Module 3 Flashcards by Mary Rose Carvajal

Part of the Central nervous system (CNS)
43 cm long, about the index finger in diameter
Extends after the foramen magnum up to about L1-L2 vertebrae
Cervical and lumbar enlargements for innervations to the limbs
Narrowest and roundest at the thoracic region
Extends caudally to end at about the level of L1 or L2 vertebrae as the conus medullaris
Extends to the sacrum as a thin stand of glial tissue called filum terminale

SPINAL CORD

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From C4-T1 segments of spinal cord
Most of the ventral rami of spinal nerves arising from it form the brachial plexus of nerves that innervates the upper limbs

Cervical enlargement

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From T11-L1 segments of spinal cord
The ventral rami of the spinal nerves arising from it make up the lumbar and sacral plexuses of nerves that innervate the lower limbs
The spinal nerve roots arising from lumbosacral enlargement and the medullary cone form the cauda equina

Lumbosacral enlargement

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Cephalad to the spinal cord as the foramen magnum is the most distal portion of the brain

Medulla Oblongata

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the distal or most inferior part of the spinal cord

Conus medullaris

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A continuous canal up to the coccyx
Composed of the adjacent vertebrae
Superior 2/3: spinal cord + spinal nerves
Inferior 1/3: spinal nerves only (arranged collectively as the cauda equina

Vertebral Canal

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bundle of spinal nerve roots running through the lumbar cistern

cauda equina

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All the tissue of the nervous system can be divided into:

Neurons
Supporting tissue
Glial connective tissue

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Supporting tissue

Fibrous connective tissue contains:
Fibrocytes
Collagen and elastic fibers
Intercellular fluid
Various other cells (e.g. Schwann cells)

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Glial connective tissue

Consists of cells and intercellular fluid
Astrocytes
Oligodendrocytes
Microglia
Ependyma

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DIFFERENTIAL GROWTH: BONY SPINE VS. SPINAL CORD

Early embryonic changes
Spinal cord extends up to the coccyx
Magkasing-haba sila End of 8th week Coccygeal cord atrophies which later becomes the filum terminale
Fetal stages
Bony spine grows faster than the cord (relative cord ascension)
Mas mabilis humaba yung bone than the cord kaya nagmumukhang pataas ang growth ng spinal cord
At birth- Cord ends at L2 or L3 vertebrae
In adult - Cord ends at L1 or L2 vertebrae

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Vestigial cord
o Or vestigial coccygeal spinal cord
o Tail which holds the spinal cord to coccyx
Gial tissue
Pierces the dural sac through sacral hiatus to attach to the dorsal coccyx
Anchors the dural sac

FILUM TERMINALE

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Three membranous connective tissue layers:

Dura mater – next layer beneath the periosteum of the bone
Arachnoid mater – next to the dura mater
Pia mater – after subarachnoid space, intimately attached to gray matter

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Are continuous membranes that collectively make up the leptomeninx (G. slender membrane)
Subarachnoid / Leptomeningeal space

Intermediate and internal layers (Arachnoid and pia mater)

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Clear liquid similar to blood in constitution
Provides nutrients but has less protein and different ion concentration
Formed by choroid plexuses of the 4 ventricles of the brain

Cerebrospinal fluid (CSF)

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o Between periosteum and dura
o Fat, venous plexus
o Additional layer in spinal cord
o Epidura – above dura (sa buto na)

Epidural Space

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o Thick, tough outer meningeal layer
o Encloses dural sac
o Continuous with cranial dura
o Dense, bilaminar membrane also called the pachymenix (G. pachy – thick; menix – membrane)

Dura Mater

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o Long tubular sheath within vertebral canal, from foramen magnum and ends at about S2
o Extends laterally up to intervertebral foramen as root sleeves pierced by exiting spinal nerve roots
o Merges with connective tissue sheaths of peripheral nerves:
 Dura – continuous with epineurium
 Arachnoid – continuous with perineurium
 Pia – continuous with endoneurium
o Caudally, anchored to the coccyx by the filum terminale
o Tension in the filum terminale stabilizes the spinal cord

Dural Sac

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o Potential space
o Only gets filled after bleeding (hematoma formation)
o Pressure of CSF pushes the arachnoid to the dura. The space between the dura and arachnoid (subdural space) is only a potential space. Nagkakaspace lang siya if may blood from subdural hematoma.

Subdural Space

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o Fibrous and elastic tissue
o Avascular
o Thick and sturdy enough to be handled
o Lines dural sac
o Encloses CSF
o Pushed against the dura by CSF pressure
o G. arachne – spider; cobweb + eidos – resemblance

Arachnoid Mater

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o Arachnoid granulations extend to the pia

o Filled with CSF

Subarachnoid Space

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o “Pinakaloob”
o Delicate transparent layer of flatcells covering of the outer surface of the cord
o Ensheaths cord and vessels
o Continues as the filum terminale caudally
o Has lateral extensions between dorsal and ventral roots, the denticulate ligament to the dura seen from foramen magnum up to about L2
o Continues distally as the coccygeal portion of the spinal cord and when it atrophies early in life, it becomes your filum terminale
o Thinner membrane that is highly vascularized by a network of fine blood vessels
o When the cerebral arteries penetrate the cerebral cortex, the pia follows them for a short distance forming a “pial coat” and a “periarterial space

Pia Mater

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– anchors pia mater; extends to the dura

Denticulate ligament

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(Pia Mater)

- holds the spinal cord steady

Denticulate ligament + filum terminale

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o Terminal portion of dural sac (L2-S2) o Contains CSF and the cauda equina o Access point for lumbar puncture procedures

Lumbar cistern

- Space between periosteum lining bony wall of vertebral canal and dura mater - Position of extradural (epidural) herniation - Contents: Fat (loose CT); Internal vertebral venous plexuses; Inferior to L2 vertebra, ensheathed roots of spinal nerves

Extradural (epidural)

- Naturally occurring space between arachnoid mater and pia mater - Contents: CSF; Radicular, segmental, medullary and spinal arteries; Veins; Arachnoid trabeculae

Subarachnoid (leptomeningeal)

o Anesthetic directly into CSF o Faster onset o Shorter duration

Subarachnoid / Spinal Block

o Indwelling catheter inserted into epidural space o Anesthetic bathes spinal nerves after they exit the dural sac o Continuous o Longer onset and duration

Epidural Block

``` 31 pairs: o 8 cervical o 12 thoracic o 5 lumbar o 5 sacral o 1 coccygeal (may be absent) ```

SPINAL NERVES

BLOOD SUPPLY: 3 LONGITUDINAL ARTERIES

Ventral median artery (1): Anterior spinal artery Paired dorso-lateral arteries (2): Posterior spinal arteries o Receives segmental arteries (radicular arteries) at regular intervals from the aorta

– great anterior segmental medullary artery; the biggest feeder

Artery of Adamkiewicz

- Anterior 2/3 of cord | - Union of branches of the posterior inferior cerebellar and vertebral arteries

Anterior Median Artery

- Posterior 1/3 of cord | - Each is a branch of the ipsilateral posterior inferior cerebellar artery and vertebral artery

Paired Posterior Arteries

- Spinal cord plexus in the subarachnoid space - Epidural (internal vertebra) plexus in the epidural space along the length of the vertebral column up to the foramen magnum - External venous plexus along the outside of the vertebral column communicating freely with the epidural plexus - Valveless, blood flow is bidirectional from spinal cord (away from the cord) - Regional network of veins of each spinal segment which eventually drain to the inferior vena cava

SPINAL VEINS: 3 LONGITUDINAL VENOUS SYSTEMS

Spread of Infection and Malignancy

- The usual route of spread of malignancy and infection between abdomino-pelvic cavity and the spine - Pwede kumalat yung malignancy from spine to viscera and from viscera to the spine. Pero usually viscera to spine kaya common site ng metastasis and spine, both the cord and the bony vertebral column.

May be due to: o Interruption (rupture) o Compression (trauma, malignancy) o Ischemia Manifests as (depending on part of cord affected and may be complete or incomplete): o Loss of sensation o Loss of motor power o Loss of autonomic function (e.g. bowel/bladder control)

LOSS OF SPINAL CORD FUNCTION

- Lumbar spine nerves increase in size from superior to inferior, whereas the IV foramina decrease in diameter - L5 spinal nerve roots are the thickest and their foramina is the narrowest. - This increases the chance that these nerve roots will be compressed if osteophytes (bony spurs) develop, or herniation of an IV disc occurs

Compression of the Lumbar Spinal Nerve Roots

- A radiopaque contrast procedure that allows visualization of the spinal cord and spinal nerve roots - CSF is withdrawn by lumbar puncture and replaced with a contract material injected into the spinal subarachnoid space and its extensions around the spinal nerve roots within the dural root sheaths.

Myelography

``` Possible causes: o Fractures o Dislocations o Fracture-dislocations  Can lead to: muscle weakness and paralysis ```

Ischemia of Spinal Cord

- Transection of the spinal cord results in loss of all sensation and voluntary movement inferior to the lesion

Spinal Cord Injuries

(Spinal Cord Injury) - No function below head level - A ventilator is required to maintain respiration

C1-C3

(Spinal Cord Injury) - Quadriplegia (no function of upper and lower limbs) - Respiration occurs

C4-C5

(Spinal Cord Injury) - Loss of lower limb function combined with a loss of hand and a variable amount of upper limb function - May be able to self-feed or propel a wheelchair

C6-C8

(Spinal Cord Injury) - Paraplegia (paralysis of both lower limbs) - The amount of trunk control varies with the height of lesion

T1-T9

(Spinal Cord Injury) - Some thigh muscle function, which may allow walking with long leg braces

T10-L1

(Spinal Cord Injury) - Retention of most leg muscle function - Short leg braces may be required for walking

L2-L3

- Divided into left and right hemispheres - Corpus callosum – commissural fibers that join the cerebral hemispheres - Median longitudinal fissure – incompletely separates the two hemispheres

CEREBRUM

Remember:

CEREBRAL CORTEX – GRAY MATER | CEREBRAL MEDULLA – WHITE MATER

LAYERS OF CEREBRUM (From superficial to deep)

1. Molecular / Plexiform Layer - Horizontal cells of Cajal – spindle shape 2. External Granular Layer - Small pyramidal cells, stellate and granulated cells 3. External Pyramidal Layer - Medium-sized pyramidal cells 4. Internal Granular Layer - Large pyramidal cells; Band of Ballerger 5. Internal Pyramidal Layer 6. Multiform / Polymorphic / Fusiform Layer - Inverted cells of Martinotti

(Classification of the Cerebral Cortex) - 90% of cerebral cortex - Also known as isocortex - Composed of 6 layers

Neocortex or isocortex

(Classification of the Cerebral Cortex) | Includes the cingulate gyrus and hippocampus

Mesocortex

(Classification of the Cerebral Cortex) - 10% of cerebral cortex - Composed of: o Paleocortex – olfactory cortex o Archicortex – hippocampus, dentate gyrus

Allocortex

- Largest lobe - 1/3 of hemispheric’s surface - Lies anterior to the central sulcus of Rolando - Superior to the lateral fissure of Sylvius

Frontal Lobe

- Primary motor area (BA 4) - 1/3 of corticospinal tract (CST) arises here - Function: Contralateral movements of face, arm, leg and trunk

Pre-central Gyrus

Manifestations of lesion in Pre-central Gyrus

o Monoplegia or hemiplegia o Initial flaccid paralysis o (+) Babinski reflex

- Premotor area (BA 6) - Anterior to pre-central gyrus - 1/3 of Cortico Spinal Tract fibers originates here - Function: o Contralateral head and eye turning o Assumption of posture o Complex patterned movements infrequent rapid incoordinate movements

Superior Frontal Gyrus

Manifestation of lesion in Superior Frontal Gyrus

- Contralateral paralysis of the head and eye movements - Head and eyes turn “toward” the diseases hemisphere - Spasticity - Increased tendon reflex added to primary motor lesion

- Fontal eye field (BA 8) - Function: o Conjugate deviation of the eyes to the other side Manifestation of lesion: o Difficulty in voluntarily moving the eyes to the opposite side

Middle Frontal Gyrus

- Broca’s Area - Pars orbitale and triangularis (BA 44 & 45) o Function: - Expressive center for speech in the dominant hemisphere - Patterns of movement for muscles producing speech - Control motor speech o Manifestation of lesion: Broca’s or motor aphasia

Inferior Frontal Gyrus

- BA 9-12 - Areas of higher cortical function - Lies rostral to the premotor and frontal eyefield areas - Has connections with the dorsomedial nucleus of the thalamus, hypothalamus, limbic lobe, anterior temporal area, and association areas of the parietal and occipital lobes - Function: Personality; Abstract thinking; Mature judgment; Foresight; Tactfulness; Self-control; Initiative; Socialization of certain autonomic functions and emotions; Monitor cortical plan of behavior

Prefrontal Area

Manifestation of lesion in Prefrontal Area

o Witzelsucht – inappropriate jocularity o Akinetic mutism – severe loss of initiative with disinterest and unconcern o Primitive reflexes – e.g. grasp, pout o Frontal ataxia – disturbance of gait o Paratonia – resistance to passive movements of limbs

- Anteriorly bounded by the paracentral sulcus - Posteirorly bounded by the marginal branch of cingulate gyrus - Function: Cortical inhibition of bladder and bowel voiding - Manifestation of lesion: INCONTINENCE OF URINE AND FECES

Paracentral Lobule

- An infection of the brain or spinal cord cuased by the spirochete Treponema palladium - Usually occurs in people who have had chronic, untreated syphilis, usually about 10-20 years after first infection - Develops in about 25-40% of persons who are not treated - Manifestation: o Lack of general sense of responsibility o Sloppiness in habits o Vulgar speech o Clownish behavior

Neurosyphilitic Frontal Atrophy

- Posterior to central sulcus | - Anterior to parieto-occipital sulcus

Parietal Lobe

- PRIMARY SENSORY OR GRANULAR CORTEX (BA 3, 1, 2) - Concerned with tactile and kinesthetic sense from superficial and deep receptors and converge - Somatopically represented - Function: RECEIVES AFFERENT PATHWAYS FOR APPRECIATION OF POSTURE, TOUCH AND PASSIVE MOVEMENTS

Postcentral Gyrus

Manifestation of lesion in Postcentral Gyrus

o Contralateral impairment of touch, pressure and proprioception o Disturbed postural and passive movement sensation o Disturbed localization of touch with loss of 2-point discrimination o Astereognosis – impaired appreciation of size, shape, texture and weight o Preceptual rivalry – sensory inattention

- Lies posterior to BA 3,1, 2 along superior border of Sylvian fissure - Manifestation of lesion: Impaired pain sensation

Secondary Somesthetic Area

- Cortical association areas | - Mnemonic constellations for understanding and interpreting sensory signals

Inferior Parietal Lobule

- BA 40 | - Function: Understanding and interpreting sensory signals

Supramarginal Gyrus

 Manifestation of lesion in Supramarginal Gyrus

o Lesion on dominant hemisphere: Tactile and proprioceptive agnosia o Lesion on non-dominant hemisphere: Confusion in left-right discrimination Body image disturbance Apraxia

- Surrounds the ascending terminal part of the superior temporal sulcus - BA 39 - Function: Association cortex which has connections with somesthetic, visual and auditory association areas - Manifestation of lesion: o Dominant hemisphere: Alexia Agraphia

Angular Gyrus

- Fibers of the optic radiation (lower visual field) pass through the parietal lobe - Manifestation of lesion: LOWER HOMONYMOUS QUADRANTINOPSIA

Visual Pathway in the Parietal Lobe

- Located at the roof of the lateral fissure of Sylvius | - Primary gustatory area (BA 43) – taste sensibility

Parietal Operculum

Function: Numbers and calculations ``` Lesions can lead to: Gertsmann’s Syndrome o Confusion of right and left limbs o Finger agnosia (difficulty in distinguishing finger from hand) o Acalculia o Agraphia ```

Dominant Parietal Lobe

Function: - Body image and awareness of external environment - Visual and proprioceptive skills - Spatial orientation ``` Lesions can lead to: Asomatognosia Anosognosia Dressing apraxia Geographical apraxia Constructional apraxia Unaware of opposite limb ```

Nondominant Parietal Lobe

o Superior temporal gyrus Auditory cortex Primary auditory area o Superior temporal sulcus o Middle temporal gyrus o Inferior temporal sulcus o Inferior temporal gyrus

Temporal Lobe

- Parallel with lateral sulcus Manifestation of lesion: o AUDITORY HALLUCINATIONS (by disease like complex partial seizure) o VERTIGO (dizziness with sensations of turning movement of the body)

Superior Temporal Gyrus

- Located on transverse gyri of Heschl (several short oblique convolutions on the inner bank of the lateral sulcus) - Upper surface of the superior temporal gyrus under the lateral sulcus - BA 41 and 42 - Function: Dominant hemisphere: Hearing language Non-dominant hemisphere: Hearing sound rhythm and music; Labyrinthine function

Primary Auditory Cortex

Manifestation of lesion in Primary Auditory Cortex

o Cortical deafness o Dominant hemisphere: difficulty hearing spoken words o Non-dominant hemisphere: amusia – difficulty appreciating sound, rhythm and music o Unilateral lesions have little effect on hearing (bilateral contribution of cranial nerve)

- Auditory association area (BA 22) - Function: Dominant hemisphere: language comprehension - Manifestation of lesion: Dominant hemisphere: Wernicke’s / receptive aphasia

Wernicke’s Area / Secondary Auditory Cortex

- Involved in memory and learning | - Lesions result in disturbance in memory and learning

Middle and Inferior Temporal Gyri

- Fibers of the optic radiation (upper visual field) pass through the temporal lobe - Manifestation of lesion: UPPER HOMONYMOUS QUADRANTINOPSIA

Visual Pathway in Temporal Lobe

- Pre-pyriformis and periamygdaloid area - Rostral part of parahippocampal gyrus - Uncus - Most medial protrusion of parahippocampal gyrus - Lateral olfactory stria

Primary Olfactory Area

- Above tentorium cerebella - Separated from parietal lobe by the parieto-occipital sulcus - Consists of the lateral occipital gyro; Cuneus; Calcimine sulcus; Lingual gyrus - Involved in visual perception

Occipital Lobe

Manifestation of lesion in Occipital Lobe

o Cortical lesion: Homonymous hemianopsia o Occipital lobe: Central hemianopsia involving the macula o Anton’s Syndrome - Results from extensive damage of the striate cortex Cortically blind (denial na bulag ka) Area 17 – bulag ka Area 18, 19 – may nakikita pero hindi alam kung ano yun

- Located on the banks of the calcarine sulcus - BA 17 - Function: o Perception from contralateral half of visual field o Receives impulses from temporal half of the ipsilateral retina and nasal half of the contralateral retina - Manifestation of lesion: CORTICAL BLINDNESS IN CONTRALATERAL VISUAL FIELD

Primary Visual Cortex

- Lies adjacent and anterior to primary visual cortex - BA 18, 19 - Function: Visual perception; Visual reflexes (i.e. visual fixation) - Manifestation of lesion: Visual agnosia

Secondary Visual Area

- Impairment in recognition of visually presented objects | - It is not due to a deficit in vision (acuity, visual field, and scanning), language, memory, or low intellect

Visual agnosia

- Olfactory Sulcus separates lateral orbit gyri and medial gyrus rectus - Olfactory bulb and tract inferior to the olfactory sulcus

Inferior Surface of the Cerebrum

- Island of Reil - Buried in the depths of the lateral sulcus - Can only be seen when temporal and frontal lobes are separated - A triangular cortical area with the apex directed toward and downward to open into the lateral fissure - Covered by the gyri breves and longus, nearly parallel to lateral sulcus - Limen insula – opening leading to insular region - Temporal, frontal, and parietal opercular regions cover the insula

Insula

- Includes in the depths of the lateral sulcus a diverse group of medial and basal telencephalic structures, which represent those regions of the cerebral cortex having the most direct connections with the hypothalamus - Defense reactions such as fear or rage – integrated diffusely - Include: hippocampus, amygdala, and septal nuclei

LIMBIC SYSTEM

- Parts of the limbic lobe and diencephalon - Concerned with emotion - HF -> Fornix -> Mammillary Bodies -> Mammillothalamic Tract -> Anterior Nuclear Group of the Thalamus -> Cingulate Gyrus

PAPEZ CIRCUITRY

- Bilateral lesion destroying the amygdala and hippocampus in male monkeys - Manifestations: o Psychic blindness o Hypermetamorphosis o Hyperorality o Hypersexuality and loss of sexual preference o Reversal of individual behavioral patterns o Marked absence of emotional response o Loss of facial expressions and vocal protests

Kluver-Bucy Syndrome

- Profound loss of the ability to acquire new information - Seen in bilateral damage of the medial temporal lobe - Also seen in Korsakoff’s psychosis (Lesions involving mammillary bodies and dorsomedial nucleus of the thalamus)

Anterograde Amnesia

(CLASSIFICATIONS OF SENSORY NEURONS) - Stimulus comes from the skin, joints, tendons, skeletal muscles and bones which are carried towards the CNS - Can be found in both the cerebral and spinal ganglia

General Somatic Afferent (GSA)

(CLASSIFICATIONS OF SENSORY NEURONS) - Stimulus comes from the visceral organs - Found in both the spinal and visceral ganglia

General Visceral Afferent (GVA)

(CLASSIFICATIONS OF SENSORY NEURONS) - Stimulus comes from the olfactory and gustatory areas, which are related to the digestive system - Found only in cerebral ganglia

Special Visceral Afferent (SVA)

(CLASSIFICATIONS OF SENSORY NEURONS) - Stimulus comes from the visual, auditory and vestibular areas - Derived from the body wall during development (ectoderm) - Found in cerebral ganglia

Special Somatic Afferent (SSA)

- innervate skeletal muscles of myotomic origin

General Somatic Efferent (GSE)

- If effector is a skeletal muscle of brachiometric origin (muscles of facial expression, mastication, phonation and deglutition - innervate smooth muscle of the viscera, intraocular muscles, heart, salivary glands

General Visceral Efferent (GVE)

- innervate skeletal and cardiac muscle derived from brachial arches

Special Visceral Efferent (SVE)

``` SVA Sensory Neuron (SN): Olfactory cells Association Neuron (AN): Mitral cells of olfactory bulb Function (F): Smell Dysfunction (DF): Anosmia ```

CN I – Olfactory Nerve

``` SSA SN: Rods and cones AN; Bipolar cells of retina F: Vision DF: Blindness ```

CN II – Optic Nerve

SN: Gasserian (Semilunar) AN: Spinal Nucleus (pain); Main Sensory (touch); Mesencephalic nucleus in Jaw (proprioception) F: - Sensation forehead pain; Touch forehead - Cheek pain and touch - Jaw pain, touch and proprioception

CN V - Trigeminal Nerve

``` SVA SN: Geniculate ganglion AN: Nucleus of solitary tract F: Taste (in anterior 2/3 of tongue) DF: Decrease taste ```

CN VII – Facial Nerve

SSA SN - AN: Vestibular ganglion - Vestibular Spiral ganglion - Dorsal and ventral cochlear nuclei F: Balance and equilibrium; Hearing DF: Disequilibrium, vertigo Decrease hearing

CN VIII – Vestibulocochlear Nerve

SVA - Inferior petrosal ganglion - Nucleus of solitary tract GVA - Inferior petrosal ganglion - Nucleus of solitary tract GSA - Superior petrosal ganglion - Spinal nerve of CN V Function: SVA: Taste (in posterior 1/3 of tongue) GVA: Sensation in pharynx, tongue, carotid reflex GSA: Sensation in back ear Dysfunction: Decrease taste; Decrease gag reflex; Decrease sensation

CN IX – Glossopharyngeal Nerve

SVA - Inferior nodose - Nucleus of solitary tract GVA - Inferior nodose - Nucleus of solitary tract GSA - Superior jugular - Spinal nucleus of CN V Function: SVA: Taste in posterior pharynx GVA: Sensation in pharynx, larynx, thoracic and abdominal viscera GSA: Sensation in external auditory meatus Dysfunction: Decrease sensation; Decrease sensation in auditory

CN X – Vagus Nerve

Main Oculomotor Nucleus (GSE) - Extraocular muscles EXCEPT lateral rectus and superior oblique Edinger-Westphal Ncleus (GVE) via ciliary ganglion - Ciliary muscle and sphincter pupillae muscles

CN III – Oculomotor Nerve

``` Motor Neuron (MN): Trochlear Nucleus (GSE) Effector (E): Superior oblique ```

CN IV – Trochlear Nerve

MN: Motor Nucleus of CN V (SVE) E: Muscles of mastication

CN V – Trigeminal Nerve

MN: Abducens Nucleus (GSE) E: Lateral rectus muscle

CN VI – Abducens Nerve

MN: Superior Salivatory Nucleus (GVE) via: - Sphenopalatine ganglion - Submandibular ganglion - Facial Motor Nucleus E: Lacrimal gland, submandibular and sublingual glands Mimetic muscles

CN VII – Facial Nerve

MN: Inferior Salivatory Nucleus (GVE) via: Otic ganglion E: Parotid glands

CN IX – Glossopharyngeal Nerve

MN: Motor Nucleus (GVE) via: Parasympathetic terminal ganglia E: Visceral organs and glands

CN X – Vagus Nerve Dorsal

MN: Spinal Accessory Nucleus (SVE) E: SCM and Trapezius muscles

CN XI – Spinal Accessory Nerve

MN: Hypoglossal Nucleus E: Tongue muscles and genioglossus

CN XII – Hypoglossal Nerve

MN: Nucleus Ambiguus E: Muscles of mastication and deglutition

CN IX, X, and XI

- These are structure made up of anterior rami of the spinal cord joined together 1. Cervical plexus 2. Brachial plexus 3. Lumbar plexus 4. Sacral plexus

Plexuses

- Formed by the anterior rami of the 1st 4 cervical nerves - Rami are joined by connecting branches = loops - Lie in front of the origins of levator scapulae and scalenus medius muscles - Covered in front by the prevertebral layer of deep cervical fascia and related to the internal jugular vein

CERVICAL PLEXUS

Cutaneous Branches of the Cervical Plexus

- Lesser occipital nerve - Great auricular nerve - Transverse cutaneous nerve - Supraclavicular nerve

(Cervical Plexus) | Muscular branches to the neck muscles:

- Prevertebral muscle - Sternocleidomastoid (proprioceptive, C2 - 3) - Levator scapulae (C3 – 4) - Trapezius (proprioceptive, C3 – 4)

- C1 (C1 fibers adjoining hypoglossal nerve) + Descending cervical nerve (C2 & C3) - branches C1 + C2 + C3 – supplies omohyoid, sternohyoid, and sternothyroid. - C1 from hypoglossal nerve – supplies thyrohyoid and geniohyoid

Ansa cervicalis

- ONLY motor supply of Diaphragm - Sensory to pleura, peritoneum of central diaphragm, pericardium - Proprioception to diaphragm - from C3, C4, C5 - formed at lateral border of scalenus anterior at level of cricoid cartilage

Phrenic nerve

- injury to one side pushes the ipsilateral diaphragm up resulting to atelectasis

Phrenic nerve

- formed in the posterior triangle - Union of C5, C6, C7, C8 and T1 - 5 roots = 3 trunks = 6 divisions = 3 cords - Divided into roots, trunks, divisions, and cords - Cords and most of branches lies in axilla - Surrounded by Axillary sheath, from prevertebral fascia - Cords lie above & lat. the 1st part of Axillary A

Brachial Plexus

Brachial Plexus: Roots to Trunks

C5 + C6 -superior or upper trunk C7 -middle trunk C8 + T1 - inferior or lower trunk

Brachial Plexus: Division to Cord

ALL posterior divisions unite - posterior cord Anterior division of upper and middle trunk unite - lateral cord Anterior division of lower trunk - medial cord

So why do we call it posterior, lateral and medial cord? This is in relation to what structure?

Axillary artery Posterior cord is seen posteriorly in axillary artery. Lateral cord is seen lateral to axillary artery Medial cord is medial to axillary artery.

5 Terminal Branches of Brachial Plexus

1. MUSCULOCUTANEOUS NERVE - Anterior / Flexor compartment of arm 2. AXILLARY NERVE - Deltoid, Teres minor 3. RADIAL NERVE - Posterior / Extensor compartment of arm and forearm 4. MEDIAN NERVE - Anterior / Flexor compartment of forearm EXCEPT Flexor carpi ulnaris and medial half of Flexor digitorum profundus Medial half of FDP – ulnar nerve Lateral half of FDP – median nerve 5. ULNAR NERVE - Intrinsic muscles of hand

Thenar Vs Hypothenar Muscles

Thenar Muscles - Median Neve | Hypothenar Muscles - Ulnar Nerve

- joined by intercostobrachial nerve | - supplies skin on the medial side of arm

Medial cutaneous nerve of arm (T1)

- supplies skin medial side forearm

Medial cutaneous nerve of forearm (C8, T1)

- supplies the subscapularis | - lower part supplies the Teres muscle

Upper and Lower Scapular nerve

- supplies the Latissimus dorsi

Thorcodorsal nerve

2 Nerve Supply of the Brachioradialis

Musculocutaneous and Radial Nerve

- Largest branch of brachial plexus - At axillary area, gives branches to: long and medial head of triceps and posterior cutaneous nerve of arm - At the spiral groove gives branches to: - medial and lateral head triceps and anconeus - lower lateral cutaneous nerve of arm - posterior cutaneous nerve of forearm

Radial nerve

Quadrilateral Space Borders and Contents

``` BORDERS Upper: Teres Minor Medial: Long head of the Triceps Inferior: Terje Major Lateral: Near the neck of the humerus ``` CONTENTS: Axillary Nerve and Posterior Circumflex Artery

- Upper lesion of the Brachial Plexus - Due to excessive displacement of head to the opposite side and depression of shoulder on the same side - injury to C5 and C6 roots - suprascapular nerve, nerve to subclavius, musculocutaneus nerve, and axillary nerve will be functionless

Erb-Duchenne Palsy

Muscles paralyzed in Erb-Duchenne Palsy

1) Supraspinatus and Infraspinatus 2) Subclavius 3) Biceps brachii, greater part of brachial, Coracobrachialis 4) Deltoid and Teres minor

- limb hang limply by the side, medially rotated - forearm is pronated - likened to a porter/waiter’s tip - loss of sensation lateral side of arm

Erb-Duchenne Palsy

- lower lesions of brachial plexus - due to excessive abduction of the arm - T1 is injured - ulnar and medial nerve are affected all the small muscles of the hand - loss sensation medial side of the arm

Klumpke palsy

- extensor digitorum un-opposed ->extends the metacarpophalangeal joint - flexor digitorum superficialis and profundus un-opposed -> flex middle and terminal phalanges respectively = Claw hand

Klumpke palsy

- injury to long thoracic nerve - injury by blow to posterior triangle or by mastectomy - inability to rotate the scapula -> difficulty of raising the arm above the head

Winged scapula

- injured by crutch pressing upward, shoulder dislocation or fracture of surgical neck of humerus. - present as impaired shoulder abduction, loss sensation of lower half of deltoid, deltoid wasting

Axillary nerve injury

Location of Fracture and Nerve Affected

1. Surgical neck of humerus - Axillary Nerve 2. Supracondylar ridge - Median Nerve 3. Radial / Spiral groove - Radial Nerve 4. Medial epicondyle - Ulnar Nerve

- Uncommon because it is protected by the muscles - May be compressed as it passes through the Coracobrachialis muscle - Manifestations: o Weakness in flexion of forearm at the elbow o Weakness in supination

Musculocutaneous Nerve Lesions

- As a result of a spinal fracture of midshaft of humerus - Wristdrop o Weakness in ability to extend the hand at the wrist o Loss of extension at the MP joints of all digits - May experience pain and paresthesia in skin over the first dorsal interosseous muscle between the thumb and index finger - Supination may be weakened BUT NOT LOST - Extension of the forearm is spared

Radial Nerve Lesions

- Cause: Supracondylar fracture of humerus; Compression between heads of pronator trees muscle - Manifestation: Altered sensation in lateral 3½ digits and thenar eminence Weakness in flexion at wrist Flexion of lateral fingers and flexion of thumb HAND OF BENEDICTION

Median Nerve Lesions: Proximal

- Cause: Lunate dislocation - Manifestation: Altered sensation in lateral 3½ digits Numbness and pain over palmar aspects of thumb, index, and middle fingers APE HAND

Median Nerve Lesions: Distal

- burning pain lateral 3 ½ finger - weakness of thenar muscles - relieved by decompressing flexor retinaculum

Carpal tunnel syndrome (Median Nerve Injury)

– fracture of medial epicondyle - At the elbow - unable to adduct and abduct the fingers - unable to grip paper placed between - impossible to adduct thumb - Froment’s sign - claw deformity (main en griffe) - Benediction sign (ulnar nerve palsy)

Injury to ulnar nerve

Strong contraction of flexor pollicis longus and flexing the terminal phalanx

Positive Froment’s sign

- nervous pathway supplying the lower limb - formed in the Psoas muscle - from anterior rami of upper 4 lumbar nerves

Lumbar Plexus

Nerves emerging from Medial border of Psoas:

- Obturator nerve | - 4th lumbar root of lumbosacral trunk

Nerves emerging from lateral border of Psoas:

- Iliohypogastric nerve - Ilioinguinal nerve - Lateral cutaneous nerve - Femoral nerve

Nerve emerging from Anterior Border of Psoas:

- Genitofemoral nerve

- skin of the lower part of anterior abdominal wall

Iliohypogastric nerve

- skin of the groin and the scrotum or labium majus

Ilioinguinal nerve

- skin lateral surface of thigh

Lateral cutaneous nerve of thigh

- largest branch of lumbar plexus | - supplies the anterior compartment of the thigh

Femoral nerve

- supplies the medial compartment of the thigh

Obturator nerve

Genitofemoral nerve – divides into the ff:

Genital branch - supplies the cremaster Femoral branch – small area on anterior surface of skin of the thigh; involved in cremasteric reflex

``` Lies in the posterior pelvic wall in front of piriformis From anterior rami of L4 to S4 Branches to lower limb - Sciatic nerve - Superior gluteal nerve - inferior gluteal nerve - nerve to quadratus femoris - nerve to obturator internus - posterior cutaneous nerve of thigh ```

Sacral Plexus

- largest nerve of the body - supplies the posterior thigh, leg and foot - give off branches: Tibial artery and common peroneal nerve

Sciatic nerve (L4 – S3)

- supplies the gluteus medius, gluteus minimus, and tensor fascia latae

Superior gluteal nerve

- supplies the gluteus maximus

Inferior gluteal nerve

- supplies the quadratus femoris and inferior gemellus

Nerve to quadratus femoris

- supplies the obturator internus and superior gemellus

Nerve to obturator internus

- supplies the skin of buttocks and back of thigh

Posterior cutaneous nerve

- supplies the muscle of perineum and external anal sphincter; skin in perineum

Pudendal nerve

- supplies the piriformis muscle

Nerve to piriformis

- sacral part of parasympathetic system | - distributed to pelvic viscera

Pelvic splanchnic nerve

- supplies lower medial buttocks

Perforating cutaneous nerve

- Susceptible to damage from an IM injection in lower medial quadrant of gluteus maximus muscle - Gluteus maximus may be compressed as a result of a posterior dislocation of the femur - L5 and S1 roots are commonly compressed o Pain that radiates into the L5 and S1 dermatomes of the leg and foot

Sciatic Nerve Injury

- Weakness in flexing leg at the knee and plantarflex at the ankle - Can’t stand on tiptoes - Paresthesia on skin of posterior leg, sole and lateral foot

Tibial Nerve Lesions

- May be performed to suppress labor pain by anesthetizing the pudendal nerve as it crosses the ischial spine - Pain of childbirth is transmitted through sensory fibers of S2-S5

Pudendal Nerve Block

Module 3 Flashcards

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