Anatomy of the Neck Flashcards
Describe the organisation of fascia in the neck
Superficial fascia (between the dermis and deep fascia):
- neurovascular supply to the skin
- superficial veins (EJV)
- platysma (CNVII - originates as 2 heads from pectoralis major and deltoid muscles and inserts on the inferior border of the mandible)
- superficial lymph nodes
- fat
Deep Fascia: Investing fascia (surrounds all neck structures: splits to surround SCM and trapezius
Pre-tracheal fascia (in anterior neck from hyoid bone to thorax):
- muscular part: encloses infrahyoid muscles
- visceral part: encloses trachea, oesophagus and thyroid gland
- posteriorly forms the buccopharyngeal fascia (covering pharynx)
Pre-vertebral fascia (surrounds vertebral column, scalene and pre-vertebral muscles, and deep muscles of the back): surrounds brachial plexus forming the axillary sheath
Carotid sheath (encloses neurovascular bundle):
- common carotid artery
- vagus nerve
- IJV
- cervical lymph nodes
Describe the fascial spaces in the neck
Pre-tracheal: between pre-tracheal and investing fascia, between neck and superior mediastinum
‘True’ retropharyngeal fascia: between buccopharyngeal and alar fascia, between base of skull and superior mediastinum
Danger space: between alar and deep layer of pre-vertebral fascia, between the base of skull and diaphragm
What are the boundaries of the anterior triangle?
- inferior border of mandible
- anterior border of SCM
- midline of neck
roof: deep investing fascia around muscles
floor: pre-tracheal fascia and carotid sheath
What is the contents of the anterior triangle?
Submandibular triangle (bound by ant. and post. bellies of digastric and body of mandible):
- submandibular gland and lymph nodes
- facial artery and vein
- part of facial nerve CNVII
Submental triangle (bound by ant. belly of digastric, midline of neck and hyoid): * submental lymph nodes
Carotid triangle (bound by post. belly of digastric, sup. belly of omohyoid and SCM):
- thyroid gland
- larynx and pharynx
- carotid sheath
- branches of cervical plexus
- deep cervical nodes
- part of accessory n and hypoglossal n.
Omo-tracheal triangle (bound by sup. belly of omohyoid, sternohyoid and SCM):
- sternohyoid muscles
- sternothyroid muscles
- thyroid and parathyroid glands
Describe the digastric muscle
- anterior belly originates at digastric fossa on lower medial mandible and is innervated by the nerve to mylohyoid (V3).
It raises hyoid and opens mouth by lowering the mandible.
- posterior belly originates at the mastoid notch of medial mastoid process and is innervated by the digastric branch of the facial nerve (CNVII)
It elevates and retracts the hyoid.
- both insert onto the tendon of hyoid
Describe the connections of hyoid (muscles, role and innervation)
Suprahyoid muscles (My, Dad, Studies, German: mylohyoid, digastric, stylohyoid, geniohyoid
- elevates hyoid in swallowing
Infrahyoid muscles (Save Our Souls Today): sternohyoid, omohyoid, sternothyroid, thyrohyoid
- can depress hyoid but is mainly gravity
Form, position, role and blood supply of thyroid gland
- 2 lateral lobes extending to 5th tracheal ring, with a middle isthmus
- some have middle pyramidal gland (remnant of thyroglossus)
- role is to release T3, T4, and calcitonin (regulated by hypothalamus and pituitary gland)
- arterial: superior thyroid artery (from external carotid a.), and inferior thyroid artery (from thyrocervical trunk of subclavian a.)
- venous: superior and middle thyroid v. to IJV, and inferior thyroid v. to brachiocephalic v.
Form, position and blood supply of parathyroid gland
- 2 pairs of small glands on posterior side of thyroid
- arterial: inferior thyroid artery
- venous: same as thyroid gland
Nerve supply and close relations of thyroid and parathyroid glands
Innervated by thyroid branches of cervical ganglia.
Closely related to recurrent laryngeal nerve of vagus (CNX)
What are the boundaries of the posterior triangle?
- posterior border of SCM
- anterior border of trapezius
- middle 3rd of clavicle
- occipital bone
Roof: deep investing fascia, SCM and trapezius
Floor: pre-vertebral fascia, spleinus captitis, levator scapulae and scalene muscles
What is the contents of the posterior triangle?
Occipital triangle: contains the accessory nerve and the brachial plexus
Omoclavicular triangle
Minor supraclavicular triangle: contains the inferior bulb of IJV
What is the contents of the retromandibular fossa?
- parotid gland
- styloglossus, stylohyoid, stylopharyngeus (Give, Him, Pain)
- stylohyoid and stylomandibular ligaments (Hate, Men)
- retromandibular vein, maxillary and superficial temporal vessels
What is the contents of the retromandibular fossa?
- parotid gland
- styloglossus, stylohyoid, stylopharyngeus (Give, Him, Pain)
- stylohyoid and stylomandibular ligaments (Hate, Men)
- retromandibular vein, maxillary and superficial temporal vessels
What is the contents of the retromandibular fossa?
- parotid gland
- styloglossus, stylohyoid, stylopharyngeus (Give, Him, Pain)
- stylohyoid and stylomandibular ligaments (Hate, Men)
- retromandibular vein, maxillary and superficial temporal vessels
Describe the cervical plexus
Formed by anterior rami of C1-4, deep to SCM
Muscular branches:
- phrenic nerve to diaphragm (C3-5)
- ansa cervicalis to infrahyoid muscles (C1-3)
Cutaneous branches (become superficial at Erb’s point):
- lesser occipital nerve (C2)
- great auricular nerve (C2-3)
- transverse cervical nerve (C2-3)
- supraclavicular nerve (C3-4)
What is the carotid sinus and body, its roles and innervations?
Carotid body:
- enlargement at bifurcation of common carotid arteries at C3/4
- monitors BP with baroreceptors in homeostasis
- innervated by glossopharyngeal nerve (IX)
Carotid sinus:
- small organ at bifurcation of common carotid arteries
- monitors O2, CO2 and temperature with chemoreceptors to respond in emergency situations
- innervated by the glossopharyngeal nerve (IX)
Describe the pathways of the superficial veins in the neck
IJV:
- continuation of sigmoid sinus which exits cranium by the jugular foramen to enter the carotid sheath
- travels lateral to common carotid artery
- joins subclavian vein to become brachiocephalic vein
EJV:
- originates at angle of mandible
- joins retromandibular and posterior auricular veins to cross SCM and pierce investing fascia
- drains to subclavian vein
AJV:
- arises near hyoid bone and runs on each side of the midline
- drains to EJV
Describe the drainage of the cervical lymph nodes
- submental and facial nodes go to submandibular nodes
- all nodes drain to superior lateral deep cervical nodes
9 groups:
- occipital
- mastoid
- parotid
- buccal
- infrahyoid
- submandibular
- superficial cervical
- deep cervical (retropharyngeal, jugulodigastric, jugulo-omohyoid)
