4. Anterior triangle - neurovascular bundle

Question 1

Contents of carotid triangle (subdivision of anterior triangle)?

Answer 1

Carotid triangle: Contains thyroid gland, larynx, pharynx, carotid sheath (& contents), branches of cervical plexus, superior root of the ansa cervicalis, deep cervical lymph nodes, & (parts of) CN XI & XII

Question 2

Vascular compartment contents?

Answer 2

Medially
• Common carotid artery
• Internal carotid artery
• External carotid artery (part)

Laterally
• Internal jugular vein

Posteriorly
• CNX

bifurcates at C3/4

Question 3

Difference between origin of R and L CCA?

Answer 3

Right CCA
• Branch of the brachiocephalic trunk

Left CCA
• Direct branch from the arch of the aorta

Question 4

When does CCC bifurcate?

Answer 4

ICA & ECA: Branches of CCA at C3/C4

Question 5

When does ICA branch?

Answer 5

ICA has no branches in the neck & ascends to enter carotid canal to supply the brain

Provides the Anterior circulation of the brain

Question 6

What is carotid sinus? Importance?

Answer 6

Carotid sinus: Enlargement/dilation at bifurcation of common carotid artery containing baroreceptors/pressoreceptors in wall of ICA
• Important in monitoring blood pressure
• Baroreceptors are sensitive to stretch
(baroreceptor reflex)
• Helps keep blood pressure within
homeostatic values

Question 7

Innervation fo the carotid sinus?

Answer 7

Innervated by CN IX via carotid sinus nerve & CN X (back to the tractus solitarius)
Action potentials travel from the baroreceptors through CN IX to the cardioregulatory & vasomotor centres in the medulla (vital centres…)

Question 8

What are fibres that surround solitary nucleus?

Answer 8

tractus solitarius

or “Solitary tract”

Question 9

What is the carotid body?

Function

Answer 9

Carotid body: Small organ (~2-5mm) which houses chemoreceptors located at bifurcation of CCA near the carotid sinus

Function:
• Important in monitoring blood O2, CO2, & pH (& temperature)
• Responds in emergency situations by increasing respiration, blood pressure & cardiac rate (not as much at rest)

Question 10

Innervation of the carotid body?

Answer 10

Innervated by CN IX via carotid sinus nerve & CN X (back to the
tractus solitarius)
• Afferent fibres from the carotid body travel to the cardioregulatory & vasomotor centres in the medulla (vital centres…)

Question 11

Branches of the ECA?
S t
A p
L
F
O
P a
S t
M

Answer 11

• Superior thyroid
• Ascending pharyngeal
• Lingual
• Facial
• Occipital
• Posterior auricular
• Superficial temporal (terminal branch)
• Maxillary (terminal branch)

Question 12

Majority of scalp & facial blood supply is from the _________ carotid artery with some from the internal carotid

Answer 12

Majority of scalp & facial blood supply is from the external carotid artery with some from the internal carotid

ICA gives off the supratrochlear and supra-orbital artery (at the forehead)

Question 13

Middle meningeal artery is a branch of…

Answer 13

the maxillary branch of ECA

Question 14

Course of IJV?

Answer 14

• Continuation of sigmoid sinus
• Exits skull via the jugular
foramen & enters carotid
sheath
• Runs lateral to CCA
• Omohyoid muscle runs
across

Question 15

Veins draining into IJV?

Answer 15

• Inferior petrosal sinus
• Pharyngeal
• Occipital
• Facial
• Lingual
• Superior thyroid
• Middle thyroid

Question 16

IJV joins _______ vein to become brachiocephalic vein (left & right)

Answer 16

IJV joins subclavian vein to become brachiocephalic vein (left & right)

Question 17

IJV has what which helps prevent infection spread?

Answer 17

Valve system (one found at inferior bulb)

Question 18

How is the EJV formed? Which vessels?

Answer 18

EJV begins at angle of mandible, joining RETROMANDIBULAR & POSTERIOR AURICULAR veins
• Post auricular – from scalp behind ear
• Retromandibular (posterior division) – from superficial temporal & maxillary veins

Question 19

Veins draining into EJV?

Answer 19

Veins draining into EJV:
• Posterior external jugular
• Transverse cervical
• Suprascapular

Question 20

Anterior jugular vein, course and drainage?

Answer 20

Anterior jugular veins arise near the hyoid bone and run on either side of midline through subcutaneous tissue communicating across the midline via the JUGULAR VENOUS ARCH.
Drains into EJV; in some instances, will drain directly into subclavian vein

Question 21

Cervical branch of CN VII innervates ________ muscle Digastric branch of CN VII innervates ____ muscle

Answer 21

Cervical branch of CN VII innervates platysma muscle Digastric branch of CN VII innervates digastric muscle

Question 22

Stylohoid supplied by

Answer 22

CN VII

Question 23

Course of the CN IX in the neck?

Include the vascular relations

Answer 23

CN IX exits the jugular foramen & travels downward between the IJV & ICA
Much of the nerve then travels forward to oral cavity, but some branches travel downward to carotid sinus (& body), pharynx (sensory) & stylopharyngeus (motor)

Question 24

Course of the CN X in neck and the vascular relations?

Answer 24

CN X exits the jugular foramen & travels downward within carotid sheath with
IJV & CCA (ICA)
As it travels downward, a motor branch to the pharynx arises as well as a branch to the carotid body, the superior laryngeal nerve & a cardiac branch
Recurrent laryngeal nerves arise inferiorly near to the subclavian artery (R) or arch of aorta (L)

Question 25

Course of the CN XI in the neck?

Arterial relations and muscles innervated?

Answer 25

CN XI (spinal) exits the jugular foramen & travels downward between the IJV & ICA
It then crosses the lateral surface of the IJV to descend to the posterior triangle of the neck
It innervates SCM & trapezius

Question 26

Course of CN XII in the neck?

Answer 26

CN XII exits the hypoglossal canal & is between the IJV & ICA
It then crosses the ICA & ECA laterally on its way to the oral cavity There are no branches to the anterior triangle of the neck

Question 27

Supply of the transverse cervical nerve in neck?

Answer 27

supply cutaneous innervation over SCM & anterior triangle

Question 28

Cutaneous supply of the great auricular nerve from C2 and C3?

Answer 28

Angle of the mandible

NOT THE TRIGEMINAL

Question 29

What nerve innervates the ansa cervicalis?

Answer 29

Ansa cervicalis (anterior rami of C1-C3) innervates infrahyoid muscles

Question 30

Two plexus’s of the neck?

Answer 30

Cervical plexus (anterior rami of C1, C2-4)
Branchial plexus from C5 to T1

Question 31

Which motor and cutaneous supply is from the cervical plexus C1-C4?

Answer 31

Infrahyoid
Diaphragm (via phrenic)
Skin of anterior/lateral neck
Skin of inferior neck

Question 32

Which branches of the brachial plexus are seen in the neck?

Answer 32

Dorsal scapular nerve
C5 branch to the phrenic nerve
Suprascapular nerve

Question 33

Which sympathetic truck ganglia are found in the neck?

Answer 33

Cervical part of sympathetic trunk gives of superior, middle and inferior cervical ganglia

Question 34

What is the ansa cervicalis? What is it’s function?

Answer 34

The ansa cervicalis is a loop of nerves, formed by nerve roots C1-C3. It gives off four muscular branches:
-Superior belly of the omohyoid muscle
-Inferior belly of omohyoid muscle
- Sternohyoid
- Sternothyroid
These muscles (the infrahyoids) act to DEPRESS the HYOID bone; an important function for swallowing and speech.