Greenberg's - Gross Anatomy, Cranial & Spinal Flashcards
Middle Frontal Gyrus
More sinuous than IFG or SFG
Connects to pre-central gyrus via thin isthmus
Central Sulcus
Joins Sylvian fissure in 2% of cases
- Subcentral gyrus in 98% of cases
Intraparietal Sulcus
Separates the superior & inferior parietal lobules
Inferior Parietal Lobule
Angular gyrus
Supramarginal gyrus
Sylvian fissure termination
Supramarginal gyrus
Brodmann’s area 40
Superior temporal sulcus termination
Angular gyrus
Br. areas 3, 1, 2
Primary somatosensory cortex
Br. areas 41 and 42
Primary auditory areas
- Transverse gyri of Heschl
Br. area 4
Precentral gyrus = primary motor cortex
Large concentration of giant pyramidal cells of Betz
Br. area 6
Premotor or supplemental motor area
- Immediately anterior to motor strip, plays a role in contra-lateral motor planning
Br. area 44
(Dominant hemisphere) Broca’s area
- Motor speech
Br. area 17
Primary visual cortex
Br. areas 40 and 39
(Dominant hemisphere) Wernicke’s area
- May also include posterior 1/3 of STG
Br. area 8
Frontal eye field
- Initiates voluntary eye movements to the opposite direction
Cingulate sulcus termination
pars marginalis
Cingulate sulcus imaging
Visible on 95% of CT, 91% of MRI
- CT: located posterior to the widest biparietal diameter
- MRI: further posterior
Curves posteriorly in lower slices, anteriorly in higher slices
- Pars bracket: handle bar configuration @ midline
Parieto-occipital sulcus
More prominent over medial surface
Longer on axial imaging
More posterior than the pars marginalis
Post central sulcus
Bifurcates and forms an arc/parenthesis/lazy-Y cupping the pars marginalis
Hand Knob
Alpha motor neuron for hand motor function
- superior aspect of pre-frontal gyrus
- projects posterolaterally into the central sulcus
Imaging: Central Sulcus
Visible on 93% of CTs and 100% of MRIs
Curves posteriorly as it approaches the interhemispheric fissure (IHF), and often terminates in the paracentral lobule, anterior to the pars marginalis (pM) within the pars bracket.
Surface Anatomy: Pterion
Region of approximation of: frontal, parietal, temporal and sphenoid (greater wing).
Estimated as 2 finger-breadths above the zygomatic arch, and a thumb’s breadth behind the frontal process of the zygomatic bone
Surface Anatomy: Asterion
Junction of lambdoid, occipto-mastoid and parieto-mastoid sutures.
Usually lies within a few millimeters of the posterior-inferior edge of the junction of the transverse and sigmoid sinuses (not always reliable – may overlie either sinus).
Surface Anatomy: Vertex
Topmost point of the skull.
Surface Anatomy: Lambda
Junction of the lambdoid and sagittal sutures.
Surface Anatomy: Stephanion
Junction of coronal suture and superior temporal line
Surface Anatomy: Glabella
Most forward projecting point of the forehead at the level of the supraorbital ridge in the midline
Surface Anatomy: Opisthion
The posterior margin of the foramen magnum in the midline
Surface Anatomy: Bregma
Junction of the coronal and sagittal sutures
Surface Anatomy: Sagittal suture
Midline suture from coronal suture to lambdoid suture.
- Although often assumed to overlie the superior sagittal sinus (SSS), the SSS lies to the right of the sagittal suture in the majority of specimens (but never by >11 mm).
The most anterior mastoid point lies just in front of the sigmoid sinus
Taylor-Haughton Lines
Constructed on an angiogram, CT scout film, or skull x-ray, and reconstructed on the patient in the O.R. based on visible external landmarks
Can be used to approximate the Sylvian fissure and motor cortex
Frankfurt Plane
Frankfurt plane, AKA baseline: line from inferior margin of orbit through the upper margin of the external auditory meatus (EAM) (as distinguished from Reid’s base line: from inferior orbital margin through the center of the EAM)
Distance from Nasion to Inion
measured across the top of the calvaria and is divided into quarters
- can be done simply with a piece of tape which is then folded in half twice
Posterior Ear Line
Perpendicular to the baseline through the mastoid process
Condylar Line
Perpendicular to the baseline through the mandibular condyle
Approximation of the Sylvian Fissure
Line connecting the lateral canthus to the point 3/4 posterior along the arc running from nasion to inion
Approximation of Angular gyrus
Just above pinna
Important in dominant hemisphere - part of Wernicke’s area
Significant individual variability in location
Approximation of Angular artery
Located 6cm above the EAM
Approximation of Motor Cortex and Central Sulcus
Individual variability - motor strip is 4 to 5.4cm behind the coronal suture
Method 1 - superior aspect of the motor cortex is straight up from the EAM near the midline
Method 2 - central sulcus approximated by connecting:
- the point 2cm posterior to the midposition of the arc extetnding from nasion to inion
- the point 5cm straight up from the EAM
Method 3 - central sulcus approximated by TH lines:
- point where the posterior ear line intersects the circumference of the skull. Usually 1cm behind the vertex and 3-4 cm behind the coronal suture
Method 4 - line drawn to 45 degrees to Reid’s base line starting at the pterion, points in the direction of the motor strip.
Relationship of Ventricles to Skull
Lateral ventricles lie 4-5cm below the outer skull surface
- Centre of the body of the lateral ventricle lies in the midpupillary line
Frontal horn is intersected by a line passing perpendicular to the calvaria along this line.
- Anterior horns extend 2cm anterior to the coronal suture
Midpoint of Twining’s line should lie within the 4th ventricle
Average length of 3rd ventricle
2.8cm
Length of frontal horn - anterior to Foramen of Munro
25mm
Distance from clivus to floor of 4th ventricle at the level of the fastigium
33>36>40mm
Length of 4th ventricle at the level of the fastigium
10>14>19mm
Distance from fastigium to opisthion
30>32>40mm
Cervical level landmarks: C1-2
Angle of mandible
Cervical level landmarks: C3-4
1cm above the thyroid cartilage ~ hyoid bone
Cervical level landmarks: C4-5
level of thyroid cartilage
Cervical level landmarks: C5-6
crico-thyroid membrane
Cervical level landmarks: C6
carotid tubercle
Cervical level landmarks: C6-7
cricoid cartilage
Scapular spine landmark
T2-3
Inferior scapular pole landmark
T6
Intercristal line
Line drawn between the highest point of the iliac crests across the back will cross the midline at either the L4 and L5 spinous process, or the L4 spinous process itself.
Cranial Foramina and their contents: Nasal slits
Anterior ethmoidal nerve, artery and vein
Cranial Foramina and their contents: Superior Orbital Fissure
Cranial nerves III, IV, VI and 3 branches of V1 (nasociliary, frontal, lacrimal)
Superior ophthalmic vein
Recurrent meningieal branch from lacrimal artery
Orbital branch of middle meningeal artery
Sympathetic filaments from ICA plexus
Cranial Foramina and their contents: Inferior Orbital Fissure
Cranial nerve V2
Zygomatic nerve
Filaments from pterygopalatine branch of maxillary nerve
Infraorbital artery and vein
Vein between inferior ophthalmic vein and pterygoid venous plexus
Cranial Foramina and their contents: Foramen lacerum
Usually nothing:
- ICA traverse the upper portion but does not enter
- 30% have vidian artery
Cranial Foramina and their contents: Carotid canal
Internal carotid artery
Ascending sympathetic nerves
Cranial Foramina and their contents: Incisive foramen
Descending septal artery
Nasopalatine nerve
Cranial Foramina and their contents: Greater palatine foramen
Greater palatine nerve, artery and vein
Cranial Foramina and their contents: Lesser palatine foramen
Lesser palatine nerves
Cranial Foramina and their contents: Internal Acoustic Meatus
Cranial nerves VII, VIII
Cranial Foramina and their contents: Hypoglossal canal
Cranial nerve XII, meningeal branch of ascending pharyngeal artery
Cranial Foramina and their contents: Foramen magnum
Spinal cord (medulla oblongata)
Cranial nerve XI
Vertebral arteries
Anterior and posterior spinal arteries
Cranial Foramina and their contents: Foramen caecum
Occasional small vein
Cranial Foramina and their contents: Cribiform plate
Cranial nerve I
Cranial Foramina and their contents: Optic canal
Cranial nerve II
Ophthalmic artery
Cranial Foramina and their contents: Foramen rotundum
Cranial nerve V2
Artery of foramen rotundum
Cranial Foramina and their contents: Foramen ovale
Cranial nerve V3
portio minor (motor for Cranial nerve V)
Cranial Foramina and their contents: Foramen spinosum
Middle meningeal artery and vein
Cranial Foramina and their contents: Jugular foramen
Internal jugular vein
Cranial nerve IX, X, XI
Cranial Foramina and their contents: Stylomastoid foramen
Stylomastoid artery
Cranial nerve VII
Cranial Foramina and their contents: Condyloid foramen
Vein from transverse sinus
Cranial Foramina and their contents: Mastoid foramen
Vein of mastoid sinus
Branch of occipital artery to dura mater
Porcus acusticus
Internal auditory meatus
Filaments of acoustic portion of VIII penetrate the lamina cribosa of the cochlear area
Porcus acusticus: Transverse crest
Separates superior vestibular area and facial canal from inferior vestibular area and cochlear canal below
Porcus acusticus: Bill’s bar
Separates the meatus from the facial canal anteriorly (containing CN VII and nervus intermedius), from the vestibular area posteriorly (containing the superior division of vestibular nerve
Bill’s bar is deeper in the IAC then the Transverse crest
5 Nerves of the IAC
Facial nerve (7-up)
Nervus intermedius
Acoustic portion of VIII (Coke-down)
Superior branch of vestibular nerve
Inferior branch of vestibular nerve
Nervus intermedius
Somatic sensory branch of VII primarily innervates:
- mechanoreceptors of hair follicles on inner surface of pinna
- deep mechanoreceptors of nasal and buccal cavities
- chemoreceptors in taste buds of anterior 2/3 of tongue
Superior branch of vestibular nerve
Passes through superior vestibular area to terminate in utricle and ampulla of the superior and lateral semicircular canals
Inferior branch of vestibular nerve
Passes through the inferior vestibular area to the saccule
Most IC lesions are caused by…
Vascular accidents
- Thrombosis
- Haemorrhage
Vascular supply of the internal capsule
Anterior choroidal artery
- retrolenticular part
- ventral part of posterior limb of internal capsule
Lateral striate branches = capsular branches of MCA
- Most of anterior and posterior limb of internal carotid
Direct branches of ICA
- Genu
4 Thalamic subradiations
Anterior:
Medial and Anterior thalamic nucleus to frontal lobe
Superior:
Rolandic areas to ventral thalamic nuclei
- General sensory fibres from body and head to terminate in post central gyrus
Posterior:
Occipital and posterior parietal to caudal thalamus
Inferior:
Transverse temporal gyrus of Heschl to medial geniculate body
- includes auditory radiation
Ligaments that connect atlas to occiput
Anterior atlanto-occipital membrane
Posterior atlanto-occipital membrane
Anterior atlanto-occipital membrane
Cephalad extension of anterior longitudinal ligament
Extends from anterior margin of foramen magnum to anterior arch of C1
Posterior atlanto-occipital membrane
Connects posterior margin of foramen magnum to posterior arch of C1
Ligaments that connect the axis to the occiput
Tectorial membrane
Alar ligaments
Apical odontoid ligament
Tectorial membrane
Superficial portion
- Cephalad continuation of the posterior longitudinal ligament
- strong band connecting the dens to the ventral surface of the foramen magnum above, and dorsal surface of C2 and 3 bodies below
Accessory portion
- located laterally connects C2 to occipital condyles
Alar ligaments
Occipto-alar portion
- Connects dens to occipital condyle
Atlanto-alar portion
- Connects side of dens to lateral mass of C1
Apical odontoid ligament
Connects tip of dens to foramen magnum
- little mechanical strength
Ligaments that connect the axis to the atlas
Transverse (atlanto-axial) ligament
Atlanto-alar portion of the alar ligaments
Descending band of the cruciate ligament
Transverse (atlanto-axial) ligament
Horizontal component of the cruciate ligament
- Traps the dens against the anterior atlas via strap like mechanism
- Provides the majority of strength (strongest ligament of the spine)
Most important structures in maintaining atlanto-occipital stability
Tectorial membrane
Alar ligaments
Without these the remaining cruciate ligament and apical dentate ligament are insufficient
Dentate ligament
Separates dorsal and ventral nerve roots
The spinal accessory nerve (CN XI) is dorsal to the dentate ligament
Anterior corticospinal tract
Skilled movement
Contralateral
Medial longitudinal fasciulus
Ipsilateral
Vestibulospinal tract
Facilitates extensor muscle tonne
Ipsilateral
Medullary (Ventrolateral) reticulospinal tract
Automatic respirations
Ipsilateral
Rubrospinal tract
Flexor muscle tone
Ipsilateral
Lateral corticospinal (pyramidal) tract
Skilled movement
Ipsilateral
Descending motor tracts
Anterior corticospinal tract
Medial longitudinal fasciulus
Vestibulospinal tract
Medullary (ventrolateral) reticulospinal tract
Rubrospinal tract
Lateral corticospinal (pyramidal) tract
Bi-directional tracts
Dorsolateral fasciulus (of Lissauer)
Fasiculus proprius
Ascending (sensory) tracts
Fasciulus gracilis
Fasciulus cuneatus
Posterior spinocerebellar tract
Lateral spinothalamic tract
Anterior spinocerebellar tract
Spinotectal tract
Anterior spinothalamic tract
Fasciulus gracilis
joint position, fine touch, vibration
ipsilateral
Fasciulus cuneatus
joint position, fine touch, vibration
ipsilateral
Posterior spinocerebellar tract
stretch receptors
ipsilateral
Lateral spinothalamic tract
pain and temperature
contralateral
Anterior spinocerebellar tract
whole limb position
contralateral
Spinotectal tract
Unknown ?nociceptive
contralateral
anterior spinothalamic tract
light touch
contralateral
Sensation: Pain and temperature
Receptors: free nerve endings
1st order neuron - small, finely myelinated afferents, soma in dorsal root ganglion (no synpase)
Enters cord at dorsolateral tract (zone of Lissauer)
Synapse - substantia gelatinosa
2nd order neuron - axon cross obliquely in the anterior white commissure ascending 1-3 segments while crossing to enter the lateral spinothalamic tract
Synapse - VPL thalamus
3rd order neurons pass through IC to postcentral gyrus (Brodmann’s area 3, 1, 2)
Sensation: Fine touch = discriminative touch, deep pressure and proprioception
Receptors - Meissner’s corpuscles, Pacinian corpuscles, Merkel’s disc, free nerve endings
1st order neuron - heavily myelinated afferents, soma in dorsal root ganglion (no synapse). Short branches synapse in nucleus proprius of posterior gray, long fibres enter the ipsilateral posterior columns without synapsing
Below T6 - fasiculus gracilis
Above T6 - fasciculus cuneatus
Synapse - nucleus gracilis/cuneatus, just above pyramidal decussation
2nd order neuron axons from internal arcuate fibres, decussate in lower medulla as medial lemniscus
Synapse - VPL thalamus
3rd order neuron pass through IC primarily to post central gyrus
Sensation: Light (crude) touch
Receptors - Meissner’s corpuscles, Pacinian corpuscles, Merkel’s disc, free nerve endings and peritrichial aborizations
1st order neuron - large, heavily myelinated afferents (type II), soma in dorsal root ganglion (no synapse)
- Ascend uncrossed in post columns (with fine touch)
most synpase in Rexed VI and VII
2nd order neuron - cross in anterior white commissure, enter anterior spinothalamic tract
Synapse - VPL thalamus
3rd order neurons pass through IC primarily to post central gyrus
Dermatome
Area of the body where sensation is subserved by a single nerve root
Peripheral nerves generally receive contributions from more than one deramtome
