Structural Anatomy of the Neck Flashcards
Division of cervical vertebrae
- Typical (C3-C6)
- Atypical (C1, 2, 7)
Features of typical cervical vertebrae
- Small body
- Large triangular foramen
- Transverse process includes transverse foramina
Describe the Atlas
- C1
- Ring-like
- Lacks spinous process or body
- Consists of two lateral masses connected by arches
Describe the Axis
- C2
- Odontoid peg projects from anterior aspect of its body
Describe the Vertebra Prominens
- C7
- Long spinous process (hence name)
- Large transverse processes
- Small transverse foramina (do not contain vertebral artery)
Level of the hyoid bone
C3
Parts of the hyoid bone
- Body
- Greater horn
- Lesser horn
Connection between hyoid and styloid process
Stylohyoid ligaments
3 divisions of the deep cervical fascia
- Investing layer
- Prevertebral fascia
- Pretracheal fascia
Function of the investing fascia
Encloses the muscles of the neck
Superior attachments of the investing fascia
- Superior nuchal lines
- Mastoid process
- Zygomatic arch
- Inferior border of mandible
- Hyoid bone
- Spinous processes of cervical vertebrae
Inferior attachments of cervical fascia
- Manubrium
- Clavicles
- Acromions and spines of scapulae
Where does the EJV pierce the investing fascia
Below omohyoid, just above the midpoint of the clavicle
What does the investing fascia enclose
- Trapezius
- SCM
- Strap muscles
- Parotid and submandibular glands
Where is the prevertebral fascia situated
- Passes across vertebrae and prevertebral muscles
- Oesophagus, pharynx, and great vessels lie in front
Describe the lateral course of the preverterbal fascia
- Covers the cervical and brachial plexuses
- Covers the muscles in the floor of the posterior triangle
- Becomes the axillary sheath
Describe the course of the pretracheal fascia
- Anterior part of neck only
- Extends from hyoid bone to fibrous pericardium
- Blends laterally with the carotid sheaths
What is enclosed by the pretracheal fascia
- Larynx
- Trachea
- Pharynx
- Oesophagus
- Thyroid gland
- Infrahyoid muscles
Describe the course of the carotid sheath
- Extends from cranial base to root of neck
- Blends anteriorly with the investing and pretracheal layers
- Blends posteriorly with the preverterbral fascia
Contents of the carotid sheath
- Carotid artery
- IJV
- Vagus nerve
Where is the retropharyngeal space
Lies between:
- Visceral part of prevertebral fascia
- Buccopharyngeal fascia surrounding the pharynx
To where does the retropharyngeal space open inferiorly
Superior mediastinum
Bounds of the anterior triangle
- Anterior = midline of neck
- Above = ramus of mandible
- Behind = anterior border of SCM
Bounds of posterior triangle
- Anterior = posterior border of SCM
- Below = middle 1/3rd of clavicle
- Behind = anterior margin of trapezius
Origins and insertion of SCM
- Sternal head to manubrium
- Superior surface of middle 1/3rd of clavicle
- Mastoid process and superior nuchal line
Contents of the SCM region of the neck
- SCM
- Superior part of EJV
- Greater auricular nerve (C2/3)
- Transverse cervical nerve
Contents of the posterior cervical region
- Trapezius muscle
- Cutaneous branches of posterior rami of cervical spinal nerves
Divisions of the posterior triangle
- Occipital triangle
2. Subclavian region
What divides the posterior triangle into its two divisions
Omohyoid muscle
Contents of the occipital triangle
- Part of EJV
- Accessory nerve (CN 11)
- Trunks of brachial plexus
- Posterior branches of cervical plexus
- Cervicodorsal trunk
- Cervical lymph nodes
Contents of subclavian region
- 3rd part of subclavian artery
- Suprascapular artery
- Supraclavicular lymph nodes
- Subclavian vein (sometimes)
Divisions of the anterior triangle
- Submandibular (digastric) triangle
- Submental triangle
- Carotid triangle
- Muscular triangle
Bounds of the submandibular triangle
- Superior = inferior border of mandible
- Anterior and posterior bellies of digastric
- Floor = mylohyoid and hyoglossus and pharyngeal constrictor
Bounds of the submental triangle
- Inferior = body of hyoid
- Lateral = right and left anterior bellies of digastric
- Floor = mylohyoid muscles which meet at the median fibrous raphe
Bounds of the carotid triangle
- Superior belly of omohyoid
- Posterior belly of digastric
- SCM
Contents of the carotid triangle
- Carotid sinus
- Carotid body
- Carotid arteries (medially)
- IJV (laterally)
- Vagus (posterior)
- Ansa cervicalis
- Deep cervical lymph nodes
Contents of the submandibular triangle
- Submandibular gland
- Submandibular lymph nodes
- Hypoglossal nerve
- Mylohyoid nerve
- Parts of facial artery and vein
Contents of submental triangle
- Submental lymph nodes
- Small veins that unite to form the anterior jugular vein
Contents of the muscular triangle
- Sternothyroid and sternohyoid muscles
- Thyroid and parathyroid glands
What is the carotid sinus and what is it innervated by
- Dilatation of the proximal part of the internal carotid artery
- Baroreceptor
- Innervated by CN 9 through the carotid sinus nerve (and 10)
What is the carotid body
- Red/brown ovoid mass in the septum of the bifurcation of common carotid (C4)
- Supplied by carotid sinus nerve and vagus
- Chemoreceptor (sensitive to fall in PaO2)
Role of the carotid body
- Chemoreceptor that monitors blood oxygen levels
- Can stimulate increase in the rate and depth of respiration, cardiac rate, and BP
Relation of ansa cervicalis to the carotid sheath
Lies on or is embedded in the anterolateral sheath
Function of the suprahyoid muscles
Elevate the hyoid and pull it forward during swallowing
What are the strap muscles
Infrahyoid muscles:
- Sternohyoid
- Omohyoid
- Sternythyroid
- Thyrohyoid
Innervation of the strap muscles
Ansa cervicalis (C1-3)
Orientation of the cervical facet joints
Parallel with the vertebral plane
Site of surgical division of the strap muscles
Upper half - the ansa cervicalis enters in the lower half
What contains haematoma post thyroidectomy
Pretracheal fascia
List the suprahyoid muscles
- Mylohyoid
- Geniohyoid
- Stylohyoid
- Anterior and posterior bellies of digastric
Mylohyoid OIIA
O = Mylohyoid line of mandible I = Body of hyoid I = Nerve to mylohyoid (branch of alveolar nerve - V3) A = Elevates hyoid, floor of mouth and tongue
Geniohyoid OIIA
O = inferior mental spine of mandible I = Body of hyoid I = C1 via hypoglossal A = Pulls hyoid anterosuperiorly
Stylohyoid OIIA
O = Styloid process of temporal bone I = Body of hyoid I = Styloid branch of facial nerve (CN 7) A = Elevates and retracts hyoid
Anterior belly of digastric OIIA
O = digastric fossa of mandible I = Intermediate tendon I = Nerve to mylohyoid (branch of inferior alveolar - V3)
Posterior belly of digastric OIIA
O = Mastoid notch of temporal bone I = Intermediate tendon I = Digastric branch of facial nerve (CN 7)
Sternohyoid OIIA
O = manubrium and medial end of clavicle I = Body of hyoid I = Ansa cervicalis A = depresses hyoid
Omohyoid OIIA
O = superior border of scapula I = Inferior border of hyoid I = Ansa cervicalis A = depresses and retracts hyoid
Sternothyroid OIIA
O = posterior surface of manubrium I = Oblique line of thyroid cartilage I = Ansa cervicalis A = Depresses hyoid and larynx
Thyrohyoid OIIA
O = oblique line of thyroid cartilage I = inferior border and body of greater horn of hyoid I = C1 via hypoglossal A = depresses hyoid and elevates larynx
What is Berry’s ligament
Connects thyroid to cricoid cartilage and trachea
Level of common carotid bifurcation
Upper border of thyroid cartilage (C3/4)
Orientation of IJV and vagus nerve to common carotid
- IJV lateral
- Vagus posterior (between artery and vein)
What separates internal carotid from external carotid on its ascent through the neck
- Styloid process
- Stylopharyngeus muscle
- Glossopharyngeal nerve
- Pharyngeal branch of vagus
List the 8 branches of the external carotid artery
- Superior thyroid
- Lingual
- Facial
- Occipital
- Posterior auricular
- Ascending pharyngeal
- Maxillary (terminal)
- Superficial temporal (terminal)
Describe the course of the IJV
- Formed at jugular foramen as continuation of sigmoid sinus
- Lies behind ICA at its start
- Moves lateral to ICA and common carotid as it descends
- Contained within carotid sheath
- At the root of the neck lies behind the gap between the heads of the SCM
- Joins subclavian vein to form brachiocephalic vein
What surrounds the IJV on its descent
Deep cervical chain of lymph nodes
Which side is IJV cannulation typically performed on
Right side
Describe the course of the superior thyroid artery
- 1st branch of ECA
- Anterior branch
- Runs deep to infrahyoid muscles to reach thyroid
- Gives branches to infrahyoids, SCM, superior laryngeal artery to larynx
Describe the course of the lingual artery
- Lies on middle pharyngeal constrictor
- Passes deep to hypoglossal nerve, stylohyoid, posterior belly of digastric
- Supplies posterior tongue
- Divides into deep lingual and sublingual arteries deep to hyoglossus muscle
Describe the course of the facial artery
- Arises anteriorly from ECA
- Gives off tonsillar and ascending palatine branches
- Supplies submandibular gland (lies between it and the mandible)
- Gives off submental branch to floor of mouth
- Hooks around middle of the inferior border of the mandible to enter the face
Describe the course of the posterior auricular artery
- Posterior branch of ECA
- Ascends between acoustic meatus and mastoid process
- Supplies adjacent muscles, parotid gland, facial nerve, structures in the temporal bone, auricle, and scalp
What is the only medial branch of the ECA
Ascending pharyngeal artery
Describe the course of the ascending pharyngeal artery
- Only medial branch of ECA
- Ascends on the pharynx deep to the ICA
- Sends branches to: pharynx, prevertebral muscles, middle ear, cranial meninges
Roof of the posterior triangle
Investing layer of deep cervical fascia
Floor of posterior triangle (inc 4 muscles)
Muscles covered by the prevertebral fascia:
- Splenius capitis
- Levator scapulae
- Middle scalene
- Posterior scalene
Features of the occipital triangle
- Occipital artery at its apex
- Crossed by the accessory nerve
Features of the subclavian triangle
- Indicated on the neck by the supraclavicular fossa
- Inferior part of the EJV crosses the triangle superficially
- Subclavian artery is deep to it
List the branches of the thyrocervical trunk
- Cervicodorsal trunk (a.k.a. transverse cervical artery)
- Suprascapular artery
- Inferior thyroid artery
- Ascending cervical artery
Relation of the 3rd part of subclavian artery to 1st rib and anterior scalene
Lies on the first rib and passes POSTERIOR to the anterior scalene
Relation of inferior trunk of brachial plexus to 3rd part of subclavian artery
Lies immediately posterior
Describe the course of the EJV
- Forms near the angle of the mandible by the union of the retromandibular vein and posterior auricular vein
- Crosses the SCM deep to platysma
- Pierces floor of the posterior triangle (investing layer)
- Terminates at subclavian vein
Relation of subclavian vein to anterior scalene muscle
Passes ANTERIOR to anterior scalene AND phrenic nerve
Describe the course of the brachial plexus in the neck
- Appear between anterior and middle scalene
- Five rami unite to form three trunks
- Passes between 1st rib, clavicle, and superior bordrer of scapula to enter axilla
Describe the course and distribution of the suprascapular nerve
- Arises from the superior trunk of the brachial plexus
- Supplies supraspinatus and infraspinatus
- Sends articular branch to GH joint
Describe how the cervical plexus is constructed
- C1-C4
- Each ramus (except first) divides into ascending and descending branches
- Adjacent branches unite to form loops
Where is the cervical plexus situated
Anteromedial to the levator scapulae and middle scalene and deep to SCM
List the branches of the cervical plexus
- Lesser occipital nerve (C2)
- Great auricular nerve (C2/3)
- Transverse cervical nerve (C2/3)
- Supraclavicular nerves (C3/4)
- Dorsal scapular nerve
- Long thoracic nerve
Distribution of lesser occipital nerve
Skin of the neck and scalp posterosuperior to the auricle
Distribution of the great auricular nerve
- Supplies skin over and sheath of the parotid gland
- Mastoid process
- Surfaces of the auricle
- Angle of the jaw
Distribution of long thoracic nerve
Supplies serratus anterior
Distribution of dorsal scapular nerve
Supplies rhomboids
Origin of the phrenic nerve
- Chiefly C4
- Contributions from C3 and C5
Risk of SCM mobilisation
Damage to accessory nerve
Course of the phrenic nerve
- Arises from C3/4/5
- Forms at superior part of lateral border of anterior scalene muscle at the level of the superior border of the thyroid cartilage
- Descends obliquely with IJV deep to the prevertebral fascia
- LEFT - crosses anterior to first part of subclavian artery
- RIGHT - crosses anterior to second part of subclavian artery
- Thus runs posterior to 1st rib
Where are the prevertebral muscles located
Deep to the vertebral deep cervical fascia
Where are the anterior vertebral muscles located
Directly posterior to the retropharyngeal space and medial to the neurovascular plane of the cervical and brachial plexuses and subclavian artery
List the anterior vertebral muscles
- Longus coli
- Longus capitis
- Rectus capitis anterior
- Anterior scalene
List the lateral vertebral muscles
- Rectus capitis lateralis
- Splenius capitis
- Levator scapulae
- Middle scalene
- Posterior scalene
Anterior scalene OIIA
- O = transverse processes of C3-6
- I = 1st rib
- I = cervical spinal nerves C4-6
- A = Flexes head
Levator scapulae OIIA
- O = posterior tubercles of transverse processes C2-6
- I = superior part of medial border of scapula
- I = dorsal scapula nerve
- A = downward rotation of scapula and tilts glenoid cavity inferiorly
Middle scalene OIIA
- O = posterior tubercles of transverse processes of C5-7
- I = superior surface of 1st rib (posterior to groove for subclavian artery)
- I = anterior rami of cervical spinal nerve
- A = flexes neck laterally, elevates 1st rib
Posterior scalene OIIA
- O = posterior tubercles of transverse processes of C5-7
- I = External border of 2nd rib
- I = anterior rami of cervical spinal nerves C7/8
- A = flexes neck laterally, elevates 2nd rib
Where is the inferior thyroid artery derived from
Thyrocervical trunk (branch of subclavian)
Where is the thyroidea ima vessels derived from
Brachiocephalic trunk
Innervation of latissimus dorsi
Thoracodorsal nerve
Site of the odontoid peg and orientation of transverse ligament
Anterior half of spinal canal with transverse ligament posterior
Describe Sibson’s fascia
- Suprapleural membrane
- Attached to inner border of 1st rib and transverse process of C6
- Subclavian artery, vein and brachial plexus lies on the membrane
Function of Sibson’s fascia
Prevents lung and pleura rising further into the neck on inspiration
Anterior relations of brachiocephalic trunk (muscular)
- Sternohyoid
- Sternothyroid
Where can the subclavian artery pulse be felt
Medial 1/3rd of the clavicle near the lateral border of SCM on deep palpation against 1st rib
Describe the 3 divisions of the subclavian artery
Relative to anterior scalene:
1st = medial to muscle
2nd = posterior to muscle
3rd = lateral to muscle
List the branches of the 1st part of the subclavian artery
- Vertebral artery
- IMA
- Thyrocervical trunk
List the branches of the 2nd part of the subclavian artery
- Costocervical trunk
List the branches of the 3rd part of the subclavian artery
- Dorsal scapular artery
Describe the course of the vertebral arteries
- Cervical part = ascends in space between scalene and longus muscles
- Vertebral part = ascends in tranverse foramina of C1-6
- Suboccipital part = enters cranial cavity through FORAMEN MAGNUM
Outline the cranial distribution of the vertebral arteries
Supply branches to:
- Medulla
- Spinal cord
- Cerebellum
- Dura of posterior cranial fossa
What does the inferior thyroid artery supply
- Larynx
- Trachea
- Oesophagus
- Thyroid and parathyroid glands
Describe the course of the subclavian vein in the neck
- Follows course of subclavian artery BUT lies anterior to anterior scalene on 1st rib
- Unites with IJV
Describe the venous angle
- Site of unity of IJV and subclavian vein
- Site where thoracic duct (left side) and right lymphatic trunk (right side) drain lymph into venous circulation
Outline the course of the thoracic duct
- Commences at the cysterna chyli between abdominal aorta and right crus of diaphragm
- Passes up through aortic hiatus in diaphragm
- Ascends behind oesophagus, inclining to left at T5
- Arches laterally at the root of the neck to lie between carotid sheath and vertebral artery
- Enters left venous angle
Outline the course of the vagus nerve in the neck
- Exits jugular foramen
- Descends in posterior part of carotid sheath
- a) Right vagus passes anterior to 1st part of subclavian and posterior to brachiocephalic vein
b) Left vagus descends between common carotid and left subclavian and posterior to SC - Recurrent laryngeal nerve arises from vagus in inferior part of neck
Difference in course between right and left recurrent laryngeal nerves
- Right = loops inferior to the right subclavian artery at T1-2
- Left = loops inferior to arch of aorta at T4-5
Distribution of recurrent laryngeal nerves
All intrinsic muscles of the larynx except cricothyroid
Level of the hyoid
C3
Level of the notch of the thyroid
C4
Level of the cricoid
C6
List the components of the larynx
- Epiglottis
- Thyroid cartilage
- Cricoid cartilage
- Arytenoid cartilage
Purpose of the larynx
Voice production
How is the epiglottis connected to the arytenoids
By the aryepiglottic folds
Shape and orientation of the cricoid cartilage
Signet ring - band part facing anteriorly
Attachments of the cricoid cartilage
- Inferior margin of thyroid via median cricothyroid ligament
- First tracheal ring via cricotracheal ligament
- Arytenoid cartilages
Describe the components of the arytenoid cartilage
- Corniculate cartilage (small nodule at apex of arytenoids)
- Cuneiform cartilage (lies at the margin of the aryepiglottic folds
What forms the vocal ligament
Upper edge of the cricothyroid membrane (A.K.A. Cricothyroid ligament)
What forms the false vocal cords
Vestibular fold - upper fold of mucosa passing forwards from arytenoids to back of thyroid cartilage
What forms the vocal cord
Lower fold of mucosa (conus elasticus) passing forwards from arytenoids to the back of the thyroid cartilage
What is the Rima Glottidis
Space between the vocal cords
Outline the 3 compartments of the larynx
- Supraglottic (vestibule) - above the false cords
- Glottic - between false cords and true cords
- Subglottic - between true cords and first tracheal ring
What is the piriform fossa
A recess on either side of the larynx where foreign bodies may lodge
What tenses the vocal cords
Cricothyroid
What abducts the vocal cords
Posterior cricoarytenoid
Innervation of cricothyroid
External laryngeal branch of the superior laryngeal nerve
Arterial supply of the larynx and their course
- Superior and inferior laryngeal arteries (branches of the superior and inferior thyroid arteries)
- Accompany the superior laryngeal and recurrent laryngeal nerves respectively
Clinical effect of superior laryngeal nerve injury
Change in the pitch of voice through loss of innervation to the cricothyroid muscle
Innervation of all intrinsic larynx muscle (apart from cricothyroid)
Recurrent laryngeal nerve
Outline the lymphatic drainage of the larynx
- Above the vocal cords = upper deep cervical nodes
- Below the vocal cords = lower deep cervical nodes
(Vocal cords separate the drainage anteriorly but there is cross-communication posteriorly)
To what spinal level does the pharynx extend to inferiorly
C6
Outline the divisions of the pharynx
- Nasopharynx - opening anteriorly into the nasal cavities
- Oropharynx - opening into the oral cavity
- Laryngopharynx - opening into the larynx and continuing down into the oesophagus
Contents of the nasopharynx
- Nasopharyngeal tonsils (adenoids)
- Orifice of the Eustachian tubes
- Chonae (paired opening of the nose)
Where is the palatine tonsil situated
Oropharynx
What forms the anterior pillar of the palatoglossal arch
Palatoglossus muscle
What forms the posterior pillar of the palatopharyngeal arch
Palatopharyngeus muscle
What forms the capsule of the palatine tonsil
Pharyngobasillar fascia which lines the inner surface of the constrictor
Platysma innervation
Cervical branch of facial nerve
What nerve provides sensory innervation to the larynx
Laryngeal branch of vagus
What type of tissue does the palatine tonsil consist of
Lymphoid tissue
What adducts (closes) the vocal cords
Lateral cricoarytenoids
Arterial supply to the palatine tonsil
Tonsilar branch of the facial artery which enters lower pole of tonsil
What vein can easily bleed during tonsillectomy
Paratonsillar vein
Lymphatic drainage of the palatine tonsil
Jugular digastric lymph node situated behind the angle of the mandible
What does tonsillectomy involve
Removal of the tonsil and the fascial capsule separating it from the loose areolar tissue clothing the superior constrictor
Limits of the laryngopharynx
- Tip of the epiglottis
- Oesophagus inlet at C6
What is the piriform fossa
Recess anterolateral to the inlet. Rich lymphatic supply and is a silent area for tumours that spread rapidly to the deep cervical nodes.
Outline the mucosal types in the pharynx (Nasopharynx Vs. Remainder)
- Nasopharynx = pseudostratified columnar epithelium
- Remaining = stratified squamous
Main 3 muscles of the pharynx
- Superior constrictor
- Middle constrictor
- Inferior constrictor
Where do the eustachian tubes enter the pharynx
Between upper border of superior constrictor and base of skull
What enters the pharynx between the middle and superior constrictors
- Stylopharyngeus
- Glossopharyngeal nerve
What occupies the space between the middle and inferior constrictors
Thyrohyoid ligament and associated structures
What are the two parts of the inferior constrictor
- Thyropharyngeus
2. Cricopharyngeus
Where is the weakest point in the pharyngeal wall and what is the significance of this
Killan’s dehiscence = gap between thyropharyngeus and cricopharyngeus in the midline posteriorly.
Common site of pharyngeal pouches
Motor innervation of the pharynx
- Stylopharyngeus = glossopharyngeal nerve
- All remaining muscles = pharyngeal branch of the vagus nerve
At what level does the inferior thyroid artery enter the gland
C6