12-09-22 - Surface Anatomy of the Neck Flashcards
Learning outcomes
• Describe the general structure of the neck as composed of vertical columns surrounded by fascial sheets with potential spaces between
• Describe the concept of the anterior and the posterior triangles of the neck, and their boundaries
• Describe the form and position of the the common and internal carotid arteries and the internal jugular vein
• Describe the form and position of the external carotid artery, external jugular vein and anterior jugular vein
• State the bony and cartilaginous landmarks used to locate and demonstrate the above structures on a living model or patient
What are the 4 fascial layers of the neck?
What do they each surround?
• Facials layer of the neck:
1) Investing (superficial) fascia
• Surrounds everything but the platysma muscle
2) Pretracheal fascia
• Surrounds visceral column
• Posterior superior part of the pretracheal fascia is buccopharyngeal fascia
3) Carotid sheath
• Surrounds carotid neurovascular bundle
4) Prevertebral fascia
• Surrounds neuro-musculo-skeletal column
What are the retropharyngeal space and danger space?
Where are they located?
Where do they extend to?
What are 4 examples of retropharyngeal abscesses?
• The retropharyngeal space and danger space are both potential spaces
• Retropharyngeal space
• Exists between the pretracheal fascia and the alar fascia
• Extends from base of the skull to the superior mediastinum
• Permits movement of pharynx, oesophagus, trachea, and larynx during swallowing
• Retropharyngeal abscesses:
1) Nasopharynx
2) Paranasal sinuses
3) Middle ear infections
4) Dental abscesses
• The danger space
• The danger space exists between the Alar fascia and the prevertebral fascia
• Extends from the base of the skull to the diaphragm
• It is a major pathway for spread of infection to the mediastinum
What are the 3 borders of the anterior and posterior triangles of the neck?
• Borders of anterior triangle of the neck:
1) Superior border – inferior border of mandible
2) Lateral border – anterior border SCM (Sternocleidomastoid muscle)
3) Medial border – sagittal line down the midline of the neck
• Borders of the posterior triangle of the neck
1) Anterior border – posterior border of SCM
2) Posterior border – anterior border of the trapezius muscle
3) Inferior border – middle1/3 of the clavicle
What are questions we might want to ask about neck lumps?
• Questions we might want to ask about check lumps:
1) Location (anterior triangle, posterior triangle, midline)
2) Tenderness
3) Heat/inflammation
4) Size/depth
5) Pulsatile (pulsation)
6) Solitary or multiple lumps
7) Movement (swallowing, sticking out tongue)
Label these structures on the skull.
What are they each responsible for?
• Styloid process
• Slender pointed piece of bone below the ear
• Serves as an anchor point for several muscles associated with the togue and larynx
• Stylomastoid foramen
• Foramen between the styloid and mastoid process of the temporal bone of the skull
• Mastoid process
• Smooth conical proception of bone located at the base of the mastoid areas of the temporal bone
• Sternocleidomastoid muscle inserts here via a thin aponeurosis (a sheet of pearly white fibrous tissue that takes the place of a tendon in flat muscles having a wide area of attachment)
Label these bony landmarks on the skull.
What important structure is between 2 of these landmarks?
What can we do at this landmark?
What is a meatus?
• Midway between the angle of the mandible and the mastoid process, we can find the position of the transverse process of atlas
• This is where we can palpate the internal carotid artery
• A meatus is a passage or opening leading to the interior of the body.
What is the hyoid bone?
Where is it found?
Where is its location compared to the thyroid cartilage?
How are muscles and ligaments attached to the hyoid bone?
• The hyoid bone is a small u-shaped solitary bone
• It is situated in the midline of the neck, anteriorly at the base of the mandible, and posteriorly at C4
• The hyoid bone can be found just superiorly to the thyroid cartilage
• The hyoid bone has 2 lesser and 2 greater horns for the attachment of muscle and ligaments
What is the thyroid cartilage?
What 3 structures does the thyroid cartilage have?
What forms the laryngeal prominence?
What does this form in men?
What does the thyroid cartilage articulate with?
What does this allow?
• The thyroid cartilage is the largest cartilage of the laryngeal skeleton
• The thyroid cartilage has 2 lamina, 2 greater horns, and 2 lesser horns
• The laryngeal prominence is formed by the fusion of inferior 2/3rds of the lamina
• The laryngeal prominence is more prominent in men, and forms the Adam’s apple
• The thyroid cartilage articulates with the cricoid cartilage
• This allows for the rotation and gliding of thyroid cartilage, which can change the length/sound of vocal cords
What are the 3 branches of the aortic arch?
• The 3 branches of the aortic arch:
1) Brachiocephalic trunk
2) Left common carotid artery
3) Left subclavian artery
What is the brachiocephalic trunk?
What is it anteriorly covered by?
Where does it pass and divide?
What 2 arteries does it divide into?
Where do these arteries go?
What is the sternoclavicular joint used for?
• The brachiocephalic trunk is the largest branch of the aortic arch
• Anteriorly, the brachiocephalic trunk is covered by the right sternohyoid and sternothyroid muscles
• The brachiocephalic trunk passes superolaterally to the right and divides into the right common carotid and the right subclavian arteries, which pass posterior to the sternoclavicular joint
• The sternoclavicular joint is used as a landmark for branching veins
Where do the right and left subclavian arise from?
What does the subclavian artery pass?
What are the 3 parts of the subclavian name in relation to?
Where does the anterior scalene muscle originate and insert?
What nerve passes on the surface of this muscle?
What are the 3 parts of the subclavian?
What arteries do they branch into?
Which part forms the axillary artery?
• Right subclavian arises from the brachiocephalic trunk
• Left subclavian rises from a divot in the branch of the aortic arch
• The subclavian passes Rib 1 on the way to the upper limb
• The 3 parts of the subclavian are named in relation to the anterior scalene muscle
* The anterior scalene originates from the anterior tubercles of the transverse processes of C3-C6.
* It is inserted into the scalene muscle tubercle of the upper face of the first rib
• The phrenic nerve passes on the anterior surface of the anterior scalene muscle (scalenus anterior)
• 3 parts of the subclavian:
1) 1st part of subclavian – from origin to medial border of anterior scalene
• Branches into:
• Vertebral artery
• Thyrocervical trunk
• Internal thoracic artery
2) 2nd part – behind anterior scalene muscle
• Branches into: Costocervical trunk
3) 3rd part – lateral border of anterior scalene muscle to lateral border of first rib
• Branches into Dorsal scapular artery
• Forms the axillary artery
Where does the common carotid artery bifurcate?
What does it bifurcate into?
Where is the common carotid covered and exposed?
What does this allow?
What is the carotid sinus?
Label these structures
• Common carotid bifurcates at the level of the superior border of the thyroid cartilage
• Common carotid bifurcates into the internal and external carotid artery
• Proximally, the common carotid is covered by muscles
• Distally, the common carotid is exposed, allowing for the palpation of the pulse (usually the internal carotid artery
• The carotid sinus is the dilation of the proximal internal carotid artery
What is the carotid sinus?
What is the carotid body?
What is the sensory and motor supply of the carotid body and carotid sinus?
What is the difference between baroreceptors and chemoreceptors?
What is the function of the carotid sinus?
What is the function of the carotid body?
What is carotid stenosis?
What is a common cause of this?
• The carotid sinus is the dilation of the proximal internal carotid artery
• The carotid body is a chemoreceptor located in the adventitia (outermost layer of vessel) of the bifurcation of the common carotid artery
• The sensory (afferent) supply of the carotid sinus and the carotid body is the afferent glossopharyngeal (carotid sinus) nerve
• The motor (efferent) supply of the carotid sinus and the carotid body is the efferent vagus nerve
• Baroreceptors are cells that monitor the changes in blood pressure.
• In contrast, chemoreceptors are cells that measure the chemical composition in blood
• The carotid sinus is a baroreceptor, which reacts to changes in arterial blood supply by monitoring blood pressure
• Stimulation of the carotid sinus baroreceptor (via stretching) stimulates the glossopharyngeal nerve
• This stimulates the vasomotor center in the medulla via the tractus solitarius cell bodies in brainstem, which then modulates the activity of the ANS (sympathetic and parasympathetics) to bring blood pressure back to normal physiological level by restricting/relaxing blood vessels
• The carotid body is a chemoreceptor, which monitors composition of the blood
• It is sensitive to pH and oxygen and co2 pressure changes in the blood
• The chemoreceptors transmit nervous signals to the respiratory centre in the brain to help regulate respiratory activity.
• Most of the chemoreceptors are in the carotid bodies.
• Carotid stenosis is the narrowing of the carotid arteries
• A common cause of this is atherosclerosis, where fatty plaque builds up and narrows the blood vessels
What is the carotid sheath?
Where is it located?
What 3 neurovascular structures does the carotid sheath cover?
What do these structures supply?
• The carotid sheath is part of the deep cervical fascia of the neck
• It is located posterior to the sternocleidomastoid muscle
• The carotid sheath covers:
1) Internal jugular vein
2) Internal carotid artery
3) Vagus nerve
• These neurovascular structures supply intracranial structures
Label these 8 branches of the external carotid.
Which of these branches are terminal?
What is a pneumonic for these branches?
What 3 Dural venous sinuses drain the cranial veins?
What happens to these 3 Dural venous sinuses?
• Dural venous sinuses that drain the cranial veins:
1) Superior sagittal sinus
2) Inferior sagittal sinus
3) Sinus rectus (straight sinus) - receives blood from inferior sagittal sinus
• These 3 Dural venous sinuses, along with the occipital sinus, come together at the confluence of sinuses to form the transverse sinus
• The sigmoid sinus is an extension of the transverse sinus
• Sigmoid sinus becomes the internal jugular vein once it reaches the jugular foramen
What does the internal jugular vein (IJV) drain?
What is it grouped with?
Where does the internal jugular vein lie?
Where does the IJV extend from?
Where is the jugular venous pulse?
When can be examine?
Which side is the best to examine?
• The internal jugular vein drains intracranial structures and superficial parts of the face and neck
• The internal jugular vein is grouped in the carotid sheath with the vagus nerve and internal carotid artery
• Internal jugular vein lies posterior to the internal carotid artery
• It then moves laterally then anterior of the common carotid as it moves down the neck
• The IJV extends from the base of the skull to the sternal end of the clavicle
• The jugular venous pulse is visible along the trajectory of the internal jugular vein
• The jugular venous pulse can only be examined with relaxed head and neck muscles
• It is better to look at the patient’s right side, as it is a continuation of the superior vena cava
What are 3 structures is the internal jugular vein related to?
• The internal jugular vein is related to many important structures
• Some of which are:
1) Vagus nerve
2) Phrenic nerve
3) Brachial plexus
Where is a central venous catheter (CVC) most commonly inserted?
Why is this?
What 2 things can the CVC be used for?
Why is the external jugular vein not used?
• Central venous catheter (CVC) is most commonly inserted into the internal jugular vein (sometimes subclavian)
• IJV is the most common choice as it has lower chances of complications, such as:
1) Pleural or carotid arterial puncture
2) Pneumothorax
3) Nerve injury
• The CVC can be used for
1) Measuring central venous pressure (CVP) – 8 to 12mmHg
2) Administering medications and fluids
• There is a risk of air embolism (bubble that blocks vessel) if the external jugular vein is used
Where does the external jugular vein (EJV) run from?
What 2 veins form the EJV?
What muscle does the EJV cross?
What does this mean in the case of right atrial pressure increase?
What does the EJV pierce?
Where does the EJV terminate?
Where does the EJV drain?
• The external jugular vein (EJV) runs from the angle of the mandible to the middle of the clavicle
• Veins that form the EJV:
1) Posterior division of the retromandibular vein
2) Posterior auricular vein
• The EJV crosses the sternocleidomastoid muscle (SCM) obliquely deep to the platysma muscle, then enters the inferior part of the posterior triangle
• This means the EJV can be distended and observed in the case of increase in right atrial pressure
• The EJV pierces the investing fascia at the posterior border of the SCM
• The EJV descends and terminates in the subclavian vein
• The EJV drains most of the scalp and side of the face
Where is the anterior jugular vein located?
Where does it drain into?
Where do the anterior jugular veins of each side anastomose?
What s this structure important for?
• The anterior jugular vein is located inferior to the hyoid bone
• Anterior jugular vein drains into external jugular or subclavian veins
• Anterior jugular veins of both sides join at the jugular venous arch
• The jugular venous arch is important for tracheostomies
Arteries of the head and neck diagram
Veins of the head and neck diagram
What is Erb’s point?
What are the 4 branches at Erb’s point?
What 2 things does the accessory nerve supply?
What does it pass across?
• Erb’s point is where four cutaneous branches of the cervical plexus become superficial:
1) Lesser occipital
2) Great auricular nerve
3) Transverse cervical
4) Supraclavicular
• The accessory nerve gives off motor control to the trapezius and SCM
• It passes across the posterior triangle of the neck
Where lymph nodes found in the scalp and face?
• There are no lymph nodes in the scalp or face
• Except parotid/buccal region
