5 - Anterior triangle and neurovascular structures Flashcards
What is contained in the carotid triangle? (8)
- thyroid gland
- larynx
- pharynx
- carotid sheath
- branches of cervical plexus
- superior root of ansa cervicalis
- deep cervical lymph nodes
- parts of CN XI and CN XII
What are the contents of the carotid sheath?
Medially
- common carotid artery
- internal carotid artery
- external carotid artery
Laterally
- internal jugular vein
Posteriorly
- CN X
Where does the carotid sheath run?
Foramen of carotid canal to aortic arch
Describe the course of the right common carotid artery.
- brachiocephalic trunk branches from the aortic arch
- CCA branches from brachiocephalic trunk
- ICA and ECA branch from CCA at C3/C4 level
Describe the course of the left common carotid artery.
- CCA branches from the aortic arch
- ICA and ECA branch from CCA at C3/C4 level
Describe the course of the internal carotid artery and what it supplies.
- no branches in the neck
- ascends to brain via the carotid canal
- provides anterior circulation to the brain
What is the carotid sinus?
- enlargement/dilation at the bifurcation of CCA
- contains baroreceptors/pressoreceptors in the wall of the ICA
- monitors blood pressure
What is the innervation of the carotid sinus?
- CN IX via carotid sinus nerve
- CN X
- action potentials travel to the medulla
What is the carotid body?
- small organ which houses chemoreceptors
- located at the bifurcation of CCA
- monitors blood gases
What is the innervation of the carotid body?
- CN XI
- CN X
- afferent fibres travel to the medulla
What are the branches of the ECA? (8)
- superior thyroid
- ascending pharyngeal
- occipital
- lingual
- facial
- posterior auricular
- superficial temporal
- maxillary
What does the ECA supply?
Structures that are external to the cranium
Which branches of the ECA are found in the carotid triangle?
- lingual artery
- superior thyroid artery
- occipital artery
- ascending pharyngeal
What do the terminal branches of the ECA supply?
- scalp (excluding forehead and orbit)
- supplied by middle meningeal artery which is a branch of the maxillary
What are the terminal branches of the ECA?
- maxillary
- superficial temporal
Where does the middle meningeal artery enter the cranium?
Foramen spinosum
What does the IJV drain?
- brain
- skull
- face
- parts of neck
Describe the course of the IJV.
- continuation of the sigmoid (venous) sinus
- exits skull via jugular foramen
- enters carotid sheath
- runs laterally to the CCA
- joins subclavian vein to form the brachiocephalic vein (both sides)
Which veins drain into the IJV? (7)
- inferior petrosal sinus
- pharyngeal
- occipital
- facial
- lingual
- superior thyroid
- middle thyroid
What is the inferior bulb of the IJV and where is it located?
- dilation which has valves
- prevents back flow when upside down or there is an increase in thoracic pressure
- located in the jugular foramen
Where is the superior bulb of the IJV?
Petrosal sinus
What muscles runs across the IJV?
Superior belly of the omohyoid
What does the EJV drain?
- scalp
- face
- superficial neck
What veins drain into the EJV? (4)
- posterior external jugular
- anterior jugular
- transverse cervical
- suprascapular
Describe the course of the EJV.
- begins at angle of mandible
- descends posteriorly and crosses SCM
- pierces fascia to drain into the subclavian vein
Describe the course of the AJV.
- arises at hyoid bone
- runs along the midline through subcutaneous tissue
- creates a communication across the midline with the opposing AJV, forming the jugular arch
- drains into the EJV
What does the facial nerve innervate in the neck?
Cervical branch - platysma
Digastric branch - digastric
Also supplies the stylohyoid muscle
What does the glossopharyngeal nerve innervate in the neck?
- carotid sinus and body
- pharynx
- stylopharyngeus
Where does the glossopharyngeal nerve exit the skull?
Jugular foramen
What does the vagus nerve supply in the neck?
- pharynx
- carotid body
- recurrent laryngeal nerves
Describe the course of the recurrent laryngeal nerves.
- both branch from the vagus nerve
- right loops around the subclavian artery
- left loops under the aortic arch
What does the accessory (spinal) nerve supply in the neck?
- SCM
- trapezius
Where does the accessory (spinal) exit the skull?
Jugular foramen
What does the transverse cervical nerve supply?
- branch of anterior rami of C2 and C3
- supplies cutaneous innervation to SCM and anterior triangle
What does the ansa cervicalis supply?
- anterior rami of C1-C3
- innervates infrahyoid muscles
What does the cervical plexus supply?
- anterior rami of C1-C4
- infrahyoid muscles
- diaphragm (via phrenic)
- skin of anterior and lateral neck
- inferior head
Where is the brachial plexus located?
C5-T1
Which branches of the brachial plexus are located in the neck?
- dorsal scapular nerve
- C5 branch to phrenic
- suprascapular
