L2: Organisation of the head and neck Flashcards
What structures do you find in the neck?
- blood vessels and nerves
- cervical vertebrae (C1-7)
- muscles
- cartilages
- glands
- muscular tubes (aerodigestive tract)
What is the aerodigestive tract?
- pharynx connects the oral cavity, any fluid/food that passes through here, goes through to the oesophagus and then the stomach
- air through nasal/oral cavity is directed into the larynx and down into the trachea and lungs
What structures can you see/palpate when you tilt your neck back?
(sometimes below your chin you can feel the hyoid bone)
-first lump is the thyroid cartilage (Adam’s apple)
-second lump is the cricoid cartilage
(then you would find the thyroid gland- this is not palpable)
-
What are the muscles of the neck?
- platysma
- trapezius
- sternocleidomastoid
- scalene muscles
- supra/infra-hyoids
Where would you find the supra/infra-hyoids?
Located above (supra) and below (infra) the hyoid bone. They are important in moving the hyoid bone up and down.
What nerves supply the supra/infra-hyoids?
Supra: cranial nerves
Infra: cervical nerves (C1-3)
What is the most superficial neck muscle?
Platysma (immediately beneath the skin)
Where is the platysma muscle found?
- 2 either side of the midline
- start from the mandible
- extend down towards the anterior chest covering up the clavicle
What is the function of the platysma?
- contract to made the skin taut (used when shaving your neck)
- upper parts contracts and can draw down the lower parts of the mouth causing a grimace
Where is the sternocleidomastoid (SCM) muscle found?
- below the platysma
- has 2 heads: one comes from the sternum, one from the clavicle
- the 2 heads join and attach to a bony prominence just below your ear: mastoid process
- run obliquely across the neck from a more lateral position to a medial position
What is the function of the sternocleidomastoid muscle?
-when it contracts it rotates the chin in the opposite direction
Which fibres of the trapezius are found in the neck?
Superior fibres, which are split by a midline called the nuchal ligament.
They extend out laterally and insert into scapula and clavicle
(involved in movements of the shoulder)
What classification of muscle does the platysma fit into?
Muscles of facial expression, despite it being located in the neck
What nerve supplies the platysma?
Facial nerve- probably the cervical branch
What nerve supplies the sternocleidomastoid muscle?
Cranial nerve 11 (accessory nerve)
What nerve supplies the trapezius muscle?
Cranial nerve 11 (accessory nerve)
What action is associated with testing the trapezius muscle?
Shrugging of the shoulders, with resistance
What are the 2 triangles of the neck called?
-anterior triangle
-posterior triangle
There are two of both
What are the borders of the anterior triangles?
Lateral boundary: anterior border of SCM
Medial boundary: imaginary mid sagittal line
Superior boundary: inferior border of the mandible
There are 2 anterior triangles
What are the borders of the posterior triangles?
The platysma muscle overlies this triangle.
Anterior boundary: posterior border of the SCM
Posterior boundary: anterior border of the trapezius muscle
Inferior boundary: clavicle
What structures are found in the anterior triangles?
Structures coursing b/w the head and the thorax e.g. aerodigestive tract
What structures are found in the posterior triangles?
Structures coursing b/w the thorax/neck to the upper limb
What venous structure runs through the posterior triangles?
External jugular vein (within the subcutaneous tissue/superficial cervical fascia.
It is found in a similar plane to the platysma muscle, but it is found deeper than the platysma.
What forms the floor of the posterior triangles?
- scalene muscles (3 of them)
- trunks of the brachial plexus which emerge through the scalene muscles
- subclavian vessels (artery & vein), these continue over the first rib and run into the upper limb
- omohyoid muscle
What muscle runs obliquely across the posterior triangles?
Omohyoid muscle (infrahyoid muscle): inferior belly
- it has 2 bellies
- origin is the hyoid bone
What is the structure of the omohyoid muscle?
- superior belly takes origin from the hyoid bone, adn descends and disappears beneath the SCM
- inferior belly is then seen again in the posterior triangle
What structures are found in the anterior triangles?
- long strap like muscles (infrahyoid muscles)
- thyroid gland (strap muscles lie anterior to the gland)
- suprahyoid muscles (including the digastric muscle)
How many bellies does the digastric muscle have?
2
-anterior & posterior bellies
What shape is the digastric muscle?
V shaped, with an attachment onto the hyoid bone
What is one of the superficial veins of the neck?
External jugular vein
What are the deep vessels than run along the neck?
Contained within a connective tissue sheath (carotid sheath)
- internal jugular vein
- common carotid artery
- vagus nerve: cranial nerve 10 (slightly posteriorly to the vessels)
Where does the vagus nerve emerge from?
Brain stem, and emerges from the base of the skull and runs down the neck to reach various structures it will be innervating.
What are the boundaries of the carotid triangle?
Carotid triangle is a subtriangle within the anterior triangle
Superior boundary: posterior belly of the digastric muscle
Anterior boundary: superior belly of the omohyoid muscle
Lateral boundary: Anterior border of the SCM
Why is the carotid triangle important?
This is where the bifurcation of the common carotid artery into its internal/external carotid artery. Here you find a slight swelling at the internal carotid artery: carotid sinus- baroreceptors to monitor pressure
What is a carotid sinus massage?
Direct pressure is applied to area of the carotid sinus to stimulate the baroreceptors: slows HR of patients with supraventricular tachycardias
-you can also easily detect a pulse here
What is the carotid body?
Chemoreceptor to monitor blood pH/pCO2/pO2
