Neurology Anatomy Flashcards
Which muscles make up the Extrinsic back muscles?
Trapezius
Levator scapulae
Rhomboids (major + minor)
Latissimus Dorsi
What is the functions of the extrinsic back muscles?
- Attach back to pectoral girdle (have attachment point somewhere outwith back)
- Move upper limb
Main innervation of the extrinsic back muscles?
Anterior rami of cervical spinal nerves
Exception = trapezius –> spinal accessory
What are the 2 main groups of Intrinsic back muscles?
Erector spinae (superficial)
Transversospinalis (deep)
What is the function of the intrinsic back muscles?
Maintain back posture
Move spine
Where is the erector spinae muscles located?
3 vertical groups located lateral to the spine
What are the common inferior and superior attachments of the erector spinae muscles?
Inferior - sacrum, iliac crest
Superior - rib, transverse process of vertebra, spinous process of vertebra
Where is the Transversospinalis intrinsic back muscle located?
Within the grooves between the transverse & spinous processes
What is the nerve supply of the intrinsic back muscles?
Segmental nerve supply (as per myotome/dermatome)
Posterior rami branches (cervical, thoracic, lumbar)
What are the three main muscles of the anterolateral abdominal wall (superficial to deep)?
External oblique
Internal oblique
Transverse abdominis
What are the main movements of the spine by erector spinae and transversospinalis?
Maintain posture + support
Extension of spine (erector spinae contracts bilaterally)
Unilateral contraction = lateral flexion
What are the sections of the vertebral column?
Cervical C1-C7 Thoracic T1-T12 Lumbar L1-L5 Sacrum (5 sacral) Coccyx (4 coxxygeal)
33 vertebrae in total
How does the size of vertebrae change as you travel down the spine?
Become larger as they become more weight bearing
Sacrum + Coccyx become smaller again once weight transferred to hip bones
What is the functions of the vertebral column?
Support head + trunk when upright
Protect spinal cord (+ nerves)
Allow movement
Explain the development of the curvatures of the vertebral column
As a fetus the spine is a continuous curve which slowly starts to develop separate curvatures as the child begins to walk and weight bear
Adults have 2 primary lordosis curvatures (cervical, sacral) and 2 secondary kyphosis (thoracic, lumbar)
What does the vertebral arch consist of?
Pedicle x2
Lamina x2
What is the function of the inferior and superior articular process of a vertebra?
Mobility with adjacent vertebrae via synovial facet joint
Where in the spine are spinal nerves found?
Intervertebral Foramen
What pathology can common affect the facet joint between articular processes?
Arthritis
What is an Intervertebral disc?
Sits between the bodies of adjacent vertebrae
Strong attachment
Between which vertebrae are there no intervertebral discs?
C1-C2
Sacrum
Coccyx
What is the formation of the intervertebral disc?
Outer fibrous ring - Annulus Fibrosus (strong)
Inner soft pulp - Nucleus Pulposus (flexibility + protection)
How much of the length of the spine is made up by intervertebral discs?
20-25%
What are the three main ligaments found within the spinal cavity?
Ligamentum flavum
Posterior longitudinal ligament
Anterior longitudinal ligament
What is the function of the anterior longitudinal ligament?
Stronger support for disc
Prevents over-extension of spine
Broad + strong
What is the function of the Posterior Longitudinal ligament?
Prevents over-flexion of spine
True or False:
Posterior longitudinal ligament provides MORE support for the disc than the anterior longitudinal ligament
FALSE
Posterior longitudinal ligament is narrow + weak
What is the function of the ligamentum flavum?
Connects adjacent laminae posterior to the spinal cord
Where does the supraspinous ligaments connect?
Connects tips of spinous process
Strong, fibrous
Where does the Interspinous ligament connect?
Connect superior and inferior surfaces of adjacent spinous processes
Weak, membranous sheet-like
Which vertebrae does not have a body or spinous process?
C1 - Atlas
Has posterior arch and anterior arch instead
Which vertebrae has an odontoid process?
C2 - Axis
Projects superiorly from body and articulates with C1
What is the main movement of the Atlanto-axial joints?
Rotation
What are the four stages of cervical vertebrae dislocation?
1 - flexion sprain
2 - anterior subluxation, 25% translation
3 - 50% translation
4 - complete dislocation (facet jumped over to other side + locked in place)
At what levels does the spinal cord begin and end?
Begins at foramen magnum - C1 segment
Ends around vertebral level L1/L2 (conus medullaris)
What is a Laminectomy?
Used to access spinal canal, posterior exposure of the spinal cord and/or spinal roots
Relieve pressure on spinal cord or nerve roots
What symptoms will patients complain of with somatic general sensory pathology?
Pain (neuralgia), pins & needles (paraesthesia), numbness, sensitivity, thermal (hot or cold), loss of coordination/balance/clumsiness
What symptoms will patients complain of with somatic motor pathology?
Muscle stiffness/tightness/spasm, muscle floppiness or looseness, muscular weakness, loss of coordination/balance/clumsiness
What are the main dermatomes of the upper limb?
C5, C6, C7, C8, T1, T2
True or False:
C1 does not have a dermatome
TRUE
C1 only has motor function/myotome
What are the main dermatomes of the lower limb?
L1 - S5
What is the arrangement of dermatomes of the lower limb?
Goes down the front (L1 - L5)
Up the back (S1 - S3)
Then circles around the groin (S3, 4, 5)
True or False:
The dorsal roots (posterior) carry sensory information only
TRUE
Ventral roots carry motor information
What are the end named nerves of the Brachial Plexus?
Musculocutaneous Axillary Median Radian Ulnar
From which cervical nerves does the brachial plexus arise from?
C5 - T1
What is the sensory nerve supply of the anterolateral neck skin and posterior scalp & neck?
Anterolateral neck = Cervical plexus (C1-4)
Posteriorly - posterior rami of C2-C8
What is the mneumonic for the named nerves of the cervical plexus supplying the anterolateral neck skin?
Little Goats Treat Softly
L - Lesser occipital nerve
G - Greater auricular nerve
T - Transverse cervical nerve
S - Supraclavicular nerve
What nerve supplies the ‘anatomical snuffbox’?
Cutaneous branches of Radial nerve
Where is somatosensory information processed in the cerebral cortex?
Postcentral gyrus
What does the C1-C4 motor axons of the cervical plexus supply?
Neck postural & strap muscles
Diaphragm
What does the C5 - T1 motor axons of the brachial plexus supply?
Muscles of upper limb
Extrinsic back muscles (move upper limb or scapula)
What do the T2-L3 motor axons supply?
Postural back muscles (via posterior rami) Intercostal muscles (via anterior rami) Anterolateral abdominal wall muscles
What do the L1-S4 motor axons supply?
Muscles of lower limb
Perineal skeletal muscles
Which spinal nerves make up the Femoral nerve?
L2-L4
What movement would you ask a patient to do to test C5 myotome?
Shoulder abduction (Deltoid)
What movement would you ask a patient to do to test C6 myotome?
Elbow flexion (biceps brachii)
What movement would you ask a patient to do to test C7 myotome?
Elbow extension (triceps brachii)
What movement would you ask a patient to do to test C8 myotome?
Finger flexion (flexor digitorum superficialis)
What movement would you ask a patient to do to test T1 myotome?
Finger abduction (dorsal interossei)
What movement would you ask a patient to do to test L3 myotome?
Knee extension (quadriceps femoris)
What movement would you ask a patient to do to test L4 myotome?
Ankle dorsiflexion (tibialis anterior)
What movement would you ask a patient to do to test L5 myotome?
Great toe extension (extensor hallucis longus)
What movement would you ask a patient to do to test S1 myotome?
Ankle plantarflexion (gastrocnemius)
What movement would you ask a patient to do to test S2 myotome?
Knee flexion (biceps femoris)
Where is the primary somatomotor cortex of the cerebellar cortex?
Precentral gyrus
Give an example of a monosynaptic stretch reflex arc?
Patellar reflex
Give a basic runthrough of how the patellar reflex works
1- patellar tendon tapped
2- stretches quadriceps fibres
3- Muscle spindles initiate APs in anterior rami axons of femoral nerve
4- sensory APs conducted to dorsal horn of L3
5- Axons pass into anterior horn to synapse on LMNs that supply quadriceps
6- APs conducted via LMN axons in femoral nerve to reach quadriceps NMJ
7- Muscle contracts to extend knee joint
Why are space occupying lesions in the skull dangerous?
Not a lot of ‘spare room’ in skull
Only capable of slow rate expansion
Increased ICP from SOL cacn result in herniation
What are the layers of the scalp?
SCALP Skin Connective tissue Aponeurosis Loose connective tissue Pericranium
True or False:
When a fracture of the skull reaches a suture line it tends to cross it
FALSE
When a fracture line reaches a suture is DOES NOT tend to cross suture line
Minimises propagation of fracture
What are the two most relevant suture lines of the neurocranium?
Sagittal suture
Coronal suture
What are sutures?
Fibrous joints
Help prevent skull fractures from spreading
Which bones make up the Pterion?
Frontal
Parietal
Temporal
Sphenoid
Which artery courses over the deep aspect of the pterion?
Middle Meningeal artery
Why is the pterion a relevant anatomical location?
Thinnest part of the skull
AND major artery runs directly underneath
What is Meningitis?
Bacterial or viral infection of the meninges
What are meninges?
Protective coverings for the brain + spinal cord
What are the 3 layers of the meninges? (outer to inner)
DURA - tough/fibrous, encloses dural venous sinus
ARACHNOID - reabsorb CSF (arachnoid granulation)
- Subarachnoid Space
PIA MATER - adherent to brain
What is the Tentorium Cerebelli?
Sheet of Dura mater that tents over the cerebellum
Has central gap to permit brainstem to pass through
Where does the tentorium cerebelli attach?
Ridges of petrous temporal bones
What is the Diaphragm sellae?
Tough sheet of dura mater forming roof (diaphragm) over Pituitary Fossa
What is the sensory innervation of the dura mater?
CN V (trigeminal)
What is the Falx Cerebri?
Separates right + left hemispheres
Midline structure made of dura mater
Where does the Falx Cerebri attach?
- Crista galli of ethmoid bone anteriorly
- Internal aspect of sagittal suture
- Internal occipital protuberance posteriorly
Where does the Cerebral veins drain to?
Drain venous blood from brain into the
Dural Venous Sinuses
Where is the Confluence of sinuses in the brain located?
In the midline of internal occipital protruberance
What is the Danger Triangle?
Area over the face with connections between superficial veins of face + cavernous sinus
Any infection in superficial veins could potentially travel back in to cranium
DON’T POP SPOTS
What is the origin of the Right Vertebral Artery?
Branch of right subclavian artery off brachiocephalic trunk
What is the course of the Right Vertebral artery into the cranial cavity?
- Branches off R subclavian artery
- Passes through transverse foraminae in cervical vertebrae
- Passes through foramen magnum to enter cavity
What does the Right External Carotid artery supply?
Remains external to cranial cavity to supply neck, face & scalp
What are the two main branches of the Common Carotid artery?
External Carotid artery
Internal carotid artery (becomes internal to cranial cavity via carotid canal)
What is the main artery of the brain formed by the right and left Vertebral Artery?
Basilar artery
What does the right anterior cerebral artery supply?
Supplies MEDIAL aspect of right cerebral hemisphere
What does the left Middle cerebral artery supply?
Supplies LATERAL aspect of left cerebral hemisphere
What is the name of the circulatory anastamosis that supplies blood to the brain and surrounding structures?
Circle of Willis
Where is the Circle of Willis?
Inferior to midbrain
Closely related to pituitary stalk + optic chiasm
Within subarachnoid space
What gives arteries some protection from compression?
They are ALL bathed in CSF
What is the subarachnoid space?
Space between arachnoid mater and pia mater (meninges)
Completely surround brain + spinal cord to provide some cushioning + protection
What is contained within the subarachnoid space?
Cerebrospinal fluid (CSF)
Where is CSF produced and reabsorbed?
Produced inside choroid plexus of ventricles
Reabsorbed into dural venous sinuses via arachnoid granulations
How much CSF is produced every day?
400-500 mls/day
Where can the subarachnoid space be accessed for CSF sample?
Accessed via Lumbar puncture at L3/4 or L4/5
Where does the subarachnoid space end in the spinal cord?
Level of S2 part of sacrum
What is the path of travel within the ventricles of the brain?
Lateral ventricle (R + L) > 3rd Ventricle > Cerebral Aqueduct > 4th Ventricle > Central canal of spinal cord (or subarachnoid space)
Where is the 3rd ventricle located?
In midline within the diencephalon
Where is the 4th ventricle located?
Between the cerebellum and pons
What is the Cerebral aqueduct?
Connects 3rd and 4th ventricles in the midline
What is the circulation of CSF from the choroid plexus to the dural venous sinus?
- Secreted by choroid plexus
- R + L lateral ventricle
- (via foraminae of Monro) to 3rd ventricle
- (via cerebral aqueduct) to 4th ventricle
- Mainly into subarachnoid space (some into central canal)
- Reabsorbed from subarachnoid space via arachnoid granulations
- Dural venous sinuses
What is Hydrocephalus?
Excessive production, obstruction to flow or inadequate reabsorption leads to increased CSF volume
How is hydrocephalus treated?
Ventricular peritoneal shunt (shunt catheter beneath skin from the lateral ventricle to the peritoneal cavity which reabsorbs CSF)
What is an Extradural haemorrhage and what is a common cause?
Between bone & dura
Ruptured middle meningeal artery (pterion fracture)
What is a Subdural haemorrhage and what is a common cause?
Separates dura from arachnoid
Torn cerebral veins
Common in falls in elderly
What is a Subarachoid haemorrhage and what is a common cause?
Bleeding into the CSF of subarachnoid space
Ruptured Circle of Willis (berry) aneurysm
Congenital aneurysm
What might a ipsilateral fixed dilated pupil (blown pupil) indicated?
Compression of oculomotor nerve by uncal herniation
What are the 4 different types of Supratentorial herniation?
Cingulate (subfalacine)
Central
Uncal (or transtentorial)
Transcalvarial
What is a clear sign of a uncal herniation?
Blown pupil (compression of oculomotor nerve from temporal lobe going down past tentorium cerebelli)
What is seen with tonsillar herniation?
Cerebellar tonsils herniate INTO foramen magnum
How long do shunts to treat hydrocephalus last?
10 years
