Head And Neck Week 1 Flashcards
Where does the neck begin and end?
The neck extends from the lower margin of the mandible superiorly
To the suprasternal notch of the manubrium and superior border of the clavicle inferiorly
What are the major functions of the neck?
Support the head
Conduit for structures passing between head and thorax/limbs
Location of the larynx, thyroid and parathyroid glands etc.
Provides flexibility to position the head - maximising efficiency of sensory organs
Why is the neck a well-known region of vulnerability?
Slender to allow flexibility of head Many important structures crowded together: -muscles -glands -arteries -veins -nerves -lymphatics -trachea -oesophagus -bones (hyoid and vertebrae) Several vital structures lack bony protection: -thyroid gland -trachea -oesophagus
Which arteries are the major supply of blood to the head and neck
Carotid arteries
What are the principal venous drainage of blood from the head and neck?
Jugular veins
Where do the carotid arteries and jugular veins lie in the neck
Anterolaterally
Which structures are commonly injured in penetrating wounds of the neck?
Carotid arteries and jugular veins
Which plexuses originate in the neck and pass inferolaterally through the axillae to supply the upper limbs?
Brachial plexuses
Where does the thyroid cartilage lie?
The middle of the anterior aspect of the neck
Where does lymph from structures int he head and neck drain into?
Cervical lymph nodes
Describe the bones that make up the skeleton of the neck
Axial skeleton: -cervical vertebrae -hyoid bone -manubrium of the sternum Appendicular skeleton: -clavicles
How many cervical vertebrae are there?
7
Which cervical vertebrae can be described as typical?
3-6th
Describe the features of the typical cervical vertebrae
- Vertebral body:
- small
- longer laterally than anteroposteriorly
- superiorly concave, inferiorly convex - Vertebral foramen:
- large
- triangular - Transverse foramen (transmits the vertebral artery, vein and nerve)
- Superior facets of articular processes directed superoposteriorly
- Inferior facets directed inferoanteriorly
- Spinous processes:
- short
- bifid
Which cervical vertebrae are described as being atypical?
C1, C2, C7
What is the alternative name for C1?
The atlas
What is the alternative name for C2?
The axis
Describe the atlas bone
- Lacks a spinous process or body
- Two lateral masses connected by an anterior and posterior arch
- Concave superior articular facets receive occipital condyles
- Facet for dens on the anterior arch
- Tubercle for transverse ligament on each lateral mass
- Flexion/extension of neck occurs between occiput and C1
Describe the axis bone
- Large vertebral body
- Strongest cervical vertebra
- Odontoid process (dens)
- Joint between C1 and C2 responsible for rotation of head
Describe C7
- Small transverse foramen (only transmits the accessory vertebral veins)
- Prominent spinous process which is not bifid
Describe the position of the hyoid bone
Lies in the anterior part of the neck
At the level of the C3 vertebra
In the angle between the mandible and the thyroid cartilage
What is unique about the hyoid bone compared to other bones of the body?
It is isolated from the remainder of the skeleton and therefore mobile
How is the hyoid bone supported?
Suspended by muscles that connect it to:
- the mandible
- styloid processes of the temporal bones
- thyroid cartilage
- manubrium
- scapulae
How is the hyoid bone attached to the styloid processes
Suspended by the stylohyoid ligaments
Describe the functions of the hyoid bone
- Attachment for anterior neck muscles
- Prop to keep the airway open
Describe the hyoid bone
- Body :
- middle portion
- faces anteriorly
- 2.5cm wide
- 1cm thick
- anterior convex surface projects anterosuperiorly
- posterior concave surface projects posteroinferiorly
- each end unites to a greater horn (by fibrocartilage in young people and by bone in older people) - Greater horn:
- projects posterosuperiorly and laterally from the body - Lesser horn:
- small
- projects superoposteriorly from each side of the superior surface of the body the body near its union with the greater horns (fibrous tissue joins to body and sometimes synovial joint between greater horn and lesser)
- may be partly or completely cartilaginous in some adults
Describe common causes of cervical pain
Inflamed lymph nodes (indicator of malignant tumour in head - primary or metastases from trunk)
Protruding IV disks
Muscle strain
Bony abnormalities (cervical osteoarthritis)
Trauma
Affected by movement of head and exaggerated by coughing/sneezing
Describe the common cause and result of a hyoid bone fracture
Commonly caused by manual strangulation (compression of throat)
Results in depression of body of hyoid bone onto thyroid cartilage –> cant elevate and move anteriorly beneath tongue during swallowing –> may lead to aspiration pneumonia due to inability to maintain separate alimentary and respiratory tracts and difficult or painful swallowing
Why are cervical vertebrae prone to dislocation
Because of the more horizontally oriented articular facets –> less tightly interlocked than other vertebrae “stacked like coins”
Why can a slight dislocation occur in the cervical region without damaging the spinal cord ?
Due to the large vertebral foramen
In what situation would n MRI be required with a suspected cervical dislocation?
If the dislocation does not result in “facet jumping” where the articular facets are locked in their displaced position
Cervical vertebrae may self-reduce (slip back into position)
Therefore X-ray may not indicate spinal cord damage
MRI will show soft tissue damage if the spinal cord has been affected
What is the alternative name for an atlas fracture?
Jefferson or burst fracture
When is an atlas fracture likely to occur?
Vertical forces e.g. Diving accidents
Compress lateral masses between occipital bones and C2
Drives them apart
Fractures one or both of the anterior and posterior arches
Is the spinal cord likely to be damaged in an atlas fracture?
No because the vertebral foramen gets larger
More likely to be damaged if the transverse ligament is also ruptured (indicated on X-ray by widespread lateral masses)
What is the alternative name for a fracture of the vertebral arch of the axis?
Hangman’s fracture
Where does a Hangman’s fracture typically occur?
Bony column formed by the superior and inferior articular processes (pars interarticularis)
What causes a fracture of the vertebral arch of the axis?
Hyperextension of the head on the neck (as opposed to hyperextension of the head and neck which causes whiplash)
What are the consequences of a Hangman’s fracture?
Injury of spinal cord or brainstem is likely
Sometimes results in:
- Death
- Quadriplegia
What is the other common fracture of the axis and how does this commonly occur?
Fracture of the dens
Blow to the side of the head or osteopenia (pathological loss of bone mass)
What is the superficial cervical fascia?
Layer of fatty connective tissue that lies between the dermis and the investing layer of deep cervical fascia
Usually thinner than in other regions - especially anteriorly
What is contained within the superficial cervical fascia?
Cutaneous nerves, blood and lymphatic vessels, superficial lymph nodes and variable amounts of fat
Anterolaterally - platysma
What is the platysma?
A broad, thin sheet of muscle in the subcutaneous tissue of the neck
Which nerve supplies the platysma?
Facial nerve (CNVII)
Which structures lie deep to the platysma?
External jugular veins and main cutaneous nerves of the neck
What is the origin and insertion of the platysma and where does it lie?
Lies of the anterolateral aspect of the neck
Fibres originate in the deep fascia covering the superior parts of the deltoid and pectoralis major muscles
Travels superomedially over the clavicles to the inferior border of the mandible
Anterior border decussates over chin and blends with facial muscles
Inferiorly the fibres diverge leaving a gap anterior to larynx and trachea
Much variation in completeness - often occurs as isolated strips
What is the function of the platysma?
Acting from its superior attachment at the mandible:
- Tenses the skin, releasing pressure on the superficial veins
Acting from its inferior attachment:
- Helps depress the mandible
- Draw the corners of the mouth inferiorly - grimace
As a muscle of facial expression - serves to convey tension or stress
What are the fascia layers of the deep cervical fascia (from superficial to deep)?
Investing
Pre-tracheal
Pre-vertebral
What are the functions of the deep cervical fascial layers?
Support the cervical viscera (thyroid gland), muscles, vessels and deep lymph nodes
Support the common carotid arteries, internal jugular veins and vagus nerves by condensing to form the carotid sheath
Provide the slipperiness for structures in the neck to slide over one another (e.g. Swallowing, turning head)
Limit the spread of infection