Anatomy of the neck Flashcards
What are the compartments in the neck?
- Musculoskeletal
- Visceral
- Left vascular
- Right vascular
What is in the musculoskeletal compartment?
- Vertebrae
- Deep cervical muscles
- Neck muscles
- Prevertebral fascia
What is in the visceral compartment?
- Trachea
- Oesophagus
- Larynx
- Pharynx
- Pretracheal fascia
What is in the vascular compartments?
- Internal jugular vein
- Common or internal carotid
- Vagus nerve
- Carotid sheath
What are the borders of the anterior triangle?
- Inferior border of the mandible
- Anterior border of sternocleidomastoid
- Midline of the neck
What is the roof of the anterior triangle?
Deep investing fascia around the muscles
What is the floor of the anterior triangle?
Pretracheal fascia and carotid sheath
What is the anterior triangle divided into?
- Submandibular triangle
- Submental triangle
- Carotid triangle
- Omotracheal triangle
What are the borders of the submandibular triangle?
- Anterior and posterior bellies of digastric
* Body of the mandible
What is in the submandibular triangle?
- Submandibular gland
- Submandibular lymph node
- Facial artery and vein
- Part of CNXII - hypoglossal
What are the borders of the submental triangle?
- Anterior belly of digastric
- Hyoid
- Midline
What is in the submental triangle?
• Submental lymph nodes
Where does the anterior belly of digastric originate?
• Digastric fossa on the lower medial aspect of the mandible
Where does the posterior belly of digastric originate?
At the mastoid notch on the medial side of the mastoid process
Where do the bellies of digastric insert?
At the attachment of their intermediate tendon at the hyoid
What is the action of digastric?
- Anterior belly: raises the hyoid and opens the mouth by lowering the mandible
- Posterior belly elevates and retracts the hyoid
What is the innervation of digastric?
- Anterior belly: nerve to mylohyoid (CN v3)
* Posterior belly: digastric branch of CNVII (facial nerve)
What are the borders of the carotid triangle?
- Posterior belly of digastric
- Superior belly of omohyoid
- Sternocleidomastoid
What is the contents of the carotid triangle?
- Thyroid gland
- Larynx
- Pharynx
- Carotid sheath
- Branches of the cervical plexus
- Ansa cervicalis
- Deep cervical lymph nodes
- Parts of CNXI and XII (glossopharyngeal and hypoglossal)
What are the borders of the omotracheal triangle?
- Superior belly of omohyid
- Sternohyoid
- Sternocleidomastoid
what is the contents of the omotracheal triangle?
- Sternohyoid
- Sternothyroid
- Thyroid muscles
- Parathyroid glands
What are the supra hyoid muscles?
- Mylohyoid
- Digastric
- Stylohyoid
- Geniohyoid
What is the function of the suprahyoid muscles?
• Raise hyoid during swallowing
What are the infrahyoid (strap muscles)
- Sternohyoid
- Omohyoid
- Thyrohyoid
- Sternothyroid
What do the infra hyoid muscles do?
Depress the hyoid
What is the innervation of the infra hyoid (Strap) muscles?
- Sternohyoid, omohyoid, and sternothyroid are innervated by the rami of C1-3
- Thyrohyoid is innervated by C1 (hitch hiking on CN XII)
Describe the position of the thyroid gland
- Within the visceral compartment of the neck
- Composed of two lateral lobes that extend from the thyroid cartilage to the 5th tracheal ring
- Midline isthmus is level of the 3rd tracheal ring
What is the midline pyramidal lobe a remnant of?
The thyroglossal duct
What is the arterial supply of the thyroid gland?
- Superior thyroid artery (1st branch of the external carotid)
- Inferior thyroid artery (branch of the thyrocervical trunk from the subclavian)
What is the venous drainage of the thyroid gland?
- Superior thyroid vein (into IJV)
- Middle thyroid vein (into IJV)
- Inferior thyroid vein (into brachiocephalic)
What is the venous drainage of the parathyroid gland?
- Superior thyroid vein (into IJV)
- middle thyroid vein (into IJV)
- Inferior thyroid vein (into brachiocephalic)
What are the parathyroid glands?
- Two pairs of small glands on the posterior surface of the thyroid (exact position varies)
- Regulate calcium and phosphorus metabolism
- Secretes parathyroid hormone and releases calcium from the stores
What is the arterial supply of the parathyroid gland?
Inferior thyroid arteries (branch of the thyrocervical trunk from subclavian)
what is the innervation of the thyroid and parathyroid?
• Thyroid branches from the cervical ganglia
What are the boundaries of the posterior triangle?
- Posterior border of sternocleidomastoid
- Anterior border of trapezius
- Middle 3rd clavicle
- Occipital bone
What is the roof of the posterior triangle?
- Deep investing fascia
* Sternocleidomastoid and trapezius
What is the floor of the posterior triangle?
- Prevertebral fascia
- splenius capitis
- Levator scapulae
- Scalene muscles
- Accessory nerve, branch of brachial plexus
What are the subregions of the posterior triangle?
- occipital triangle
- Omoclavicular
- Minor supraclavicular triangle
What is in the occipital triangle?
- Accessory nerve
* Brachial plexus
What is in the minor supraclavicular triangle?
- Inferior bulb of internal jugular vein
* Between 2 heads of sternocleidomastoid
What is in the retromandibular fossa?
- Parotid gland
- Styloglossus, stylohyoid, stylopharyngeal
- Stylomandibular and stylohyoid ligaments
- Retromandibular vein, maximally are superficial temporal vessels
What forms the cervical plexus?
• Anterior rami of C1-4 deep to sternocleidomastoid
What are the muscular branches of the cerivcal plexus?
- Phrenic nerve (C3-5) to the diaphragm
* Ansa cervicali (C1-3) to the infra hyoid muscle (1 branch from cervical plexus, 1 from hypoglossal)
What are the cutaneous branches of the cervical plexus?
- Lesser occipital nerve (C2)
- Great auricular nerve (C2-3)
- Transverse cervical nerve (C2-3)
- Supraclavicular nerve (C3-4)
What is Erb’s point?
- Where the cutaneous branches become superficial
* Halfway on the posterior border of sternocleidomastoid
What are the common carotids branches of?
- aortic arch on the left
* brachiocephalic trunk on the right
When does the carotid bifurcate into the internal and external arteries?
c3/4
What is the carotid sinus?
Enlargement or dilation at the bifurcation of the common carotid artery
• Contains baroreceptors sensitive to stretch
• Monitors blood pressure and helps keep it within homeostatic values
Innervation of the carotid sinus
- CNIX
- To the cardioregulatory and vasomotor centre in the medulla
- To the dorsal nucleus of the vagus
What is the carotid body
- Small body (approx 2-5mm) which houses chemoreceptors located at the common carotid artery
- Monitors blood O2, CO2 and pH
- Responds in emergency situations by increasing respiration, blood pressure and cardiac rate
What is the innervation of Carotid body?
- CNIX
- Nucleus to the tracts solitaires
- to the cardioregulatory and vasomotor centres in the medulla
- To the dorsal nucleus of the vagus
What are the superficial veins of the neck?
- Internal jugular
- Anterior jugular
- External jugular
What is the internal jugular vein a continuation of?
Sigmoid sinus
Where does the internal jugular vein exit the skull?
Via the jugular foramen
Describe the route of the internal jugular vein
- Enters the carotid sheath and runs lateral to the common carotid artery
- Joins the subclavian vein to become the brachiocephalic vein
Where does the external jugular vein begin?
At the angle of the mandible, joining the retromandibular and posterior auricular veins
Describe the course of the external jugular vein
- begins at the angle of the mandible, joining the retromandibular and posterior auricular veins
- Crosses over SCM
- Pierces investing fascia to enter and drain into subclavian vein
What are the risks of cannulating the external jugular vein?
Pressure is negative within because of fascia, air could be sucked in if cannulated
Where does the anterior jugular vein arise?
Near the hyoid bone
Where does the anterior jugular vein drain?
Into the external jugular vein
What is the jugular venous arch?
Connection of left and right anterior jugular veins
