Triangles Of Neck Flashcards
What arch forms CN V?
First arch
What arch forms CN VII?
Second arch
What arch forms CN IX?
Third arch
What arch forms CN X?
Fourth/sixth arch
What is cervical fascia?
Component of connective tissue forming
sheaths around structures in the neck
• Covers the triangles of the neck
Contrast a deep and superficial. Cervical fascia
• Superficial fascia
– Loose, fatty subcutaneous layer (contains the platysma m.)
• Deep fascia
- Carotid sheath
- Superficial (investing) layer
- Middle (pretracheal) layer
Infrahyoid/muscular fascia (A)
Visceral fascia
– Pretracheal fascia (B)
– Buccopharyngeal fascia (C) - Deep (prevertebral) layer
All layers contribute to carotid sheath
What is the investing fascia?
Deep to superficial fascia and embedded platysma muscle
Surrounds the neck ‘investing’ around the SCM and trapezius m.
What are the boundaries of the posterior triangle?
Boundaries of posterior triangle – trapezius m. (CN XI) posterior triangle • Upper fibers- elevate scapula • Middle fibers- adduct scapula • Lower fibers- depress scapula
– sternocleidomastoid m. (CN XI)
• Unilateral headrotationto
opposite side
• Bilateral draw head forward
– clavicle
What are the boundaries of the anterior triangle?
Boundaries of anterior triangle
– midline
– sternocleidomastoid m. (CN XI)
– mandible
What does the Omohyoid muscle do?
Omohyoid (inf. belly)
- subdivides the posterior triangle into occipital and subclavian (supraclavicular) triangles
What nerves innervate posterior, anterior and middle scalene?
C3-7
What innervates splenus capitus?
(Dorsal ramus)
What nerve innervates the levator scapulae?
Dorsal scapular nerve
What’s the importance of cervical plexus?
Cervical plexus – ventral rami
of spinal nerves C1-C4
What are the cutaneous branches of the posterior triangle?
Cutaneous branches emerging from the posterior triangle
Lesser occipital (C2) Great auricular (C2,3) Transverse cervical (C2,3) Supraclavicular (C3,4)
What are the motor and cutaneous areas of the cervical plexus?
Formed by ventral rami of cervical spinal nerves C1-C4
Motor - to infrahyoid and prevertebral muscles of the neck and diaphragm (phrenic n.)
Cutaneous - areas of head, neck, shoulder upper chest, and central part of diaphragm (phrenic n.)
What is the path of the hypoglossal nerve?
Path of the nerve:
• exits the skull through hypoglossal canal and descends medial to ICA and IJV
• passes between ICA and IJV and hooks around occipital a.
• passes deep to digastric and stylohyoid mm.
• disappears deep to mylohyoid m. on its way to tongue
What does the hypoglossal nerve innervate?
C1 fibers piggyback along hypoglossal n. to geniohyoid and thyrohyoid mm.
All other infrahyoid muscles are innervated by the ansa cervicalis (C1-C3)
What spinal level innervate the nerve to thyrohyoid?
C1
What are the contents of the carotid sheath?
Contents of the carotid sheath:
Internal jugular v. (IJV)
Common carotid a. (CCA)
Vagus nerves
What are the contents of the posterior sheath?
Carotid sheath:
Internal jugular v. (IJV)
Common carotid a. (CCA)
Vagus nerves
Inferior thyroid artery
Thyrocervical trunk
Phrenic nerve-
Phrenic n. (C3,4,5)
* On top of anterior scalene muscle
Transverse cervical artery
1. superficial branch
2. deep (descending) branch
Maybe absent if it came off directly from subclavian as the dorsal scapular artery
Structures emerging through the scalene gap (triangle) formed by ant. & mid. scalene muscles:
- Brachial plexus trunks (C5-T1) - Subclavian a.
What does NOT pass through the scalene gap?
Subclavian v.
What is the anterior triangle divided into?
Subdivided by digastric and omohyoid mm. into: 1. submental triangle 2. digastric (submandibular) triangle 3. carotid triangle 4. muscular triangle
What is the vasculature from the internal and external carotid artery?
Internal carotid a. (ICA):
No branches until inside skull
External carotid a. (ECA):
- sup. thyroid artery
- ascending pharyngeal a.
- lingual a.
- facial a.
- occipital a.
- post. auricular a.
- maxillary a.
- superficial temporal a.
What is the Carotid sinus?
Carotid sinus
dilated portion at the proximal part of ICA
• Contains baroreceptors to monitor blood
pressure
• Innervated by branches of CN IX
What is the carotid body?
Carotid body small cluster of cells near carotid sinus • Contains chemoreceptors to monitor blood chemistry (i.e. O2, pH) • Innervated by branches of CN IX and X
What is the thyroid gland?
2 lobes connected by isthmus (anterior to 2nd and 3rd tracheal cartilages)
Pyramidal lobe (if present) – along the path of thyroglossal duct
What is the arterial supply of the thyroid gland?
• superior thyroid (from ECA)
• inferior thyroid (from
thyrocervical trunk)
• thyroid ima – (variable presence)
Whaat is the venous drainage of the thyroid gland?
- Venous drainage
• superior thyroid (into IJV)
• middle thyroid (into IJV)
• inferior thyroid (into brachiocephalic vein)
Where does the recurrent pharyngeal nerve course in relation to the thyroid gland?
The recurrent laryngeal nerve courses posterior to the thyroid gland in the tracheoesophageal groove
What are the contents of the carotid sheath?
Fascial tube extending from the base of the skull to thorax
contents:
• CCA (ICA)
• IJV
• Vagus n. (CN X)
• (CN IX, XI, XII – in the uppermost part of sheath for part of their course)
What are the relationships of the carotid sheath?
Relationships:
– Phrenic n. lies posterior on top of anterior scalene (covered by prevertebral fascia)
– Sympathetic chain lies posteromedial to sheath (in front of prevertebral fascia)
– Inside the sheath the IJV is usually large and more superficial (anterior or lateral) to the CCA
– Vagus n. is usually found posterior to, and between CCA/IJV
What are the collar lymph nodes?
Collar nodes (superficial): • occipital • mastoid (posterior auricular) • parotid (pre-auricular) • submandibular • submental
- afferents drain superficial structures of face, scalp, and head
- form a collar around the neck and efferents drain mainly to the
deep cervical nodes (along IJV)
What are the superficial cervical nodes?
Superficial cervical nodes
- organized into anterior group (along anterior jugular v.) and posterolateral group (along EJV)
- afferents drain superficial structures of the neck – efferents drain to the deep cervical nodes
Describe the deep cervical lymph nodes
Deep cervical nodes:
- Receive most of the lymph from head and neck - located in a vertical chain along the IJV
- afferents drain superficial cervical nodes and various other outlying nodes including: prelaryngeal, pretracheal, paratracheal, retropharyngeal, infrahyoid
- efferents eventually form R & L jugular trunks and drain to right lymphatic duct or thoracic duct
- often divided into superior and inferior groups where the omohyoid tendon crosses IJV
- Jugulo-digastric (tonsilar) node – large prominent node draining tonsillar region
- Jugulo-omohyoid node – large prominent node draining the tongue
