Head and Neck 1: Front of Neck SDL Flashcards
Where is the hyoid bone?
situated in the anterior midline of the neck between the chin and the thyroid cartilage
Where is the thyroid cartilage?
Below hyoid bone and above cricoid cartilage
Position of cricoid cartilage
Where is the cricothyroid membrane? Clinical relevance?
- Between thryoid and cricoid cartilage
- This ligament is cut during emergency cricothyrotomy. This kind of surgical intervention is necessary if the airway is blocked above the level of vocal folds.
What are the 3 unpaired cartilages of the larynx?
- Thyroid
- Cricoid
- Epiglottis
Location of suprasternal notch? Vertebral level?
- Seen as a visible dip between the two clavicles.
- Generally, lies at the T2 vertebral level
Attachments of sternocleidomastoid muscle?
Is a two-headed neck muscle with attachments to the manubrium of sternum (sterno-), the clavicle (-cleido-), and the mastoid process of the temporal bone (-mastoid).
Vertebral level of hyoid bone?
C3 vertebral level
How to palpate thyroid cartilage?
Place your finger on the tip of your chin. Slide your finger down the midline and the first hard structure you hit is the laryngeal prominence (typically known as the Adam’s apple) of the thyroid cartilage. The hyoid is just above that
Vertebral level of thyroid cartilage?
Between C4-5 vertebral levels
Vertebral level of cricoid cartilage?
C6 vertebral level
How to palpate cricoid cartilage?
Lies below the thyroid cartilage but is not easy to palpate
Location of thyroid gland? What vertebrae does it span?
The thyroid gland is located in the anterior neck and spans the C5-T1 vertebrae.
Structure of thyroid gland?
- Right lobe
- Left lobe
- Isthmus
Where can the lobes of the thyroid gland be palpated?
- Inferior to the position of the oblique line of the thyroid cartilage.
- Find the laryngeal prominence and arch of the cricoid cartilage, then feel posterolateral to the larynx. The thyroid gland also rises upon swallowing.
Where is the isthmus of the thyroid gland located?
- In the midline, anterior to the upper end of the trachea.
- Cannot be palpated easily.
Where can the trachea be palpated?
Can be felt at the anterior neck below the larynx.
Vertebral level of trachea?
Spans vertebral levels C6-T4 (T4 is the level of the terminal bifurcation of the trachea)
Level of bifurcation of trachea?
T4
Where can the carotid pulse be palpated? What should be noted?
- Palpating lateral to the upper border of the thyroid cartilage and just medial to the anterior border of SCM
- Do not palpate both sides at once and do not rub the vessel
The neck can be be divided into anterior and posterior triangles on each side. What are the anterior and posterior triangles divided by?
The sternocleidomastoid muscle
What forms the:
- Base?
- Posterior boundary?
- Anterior boundary?
of the posterior triangle of the neck?
- Base: middle 1/3 of clavicle
- Posterior boundary: anterior border of trapezius
- Anterior boundary: posterior border of sternocleidomastoid
Between the sternocleidomastoid and trapezius muscles the important contents of the posterior triangle can be identified. What are these?
- trunks of the brachial plexus
- the spinal accessory nerve
- the inferior belly of omohyoid muscle
- the external jugular vein.
Stab wounds in the posterior triangle may damage the upper trunk of the brachial plexus and/or the apex of the lung - why?
- Apex of lung extends above clavicle
- Upper trunk of brachial plexus located in posterior triangle of neck
The accessory nerve (cranial nerve XI) also descends posteroinferiorly through the posterior triangle.
Which muscles are supplied by this nerve?
- Trapezius
- Sternocleidomastoid
Where is the external jugular vein (EJV) formed? Where does it travel?
Forms near the angle of the mandible and descends through the subcutaneous tissue of the neck coursing medially to laterally across the surface of the sternocleidomastoid muscle towards the middle of the clavicle.
What does the external jugular vein drain into?
The subclavian vein
Surface markings of external jugular vein (LARGE arrows)
can be found by following an imaginary line from the earlobe, across angle of mandible to the middle of the clavicle, passing superficial to SCM.
What forms the:
- superior boundary?
- lateral boundary?
- medial boundary?
of the anterior triangle of the neck?
- superior: inferior border of mandible
- medial: sagittal line down midline of neck
- lateral: anterior border of sternocleidomastoid
What are the contents of the anterior triangle of the neck?
- lobes of the thyroid gland
- suprahyoid muscles and infrahyoid muscles (except the inferior belly of omohyoid which is found in the posterior triangle)
- the common carotid artery and its division into internal and external carotid arteries
- the internal jugular veins
- numerous cranial and peripheral nerves
Where are the infrahyoid muscles (‘strap’ muscles)?
This group of muscles lie distal to the hyoid bone
Function of infrahyoid muscles?
depressing the hyoid bone during swallowing
How many infrahyoid muscles are there? What are they?
4:
- Omohyoid
- Sternohyoid
- Sternothyroid
- Thyrohyoid
What 2 groups can the infrahyoid muscles be divided into? Which muscles are in which group?
Superficial plane – omohyoid and sternohyoid muscles.
Deep plane – sternothyroid and thyrohyoid muscles.
Attachments of omohyoid?
The omohyoid is comprised of two muscle bellies, which are connected by a muscular tendon.
- The inferior belly arises from the scapula. It runs superomedially underneath the sternocleidomastoid muscle.
- It is attached to the superior belly by an intermediate tendon, which is anchored to the clavicle
- From here, the superior belly ascends to attach to the hyoid bone.
Attachments of sternohyoid?
Originates: from the sternum and sternoclavicular joint.
Inserts: It ascends to insert onto the hyoid bone.
Attachments of sternothyroid?
Origin: the manubrium of the sternum
Inserts: the thyroid cartilage.
Attachments of thyrohyoid?
Origin: the thyroid cartilage of the larynx
Inserts: the hyoid bone.
What are most of the infrahyoid muscles innervated by?
Anterior rami of C1-C3, carried by a branch of the ansa cervicalis.
What are the ansa cervicalis?
a loop of nerves which are formed for the first three cervical nerves (C1–C3)
What is the only exception to the innervation of the infrahyoid muscles?
The thyrohyoid muscle
What is the thyrohyoid muscle innervated by?
Anterior ramus of C1, carried within the hypoglossal nerve.
From which nerve(s) do the roots of ansa cervicalis take origin?
first three cervical nerves (C1–C3)
Where are the suprahyoid muscles located?
Above the hyoid bone
What do the suprahyoid muscles form?
The floor of the mouth
How many suprahyoid muscles are there? What are they?
4:
- Stylohyoid
- Digastric
- Mylohyoid
- Geniohyoid
Function of the suprahyoid muscles?
have an important function in moving the hyoid bone during swallowing –> elevate the hyoid
What are the attachments of digastric?
The digastric is comprised of two muscular bellies, which are connected by a tendon.
Origin:
- The anterior belly arises from the digastric fossa of the mandible.
- The posterior belly arises from the mastoid process of the temporal bone.
Inserts:
- The two bellies are connected by an intermediate tendon, which is attached to the hyoid bone
What is the function of the digastric muscle?
Depresses the mandible and elevates the hyoid bone