

What are the boundaries of the anterior triangle?

Answer 9

Anterior border of SCM
Inferior border of the mandible
Midline of the neck
The anterior triangle is further subdivided by:
-Anterior and posterior bellies of digastric
Superior belly of omohyoid

Question 10

What 4 smaller triangles is the anterior triangle further sub-divided into?

Answer 10

1. Submandibular triangle = mandible superior ant. and post., bellies of digastric
2. Submental triangle = hyoid bone inferiorly, ant. belly of digastric laterally and the midline
3. Muscular triangle = hyoid bone superiorly, belly of omohyoid superiorly, border of SCM anteriorly
4. Carotid triangle = superior belly of omohyoid , anteroinferiorly, post. belly of digastric

Question 11

Detail on the hyoid bone.

Answer 11

• U shapes
• supra and infrahyoid muscles move this bone up and down
• styloid ligament runs from styloid process and attaches to lesser cornu of hyoid
• styloid muscle runs from styloid process to greater cornu
  associated with strangulation / induced vomiting / trauma ; then results in pain when turning the head and painful dysphagia

Question 12

Detail on the thyroid cartilage.

Answer 12

• largest cartilage in neck
• composed of two flat lamina (sheet cartilage), these meet anteriorly at a sharp angle called the laryngeal prominence. On the superior border there is a very sharp notch called the superior thyroid notch
• Inferior cornu articulates with the cricoid at the cricothyroid joint

Question 13

Detail on the cricoid cartilage.

Answer 13

• Fill ring of cartilage
• thin band anteriorly, larger posteriorly
• on lateral sides there is a facet of inferior horn of the thyroid cartilage
  Everything after cricoid cartilage becomes the trachea

Question 14

What are the membranes of the larynx?

Answer 14

Thyrohyoid membrane
Cricothyroid membrane
Membranes of hyoid and laryngeal skeleton

Question 15

What are the suprahyoid muscles ?

Answer 15

Geniohyoid
Stylohyoid
Digastric
Mylohyoid

Question 16

What are the infrahyoid muscles?

Answer 16

Omohyoid
Sternohyoid
Thyrohyoid
Sternothyroid

Question 17

Which 3 structures are always in the carotid sheath?

Answer 17

internal jugular vein, common carotid artery, vagus nerve

Question 18

At vertebral level C3 what happens to the common carotid?

Answer 18

Bifurcates into:
External carotid - has many branches which supply the head and neck. Terminal branches are the superficial temporal artery and the maxillary artery.
Internal carotid - travels up into the skull entering through the carotid canal, there are no branches until inside the skull.

Question 19

What are the 6 branches and two terminal branches of the external carotid artery?

Answer 19

(anterior) Superior thyroid artery - supplies thyroid gland. A notable branch of this artery is the superior laryngeal artery which passes through the lateral aperture of the thyrohyoid membrane.
(posterior) Ascending pharyngeal artery - goes up the back of the pharynx
(anterior) Lingual artery - passes through the suprahyoid muscles to get into the oral cavity to supply the tongue
(anterior) Facial artery - goes up and over the inferior border of the mandible to supply the face
(posterior) Occipital artery - goes towards the back of the scalp
(posterior) Auricular artery - goes behind the ear
(terminal branch) Maxillary artery (horizontal) - passes over the neck of the mandible and dives deep towards the maxilla
(terminal branch) Superficial temporal artery (vertical) - goes over the temples
Mnemonic: Some Anatomists Like Freaking Out Poor Medical Students

Question 20

What is the ansa cervicalis?

Answer 20

Ansa cervicalis continuation of the cervical plexus
C1-C3 loop of the ventral rami of spinal nerve fibres that innervate the ‘strap muscles’
2 roots: superior and inferior
C1 nerve fibres ‘hit a lift’ with the hypoglossal nerve - this is the superior root of ansa cervicalis
Inferior root originated from C2-C3 fibres
Meet in a loop over the lateral side of the internal jugular vein in the carotid sheath
Innervate infrahyoid muscle