57 - Bones and Joints of the Neck Flashcards
Layers of fascia in the neck 1 2 3 4 5
Superficial fascia. Deep cervical fascia (four layers) 1) Investing layer 2) Pretracheal layer 3) Prevertebral layer 4) Carotid sheath
Location of pretracheal fascia
Around trachea and oesophagus, also contains thyroid
Bundles of nerves and vessels in the neck
Common carotid artery (most interior), internal jugular vein (most exterior), vagus nerve (most posterior)
What encloses the common carotid artery, internal jugular vein and vagus nerve
Carotid sheath
Where are the majority of cervical muscles located?
Between transverse and spinous processes of cervical vertebrae (extension of erector spinae)
Layer of fascia that contains muscles around cervical vertebrae
Prevertebral fascia
Two muscles attached to tip of the cervical transverse process
Scalenus anterior and scalenus medius (the scalenes)
Importance of scalenus anterior and medius
Create a gap for brachial plexus and subclavian arteries to exit neck.
Outermost layer of fascia in the neck
Investing layer of fascia
What does the investing layer of fascia enclose?
Trapezius (posterior) and sternomastoid (anterior)
Number of cervical vertebra
Seven
First two cervical vertebra
Atlas and axis
Regions of the neck 1 2 3 4 5
1) Back of the neck (vertebral region)
2) Posterior triangle
3) Sternomastoid region
4) Anterior triangle
5) Root of the neck
1-3 are posterior, 4-5 are anterior
Where does the line of gravity of the head fall?
Anterior to vertebral column.
Hence need posterior muscles of back to keep head upright.
Ligamentous band of fibres in posterior neck
Ligamentum nuchae.
Formed by tendinous insertions of muscles of neck at midline.
Typical cervical vertebrae 1 2 3 4 5 6 7
- Transverse mass – anterior & posterior tubercles
- Transverse foraminae
- Bifid spinous processes (to increase surface area for muscle and ligament contact)
- C7 (atypical) has longest spinous process (vertebra ‘prominens’)
- Articular surfaces oriented at ~45º
- I-V foramen
- ‘Uncinate’ (hook-like) processes on bodies C3-6
Angle of pedicles from cervical vertebral bodies
Angle of about 45 degrees.
Means that spinal nerves also need to exit at about 45 degrees
Transverse mass of cervical vertebra
Transverse process has a hole in it -> Transverse foramen.
Termination of transverse processes have two tubercles.
Bar linking tubercles is a remnant of rib process.
Role of transverse foramen
Makes tube for vertebral arteries
Uncinate processes
Hooklike processes from vertebral bodies of C3 to C6.
Atypical aspects of C1 1 2 3 4 5 6
- No body
- Made up of anterior & posterior arches
- Facet for dens (dens is an articular surface on the axis, articulates with anterior arch of the atlas)
- Shift of position of facet surfaces anterior, relative to other C-vertebrae
- Saucer-shaped (very concave) upper surfaces for occipital condyles
- Long transverse process
What happened to vertebral body of C1?
Attached to C2 during development, to form the spike of the axis
Atypical aspects of C2
1
2
3
- Dens (odontoid process) –developmental body C1
- Surfaces on dens for articulation with anterior arch of atlas
- Strong spinous process
Cranial shift
Rib can begin on C7
Caudal shift
Larger rib on T12, rib developed on L1
Attachment of scalenus anterior
Anterior tubercle of C vertebrae
Role of scalenes
Elevate 1st rib
Prevertebral muscles, location and function
- Prevertebral muscles located anteriorly, deep to prevertebral fascia
- Largest is longus colli - helps maintain curvature of cervical spine
- Provides access to cervical discs & spinal cord
Muscles attaching to spinous process of C2
Erector spinae
Where does common carotid bifurcate?
C4
Where does the vertebral artery enter the transverse foramen?
C6 (at anterior tubercle or carotid tubercle)
Where must spinal nerves pass to exit C1 and C2, versus other cervical vertebrae?
Must pass behind facet joints of C1 and C2, because articular surfaces are more anterior.
Other C vertebrae have more posterior articular surfaces, and nerves pass anterior to them.
Effect of ageing on C vertebrae and nerves and vessels
Osteophytes can form, impinging on anterior rami of spinal nerves, or vertebral arteries (more in lower C vertebrae, less in C1 and C2)
Joints in the C spine
•Inferior joints (C2-C7)
- intervertebral discs
- facet (zygapophyseal) joints
•Superior (suboccipital) joints
- atlanto-occipital (0-C1)
- atlanto-axial (C1-2)
Largest discs in the vertebral column (relative to the vertebra)
In the C spine
Primary contributors to cervical lordosis
IV discs
Processes that hold IV disc of C spine in place
Uncinate processes
Features of IV facet joints of the C spine 1 2 3 4
1) Plane synovial joints, capsule innervated by posterior rami
2) Oriented at 45deg between coronal & horizontal planes (more horizontal in childhood).
3) Permit flexion/extension + rotation
4) Look for symmetry of facet surfaces (shingling) on CT
Whiplash injury of spine
1
2
3
1) Acceleration of head in an antero/posterior direction
2) Injury of facet capsule & articular surfaces, + supporting ligaments
3) Particularly susceptible to compression injury in hyper-extension
Atlanto-occipital joints
Two lateral synovial joints between occipital condyles and upper surfaces on atlas.
Allows nodding, limits rotation
Atlanto-axial joints 1 2 3 4 5
- Three synovial joints specialised for rotation (no IV disc)
- Median pivot joint between dens of C2 & anterior arch of atlas
- ‘Bursa’ between transverse ligament and dens
- Two lateral facet joints
- Allow approx 50% of rotation of cervical spine
Role of transverse ligament in atlanto-axial joint
Allows dens to tilt backwards into vertebral canal
Ligaments of the neck 1 2 3 4
• Ligamentum nuchae (supraspinous ligament)
• Ligament between atlas & occiput
- Posterior atlanto-occipital membrane
- Anterior atlanto-occipital membrane
• Ligaments between axis & occiput
- membrana tectoria (extension of posterior longitudinal ligament)
• All ligaments resist movements in sagittal plane (F/E)
Specialised ligaments of the neck
1
2
Transverse ligament
Alar ligaments
Transverse ligament role
Stabilises dens, prevents posterior translation of dens into vertebral canal
Role of alar ligaments
Limits rotation of occipital bone around the axis.
Link dens and occiput.
Effect of ageing on C spine
1
2
3
Degeneration of IV discs.
Causes vertebral wedging, reduces C spine lordosis.
Osteophytes can develop from uncinate processes and facet surfaces
Hangman’s fracture
Extension fracture of the C spine.
Both pedicles are fractured.
Dens are rarely fractured.
Jefferson’s fracture
From falling onto top of skull.
Bilateral fracture of anterior arch and pedicle.
