1.3 Cervical spine & neck Flashcards
Neck regions
Post: back of neck/vertebral region, posterior triangle, sternomastoid region
Ant: anterior triangle, root of neck
Features of ‘typical’ cervical vertebrae
- transverse foraminae
- bifid spinous process
- articular surfaces oriented at 45degree
- C7 (atypical) has longest spinous process (vertebra prominens)
- uncinate processes (guide movement in sagittal planes
Variations of (cervical) vertebral column
- Variations reflecting developmental changes, occurs in 1% population
- Occurs at transitional regions
- Cranial & caudal shifts
- Structures develop as all vertebrae have costal facets, but only thoracic usually develop ribs.
- Cervical rib: elongation of anterior tubercle
- Can compress and irritate structures emerging from neck.
Atypical cervical vertebrae
ATLAS
- no vertebral body
- anterior & posterior arches
- facet for dens
- saucer-shaped upper surfaces for occipital condyles
- long transverse process
AXIS
- dens (odontoid process) - developmental body C1, allows rotational movement of ring of bone
- surfaces on dens for articulation with anterior arch of atlas
Joints of cervical spine
Superior (suboccipital) joints
- atlanto-occipital (0-C1)
- atlanto-axial (C1-2)
Inferior joints (C2-C7)
- intervertebral discs
- facet joints
Describe the IV discs and the uncovertebral joints of the cervical vertebrae?
- Thick IV discs with central nucleus help form cervical lordosis.
- Cervical bodies are the relative largest throughout vertebral column. And act in the same way as lumbar discs (weight-bearing).
-Uncinate processes (‘Uncovertebral joint of Luschka’) form on superior margins of body and guide movement.
Atlanto-axial joints
- 3 synovial joints specialised for rotation (no IV disc)
- median pivot joint between dens of C2 and anterior arch of atlas
- 2 lateral facet joints angulated close to transverse plane
- allow approximately 50% of rotation of cervical spine + small amount of F/E & LF
Longitudinal ligaments of cervical spine
Between atlas & axis
- PAOM posterior atlanto-occipital membrane (ligamentum flavum)
B/w axis & occiput
- TM tectorial membrane/membrana tectoria (PLL)
- AAOM anterior atlanto-occipital membrane (ALL)
- Ligamentum nuchae
*all ligaments resist movements in sagittal plane (F/E)
Specialised ligaments between occiput & C2
Transverse ligaments - stabilise dens, prevents posterior translation of dens into vertebral canal
*rheumatoid arthritis causes lax of this ligament
Alar ligaments - ‘check’ range of rotation of atlas around dens
*susceptible to injury when head flexed & rotated & muscles relaxed
Other posterior ligaments = TM, AAOM. PAOM, LN
Facet joints of cervical vertebrae
Plane synovial joints, oriented at 45deg between coronal & horizontal planes (more horizontal in childhood, resulting in an increase in the risk of subluxation)
Upper facets more vertical, lower facets more horizontal
Facet surfaces bear weight & susceptible to injury, particularly in hyperextension
Fascia of neck
- Superficial fascia
- Deep cervical fascia
- investing layer
- pretracheal layer
- prevertebral layer
- carotid sheath
*potential space between 2 adjacent fascia can result in build up of pus, blood or infected material
Muscles of neck
- Superficial (trapezius, sternomastoid, global muscles) act on shoulder girdle.
- Anterior (hyoid muscles) stabilise hyoid bone/mouth
- Prevertebral responsible for head and neck flexion
- Lateral vertebral laterally flex & rotate head
- Postvertebral muscles extend neck and head.
Sterno(cleido)mastoid
- Separates anterior from posterior triangle in neck.
- Lies within 2 folds of investing fascia.
- Has 2 heads: manubrium of sternum, medial third of clavicle
- Innervated by XI cranial nerve (like trapezius, both are branchial arch muscles)
Actions:
- Bilaterally: flex neck (when in extended position)
- Unilaterally: laterally flexes to same side & rotates to opposite side
Anterior (‘strap’) muscles
- Suprahyoid & infrahyoid muscles
- Deep to investing fascia
- Act to steady or move the hyoid bone & larynx
Prevertebral (anterior vertebral) muscles
- Located deep to prevertebral fascia
- Flex and LF neck
- Act as ‘local’ muscles/segmental stabilisers
- Longus colli maintains curvature of cervical lordosis
Lateral vertebral muscles
Lateral muscles
- scalenus medius
- scalenus anterior
- scalenus posterior
- Act to laterally flex neck & as accessory muscles of respiration
- Attachments to TPs (ant & post tubercles) to 1st and 2nd ribs
- Important r/ship to roots of brachial plexus & subclavian artery
Postvertebral muscles
Oppose the weight of the head which acts in front of the occipital condyles (axis of rotation).
Extend the head on the neck, and extend the cervical spine.
