The Neck Flashcards
What are the facial layers of the neck?
Superficial cervical fascia (contains neurovascular supply to the skin, superficial veins and lymph nodes, fat and platysma muscle)
Deep cervical fascia - Has investing layer, pretracheal layer, prevertebral layer and carotid sheath.
What are the potential spaces in the neck?
- Pretracheal space (between investing layer and pretracheal fascia),
- ‘True’ retropharyngeal space (extends between base of skull and superior mediastinum),
- Danger/alar space which is within the prevertebral layer (extends between base of skull through posterior mediastinum to diaphragm)
What are the boundaries of the anterior triangle?
Bounded by inferior border of mandible, anterior border of SCM and the midline of neck.
Roof is the deep investing fascia and the floor is the pretracheal fascia and carotid sheath.
What are the subdivisions of the anterior triangle?
- Carotid triangle,
- Submental triangle,
- Submandibular (digastric) triangle,
- Muscular (omotracheal) triangle
What are the boarders and contents of the submandibular triangle?
Boarders - Anterior and posterior bellies of digastric, body of mandible.
Contents - Submandibular gland, submandibular lymphnodes, fascial artery, vein and part of CN XII.
What are the boarders of the submental triangle and its contents
Boarders - anterior belly of digastric, hyoid and midline.
Contents - Submental lymph nodes
What are the origins and innervations of the digastric muscle?
Anterior belly - digastric fossa of mandible. Innervated by nerve to mylohyoid (CN V3).
Posterior belly - Mastoid notch on mental side of mastoid process. Innervated by digastric branch of CN VII
What are the boarders and contents of the carotid triangle?
Boarders - Posterior belly of digastric, superior belly of omohyoid and SCM.
Contents - Thyroid gland, larynx, pharynx, carotid sheeth, branches of cervical plexus, ansa cervicalis, deep cervical LNs and deep parts of CN XI and XII.
What are the boarders and contents of the omotracheal triangle?
Boarders - Superior belly of omohyoid, sternohyoid and SCM.
Contents - Sternohyoid muscle, sternothyroid muscle, thyroid gland and parathyroid gland
What is unique about the hyoid bone?
It isnt attached to any other bone, it is suspended by suprahyoid muscles (mylohyoid, digastric, stylohyoid and geniohyoid) and infrahyoid muscles (sternohyoid, omohyoid, thyrohyoid, sternothyroid.)
What are the actions and innervations of the infrahyoid (strap) muscles
Actions - depress the hyoid.
Innervation - sternohyoid, omohyoid and sternothyroid are supplied by anterior rami of C1-3. Thyrohyoid is innervated by C1 which hitchhikes CN-XII.
Describe features of the function of the thyroid gland?
- Endocrine gland which is required for metabolism and growth. Produces T3 and T4 (thyroxine). Responds to TSH which is released by the pituitary. Also releases calcitonin.
Describe the anatomy of the thyroid gland?
Found within visceral compartment of neck. Composed of two lateral lobes connected by midline isthmus (level of 3rd tracheal ring) There may also be present the midline pyramidal lobe (remnant of thyroglossal duct)
What is the arterial supply and venous drainage of the thyroid gland?
Arterial supply - Superior thyroid artery (Branch of external CA) and inferior thyroid artery (branch of thyrocervical trunk).
Venous Drainage - Superior thyroid vein and middle thyroid vein which drain to the IJV and the inferior thyroid vein which drains to brachiocephalic vein.
Describe features of the parathyroid gland?
Two pairs on the posterior surface of thyroid, which are supplied by inferior thyroid arteries (same venous drainage as thyroid) and is innervated by cervical ganglia. It releases parathyroid hormone which mobilises calcium from reservoirs.
What are the boarders of the posterior triangle?
Bounded by the posterior aspect of SCM, anterior boarder of trapezius, middle 3rd of clavical and occipital bone.
Roof is deep investing fascia, SCM and trapezius.
Floor is paravertebral fascia, splenius capitis, levator scapulae and scalene muscles
What are the subtriangles of the posterior triangle?
- Occipital triangle (contains accessory nerve and brachial plexus).
- Omoclavicular triangle,
- Minor supraclavicular triangle (contains inferior bulb of internal jugular vein)
What are the contents of the retromandibular fossa?
- Parotid gland,
- styloglossus, stylohyoid and stylopharyngeal muscles,
- Stylomandibular and stylohyoids ligaments,
- Retromandibular vein, maxillary and superficial temporal vessels
Describe features of the cervical plexus?
It is formed by the anterior rami of C1-4 deep to the sternocleidomastoid.
Muscular branches are phrenic nerve (C3-5) to diaphragm and ansa cervicalis (C1-3) to infrahyoid muscles
What is Erbs point?
Where the cutaneous branches of the following nerves become superficial;
- Lesser occipital (C2),
- Greater auricular nerve (C2-3),
- Transverse cervical nerve (C2-3),
- Supraclavicular nerve (C3-4)
What are features of the carotid arteries?
Bifurcates at C3/4 or upper margin of thyroid cartilage. Internal carotid has no branches in the neck. Enlargement/dilation occurs at the bifurcation and is names the carotid sinus which contains baroreceptors sensitive to stretch so monitors blood pressure. Innervated by IX.
Describe features of the carotid body
Small organ which houses chemoreceptors at the bifurcation of the common carotid artery. Monitors blood O2, CO2, pH and temperature.
Describe features of internal jugular vein
Continuation of sigmoid sinus, enters carotid sheath and runs lateral to common carotid artery. Joins subclavian to becomes brachiocephalic.
Decribe features of external jugular vein
Beings at angle of mandible from the joining of retromandibular and posterior auricular veins. Crosses SCM and pierces investing fascia to drain into the subclavian vein.
Describe features of anterior jugular vein
Arises near the hyoid bone and run on either side of midline, drains into external jugular vein.
