27-10-23 – The neck Flashcards
Leaning outcomes
- Describe the organization of the fascias of the neck in relation to the compartments of the neck and fascial spaces
- Describe the boundaries and contents of the anterior and posterior triangles of the neck
- Describe the boundaries and contents of the retromandibular fossa
- Describe the position and relations of the thyroid and parathyroid glands and their neurovascular supply
- Describe how the cervical plexus is formed and name its muscular and cutaneous branches
- Describe, briefly, the superficial veins of the neck
- Describe the location, function and connections of the carotid sinus and carotid body
- Describe the cervical lymph nodes and the lymph drainage pattern of the head and neck
Where is the neck located?
What are each of the fascial layers of the neck layers of?
What muscle does the superficial fascia contain?
What are the 3 different compartments of the neck?
What fascia are they each surrounded by?
- The neck is located between the cranium and clavicles
- Each of the fascial layers of the neck are layers of investing fascia, except for the superficial fascia, which runs around the whole neck
- The superficial fascia contains the platysma
- 3 different compartments of the neck:
1) Visceral compartment
* Surrounded by pre-tracheal fascia
2) 2x Vascular compartments
* Surrounded by carotid sheathe
3) Vertebral compartment
* Surrounded by prevertebral fascia
What are the 3 fascial spaces (potential spaces)?
Where are they located?
Where do they extend between?
- 3 fascial spaces (potential spaces):
1) Pretracheal space
* Between investing layer & pretracheal fascia
* Area extends between neck & superior mediastinum
2) ‘True’ retropharyngeal space
* Pre-tracheal fascia posteriorly and superiorly is buccopharyngeal fascia
* Between buccopharyngeal fascia & superficial prevertebral fascia (alar fascia)
* Area extends between base of skull & superior mediastinum
3) Danger (alar) space/fascial space within prevertebral layer
* Within prevertebral layer (alar fascia & deep prevertebral layer) - The prevertebral layer divides into 2 layers Infront of the vertebral bodies, the alar fascia is more anterior and the deep prevertebral fascia is more posterior
* Covers anterior surface of transverse processes & bodies of cervical vertebrae
* Area extends from base of skull through posterior mediastinum to diaphragm
When is the danger (alar) space is indistinguishable from the ‘true’ retropharyngeal space?
How can infections spread from the pharynx to the posterior mediastinum?
What can be visible in radiological investigations concerning the alar space?
- In healthy individuals, the danger (alar) space is indistinguishable from the ‘true’ retropharyngeal space
- Infections from the pharynx can spread via the ‘true’ retropharyngeal (e.g. retropharyngeal abscess) & danger (alar) spaces into the posterior mediastinum
- Fluid collection & abscesses in the danger (alar) space are visible in radiological investigations
What can easily spread in compartments of the neck?
What other structures are at risk?
- Infection/fluid/gas/tumours can easily spread within each compartment or within the spaces since enclosed with or bounded by fascia
- The thoracic structures are at risk since many of the compartments & spaces extend into the thorax
What 3 structures is the anterior triangle of the neck bound by?
What forms the roof of the anterior triangle?
What 2 structures form the floor of the anterior triangle?
- 3 structures the anterior triangle of the neck is bound by:
1) Inferior border of mandible
2) Anterior border of sternocleidomastoid (SCM)
3) Midline of neck - The roof of the anterior triangle is formed by the deep investing fascia around muscles
- 2 structures form the floor of the anterior triangle:
1) Pretracheal fascia
2) Carotid sheath (posterolaterally)
What 4 important triangles is the anterior triangle of the neck broken up into?
- 4 important triangles the anterior triangle of the neck broken up into:
1) Submandibular (digastric) triangle
2) Submental triangle
3) Carotid triangle
4) Muscular (omotracheal) triangle
What 3 structures make up he submandibular triangle?
What are 4 structures within the submandibular triangle?
- 3 structures make up he submandibular triangle:
1) Anterior belly of digastric muscle
2) Posterior belly of digastric
3) Body of mandible - 4 structures within the submandibular triangle:
1) Submandibular gland
2) Submandibular lymph nodes
3) Facial artery (pulse) and vein
4) (part of) CN XII
What 3 structures make up the submental triangle?
What structure does the submental triangle contain?
- 3 structures make up the submental triangle:
1) Anterior belly of digastric
2) Hyoid
3) Midline - The submental triangle contains the submental lymph nodes
Where do the anterior and posterior bellies of the digastric originate and insert?
Describe the action of the bellies of the digastric.
- The anterior belly of the digastric originates at digastric fossa on lower medial aspect of mandible
- The posterior belly of the digastric originates at mastoid notch on medial side of mastoid process
- Both bellies insert at attachment of their intermediate tendon at hyoid
- Anterior belly raises hyoid & opens mouth by lowering mandible
- Posterior belly elevates & retracts hyoid bone
What does the digastric develop from?
What is the digastric muscle innervated by?
- Digastric muscle is innervated by:
1) Anterior belly (derived from 1st pharyngeal arch)
* Nerve to mylohyoid (CN V3)
* Nerve of the first pharyngeal arch
1) Posterior belly (derived from the 2nd pharyngeal arch
* Digastric branch of CN VII
* Nerve of the 2nd pharyngeal arch
What 3 structures make up the carotid triangle?
What 8 structures does the carotid triangle contain?
- 3 structures make up the carotid triangle:
1) Posterior belly of digastric
2) Superior belly of omohyoid
3) Sternocleidomastoid - 8 structures does the carotid triangle contain:
1) Thyroid gland
2) Larynx
3) Pharynx
4) Carotid sheath (and its contents)
5) Branches of cervical plexus
6) Ansa cervicalis
7) Deep cervical lymph nodes
8) (Parts of) CN XI and XII
What 3 structures make up the omotracheal triangle?
What 4 structures are in the omotracheal triangle?
- 3 structures make up the omotracheal triangle:
1) Superior belly of omohyoid
2) Sternohyoid
3) SCM - 4 structures are in the omotracheal triangle:
1) Sternohyoid muscles
2) Sternothyroid muscles
3) Thyroid gland
4) Parathyroid glands
Where are the suprahyoid and infrahyoid muscles located?
Where do they connect?
1) Suprahyoid muscles
* Above hyoid
* Connect to skull or mandible
2) Infrahyoid Muscles
* Below hyoid
* Connect to inferior structures (sternum, scapula, thyroid cartilage)
What is the action of the suprahyoid muscles?
What are the 4 suprahyoid muscles?
- The suprahyoid muscles raise the hyoid bone for swallowing
- 4 suprahyoid muscles:
1) Mylohyoid
2) Digastric
3) Stylohyoid
4) Geniohyoid
What is the role of the Infrahyoid (strap) muscles?
What are the 4 Infrahyoid (strap) muscles?
What are the 2 sources of innervation to the Infrahyoid (strap) muscles?
- The Infrahyoid (strap) muscles pulls the hyoid bone back into position (depression), which is mostly done by gravity
- 4 Infrahyoid (strap) muscles:
1) Sternohyoid
2) Omohyoid
3) Thyrohyoid
4) Sternothyroid - 2 sources of innervation to the Infrahyoid (strap) muscles:
1) Sternohyoid, Omohyoid, Sternothyroid by anterior rami of C1-3
2) Thyrohyoid by C1, hitchhiking CN-XII
What is the thyroid gland?
What is it required for?
What are 3 thyroid hormones?
- The thyroid gland is an endocrine gland
- The thyroid gland is required for metabolism and growth/development
- The 3 thyroid hormones:
1) T3
2) T4
3) Calcitonin (lowers blood calcium)
What compartment in the neck is the thyroid gland located?
What 3 structures is the thyroid gland composed of?
- The thyroid gland is located in the visceral compartment of neck, which is within the pretracheal fascia
- 3 structures is the thyroid gland composed of:
1) 2 lateral lobes (right & left) (extends from thyroid cartilage to 5th tracheal ring)
2) Midline isthmus (level of 3rd tracheal ring)
3) Midline pyramidal lobe (variably present, remnant of thyroglossal duct)
What are the 2 arterial supplies to the thyroid gland?
What are the 3 venous drainages of the thyroid gland?
- 2 arterial supplies to the thyroid gland:
1) Superior thyroid artery (1st branch of external CA)
2) Inferior thyroid artery (branch of thyrocervical trunk from subclavian) - There is extensive anastomoses between these 2 arterial supplies
- 3 venous drainages of the thyroid gland (thyroid plexus divides into 3):
1) Superior thyroid vein (into IJV)
2) Middle thyroid vein (into IJV)
3) Inferior thyroid vein (into brachiocephalic)
What are parathyroid glands?
Where are they located?
What is their arterial supply and venous drainage?
Where hormone does the paraythroid gland secrete?
- The parathyroid glands consist of two pairs (superior & inferior) of small glands
- Usually on posterior surface of thyroid, but exact position varies
- Supplied by inferior thyroid arteries (branch of thyrocervical trunk from subclavian)
- Venous drainage is the same as the thyroid (thyroid venous plexus)
- The parathyroid gland secretes parathyroid hormone (PTH)
- PTH can mobilise calcium into the blood from the bones through activation of osteoblasts
What are the thyroid and parathyroid glands innervated by?
What nerves are located near these glands?
- Both thyroid & parathyroid glands are innervated by thyroid branches from the cervical (sympathetic) ganglia
- Note where the recurrent laryngeal nerve is located and its relationship to the thyroid and parathyroid glands
What 4 structures is the posterior branch of the neck bound by?
What 2 structures form the roof of the posterior neck of the triangle?
What structures form the floor of the posterior triangle of the neck?
What does the posterior triangle of the neck connect?
- 4 structures the posterior branch of the neck is bound by:
1) [Posterior border] of SCM
2) Anterior border of trapezius
3) Middle 3rd of clavicle
4) Occipital bone - 2 structures form the roof of the posterior neck of the triangle:
1) Deep investing fascia
2) SCM and trapezius - The floor of the posterior triangle of the neck is formed by structures in the prevertebral fascia within the vertebral column (splenius capitis, levator scapulae, and scalene muscles)
- This triangle connects the head and neck to the upper limb through the axillary inlet
What are 3 subregions of the posterior triangle?
What do they contain?
- 3 subregions of the posterior triangle:
1) Occipital triangle
* Accessory nerve
* Brachial plexus
2) Omoclavicular (Major supraclavicular) triangle
3) Minor supraclavicular triangle
* Between 2 heads of SCM and clavicle
* Contains Inferior bulb of internal jugular vein (slight dilation)
* This means we can access the IJV through here for central venous access
Where is the retromandibular fossa located?
What 4 structures does the retromandibular fossa contain?
- The retromandibular fossa is located posterior to the mandible, between the external acoustic meatus, angle of the mandible, and ramus of the mandible
- 4 structures the retromandibular fossa contains:
1) Parotid gland
2) Styloglossus, Stylohyoid, Stylopharyngeal muscles
3) Stylomandibular and Stylohyoid ligaments
4) Retromandibular vein, maxillary and superficial temporal vessel
What is the cervical plexus formed by?
Where is it formed?
What are the 2 muscular branches of the cervical plexus?
- The cervical plexus is formed by the anterior rami of C1-4, deep to sternocleidomastoid
- 2 muscular branches of the cervical plexus:
1) Phrenic nerve (C3-5) to the diaphragm (C3-5 keep diaphragm alive)
2) Ansa cervicalis (C1-3) to infrahyoid muscles
Where is Erb’s point located?
What does this area provide in terms of anaesthetic?
Which 4 cutaneous branches are superficial at Erb’s point?
- Erb’s point is located half-way on the posterior border of SCM
- This area can provide a wide area of numbness for anaesthetic
- 4 cutaneous branches are superficial at Erb’s point:
1) Lesser occipital nerve (C2)
2) Great auricular nerve (C2-3)
3) Transverse cervical nerve (C2-3)
4) Supraclavicular nerve (C3-4)
What are the common carotids branches of?
Where do common carotids bifurcate?
Which carotid artery has no branches in the neck?
- Common carotids are branches of the aortic arch on the left, brachiocephalic trunk on the right
- Bifurcates to internal and external carotid arteries at C3/4 vertebral level or upper margin of thyroid cartilage
- Internal carotid artery has no branches in the neck
Where is the carotid sinus located?
What does it contain?
What is the role of baroreceptors?
Describe the innervation of the carotid sinus.
- The carotid sinus is an Enlargement/dilation at bifurcation of common carotid artery or beginning of internal carotid artery
- It contains baroreceptors
- The carotid sinus monitors blood pressure and helps keep blood pressure within homeostatic values
- The carotid sinus is Innervated by CN IX:
1) Nucleus of tractus solitarius
2) To the cardioregulatory & vasomotor centres in the medulla (vital centres)
3) To dorsal nucleus of vagus
* The vagus is parasympathetic and supplies the smooth muscles of the artery walls, allowing it to relax these muscles to reduce BP
What is the carotid body?
Where is it located?
What is its role?
Describe the innervation of the carotid body
- The carotid body is a small organ (~2-5mm) which houses chemoreceptors
- It is located at bifurcation of CCA
- It monitors blood O2, CO2, & pH (& temperature)
- The carotid body responds in emergency situations by increasing respiration, blood pressure & cardiac rate (not as much at rest)
- The carotid body is innervated by CN IX;
1) Nucleus of tractus solitarius
2) To the cardioregulatory & vasomotor centres in the medulla (vital centres)
That are the superficial veins of the neck?
What is the IJV continuation of?
Where does it exit the skull?
What structure does it enter?
What structure does it then join?
- The superficial veins of the neck are the Internal, anterior and external jugular veins
- Internal jugular vein (drains intracranial venous blood):
- Continuation of sigmoid sinus
- Exits skull via the jugular foramen
- Enters carotid sheath and runs lateral to Common carotid artery
- Joins subclavian vein to become brachiocephalic vein
Where does the external jugular vein begin?
What structure does it cross?
What structure does it pierce?
What does it drain into?
What vein does it also have connections with?
- External jugular vein
- Begins at angle of mandible, formed by the fusion of retromandibular & posterior auricular veins
- Crosses over SCM
- Pierces investing fascia to enter & drain into subclavian vein
- As it goes on, also has connections with the internal jugular
Where does the anterior jugular vein arise from?
Where does it drain into?
What structure does it form?
- Anterior jugular vein
- Arise near the hyoid bone & run on either side of midline
- Drains into the external jugular vein
- The anterior jugular vein forms the jugular venous arch
Superficial and deep lymphatic chain of the neck (in picture)
Lymph nodes in the neck diagram (in picture)
Lymph nodes in the neck flow chart (in picture)
What are the only lymph nodes in the scalp or face region?
Where can stomach cancers metastasize to?
- No lymph nodes in the scalp or face, except parotid/buccal region
- Stomach cancers can metastasise to the supraclavicular lymph nodes
