6. Cervical Spine And Brachial Plexus Flashcards
Number of cervical vertebrae
7
Number of thoracic vertebrae
12
Number of lumbar vertebrae
5
Number of sacral vertebrae
5
Number of coccygeal vertebrae
4
3 functions of the vertebral column
- Protect spinal cord and spinal nerves
- Support weight of the body superior to the level of the pelvis
- Partly rigid and flexible axis for the body and an extended base on which head is placed and pivots
nucleous pulposus
Middle part of intervertebral disc
Remnant of notochord
General structure of vertebrae
– x1 spinous
– x2 transverse
– x4 articular
* Pedicle * Lamina * Vertebral body
the facet/zygapophysial joint
• Vertebrae articulate at inferior & superior articular processes (forming the facet/zygapophysial joint) - synovial joints
• Superior & inferior vertebral notch
• Superior & inferior vertebral notch of adjacent vertebrae form IV foramen (spinal nerves go through here)
Nerve roots - exits
• Nerve roots in c-spine exit ABOVE their vertebral body – UNTIL C7/T1
C1 – C7 vertebrae
Nerve exits
• Spinal nerves exit above the vertebrae pedicle
C8 nerve ext
• Spinal nerve emerges inferior to the vertebrae pedicle
At C7
From t1
- nerve exits
Nerves come out inferior to pedicle
Vertebral canal
Succession of vertebral foramina form the vertebral canal (which contains spinal cord and spinal nerve roots, meninges, fat, vessels)
Cervical vertebrae
Located between the cranium & thoracic vertebrae
• Smallest of the 24 moveable vertebrae
• Thereis no IV disc betweenthe occiput,C1 &C2
Cervical foramen
2 openings = Foramen transversarium (aka transverse foramen)
• Vertebral arteries & veins pass through here
• • (except C7, only small accessory veins)
• – C7 transverse foramen are small and sometimes absent
Cervical vertebrae - structure
• Anterior & posterior tubercle of transverse process provide attachment for cervical muscles (levator scapulae & scalenes)
• Scalenes anterior and medius, between these are the roots of the spinal nerves C5-T1
– Anterior rami of spinal nerves run in the groove of transverse process
• Anterior tubercle of C6 is called carotid tubercle
Cervical vertebrae have bifid spinous processes
C3-C7 are typical cervical vertebrae
– Large foramina (to accommodate cervical enlargement of spinal cord)
– Articulation allows flexion/extension, some lateral flexion
C7
• C7 has a long spinous process (C7 sometimes called vertebra prominens)
C1 - arias
• C1 has NO body and NO spinous process
– During development, body of C1 fuses with C2 to become the dens of C2 – odontoid peg
• Ring shaped with two lateral masses
– Each mass articulates above with an occipital condyle (atlantooccipital joint), and below with superior articularprocess of C2
• AO joint allows nodding movement
odontoid peg
– During development, body of C1 fuses with C2 to become the dens of C2 – odontoid peg
Vertebral artery
Vertebral artery runs in the groove on the superior surface of posterior arch
– C1 nerve also runs in this groove
3 branches of Aortic arch
• Brachocephalic artery
• Common carotid artery
Subcalivian artery – shows stenosis in subclavian, subclavian goes to vertebral artery
Subclavian steals syndrome
○ Subclavian steal syndrome – arm steals blood so less goes to head
C2 - axis
• Has two large superior articular facets on which the atlas rotates
• Large bifid spinous process
• Distinguishing feature is the odontoid peg (dens)
– Projects superiorly from the body
• Allows rotation of the head
TRANSVERSE LIGAMENT
Dens is held in position by the transverse ligament of the atlas
– Ligament is between lateral masses of atlas
• Runs between dens and spinal cord
– Prevents posterior displacement of the dens and anterior displacement of atlas
ALAR LIGAMENT
Alar ligament extends from side of dens to lateral margins of foramen magnum – Prevent excessive rotation at the joints
6 Ligaments of vertebral column
- Anterior longitudinal ligament = strongest, prevent hyperextension of neck
- Posterior longitudinal ligament
- Ligamenta flava
- Supraspinous ligaments
- Interspinous ligaments
- Intertransverse ligaments
Interspinous ligament
Between spines
• Ligamenta flava
– Thin broad elastic ligaments
• Form part of posterior surface of vertebral canal
– Extends from superior lamina to cervical lamina below
» Help preserve normal spinal curvature
• Nuchal ligament
– Sheet of strong fibrous tissue
• Found in medial saggital plane
– From external occipital protuberance to foramen magnum, to spinous process of C7
• Supraspinous ligament
– Band connecting tips of spinous processes from C7 to sacrum
• Merges superiorly with nuchal ligament
Anterior longitudinal ligament
– strongest = Strong broad fibrous band
• Prevents hyperextension
– Attached to vertebral bodies & IV discs
» Extends from pelvic surface of sacrum to anterior tubercle C1
• Continues superiorly as anterior atlanto-axial membrane and atlantooccipital membrane
• Posterior longitudinal ligament
– Narrower, weaker band
• Runs within vertebral canal on posterior part of vertebral bodies
– Attached mainly to IV discs from C2 to sacrum
• Tectorial membrane
– Is the upper part of posterior longitudinal ligament connecting C2 to inside of base of skull
Dislocation of cervical vertebrae
Cervical vertebrae articular facets are more horizontal than other vertebrae
• Can slip over each other more easily
- Can be dislocated with less force than is required to fracture them
- Because of large vertebral canal, slight dislocation can occur without damaging spinal cord
- Dislocation may self-reduce (slip back into place) so X-ray may not show any damage
Fracture and dislocation of atlas C1
Taller side of the lateral mass is on the outside
– vertical forces (e.g. striking the bottom of the pool in a diving accident) compress the lateral masses between occipital condyles & axis, driving lateral masses apart
• Fracture of anterior/posterior arches can occur
Fracture and dislocation of axis C2
• Fracture of vertebral arch most common
– Usually occurs in pars interarticularis (bony column formed by superior & inferior articularprocesses)
• Fracture here is called traumatic spondylolysis
– Usually occur because of hyperextension of head on the neck (anterior longitudinal ligament prevents hyperextension)
• Aka hangman’s fracture
• Severe injuries cause C2 to displace anteriorly leading to quadriplegia or death
Fracture of the dens of axis
• Most common dens fracture occurs at its base – inferior to base of dens
• Often fractures are unstable (do not reunite)
– Transverse ligament becomes interposed between fragments
– Dens no longer has blood supply resulting in avascular necrosis
Fractures of vertebral body
• Fractures of vertebral body occur inferior to base of dens
– Heals more readily as fragments retain blood supply
Cervical spondylosis
• Degenerative disorder of cervical IV discs leading to:
– osteophyte formation = rough regrows of bone can cause pain, like little spurs
– Hypertrophy of adjacent facet joints & ligaments
– Loss of disc height
• Pressure on nerve roots leads to radiculopathy
• Pressure on the spinal cord leads to myelopathy
Cervical myelopathy
Cord compression resulting from spondylitic disease
• Myelopathy due to cervical degenerative change is most common cause of spinal code dysfunction aged 55 & over
Thoracic vertebrae
Bilateral costal facets (demifacets)on the vertebral bodies
– For articulation with the head of the rib
• Costal facets on the transverse processes (costa means rib – 2 costal facets on each side of body)
– For articulation with the tubercles of ribs
• (Except for inferior two or three thoracic vertebrae)
• Long, inferiorly slanting spinous processes
T1 - t4
• T1-T4 share some features with cervical vertebrae
T5- t8
• T5-T8 show all typical features
T9-t12
• T9-T12 show some features of lumbar vertebrae
Axilla
—> Irregularly shaped pyramidal space
- Inferior to glenohumeral joint and superior to axillary fascia at the junction of arm and thorax
- Allows thing to pass through
Cords
Cords names are derived from relationship to the second part of the axillary artery (posterior to pec minor)
– E.g. lateral cord is lateral to axillary artery
Structure of vessels in axial
Roots C5 – T1 lie between scalaneus anterior and medius
Trunks 1,2,3 upper, middle and lower run across posterior triangle of neck
Divisons occur under clavical
Subclavian artery – under surface of clavicle –as cords form out from the clavicle they are related to the axilalry artery
axillary inlet margins
– Medial margin: lateral border of rib I
– Anterior margin: posterior surface of clavicle
– Posterior margin: superior border of the scapula
– Apex formed by medial aspect of coracoid process
Walls of axilla
Anterior wall
– Lateral pectoralis major, pec minor, subclavius & clavipectoral fascia
• Medial wall
– Upper thoracic wall & serratus anterior
• Lateral wall
– Intertubercular sulcus of humerus
• Posterior wall
– Costal surface of scapula & subscapularis, lat dorsi, teres minor, long head of triceps
Base
– Formed by skin, subcutaneous tissue,axillary fascia
Axilalry contents
Blood vessels
– Axillary artery & vein + branches of both
• Lymph vessels & axillary lymph nodes
• Fat
• Nerves
– Brachial plexus
Axillary sheath
extension of cervical fascia - covers contents of axilla
5 main groups of Lymph nodes
– Pectoral (anterior) – Subscapular (posterior) – Humeral (lateral) – Central – Apical
• Pectoral nodes
– 3-5 nodes along the medial wall of the axilla
– Receive lymph from the anterior thoracic wall, including most of the breast
• Subscapular nodes
– 6-7 nodes along posterior axillary fold
– Receive lymph from the posterior aspect of thoracic wall & scapular region
• Humeral nodes
– 4-6 nodes along lateral axillawall
– Receive lymph from upper limb (except that carried by vessels accompanying the cephalic vein)
Lymph drainage
- central
- apical
- Subclavian lymphatic trunk
- Right lymphatic duct or left thoracic duct
Roots of brachial plexus
Roots C5-T1
- Anterior rami of C5-T1
- Receive gray rami sympathetic fibres from cervical ganglia
- Enter posterior triangle of the neck by passing between anterior and middle scalene muscles, lie superior & posterior to subclavian artery
Parts of brachial plexus
- Roots
- Trunks – superior, middle, inferior
- Divisions
- Cords – lateral, posterior, medial
- Terminal nerves/ branches
What is the brachial plexus
• Major nerve network supplying the upper limb
– Starts in neck, extends into axilla
– Formed by the union of anterior rami of C5-T1
3 nerves that come off from the roots
- Dorsal scapular (C5) supply rhomboids
- Subclavius nerve supplies subclavian muscle (C5,6)
- Long thoracic (C5,6,7) supply sorateus anterior muscle
Nerve that comes off trunk
Only 1 nerve comes from the trunks – suprascapular nerve
3 nerves from lateral cord
- Musculocutaneous nerve – supply briceps bracheolous and coraco brachiallis
- Lateral pectoral nerve supplies pectorus major muscle
- Median nerve – supply forearm flexors
5 nerves from posterior cord
- Thoracodorsal – supplie litimus dorsal muscle (c6,7,8\0
- Upper and lower subscapular nerves (C5,C6)
- Axillary nerve
- Radial nerve – supply forearm extensor muscles (c5,t1)
5 nerves from medial cord
• Medial pectoral nerve
• Ulna nerve
• Cutaneous nerve of arm and forarm
Part that forms medial nerve
Dorsal horn
Sensory nerves go into dorsal horn
Ventral horn
Somatic motor merves go out of ventral horn
Trunks
- 3 trunks originate from roots
- Pass laterally over rib 1 & enter axilla
- Superior trunk = C5 + C6
- Middle trunk = C7
- Inferior trunk = C8 + T1
• Each trunk divides into anterior & posterior
Divisions
• Each trunk divides into an anterior & posterior division
Anterior division - brachial plexus
– Ant divisions supply anterior(flexor) compartments of upper limb
Posterior division - brachial plexus
– Post divisions supply posterior (extensor) compartments
Cords
• 3 cords formed from the divisions
– Lateral cord, formed from superior & middle trunk anterior divisions
– Medial cord, formed from inferior trunk anterior division
– Posterior cord, all three trunk posterior divisions
Axillary artery
- Is a continuation of the subclavian artery, and eventually continues as the brachial artery
- Divided into 3 sections based on location relative to pectoralis minor
– First part: location between lateral border of 1st rib & medial border of pec minor muscle
– Second part: posterior to pec minor
– Third part: extends from lateral border of pec minorto inferior border of teres major
Branches of axillary artery
– First part has 1 branch: superior thoracic artery
– Second part has 2 branches: thoracoacromial, lateral thoracic arteries
– Third part has 3 branches: subscapular, anterior circumflex humeral, posterior circumflex humeral arteries
Cervical ribs
• Common anomaly
• 1-2% of people
• Extra rib, of varying length articulating with C7
– May put pressure on structures e.g. subclavian artery,impinge on brachial plexus
• Can cause thoracic outlet syndrome
Each vertebrae has transverse processes – sometimes these can grow out to form cervical ribs
Location of roots
• Between scalenus anterior and medius
Location of trunks
• Posterior triangle of neck
Location of division
• Behind the clavicle
Location of cords
• In the axilla
Location of nerves/branches
• Junction axilla/upper limb
Identifying site of injury in brachial plexus
—> different lesions and things
If damage is at the roots = no movement of upper limb – dangerous
If lesions are distal – some parts are still preserved
Supraclavicular injury
- Injury above clavicle affecting trunks
* – high energy, result in stretch injury
Avulsion V’s rupture
• Traction, pulling, stretching out = too much stretching = rupture
Disc compression of the nerve
Cervical disc prolapse
- Aka “slipped disc”
- Herniated disc material protrudes through a tear in the annulus fibrosus causing compression on a root – annular rings like a tree trunk round nucleus pulposus, due to tear the nucleous pulposus bulges through
- Tear in annulus due to compression& rotation of disc
Leffert classification
- Open
- Closed
2a supraclavicular
2b infraclavicular - Radiation
- Obstetric 4a Erbs 4b Klumpkes 4c mixed
Obstetric brachial plexus injury
• Similar to the supraclavicular motorcycle injury – stretch involving upper parts of the brachial plexus
Erb’s palsy C5/6
“waiter’stip” positon adducted, internally rotated shoulder; pronated forearm, extended elbow
• Can’t supinated
• Biceps is c5,6
Klumpke’s palsy c8,t1
—> lower trunk, ulnar nerve
Deficit of all of the small muscles of the hand →“claw hand”
• wrist in extreme extension because of the unopposed wrist extensors
• hyperextension of MCP due to loss of hand intrinsics (lumbricals)
• flexion of IP joints due to loss of hand intrinsics (lumbricals)
Horner’s syndrome
• Lesion of cervical sympathetic trunk in neck results in sympathetic disturbance
T1 can convey autonomotic sympathetic symptoms
• Constriction of pupils
• Ptosis – of the eyelids – drooping
• Anhydrosis – absence of sweating on forehead
Diagnosis of brachial plexus injury
Nerve injury
Spontaneous recovery
Clinical examination
Intervention vs Observation
Nerve injury
- Motor loss
* Sensory loss
Spontaneous recovery
- Complete
* Incomplete
Clinical examination
- Imaging Nerve
* conduction studies
Intervention vs Observation
Optimal time frames for repair so:
• Have brachial plexus injury on your radar
• Assess patient carefully and serially
• Liaise with specialist unit early
Wallarian degernation of distal segment
• Regernation of the nerves
Axon (fibre) transected, proximal cell body is “OK”
*Myelin sheath - phagocytosed by macrophages (neurilaemmal sheath unaffected)
Schwann cells proliferate rapidly and fill the tube
Proximal end undergoes regeneration and grows down the tube
Neuropraxia
• endoneurial tube in tact
Neurotmesis
• epineurium divided, damaged, no recovery potential
Axonotmesis
• endoneurial tube NOT in tact but epineurium in tact
Nerve grafting
- use the Sural nerve – superficial nerve beteen gastronemius
- Supplies lateral aspect of foot
- Can be used as a graph
Whiplash
Nerve injury
-Damage to anterior longitudinal ligaments
Can dislocate cervical vertebrae
