L8: The cervical and thoracic spine and the brachial plexus Flashcards
How many cervical vertebrae are there?
Seven
C1, C2 and C7 are atypical
C3-C6 are typical
Describe the anatomy of a typical cervical vertebrae?
VB–> small and broad from side to side
Large triangular vertebral foramen
Bifid spinuous process
Transverse foramen (foramen transversarium) in transverse process–> passage way for vertebral artery, vein and symphathetic plexus
Anterior tubercle
Posterior tuberlce
Groove for spinal nerve
Articular facets–> coronal plane at 45 degree to axial plane
Superior articular facets–> upwards and backwards
Inferior articular facets–> downwards and forwards
What is the structure of the C1 vertebrae?
Atlas
Anterior and posterior arch connected by two lateral masses –> vertebral arches
Widest of cervical vertebrae
No spinous process or vertebral body
Anterior arch occupies 20% of circumference of ring–> attachment of anterior longitudinal ligament
Posterior arch 40% of ring–> attachment ligament nuchae
Articular facets on lateral masses
Superior articular facets–> cup shaped articulate with occipital condyles
Inferior articular facets–> C2 vertebrae
Transverse process with transverse foramen in them
What are the names of the joints found between the skull and C1 and C1 and C2?
Atlanto-occipital joint–> permits nodding
–> 50% of flexion and extension of the head
Atlanto-axial joint–> 50% total rotation of head and neck
C2 –> provides pivot on which the atlas rotates
What is the anatomy of the C2 vertebrae?
Axis
Strongest cervical vertebrae
Rugged lateral mass and large spinous processes
Odontoid process aka dens or odontoid peg–> projects upwards from body
Held in place by transverse ligament of the atlas acts as a pivot joint
Transverse process with transverse foramen in
What are the ligaments associated with the axis (C2)?
Transverse ligament–> holds dens in place
Apical ligament–> Attaches between odontoid process and base of skull
What is excessive movement between the atlas and axis called?
Atlantoaxial instability
Can cause neurological damage
Describe the anatomy of the C7 vertebrae?
C7–> vertebra prominens
Longest spinous process–> not bifid
Foraman transversium are small–> only transmit accessory vertebral veins
In the cervical region where does the spinal nerve run?
Spinal groove
Across the superior aspect of the vertebral pedicle
Between the anterior and posterior tubercles of the transverse process
Spinal nerve–> posterior to vertebral artery
Vertebral artery ascends through the foramina transvrsaria in C1-6 with vertebral vein and sympathetic plexus
Compared to the thoracic and lumbar region how does the spinal nerve exit the cervical region?
Spinal nerve exits above vertebrae
Until C7/T1 junction where C8 nerve root is the exiting nerve root
Neural segments also more inline with vertebrae
Spinal nerve leave horizontally to pass through IV foramina
Clinical impact–> no traversing nerve root, exiting root compressed
What is the ligamentum nuchae?
Thickening of the supraspinous ligament
Extends from the external occipital protuberance of the skull and the medial nuchal line to the spinous process of C7
Anterior border–> fibrous lamina attaches to the posterior tubercle of atlas and spinous process of vertebrae
Continuous inferiorly with the supraspinous ligament
What are the roles of the ligamentum nuchae?
Maintain the secondary curvature of the cervical spine
Assist cerivical spine to support the weight of the head
Major attachment site for muscles of the neck and trunk
What is the anterior longitudinal ligament?
Anterior border of the vertebral body From tubercle of atlas to sacrum Continuous with periosteum of VB Loosely adhered to the IVD Function: prevent hyperextension of vertebral column
What is the posterior longitudinal ligament?
Posterior VB
Body of axis to sacral canal
Superior to axis –> tectorial membrane of the atlanto-axial joint
Prevents hyperflexion
Clinical relevance–> disc prolapse tends to occur lateral to this
What are the movements of the cervical spine?
One of most mobile segments of spine
50% of nodding flexion and extension at atlanto-occipital joint –> remainder takes place at cervical facet joints
50% rotation (shaking head)–> atlanto-axial joint –> remainder at facet joints
Permits 45 degrees of lateral flexion –> occurs at facet joints
Describe the anatomy of the thoracic vertebrae?
12 thoracic vertebrae
Medium sized heart shaped VB
Vertebral foramen small and circular
Prominent transverse process with transverse costal facets (articulation with ribs)
Demi facets T2-T8 and whole facets T9-T10 on VB for articulation with head of ribs
T11-T12–> whole facets on pedicle
Long, spinous process, angulated inferiorly
Articular facets angulated at 20 degrees to coronal plane, 60 degrees to axial (transverse) plane–> superior face posterolaterally, inferior face anteromedially–> permits lateral flexion and rotation but prevents flexion and extension
What do the ribs attach to?
T1-T12
–>T2-8 demi facets on side of VB, superior and inferior demi facets for articulation with rib of same number and the rib below
–>T9-10 whole facets on VB
–>T11-12 facets on pedicle
Rib 1-7 curve round insert onto sternum via costal cartilgae
Ribs 8-10 insert onto costal cartilage of superior rib
Ribs 11-12 –> no anterior attachment, terminate in abdominal musculature
Head of rib articulates with a costal facet–> cartilage lined depressions
What does the thoracic spine, ribs and sternum do?
Provide stability and protection for the heart, lungs, liver and other organs
Ribs connected to T11-12–> protection of retroperitoneal kidneys
Which of the thoracic vertebrae are atypical and posses whole facets?
T1: superior facet is whole, articulates with head of rib 1, inferior costal facet is demi
T9 and 10: whole costal facets, extend from head of VB to pedicule
T11 and 12: whole costal facets located on pedicule
What changes occur to the spinous process as you go down the thoracic spine?
Becomes shorter and less oblique from T1-T12
T12 spinous process more similar to lumbar vertebrae
What does the tubercle of the rib articulate with?
Costal demi facet on transverse process
What angle are the facets joints at? How does this affect the movement of the thoracic spine?
60 degrees to transverse plane
20 degrees to coronal plane
Superior articular facets face posterolaterally
Inferior articular facets face anteromedially
Permit lateral flexion and rotation
Limits Flexion and extension
Describe the anatomy of the lumbar vertebrae?
Large, kidney, shaped vertebral body Triangular shaped vertebral canal Large blunt transverse processes Short blunt spinous processes Facet 90 degress to transverse plane, 45 degress to coronal plane Superior face posteromedially Inferior anterolaterally Large range of flexion and extension, small amount of rotation and lateral flexion
What is the brachial plexus?
Union of anterior rami of C5-T1 spinal nerves
Commences in the neck and terminates in the axilla
(Posterior rami–> skin and musculature of intrinsic back muscles)
What are the different parts of the brachial plexus?
Roots, trunks, divisions, cords and branches
What forms the roots of the brachial plexus? Where does it pass?
Roots formed by the anterior rami of C5-T1
Pass between the scalenus anterior and scalenus medius–> enter posterior triangle of the neck
What are the trunks made up of?
Three trunks
Convergence of the roots
Named after relative anatomical locations
Superior trunk: C5 and C6
Middle trunk: C7
Inferior trunk: C8 and T1
Travel inferolaterally across the posterior triangle of neck
What are the division of the brachail plexus?
Trunks divide in posterior triangle
Anterior division and posterior division
Divisions leave posterior triangle and enter axilla - behind clavicle
Anterior supplies flexor, posterior supply extensors)
What are the cords?
In axilla, division recombine to form the cords
Name according to position relative to axillary artery
Lateral cord: union of anterior division of superior and middle trunk
Posterior cord: union of posterior division of superior, middle and inferior trunks
Medial cord: continuation of anterior division of inferior trunk
What are the branches of the brachial plexus?
5 major terminal branches Supply entire compartment of upper limb Musculocutaneous nerve C5,6,7 Axillary C5, 6 Median C6, 7, 8, T1 Radial C5, 6, 7, 8, T1 Ulnar C8, T1
Which nerves come off before the branches of the brachial plexus?
Long thoracic nerve (C5-7 directly from anterior rami (roots))
Medial pectoral nerve (C8-T1 from medial cord)
Lateral pectoral nerve (C5-7 from lateral cord)
Upper subscapular nerve
Thoracodorsal nerve
Lower subscapular nerve
–> All three of posterior cord
What are 6 key points about the brachial plexus
- Each muscle supplied by more than one spinal cord segment
- More distal muscles supplied by inferior cord segments
- Divergence of fibres in plexus as both flexors and extensors are supplied
- Needs to be re-assortment of nerve fibres
- Number of spinal nerves contributing to the terminal branch is roughly the same as the number of joints it supplied
- Sensory innervation to the limb bud follows loop like pattern
What can you look for in the cadaver when dissecting to help get your bearings?
M shape
Made from Musculocutaneous, median and ulnar nerves
Lie superficial to the axillary artery
What happens if you injury the brachial plexus?
Affect motor function and cutaneous sensation
Traction injuries affect upper or lower nerve roots of brachial plexus
What happens if you get an upper brachial plexus injury?
Result from excessive increase in angle between neck and shoulder
Result of trauma or during child birth if baby’s head is pulled and the shoulders are stuck
C5 and C6 damaged
C5- shoulder abduction and external rotation affected
C6- elbow flexion, wrist extension and supination affected
Which muscles are affected by an upper brachial plexus injury?
Deltoid (axillary nerve C5 and 6) Teres minor (axillary nerve) Biceps Brachii (musculocutaneous C5-7) Brachioradialis (radial nerve C5-T1) Brachialis (musculocutaneous C5-7) Coracobrachialis (musculocutaneous C5-7)
What is the clinical presentation of a upper brachial plexus injury?
Erb's palsy Arms hang by side Internally (medially) rotated Adducted arm Extended elbow Wrist flexed Waiters tip position
What happens with lower brachial plexus injury?
Forced hyperextension or hyperabduction
Childbirth- traction injury if arms are delivered first and used to pull baby out
Klumpke’s palsy
Nerve roots C8 and T1 affected
C8: finger flexion/ finger extension
T1: Finger abduction and finger adduction
What muscles are affected in an lower brachial plexus injury?
Intrinsic muscles of the hand
Flexor carpi ulnaris, and ulnar half of flexor digitorium profundus
Also muscles supplied by C8 and T1 fibres of medial and radial nerves
What is the classical clinical presentation of a lower brachial plexus injury?
Claw hand
Hyperextension of the metacarpalphalangeal joints
Flexion of interphalangeal joints
Abduciton of the thumb and wasting of interossei
Where is the pectoral region?
Anterior chest wall
What are the muscles of the pectorial region?
Pectoralis Major Pectoralis Minor Serratus Anterior Coracobrachialis (not really chest wall but important landmark) Subclavis Deltoid
What is the origin, insertion, innervation and function of the Pectoralis Major muscle?
Sternal head and claviular head
Origin: Sternal head–> Anterior surface of sternum, upper 6 CC, aponeurosis of external oblique muscles
Clavicular head–> Anterior surface of medial clavical
Insertion: Intertubercular sulcus of the humerus
Fibres from the clavicular head overlap fibres of sternal head
Function:
- -> Abducted arm, sternocostal head pulls humeral insertion towards fixed sternocostal origin adducting the arm
- -> Anatomical postion, contraction of clavicular head, flexion of arm at shoulder joint
- -> Humerus externally rotated, contraction internally rotate it
Innervation:
- -> Medial pectoral nerve (C8-T1)
- -> Lateral pectoral nerve (C5-7)
What is the origin, insertion, innervation and function of the Pectoralis Minor?
Origin: 3-5th ribs
Insertion: coracoid process of the scapular
Function: Stabilises the scapular by drawing it anteroinferiorly against the thoracic wall
Innervation: Medial pectoral nerve (C8-T1)
What is the origin, insertion, innervation and function of the Serratus Anterior?
Origin: Ribs 1-8
Insertion: Medial border of costal surface of scapula
Function: Protracts (abducts) the scapula, rotates medial border of the scapula anterioinferiorly so glenoid cavity rotates upwards, enables the upper limb to be abducted above 90 degrees at the shoulder
Innervation: Long thoracic nerve (C5-7)
What is winging of the scapula? How is it diagnosed?
Medial border of the scapula protrudes out of the back
Damage to long thoracic nerve due to trauma
Patient asked place palm of hand on wall and push–> force back along arm–> scapula lifts off
or
Patient asked to place palm of affected side on unaffected shoulder and pull it forward–> traction of scapula of affected limb so medial border elevates
When do the pectoralis major, pectoralis minor and serratus anterior acts as accessory muscles?
Respiration
High metabolic demand or respiratory disease
Hyperventilating, severe metabolic acidosis, asthma
Elevate the ribs increasing the volume of the thoracic cavity
What is the origin, insertion, innervation and function of the coracobrachialis?
Deep to biceps brachii
Origin: Coracoid process of scapula
Insertion: Medial side of humeral shaft level of deltoid tubercle
Function: Flexes the arm at the shoulder, weak adductor
Innervation: Musculocutaneous nerve (C5-7)
What is the origin, insertion, innervation and function of the subcalvius?
Small, located directly under the clavicle
Protection to neurovasculature under the clavicle
Origin: junction of the 1st rib and its costal cartilage
Insertion: Inferior surface of the middle third of clavicle
Function: Anchor and depress calvicle
Innervation: Nerve to subclavius
What is the origin, insertion, innervation and function of the deltoid?
Triangular muscle divided into anterior, middle and posterior parts
Origin: Anterior border and upper surface of lateral third of clavicle, acromnion and spine of scapula
Insertion: deltoid tuberosity on lateral surface of humerus
Function:
- -> Anterior fibres–> flex and medially rotate arm at shoulder
- -> Middle fibres–> Abduct the arm from 15-90 degrees, (supraspinatus does first 15 degrees)
- -> Posterior fibres–> extend and laterally rotate arm at shoulder
Innervation: Axillary nerve (C5, 6)
What is the axilla?
Pyramidal space at the junction of the upper limb and thorax
Passageway for which neurovascular and muscular structures can enter and leave the limb
Size and shape varies with amount of arm abduction
Arm fully abducted axillary fascia taught, contents compressed against proximal humerus
What are the borders of the axilla?
Anterior: pectoralis major and minor and subclavis
Posterior: Subscapularis, teres major and latissimus dorsi
Medial: Serratus anterior, ribs and intercostal muscles
Lateral: Intertubercular sulcus of humerus
Base: Axillary fascia, (thick layer of fascia spanning between the inferior borders of pectoralis major and latissimus dorsi) and skin
Apex: lateral border of first rib, superior border of scapula and posterior border of the clavicle
What are the contents of the axilla?
Axillary artery and branches
Axillary vein and tributaries
Cords of brachial plexus
Branch of brachial plexus
Intercostobrachial nerve –> cutaneous supply to upper medial arm and floor of axilla
Axillary lymph nodes –> drain the arm and pectoral region
Biceps brachii (short head) and coracobrachialis–>muscles originate from coracoid process tendons pass through into arm
What are the main routes into and out of the axilla?
Inferiorly and laterally into upper limb
Via quadrangular space to posterior arm and shoulder
Via clavipectoral triangle (deltopectoral triangle)–> opening in the anterior wall of axilla bounded by pec major, deltoid and clavicle
What are the borders of the quadrangular space? What passes through the quadrangular space?
Teres minor, Teres major and long head of triceps brachii
Axillary nerve
Posterior circumflex humeral artery encircle surgical neck of humerus
What passes through the clavipectoral triangle?
Cephalic vein
Medial and lateral pectoral nerves
How are the lymph nodes arranged in the upper limb? Where do they drain?
APICAL
Anterior (pectoral) group–> Lower border of pectoralis minor, behind pectoralis major–> lymph from lateral breast, anterolateral abdominal wall above umbilicus
Posterior (subscapular) group–> front of subscapularis muscle –> lymph from back down to iliac crest
Infraclavicular (deltopectoral) group–> located outisde axilla, groove between deltoid and pectoralis major–> superficial lymph from lateral side of hand, forearm and arm
Central group–> centre of axilla within the fat, lymph from anterior, posterior and lateral
Apical group–>Apex of axilla, lateral border of first rib, nodes receive efferent lymph from all other axillary nodes
Lateral group–> Medial side of axillary vein–> lymph from upper limb
Where do they axillary lymph nodes drain into?
Converge forming the subclavian lymphatic trunk
Right subclavian trunk–> right lymphatic duct–> right venous angle
Left subclavian trunk–> thoracic duct–> left venous angle
What is axillary lymphadenopathy?
Enlargement of the axillary lymph nodes
Caused by:
Infection of upper limb (lypmphangitis- inflammation of lymph vessel)–> red, warm, tender streak on arm
Infection of pectoral region and breast
Metastases from breast cancer
Leukaemia or lymphoma
Metastases from malignant melanoma in upper limb
What is axillary node dissection?
Removal and analysis of axillary lymph node part of staging of breast cancer
Interruption in lymphatic drainage from the upper limb–> lymphodema–> painful swelling of upper limb
Risk of damage to long thoracic nerve supply–> winged scapula, or thoracodorsal nerve supply
What is the main arterial supply to the upper limb?
5 main vessels–> proximal to distal
- Subclavian artery
- Axillary artery
- Brachial artery
- Radial artery
- Ulnar artery
When does the subclavian artery become the axillary artery? What are the different parts of the axillary artery called?
Lateral border of the first rib to the lower border of teres major
First part- proximal to pectoralis minor
Second part- posterior to pectoralis minor
Third part- distal to pectoralis minor
What are the main branches of the axillary artery?
First part–> superior thoracic artery
Second part–> Thoracoacromial artery and lateral thoracic artery
Third part–> Subscapular artery, anterior circumflex humeral artery and posterior circumflex humeral artery –> anterior and posterior anastomotic network around surgical head of humerus
What is the course of the axillary vein?
Lower border of teres major from union of paired brachial veins and basilic vein
Ascends through the axilla anteromedially to the axillary artery continuous with the subclavian at the lateral border of the first rib
What are the different parts of the axillary vein?
First part–> above pectoralis minor–> receives blood from cephalic vein
Second–> posterior
Third–> distal
Receive tributaries that correspond with the artery
Thoracoacromial vein, lateral thoracic vein, subscapular vein, anterior circumflex humeral vein and posterior circumflex humeral vein
What does the axillary vein drain?
Arm, axilla and superolateral chest wall
What are the superficial veins of the upper limb?
Cephalic and Basilic
Form the pre-axial and post-axial borders of the arm respectively
What is the course of the bascilic vein?
Dorsal venous network of the hand
Ascends medial upper limb
Inferior border of teres major, bascilic vein moves deep into the arm
Combines with paired brachial veins–> axillary vein
What is the course of the cephalic vein?
Dorsal venous network Ascends anterolateral aspect of arm Passes anteriorly at elbow At shoulder cephalic vein travels between the deltoid and pectoralis major muscle (in the deltopectoral groove) and enter the axialla via clavicopectoral (deltopectoral) triangle In axilla drains into axillary vein
What connects the cephalic and bascili vein at the elbow?
The median cubital vein
What is cervical spondylosis?
Chronic degenerative osteoarthritis
Affect intervertebral joints in the cervical spine
What changes occur with cervical spondylosis?
Age related disc degeneration—> loss of disc height
Osteophyte formation—> bony projections
Facet joint osteoarthritis
What is one of the problems of osteophyte generation in cervical spondylosis?
Narrowing of the intervertebral foramina—> Radiculopathy—> compression of the spinal nerves
OR
Narrowing of the spinal canal—> Myelopathy—> pressure on spinal cord
What symptoms does radiculopathy and myelopathy present with?
Radiculopathy—> dermatome and sensory symptoms—> paraesthesia, numbness, pain and muscle weakness in area supplied by that spinal nerve
Myelopathy—> global muscle weakness, gait dysfunction, loss of balance, loss of bowel and bladder control etc… depends on which part of spinal cord is compressed—> all areas below affected
What are names of the different fractures that can occur to the cervical vertebrae?
Jefferon’s fracture
Hangman’s fracture
Fracture of the odontoid process (peg fractures)
What is a Jefferson’s fracture? What is the mechanism of injury?
Fracture of the atlas
Anterior and posterior arches fractured —> bursting open
Axial loading—> diving into shallow water, hitting head against roof of vehicle etc…
What does a Jefferson’s fracture result in?
Pain but no neurological signs
Bursting open—> no impingement of spinal cord
Potential arterial damage (base of skull)—> secondary neurological sequelae —> ataxia, stroke, Horner’s syndrome etc…
What is a Hangman’s fracture? What is the mechanism of injury?
Fracture of Axis (C2)
Pars interarticularis fractured—> region between superior and inferior articulatar processes
Forcible hyperextension of head
What does Hangman’s fracture result in?
Unstable fracture—> treatment required
Expands vertebral canal —> no neurological damage (no compression of spinal cord), pain
What causes Fracture of the odontoid process?
Flexion or extension injuries
Commonly—> elderly patient with osteoporosis falling forward and impacting forehead on pavement —> hyperextension of cervical spine—> fracture
Alternative—> blow to back of head—> hyperflexion injury—> falling backwards down stairs
How is a fracture to the odontoid process detected?
Open mouth AP X-ray
CT scan of cervical spine
Odontoid peg not easily seen on normal x-ray
What is a whiplash injury?
Forceful hyperextension-hyperflexion injury of the cervical spine
Tearing of the cervical muscle and ligaments
Secondary oedema, haemorrhage and inflammation may occur
Muscles respond—> contraction (spasm) surrounding muscle recruited in an attempt to splint the torn muscle
What are the common signs and symptoms of Whiplash injury?
Pain and stiffness due to muscle spasms
Arm pain and paraesthesia—> injury to spinal nerves
Shoulder injury
Lower back pain in 40-50% patients
Why is the cervical spine prone to Whiplash injury?
7-10% body weight balanced
High mobility and low stability of cervical spine
Ligaments and capsule of the joints are weak and loose
What is a secondary tissue response of Whiplash injury?
Myofascial pain syndrome
- Secondary tissue response to disc or facet-joint injury
High prevalence of chronic pain
What is the classical mechanism of Whiplash?
Impact—> vehicle accelerates forward, patient torso and shoulder follow (100ms delay) induced by car seat acceleration
Head—> no forces acting on it so it stays still—> forced extension of head
Head accelerated forward—> neck acts as lever—> forced flexion of head
Hyperextension followed by hyperflexion—> results in tearing
What is one protective factor against spinal cord injury in the cervical region?
Vertebral foramen is relatively large
Normal diameter - 17-18mm
Spinal cord diameter- 10mm
What is cervical disc prolapse? What is it associated with?
Herniation of IVD –> tear in annulus fibrosis of disc
Nucleus pulpous protrudes from disc
Compression of spinal nerve or spinal cord
(Sometimes sequestration occurs (separation of nucleus pulpous from main body of disc) can be reabsorped and symptoms disappeared)
What are the symptoms associated with cervical disc prolapse?
Exiting nerve root compressed
Symptoms depend on the site of prolapse
Discs not very large but little space for exiting nerves –> impingement–> pain
Paracentral prolapse–> spinal nerve compression–> Reticulopathy
Canal-filling prolapse–> spinal cord compression–> myelopathy
What is a cervical myelopathy?
Spinal cord dysfunction due to compression of spinal cord
Casued by narrowing of the spinal canal
What is the most common causes of cervical myelopathy?
Degenerative stenosis of the spinal canal
Caused by cervical spondylosis (degenerative osteoarthritis)
Commonly affects 50-80yr olds
What is cervical spondylotic myelopathy?
Myelopathy secondary to cervical spondylosis
What cause cervical spondylotic myelopathy?
Degenerative change
Occur with age
Ligamentum flavum hypertrophy or buckling
Facet joint hypertrophy
Disc protrusion and osteophyte formation
Result in canal narrowing—> cord compression
What are some of the other causes of cervical myelopathy?
Congential stenosis (narrowing) of spinal canal
Cervical disc herniation
Spondylolisthesis (anterior slippage of vertebral body on vertebrae below)
Trauma
Tumour
Rheumatoid arthritis
What are the symptoms associated with cervical myelopathy?
Range of symptoms
Compression of long tract of spinal cord
Damage to upper and lower limbs
Usually non specific
Classical presentation
- Loss of balance
- Poor coordination
- Decrease dexterity
- Weakness
- Numbness
- Paralysis
- Pain (sometimes)
Upper cervical lesions
- loss of manual dexterity, difficulties writing, nonspecific alterations in am weakness and sensation, dysdiadochokinesia -impaired ability to perform rapid alternating movements
Lower cervical lesions
- Spasticity, lots of leg proprioception, legs feel heavy, gait disturbances and multiple falls
What is Hoffman’s test?
Dr hold patient middle finger at the middle phalanx
Flick the nail
No movement of index finger or thumb —> patient has negative Hoffman’s sign
Index finger and thumb move—> Positive Hoffman’s sign–> over reaction to stimuli shows long tract damage
What is Hoffman’s test and Babinski sign used to show?
Long tract damage
Normally signals in the long tracts dampen the spinal reflex’s so a person doesn’t overact to stimuli
When long tract damaged —> exaggerated response to stimulation
What is Babinski sign?
Lateral side of foot stroked with a blunt instrument from heel to toes
Normally results in flexion (plantarflexion) of the toes —> negative Babinski —> normal
If hallux dorsiflexes and toes fan out —> positive Babinski —>abnormal —> damage to spinal cord
What is a classical sign of cervical myelopathy?
L’Hermitte’s phenomenon
Sensation of intermittent electric shocks in the limbs—> exacerbated by neck flexion
Severe compression—> sphincter dysfunction and quadriplegia
What is thoracic cord compression?
Compression of the thoracic spinal cord
What are the causes of thoracic cord compression?
Commonest cause—> vertebral fracture and tumours in the spinal canal
Spinal cord second most common site for skeletal metastases
What is important to remember when considering the clinical effects of thoracic cord compression?
Lower thoracic spine and in the lumbar spine the neural segments do not line up with their respective vertebrae
E.g. Metastases in T12 vertebra will compress L4-L5 segments of spinal cord
How can pathogens reach the bone and tissues of the spine?
Haemtogenous —> blood route into arterial supply to VB or retrograde venous flow into VB
Direct inoculation during invasive spinal procedures
Spread from adjacent soft tissue
What is infection of the intervertebral disc called?
Spondylodiscitis or discitis
How does discitis occur?
IVD avascular
Organisms deposited in vertebral body via segmental artery—> bony ischaemic and infarction
Necrosis of bone—> direct spread of organism to adjacent disc space, epidural space and adjacent vertebral bodies
What does infection of the spinal canal lead to? How?
Neurological damage
Via:
- Septic thrombosis leading to ischeamia
- Compression of neural element by abscess/ inflammatory tissue
- Direct invasion of neural elements by inflammatory tissue
- Mechanical collapse of bone leading to instability, particularly in chronic infections
What are the most common infections seen in the spinal cord?
Staphylococcus aureus (50%)
E.Coli (30%)
Invasive spinal procedures—> Coagulase negative Staphylococci (Staph epidermis) become more frequent
Injecting drug users potentially Pseudomonas, Candida
