Anatomy of Anterior and Posterior Neck

Question 1

What is the neck?

Answer 1

Region of the body lying between:
- the lower margin of mandible and superior nuchal line of the occipital bone above
- and the suprasternal notch and upper border of clavicles below

Question 2

Describe the innervation of the skin of the neck?

Answer 2

At the back – supplied segmentally by posterior rami of c2-c5
At front and sides – supplied by anterior rami of c2-c4

Question 3

Describe the superficial fascia of the neck?

Answer 3

forms a thin layer that encloses the platysma muscle.
> embeds cutaneous nerves, superficial vessels & lymphatics

Question 4

Describe the deep fascia of the neck?

Answer 4

consists of areolar tissue that supports muscles, vessels and viscera

Question 5

What are the fibrous sheets of the deep fascia?

Answer 5

1. Investing layer - surrounds all structures in the neck
2. pre-tracheal layer
3. prevertebral layer
4. carotid sheath

Question 6

Name the 3 compartments of the neck and their contents?

Answer 6

1. Visceral Compartment
   - Digestive and respiratory systems + several endocrine glands
2. Vertebral Compartment
   - Cervical vertebrae, spinal cords, cervical nerves, associated muscles
3. Vascular Compartments
   - Major blood vessels and vagus nerve [X]

Question 7

What divides the neck into anterior and posterior triangles?

Answer 7

sternocleidomastoid

Question 8

What are the boundaries of the anterior triangle?

Answer 8

1. Anterior border: Imaginary midline of the neck
2. Posterior Border: Anterior border of SCM
3. Superiorly (Base): inferior margin of mandible
   > The roof is formed by skin, superficial fascia, platysma and investing layer of deep fascia

Question 9

What are the 4 divisions of the anterior triangles?

Answer 9

1. submandibular (digastric)
2. submental
3. carotid
4. muscular

Question 10

Which muscles form the 4 divisions of the anterior triangle?

Answer 10

1. digastric muscles
2. superior belly of Omohyoid

Question 11

What are the contents of the submental division of the anterior triangle?

Answer 11

• submental lymph nodes
• beginning of anterior jugular vein

Question 12

What are the contents of the submandibular division of the anterior triangle?

Answer 12

• submandibular salivary gland
• lymph nodes
• facial artery & vein
• carotid sheath
• hypoglossal nerve

Question 13

What are the contents of the carotid division of the anterior triangle?

Answer 13

• carotid sheath
• branches of external carotid artery
• internal jugular vein
• hypoglossal
• accessory and vagus nerves

Question 14

What are the contents of the muscular division of the anterior triangle?

Answer 14

sternohyoid and sternothyroid form the floor beneath which lies the:
- thyroid gland
- larynx
- trachea
- oesophagus

Question 15

Name the supra-hyoid muscles of the anterior triangle and their action?

Answer 15

Stylohyoid
digastric
mylohyoid
geniohyoid
> Raise hyoid bone or depress mandible (mylohyoid and digastric)

Question 16

What is the innervation of the supra-hyoid muscles?

Answer 16

1. Facial nerve
   > posterior belly of digastric and stylohyoid
2. Mandibular division of trigeminal CNV3
   > anterior belly of digastric and mylohyoid
3. branches from anterior ramus of C1 carried along the Hypoglossal nerve [XII]
   > geniohyoid

Question 17

What are the infrahyoid muscles and what is their action?

Answer 17

Omohyoid
sternohyoid
thyrohyoid
Sternothyroid
- depress hyoid bone
Note: Names indicate sites of attachment

Question 18

What is the innervation of the infrahyoid muscles?

Answer 18

Ansa cervicalis
> except thyrohyoid = C1 via hypoglossal CN XII

Question 19

Describe the cervical plexus?

Answer 19

• Anterior rami C1-4
• Joined into loops that lie anterior to levator scapulae and scalenus medius
• Covered by pre-vertebral layer of deep cervical fascia
• Somatic motor and sensory (plus sympathetic)

Question 20

Describe the course of the vagus nerve?

Answer 20

Descends in carotid sheath
Recurrent laryngeal branches to muscles of larynx = L around arch of aorta, R around subclavian artery
Internal and external laryngeal branches
Through thoracic inlet into superior mediastinum – parasympathetic to thorax and abdomen

Question 21

Describe the course of the common carotid artery?

Answer 21

LCA from arch of aorta
RCA from brachiocephalic
No branches but terminal 2 = internal and external
Internal carotid to brain
External carotid to head, face, neck
Within carotid sheath with internal jugular vein and vagus nerve

Question 22

Describe the thyroid gland in the anterior triangle?

Answer 22

Endocrine – regulates metabolic rate
2 lobes, isthmus and capsule
From lamina of thyroid cartilage down to 6th tracheal ring
Isthmus over tracheal ring 2 or 3
Parathyroid glands embedded into posterior surface

Question 23

Describe the arterial supply of the thyroid gland?

Question 24

Describe the venous drainage of the thyroid gland?

Question 25

Describe the course of the submandibular salivary gland?

Answer 25

Inferior to mylohyoid, plus part in floor of mouth superior to mylohyoid One duct each side opens between the first and second lower incisor (either side of frenelum)

Question 26

What are the borers of the posterior triangle?

Answer 26

1. anterior - posterior border of SCM 2. posterior - anterior border of trapezius 3. base - clavicle 4. Floor - splenius capitis, levator scapulae, posterior, middle and anterior scalene muscles > The floor is formed by prevertebral layer of deep fascia > The triangle is covered by skin, sup fascia, platysma, and investing layer of deep fascia (roof)

Question 27

What are the contents of the posterior triangle?

Answer 27

external jugular vein roots of brachial plexus accessory nerve cervical and supra-clavicular lymph nodes Occipital artery 3rd part of subclavian Lateral branches of thyrocervical trunk

Question 28

Describe the floor of the posterior triangle?

Answer 28

1. Omohyoid • Superior border of scapula - inferior border of hyoid bone • Depress hyoid bone 2. Ansa cervicalis 3. Splenius capitis • Nuchal ligament, spinous process of C7-T4 to mastoid process • Extend the neck, rotate 4. Dorsal rami middle cervical

Question 29

Cutaneous branches of cervical plexus running across the posterior triangle?

Answer 29

1. lesser occipital (C2) 2. great auricular (C2,3) 3. lateral supraclavicular (C3,4) 4. intermediate supraclavicular (C3,4) 5. medial supraclavicular (C3,4) 6. transverse cervical (C2,3)

Question 30

Locations of nerves of the posterior triangle?

Answer 30

1. CN XI crosses obliquely on surface of L. scapulae 2. phrenic nerve - crosses obliquely over anterior scalene 3. brachial plexus - passing between middle and anterior scalene

Question 31

What are the divisions of the posterior triangle and what separates these divisions?

Answer 31

1. Occipital triangle (larger – above) 2. Supraclavicular triangle (smaller – below) > subdivided by inferior belly of omohyoid

Question 32

Describe the action of the sternocleidomastoid muscle?

Answer 32

1. unilateral = lateral flexion of neck to same side (face opposite) 2. bilateral = flexion of neck

Question 33

Describe the innervation of the sternocleidomastoid muscle?

Answer 33

motor = spinal accessory nerve (CN XI) pain and proprioception = cervical plexus C2, C3

Question 34

Describe the action of the trapezius muscle?

Answer 34

1. ascending part (inferior) = depress scapula 2. transverse part (middle) = retracts scapula 2 descending part (superior) = elevate scapula, rotate glenoid cavity > holds scapula in position - weightlifting

Question 35

Describe the innervation of the trapezius muscle?

Answer 35

spinal accessory nerve (CN XI), cervical plexus C3,C4 (proprioception)

Question 36

Describe the action of the levator scapulae muscle?

Answer 36

Help control scapular position, elevate shoulder (with trapezius), shoulder fixed can laterally flex neck to the same side

Question 37

Location of levator scapulae?

Answer 37

Transverse processes of atlas and axis, 3rd and 4th C vertebrae to medial scapular border between superior angle and medial end of scapular spine

Question 38

Location of scalene muscles?

Answer 38

Origin: From transverse processes of: 1. C3-6 (anterior), 2. C2-7 (middle) 3. C4-6 (posterior) Insertion: 1. To ribs 1 (scalene tubercle m) = anterior 2. Upper surface of rib 1 = middle - Artery lies between it and tubercle 3. Upper surface of rib 2 (posterior)

Question 39

Innervation of scalene muscles?

Answer 39

1. anterior - ant. rami C4-7 2. middle - ant. rami C3-7 3. posterior - ant. rami C5-7

Question 40

Action of scalene muscles?

Answer 40

flex neck (bilateral) tilt head to same side (unilateral) elevate upper ribs

Question 41

What is an emergency cricothyroidotomy?

Answer 41

an incision made through the skin and cricotyroid membrane to establish a patent airway during certain life-threatening situations e.g. airway obstruction by foreign body, angioedema or massive facial trauma