3 - Organisation of the Neck and Posterior Triangle Flashcards
What are the boundaries of the neck?
Superior - base of skull, inferior border of mandible
Inferior - top of sternum, clavicle, acromion and C7
What are the neck compartments?
- visceral compartment
- vascular compartments (2)
- vertebral compartment
What is the visceral compartment?
- in the midline
- contains parts of the respiratory system (trachea), digestive system (oesophagus) and endocrine glands
What are the vascular compartments?
- 2 laterally
- contain blood vessels and nerves (CN X)
What is the vertebral compartment?
- in the midline
- contains cervical vertebrae, spinal cord, muscles, cervical neves
What are the different types of fascia in the neck?
- superficial fascia (cervical subcutaneous tissue)
- deep fascia (investing, pretracheal, prevertebral)
Describe superficial fascia.
- cervical subcutaneous connective tissue
- continuous with superficial fascia of thorax
- connects to mandible and facial muscles
- contains cutaneous nerves, vessels, lymph nodes and fat
- contains platysma (anterolaterally)
What is investing fascia?
- surrounds all neck structures deep of the skin
- splits into superficial and deep layers to invest the SCM and trapezius
- pierced by external and anterior jugular veins and some nerves including cervical plexus
What is pretracheal fascia?
- visceral part (trachea, oesophagus and thyroid gland)
- muscular part (infra hyoid muscles)
- forms pulley for intermediate tendon of digastric (suspends hyoid)
What is the prevertebral fascia?
- surrounds vertebral column and the pre/post-vertebral muscles
- pierced by cutaneous branches of cervical plexus and cervical parts of sympathetic trunk
What is the carotid sheath?
- connects the cranial cavity with the mediastinum in the thorax
- surrounds major vasculature (CCA/ICA/IJV) and CN X
- blends with all 3 layers of deep fascia
What are the boundaries of the anterior triangle?
- inferior border of mandible
- anterior border of SCM
- midline of neck
What are the boundaries of the posterior triangle?
- posterior border of SCM
- middle third of clavicle
- anterior border of trapezius
- superior nuchal line of occipital bone
What is the platysma?
Superficial muscle found in the neck, “holds everything in”
What is found in the SCM region?
- SCM
- great auricular nerve
- transverse cervical nerve
- external jugular vein
What is found in the posterior cervical region?
- trapezius
- cutaneous branches of posterior rami of cervical spinal nerves
What are the subdivisions of the posterior triangle?
- occipital triangle
- omoclavicular triangle (subclavian)
- these are divided by the inferior belly of omohyoid
What are the roof and floor of the posterior triangle?
Roof - investing layer of deep fascia, platysma
Floor - prevertebral fascia surrounding muscles (splenius capitis, elevator scapulae and the scalenes)
What is the origin of SCM?
Sternal head (rounded) - manubrium
Clavicular head (thick/fleshy) - superior surface of medial third of clavicle
What is the insertion of SCM?
- lateral surface of mastoid process
- lateral half of superior nuchal line
What is the innervation of SCM?
Spinal accessory nerve
What are the actions of SCM?
- draws head forward (when acting bilaterally)
- tilts head towards ipsilateral shoulder (when working unilaterally)
What is the origin of trapezius?
- superior nuchal line
- external occipital protuberance
- ligamentum nuchae
- spinous processes of C7-T12
What is the insertion of trapezius?
- lateral 3rd of clavicle
- acromion
- spine of scapula
What is the innervation of trapezius?
Spinal accessory nerve (CN XI)
What are the actions of trapezius?
- assist in rotating scapula during humerus abduction
- upper fibres elevate scapula
- middle fibres abduct scapula
- lower fibres depress scapula
Where do the cutaneous branches of lesser occipital nerve originate?
C2
Where do the cutaneous branches of great auricular and transverse cervical nerves originate from?
C2, C3
Where do the cutaneous branches of supraclavicular nerves originate from?
C3, C4
Where do the muscular branches of phrenic nerve originate from?
C3, C4, C5
Where do the muscular branches of ansa cervicalis originate from?
C1, C2, C3
What is the ansa cervicalis?
- anterior rami of C1-C3
- has superior and inferior roots
- innervates the infra hyoid muscles (except for the thyrohyoid)
- loops around the carotid sheath
What vasculature is found in the posterior triangle?
- external jugular vein
- posterior external jugular vein
