Triangles of the neck Flashcards
What are the 4 types of fascia in the neck?
Investing layer of deep cervical fascia
Prevertebral fascia
Carotid sheath
Pretracheal fascia
Where is the investing layer of deep cervical fascia located?
Attached posteriorly to the ligamentum nuchae and is continuous around the neck
What is enclosed by the investing layer of deep cervical fascia?
sternocleidomastoid, trapezius and parotid glands
What are the parotid glands?
Largest of the salivary glands, 1 present either side of the mouth in front of the ears
Where is the prevertebral fascia located?
Anterior to the prevertebral muscles and posterior to the pharynx and oesophagus
What is covered by the prevertebral fascia?
Cervical and brachial plexuses and muscles in the floor of the posterior triangle
What is the carotid sheath made from?
Areolar tissue
How does the composition of the carotid sheath vary over the vessels it covers?
Why is this variation necessary?
Strong over the carotid arteries and weak over the jugular vein to allow for expansion
Where does the pretracheal fascia attach?
Thyroid and cricoid cartilages and the 2nd-4th tracheal rings
What is enclosed by the pretracheal fascia?
Invests the thyroid gland and passes down into the thorax to the pericardium
What forms the posterior border of the anterior triangle of the neck?
The anterior border of the sternocleidomastoid
What forms the anterior border of the anterior triangle of the neck?
The midline between the mentum and the suprasternal notch
What forms the superior border of the anterior triangle of the neck?
Inferior aspect of the mandible, rising to an apex at the mastoid process of the temporal bone
What are the major structures passing through the anterior triangle of the neck?
Pharynx
Larynx
Trachea
Oesophagus
Thyroid gland
Common carotid
Internal and external carotid arteries
Jugular veins
Vagus nerves
Does the shape of the posterior triangle of the neck remain constant?
No, it changes shape as the position of the head is altered
What forms the posterior border of the posterior triangle of the neck?
Anterior border of the trapezius
What forms the anterior border of the posterior triangle of the neck?
Posterior border of the sternocleidomastoid
What forms the inferior border of the posterior triangle of the neck?
Middle third of the clavicle
Which structures pass through the posterior triangle of the neck?
Most structures supplying the upper limb and the spinal accessory nerve
Where is the origin of the sternocleidomastoid?
The mastoid process and lateral third of the superior nuchal line
What direction does the sternocleidomastoid run?
Inferomedially
Where is the insertion of the sternocleidomastoid?
Fleshy insertion on the medial end of the clavicle
Tendinous insertion on the anterior aspect of the manubrium
What is the function of the sternocleidomastoid?
Rotates face in opposite direction and tilts ear towards same shoulder
Acting bilaterally, the muscles cause both flexion of the lower cervical spine and extension of the upper cervical spine
Where is the origin of the trapezius?
Superior nuchal line
External occipital protuberance
Ligamentum nuchae
The spines and supraspinous ligaments of all of the thoracic vertebrae
Where is the insertion of the trapezius?
Lateral third of the posterior border of the clavicle
Medial border of the acromion
Upper border of the spine of the scapula
What is the function of the trapezius?
Elevation of the shoulder (shrugging)
Bracing of the shoulder
Rotation of the scapula (with serratus anterior) so that the glenoid cavity faces upwards in full abduction of the upper limb
What is the action performed by the trapezius when acting unilaterally?
Rotates the head to the opposite side
What is the action performed by the trapezius when acting bilaterally?
Extends the cervical spine
Which nerve supplies sternocleidomastoid?
Spinal accessory nerve
Which nerve supplies the trapezius?
Spinal accessory nerve
Describe the path taken by the spinal accessory nerve to supply the sternocleidomastoid and trapezius
Emerges one third of the way down the posterior border of the sternocleidomastoid and crosses the posterior triangle to supply trapezius by entering its anterior border at the junction between its lower third and upper 2 thirds
Is the spinal accessory nerve superficial or deep?
Why is it said to have a characteristic appearance?
Superficial
Characteristic ‘wavy’ appearance
Which muscles form the floor of the posterior triangle?
Scalenes and levator scapulae
Which type of fascia covers the scalenes?
What movement does this enable?
Prevertebral fascia
Movement between scalenes and structures lying anteriorly
Where is the origin of the scalenes?
The transverse processes of the cervical vertebrae
Which direction do the scalenes run?
Inferolaterally
Where do the scalenes attach?
Scalenus anterior and medius:
-first rib
Scalenus posterior:
-second rib
What are the main parts of the hyoid bone?
Body with greater and lesser horns
What is the significance of the hyoid bone?
Supports the floor of the mouth and the tongue
Intimately related to the larynx and pharynx
What functions are related to the hyoid bone?
Chewing, swallowing and speech
What are the suprahyoid bones?
Diagrastic
Stylohyoid
Mylohyoid
Geniohyoid
Where is the origin of the diagrastic?
ANTERIOR BELLY:
diagrastic fossa on the back of the body of the mandible
POSTERIOR BELLY:
deep to the mastoid process
What are the components of the diagrastic muscle?
2 bellies and an intermediate tendon
Where does the tendon of the diagrastic run?
Through a pulley attached to the hyoid bone
What is the function of the diagrastics?
Elevate the hyoid in swallowing and depress the manible in chewing
What are the 4 infrahyoid strap muscles ?
Sternohyoid
Sternothyroid
Omohyoid
Thyrohyoid
Where is the origin of the sternohyoid?
Behind the manubrium and the clavicle
What direction does the sternohyoid run?
Upwards
Where is the insertion of the sternohyoid?
Hyoid bone
Where is the insertion of the sternothyroid?
Manubrium
What is more anterior, the sternohyoid or the sternothyroid?
Sternohyoid
Where is the insertion of the sternothyroid?
Oblique line on the thyroid cartilage
Where does the thyrohyoid originate?
Oblique line on the thyroid cartilage
Where does the thyrohyoid insert?
Hyoid
Describe the structure of the omohyoid
2 bellies united by an intermediate tendon
Where is the origin of the omohyoid?
Upper border of the scapula
Where is the insertion of the omohyoid?
Hyoid bone
What is the function of the infrahyoid muscles?
Chewing, swallowing and speech
They fix the hyoid so that the suprahyoid muscles have a fixed point from which to act
What is the innervation of the infrahyoid muscles?
First 3 cervical nerves via a loop of nerves called the ansa cervicalis
Where is the thyroid gland located?
Within the pretracheal fascia, deep to the strap muscles
How by the left and right lobes of the thymus gland connected?
Via an isthmus lying across the 2nd-4th tracheal rings
Why can the thyroid gland not ascend any higher than the oblique line?
The sternothyroid attaches to the thyroid cartilages
In what direction does an enlarged thyroid expand?
Laterally and downwards, even into the superior mediastinum
What is produced by the thyroid gland?
Thyroxine and calcitonin
What is the function of thyroxine?
Maintains the basal metabolic rate
What is the function of calcitonin?
Lowers serum calcium
Which arteries supply the thyroid gland?
Superior thyroid and inferior thyroid
The superior thyroid is a branch of which artery?
External carotid
The inferior thyroid is a branch of which artery?
Thyrocervical trunk from the subclavian
Which vessels control venous drainage from the thyroid gland?
Superior, middle and inferior thyroid veins
Where do the superior and middle thyroid veins drain to?
Internal jugular
Where does the inferior thyroid vein drain to?
Left brachiocephalic vein
How many parathyroid glands are there?
4
2 upper and 2 lower
Where are the parathyroid glands located?
The back of the lateral lobes of the thyroid gland
What is secreted by the parathyroid glands?
What is the function of this?
Parathormone
Raises serum calcium by mobilising it from the skeleton
Is the position of the parathyroid glands constant or variable?
Variable
particularly inferior ones
How is blood supplied to the parathyroid glands
Via branches arising from anastomotic channels between superior and inferior arteries
Where does the carotid sheath attach?
The base of the skull at the margins of the carotid foramen
Where does the vagus nerve lie in the neck?
Posterior between the internal jugular vain and common carotid artery
Where does the phrenic nerve lie in the neck?
Under the prevertebral fascia on scalenus anterior, lateral to the sympathetic chain
Where is the sympathetic chain located in the neck?
Medial to the phrenic nerve, anterior to the prevertebral fascia
How is the external jugular vein formed?
The union of the posterior division of the retro-mandibular vein with the posterior auricular vein
Where is the external jugular vein located?
Superficial to sternocleidomastoid
Where does the external jugular enter the subclavian vein?
Just above the midpoint of the clavicle
How is the brachiocephalic vein formed?
The internal jugular vein joins the subclavian vein behind the sternoclavicular joint
What groups are the deep cervical lymph nodes divided into?
Superior and inferior
Which group of the deep cervical lymph nodes are jugulodigrastic nodes found in?
What are these nodes especially associated with?
Superior
Afferents from the palatine tonsils
Where do jugulodigrastic nodes receive lymph from?
Submanibular nodes, cranium, tongue, larynx, lower pharynx and thyroid gland
Do afferents or efferents drain into the inferior deep cervical lymph node?
Efferents
Which group of the deep cervical lymph nodes are the jugulo-omohyoid nodes found in?
Inferior
What happens to efferents of the deep cervical lymph nodes?
Form a single trunk, the jugular lymphatic trunk, which opens into the thoracic duct on the left and the right lymphatic duct on the right
