Gross Anatomy Flashcards
What is the role of dendrites?
Increase surface area
Communicate with adjacent neurones
What is the role of myelin sheath?
Coat axons to help speed up action potentials
What is the myelin sheath produced by in the PNS versus the CNS?
Shwann cells
Oligodendrocyte
What are the two types of neurones?
Multipolar - 2 or more dendrites and cell body in CNS
Unipolar - double process (pseudounipolar) and cell body in PNS
What neurones are classed as multipolar?
All motor neurones of SkM and ANS (pre-synaptic)
What neurones are classed as unipolar?
Sensory post-synaptic neurones in the ANS
In what direction do efferent impulses move?
MOTOR - Exits brain and moves towards body wall, cavity or organ
In what direction do afferent impulses move?
SENSORY - impulse Arrives at brain
What is a nerve? What is this referred to in the CNS?
Collection of axons surrounded by CT and blood vessels
Tract
What are the two types of nerves?
Single modality - one of somatic motor/ sensory, special sensory, sympathetic, parasympathetic or visceral afferent
Mixed modality - somatic motor, somatic sensory and sympathetic all in one nerve
A tract is most likely to be single modality. True/ False?
True
Give the first cranial nerve, it’s modality, function and foramen
1 (CNI) Olfactory - Cribiform plate (Forebrain) - Sensory (special) - Smell
Give the second cranial nerve, it’s modality, function and foramen
2 (CNII) Optic - Optic canal (Forebrain) Sensory (special) - Vision
Give the third cranial nerve, it’s modality, function and foramen
3 (CNIII) Oculomotor - Superior orbital fissure (Midbrain) -Motor - 4 extrinsic eye muscles and levator palpebrae superioris
- PS - pupillary sphincter
Give the fourth cranial nerve, it’s modality, function and foramen
4 (CNIV) Trochlear - Superior orbital fissure (Midbrain) Motor - Superior oblique
Give the fifth cranial nerve, it’s modality, function and foramen
5 (CNV) Trigeminal: PONS
Ophthalmic - Superior orbital fissure - Sensory - Scalp, forehead and nose.
Maxillary - F. rotundum - Sensory - Cheeks, lower eye lid, nasal mucosa, upper lip, upper teeth and palate.
Mandibular - F. ovale
Sensory - anterior 2/3 tongue, skin over mandible and lower teeth.
Motor: muscles of mastication
Give the sixth cranial nerve, it’s modality, function and foramen
6 (CNVI) Abducens - Superior orbital fissure (Junction between pons and medulla) - Motor - Lateral rectus
Give the seventh cranial nerve, it’s modality, function and foramen
7 (CNVII) Facial - Internal acoustic meatus > stylomastoid f. (Junction between pons and medulla) - Both - Sensory (special): sensation to part of ext. ear., taste from ant. 2/3 tongue, hard and soft palate., muscles of facial expression.
Motor and PS: lacrimal, submandibular, sublingual glands and mucous glands of mouth and nose.
Give the eighth cranial nerve, it’s modality, function and foramen
8 (CNVIII) Vestibulocochlear - Internal acoustic meatus - (Junction between pons and medulla) - Sensory (special) - Hearing and balance
Give the ninth cranial nerve, it’s modality, function and foramen
9 (CNIX) Glossopharyngeal - Jugular f. (Medulla) - Both:
Sensory: post. 1/3 tongue, nasopharynx, oropharynx, laryngopharynx, palatine tonsil, eustachian tube, ext. ear, and middle ear cavity.,
Special sensory: taste from post. 1/3 tongue(vallate papillae)
VA: carotid sinus receptors and carotid body
Motor: stylopharyngeus
PS: to parotid gland
Give the tenth cranial nerve, it’s modality, function and foramen
10 (CNX) Vagus - Jugular f. (Medulla) - Both:
Sensory: ext. ear, larynx and pharynx., larynx, pharynx and, thoracic & abdominal viscera., taste from epiglottis region of tongue
Motor and PS: smooth muscles of pharynx, larynx and most of the GIT
Give the eleventh cranial nerve, it’s modality, function and foramen
11 (CNXI) Spinal accessory - Jugular f. (Spinal cord) Motor: trapezius and sternocleidomastoid., a few fibres run with CNX to viscera.
Give the twelth cranial nerve, it’s modality, function and foramen
12 (CNXII) Hypoglossal - Hypoglossal canal (Medulla) Motor: Intrinsic and extrinsic tongue muscles (except the palatoglossus).`
There are 31 pairs of spinal nerves, how are they divided in the spinal cord?
Cervical (C1 - C8) Thoracic (T1 - T12) Lumbar (L1 - L5) Sacral (S1 - S5) Coccygeal (Co1)
There are 8 cervical spinal nerves, but how many vertebrae are there?
7
Where are spinal nerves found at the vertebrae, and what do they branch into?
Intervertebral foramina
Anterior (supply larger anterolateral body wall) and posterior ramus (smaller posterior wall)
What is the route taken by all sensory axons to the horn of the spinal cord?
Posterior root –> rootlets —> horn
What is the route taken by all motor axons to the spinal nerve?
Anterior horn of the spinal cord –> rootlets –> root –> spinal nerve
What is the function of the dorsal root ganglion?
Location of cell bodies of primary afferent neurones
Roots/rootlets are ____ modality and ramii are ____ modality
Single
Mixed
What three types of nerve supply does a spinal nerve supply to unilateral area of the body?
General sensory to all structures
Somatic motor to skeletal muscle
Sympathetic to skin and smooth muscle of arterioles
NOT PARASYMPATHETIC
What is a dermatome?
Area of skin supplied with sensory innervation from a single spinal nerve
What is a myotome?
SkM supplied with motor innvervation from single spinal nerve
In the dermatome map, what level is the male nipple at?
T4
In the dermatome map, what level is the umbilicus at?
T10
In the dermatome map, what level is the posterior scalp, neck and shoulder at?
C2-C4
In the dermatome map, what level is the upper limb at?
C5-T1
In the dermatome map, what level is the lower limb, gluteal region, perineum at?
L2-Co1
What is a nerve plexus?
Intermingled anterior rami from a number of adjacent spinal nerves
What levels is the cervical plexus, and what does it supply?
C1-C4
Posterior scalp, neck and diaphragm
What levels is the brachial plexus, and what does it supply?
C5-T1
Upper limb
What levels is the lumbar plexus, and what does it supply?
L1-L4
Lower limb
What levels is the sacral plexus, and what does it supply?
L5-S4
Lower limb, gluteal region, perineum
Sympathetic outflow from the brain enters the spinal cord at what levels? What is this known as?
T1 - L2
Thoracolumbar outflow
What is the route taken by sympathetic nerves to the area it is supplying?
Lateral horns of T1-L2 —> sympathetic chain —> spinal nerves —> anterior and posterior rami —> hitch a ride with arteries —> supply sweat glands, skin arrectors, arterioles
What are the four nerve routes taken by sympathetic outflow in all spinal nerves?
Heart
Lungs
Abdomniopelvic organs
Adrenal medulla
What allows a sympathetic axon to pass onto a paravertebral ganglion of the sympathetic trunk?
Rami communicans
Where do sympathetic presynaptic axons in the heart synapse?
Synapse in T1 or cervical paravertebral ganglia
What is the route taken by sympathetic postsynaptic axons in the heart?
Pass in cardiopulmonary splanchic nerves to the SA and AV nodes and myocardium
Where do sympathetic presynaptic axons in the lungs synapse?
Synapse in upper thoracic paravertebral ganglia
What is the route taken by sympathetic postsynaptic axons in the lungs?
Pass in cardiopulmonary splanchic nerves to bronchiolar SM and mucous glands
Where do sympathetic presynaptic axons of the abdominopelvic organs synapse?
In one of the prevertebral ganglia
List the sympathetic prevertebral ganglion associated with abdominopelvic organs for the foregut, midgut and hindgut respectively
Celiac ganglion of celiac plexus (FOREGUT)
Superior mesenteric ganglion of SM plexus (MIDGUT)
Inferior mesenteric ganglion of IF plexus (HINDGUT AND PELVIC/PERINEAL ORGANS)
List the sympathetic prevertebral ganglion associated with abdominopelvic organs, in this case for the kidney
Aorticorenal ganglion
Where are these sympathetic prevertebral ganglion located anatomically?
At named artery as it branches from the abdominal aorta
What is the route taken by presynaptic sympathetic axons to reach the adrenal medulla?
Pass through aorticorenal ganglion
Synapse DIRECTLY onto adrenaline/ NA secreting cells of the adrenal medulla
How do presynaptic axons of parasympathetic outflow leave the CNS? What is this known as?
Via CN III, VII, IX, X and sacral spinal nerves
Craniosacral outflow
What do presynaptic parasympathetic axons travel on to reach the eye?
Ciliary ganglion
What do presynaptic parasympathetic axons travel on to reach the lacrimal and salivary glands?
Parasympathetic ganglia in the head
What do presynaptic parasympathetic axons travel on to reach the organs of the head, neck, chest and abdomen as far as the midgut?
Vagus nerve
What do presynaptic parasympathetic axons travel on to reach the hindgut, pelvis and perineum?
Sacral spinal nerves
What is a classical clinical example of impaired sympathetic innervation to head and neck?
Horner’s syndrome
What are the symptoms of Horner’s syndrome?
Miosis
Ptosis
Reduced sweating (anhydrosis)
Increased warmth and redness
What are the causes of compression of the cervical parts of the sympathetic trunk in Horner’s syndrome?
Root of neck trauma Carotid dissection Internal jugular vein engorgement Deep cervical node metastases Pancoast tumour (lung apex)
What vertebrae can be palpated first on the back?
T1 spinous process
What do skin dimples on the lower back represent?
PSIS
What are the three parts of the trapezius, relative to their position on the back?
Descending (superior)
Transverse (middle)
Ascending (inferior)
Which rotator cuff muscle can be palpated on the back?
Teres major
Which muscle may be affected in lower back pain?
Erector spinae
What are the extrinsic back muscles (top - bottom), and what do they attach to?
Levator scapulae Rhomboid major and minor Trapezius Latissimus dorsi PECTORAL GIRDLE
What is the function of the extrinsic back muscles?
Move upper limb
What is the function of the intrinsic back muscles?
Maintain posture and extend the spine (ES) or rotate the spine (TVSPS)
What is the main superficial intrinsic back muscle? Where does it attach inferiorly?
Erector spinae
Common tendon to sacrum and iliac crest
What are the divisions of the erector spinae, and thus where do they attach superiorly?
Rib (Costalis)
Transverse process of vertebra (Longus)
Spinous process of vertebra (Spinous)
What is the main deep intrinsic back muscle? Where is it located?
Transversospinalis
Within grooves between transverse and spinous processes
Where do the muscle fibres of transversospinalis attach between?
Vertebra and skull
Vertebra and rib
One vertebra and another
Sacrum and vertebra
What is the nerve supply to the back muscles?
Segmental (as per dermatome/ myotome)
Via posterior ramii branches (cervical , thoracic, lumbar)
What muscles lie laterally to the vertebral column?
MUSCLES OF POSTERIOR ABDO WALL
Psoas major
Quadratus lomborum
What muscles lie posterally to the vertebral column?
INTRINSIC BACK MUSCLES
Transversospinalis
Erector spinae
What muscles lie laterally to the posterior abdominal wall muscles?
MUSCLE OF UL Latissimus dorsi MUSCLES OF ANTEROLATERAL ABDO WALL Transverse abdominus Internal oblique External oblique
If the erector spinae muscle contracts bilaterally the spine will undergo…
Extension
If the erector spinae muscle contracts unilaterally the spine will undergo …
Lateral flexion
What muscles control flexion of the spine?
Rectus abdominus
Psoas major
How many vertebrae are there in the adult vertebral column?
33
How are the vertebrae divided?
7 cervical (C1 - C8) 12 thoracic (T1 - T12) 5 lumbar (L1 - L5) 5 sacral (1 sacrum) 4 coccygeal (1 coccyx)
What are the 3 functions of the vertebrae?
Support head and trunk when upright
Protect spinal cord and nerves
Allow movement of head on neck and trunk
What are the main curvatures of the spine and are they primary or secondary?
Cervical lordosis (2) Lumbar lordosis (2) Thoracic kyphosis (1) Sacral kyphosis (1)
What curvature pathology is caused by excessive anterior weight e.g. in pregnancy or obesity?
Excessive lumbar lordosis
What curvature pathology is caused by old age typically?
Excessive thoracic kyphosis
List the parts of a vertebra
Spinous process x 1
Transverse process x 2
Inferior and superior articular processes x 4
Vertebral foramen
Vertebral body
Vertebral arch (made up of 2 x pedicle (superior) and 2 x lamina)
What type of joint is the articulation between articular processes and adjacent vertebrae?
Synovial facet joint
Which structure contains and protects the spinal cord and nerves?
Intervertebral foramen
What joints are affected in arthritis of the spine?
Facet joint
Where are IV discs found? What are they at risk of?
Between adjacent vertebral bodies
Disc herniation
Where is there an abscence of IV discs?
Between C1 and C2
Describe the structure of an IV disc
Outer fibrous ring - annulus fibrosis
Inner soft pulp - nucleus pulposis
Which short ligament connects the adjacent lamina posteriorly to the spinal cord?
Ligamentum flavum
What is the function of the posterior longitudinal ligament?
Narrow and weak
Prevents overflexion
What is the function of the anterior longitudinal ligament?
Broad and strong
Prevents overextension
What is the function of the supraspinous ligaments?
Strong, fibrous
Connects tips of spinous processes
What is the function of the interspinous ligaments?
Weak, membranous
Connect superior and inferior parts of adjacent spinous processes
List the ligaments of the vertebral column
Ligamentum flavum Posterior longitudinal ligament Anterior longitudinal ligament Supraspinous ligaments Interspinous ligaments
Which vertebra are classed as atypical and why?
C1: ATLAS - no body or spinous process - A + P arch instead
C2: AXIS - odontoid process, which projects superiorly from body
C7: VERTEBRA PROMINENS - 1st palpable spinous process
Which ligament connects C1 and C2 vertebra?
Transverse ligament
Where does the atlanto-occipital joint connect?
Between occipital condyles of C1 and superior articular facets of atlas
What type of joint is the atlanto-occipital joint? What is it’s function?
Synovial joint
Flexion and extension of neck (yes, no)
Some lateral flexion and rotation
Where does the atlanto-axial joint connect?
3 articulations
2 x inferior articular facets of atlas and superior articular facets of axis
1 x anterior arch of atlas and odontoid process of axis
What is the main role of the atlanto-axial joint?
Rotation
What are the names given to the area at the top and bottom of the sacral canal?
Sacral promontory
Sacral hiatus
What are commonly classed as the ‘wings’ of the sacrum?
Left and right ala
What exists within the sacral canal?
Cauda equina
Meninges
Which part of the sacrum is palpable?
Sacral hiatus
Which part of the sacrum is caudal anaesthesia inserted into to anaesthetise sacral spinal roots?
Sacral hiatus
Where does the spinal cord start and end?
Foramen magnum (C1) Vertebral level L1/L2 (Co1 segment)
What is the cauda equina?
All spinal nerve routes from L2 to Co that have descended to numbered vertebra where the spinal nerve is in IV foramen
What is the spinal cord surrounded by?
3 layers of meninges (dura, arachnoid matter, pia) Epidural fat (and venous plexuses)
What is a laminectomy?
Removal of 1 or more spinous processes and adjacent lamina to relieve pressure on the spinal cord/ nerve roots
What type of receptors exist in all body wall structures for somatic general senosry spinal nerves. List some examples
Sensation specific receptors
Pain, touch, temperature, proprioception, vibration
What type of fibres do somatic motor axons on spinal nerves synapse onto on the body wall?
Skeletal muscle
What type of fibres do sympathetic axons on spinal nerves synapse onto?
Smooth muscle
What fibres does the spinal cord segmental synapse between for spinal reflexes?
Somatic sensory and somatic motor axons
Describe the types of general sensory somatic symptoms that the body wall percieves
Pain (neuralgia) Pins and needles (paraesthesia) Numbness (anaesthesia) Sensitivity (hyperanaesthesia) Hot or cold Loss of coordination/ balance/ clumsiness (ataxia)
Describe the types of somatic motor symptoms that the body wall percieves
Muscle stiffness, tightness or spasm (cramp)
Muscle flappiness or looseness (hypotonia)
Muscular weakness (reduced power)
Loss of coordination/ balance/ clumsiness (ataxia)
What are the neural components of the body wall?
Somatic general sensory fibres
Somatic motor fibres
Sympathetic fibres (motor to organs)
Spinal reflexes
What is used to test sensory function of spinal nerves?
Dermatomes
What is used to test motor function of spinal nerves?
Myotomes
In what situation, would we test both motor and sensory function of spinal nerves?
Spinal reflexes
What area of the brain is common for CVA?
Internal capsule
Identify the dermatomal locations of the cervical roots in the upper limb
C1: SN has no sensory axons
C2: Back of scalp and Adams apple (area that looks like a helmet with a strap tied below the chin)
C4: Clavicle and shoulder tip (neck lace)
C3: Back of neck and jugular notch (area between C2 and 4)
C5: ‘Badge patch’ (anterior chest and continues to wrist) WE DIVE TO T1 (most of arm)
C6: Thumb (+ index finger, if you join together they make 6) and lateral posterior arm
C7: Index and middle finger (continuation) and middle posterior forearm
C8: Ring and little finger (continuation) and medial posterior forearm
Identify the dermatomal locations of the thoracic roots in the upper limb and trunk
Entire area makes the letter T
T1: Medial forearm (limbs are topmost )
T2: Medial arm and sternal angle
T4: Male nipple ('boob')
T10: Umbilicus (bell butTEN)
T12: Pubic symphysisIdentify the dermatomal locations of the lumbar roots in the pelvis and lower limb
Supplies legs and loin
L1: Groin ‘hands in pockets’ (1nguinaL area)
L2: Anterior thigh
L3: Anterior thigh
L4: KNEE (to medial malleolus) (down on L4s) and great toe (great ‘fire’ of London)
L5: Dorsum of foot (middle part of sole is triangle like an inverted V (roman for 5)
Identify the dermatomal locations of the sacral roots in the lower limb
Concentric fashion (out to in)
S1: Heel (POSTERIOR LEG)
S2: Posterior knee (lateral leg and foot inc. little toe) (FREE INC, GENITAL AREA)
(BULLSEYE OF ANUS)
S3: Buttock (FREE INC. GENITAL AREA)
S4: Perineum
S5: Perianal skin (anus)
What is the sensory area supplied by the posterior ramii, allowing us to test these ramii?
Supply a strip of skin centrally down back and posterior neck (C2 - C8 spinal nerves)
How would we test the sensory component of the anterior ramii?
Forms plexuses - cervical, brachial, lumbar, sacral which can be tested
Which spinal cord levels do not contribute to anterior ramii?
T2 - T12
Which nerves are formed from the bifurcation of L1?
Ilioinguinal and iliohypogastric
Which nerves are formed from the anterior ramii of T2 - T11?
Intercostal nerves
Which nerve is formed from the anterior ramii of T12?
Subcostal nerve
What is the difference between a spinal nerve and a named nerve?
Spinal nerves are axons originating from one spinal cord level e.g. L5 spinal nerve, whereas named nerve are axons originating from 1 or more spinal cord levels supplying an area e.g. musculocutaneous nerve (C5, 6, 7)
Identify the plexus and list the nerve roots giving rise to the named nerve cutaneous innervation of the neck
CERVICAL PLEXUS
Anterior ramii of C1, 2, 3, 4
Identify the specific sensory nerves and roots which form the named nerve cutaneous innervation of the neck
CERVICAL PLEXUS
LITTLE GOATS TRED SOFTLY:
Starting from -
11 o’clock: Lesser occipital nerve (C2) - posterior to external ear
1 o’clock: Great auricular nerve (C2, 3) - angle of mandible and external ear
3 o’clock: Trasverse cervical nerve (C2, 3) - anterior neck
6 o’clock: Supraclavicular (C3, 4) - clavicle, shoulder pain
What is the nerve point?
Point at which sensory nerves of cervical plexus converge
Which sensory nerve is involved in referral of pain from the diaphragm?
Supraclavicular nerve (C3, 4)
Which nerve roots are important in referred pain from the myocardium?
T1, T2
What supplies the anatomical snuffbox?
Cutaneous branches of the radial nerve
Identify the specific sensory nerves and roots that form the named nerve cutaneous innervation of the upper limb
BRACHIAL PLEXUS
Shoulder - middle finger (lateral) and back up (medial)
Supraclavicular (C3,4) - Shoulder
Axillary nerve (C5, 6) - Badge patch area
Radial nerve (C5, 6, 7, 8, T1) - Lateral arm (and most of posterior)
Cutaneous branch of musculocutaneous (C5, 6, 7) - Lateral half of anterior forearm (and a bit posterior)
Radial nerve (Lateral hand - snuffbox)
Median nerve (C5, 6, 7, 8, T1) - Lateral 3 1/2 digits (and posterior fingertips of these fingers)
Ulnar nerve (C7, C8, T1) - Medial 1 1/2 fingers (and these fingers posteriorly)
Median antebrachial cutaneous nerve
Identify the sensory nerves of the lumbosacral plexus that form the named nerve cutaneous innervation of the ANTERIOR lower limb
1ST LAYER: lateral to medial Subcostal nerve (T12) - corner Genitofemoral nerve (L1, L2) - 1 or 2 balls Ilioinguinal nerve (L1) - 1lioinguinaL
2ND LAYER: lateral to medial
Lateral cutaneous nerve of the thigh (L3, L4)
Femoral nerve (L2, L3, L4) - FRONT
Obturator nerve (L2, L3, L4) - OPEN YOUR LEGS
3RD LAYER: lateral to medial
Common fibular nerve (L2, L3) - TELLING A FIB - HIDING SOMETHING
Saphenous nerve (L3, L4) - from femoral - SECRET
4TH LAYER: lateral to medial
Sural nerve (S1, S2) - ‘sweet’ little toe
Superficial fibular nerve (L4, L5, S1) - shoe (most of foot)
Deep fibular nerve (L5) - ‘fin’ - toe web
Identify the sensory nerves of the lumbosacral plexus that form the named nerve cutaneous innervation of the POSTERIOR lower limb
1ST LAYER: lateral to medial
Iliohypogastric nerve (L1) - ‘1Lio’
Posterior ramii (cluneal nerves) (S1, S2, S3) - ‘No clue = hiding at back)
Ilioinguinal nerve
2ND LAYER: lateral to medial
Lateral cutaneous nerve of thigh
Posterior cutaneous nerve of thigh (S1, S2, S3)
Obturator and femoral nerves
3RD LAYER: lateral to medial
Common fibular nerve
Sural nerve (from tibial and common fibular: S1, S2 - SECRET (in middle)
Saphenous nerve
4TH LAYER: lateral to medial
Tibial nerve (L4, L5, S1, S2, S3)
Calcaneal nerve (HEEL)
Medial and lateral plantar nerves (SOLE)
Describe the route of a somato-sensory action potential from the skin to the somatosensory cortex
Stimulated nerve
AP generated by receptors in L2 dermatome
AP enters lumbar plexus and reaches L2 anterior ramii
AP continues to L2 spinal nerve, then posterior root and rootlets
AP reaches posterior horn of spinal cord
Identify the myotomes supplied by the cervical plexus
C1 - C4 motor axons - neck and strap muscles, diaphragm
Identify the myotomes supplied by the brachial plexus
C5 - T1 motor axons - muscles of upper limb, extrinsic back muscles (control upper limb and scapula)
Identify the myotomes supplied by the lumbosacral plexus
L1 - S4 motor axons - muscles of lower limb, perineal skeletal muscle
Identify the myotomes supplied by T12 - L3 motor axons
Postural back muscles (posterior ramii) Intercostal muscles (anterior ramii) AL abdominal wall muscles (via thoracoabdominal, subcostal, iliohypogastric, ilioinguinal)
How do you clinically test the C5 motor axons, supplying a myotome? What muscle are you testing?
Shoulder ABD (also elbow flexion) Deltoid
How do you clinically test the C6 motor axons, supplying a myotome? What muscle are you testing?
Wrist EXT
Biceps brachii
How do you clinically test the C7 motor axons, supplying a myotome? What muscle are you testing?
Elbow EXT
Triceps brachii
How do you clinically test the C8 motor axons, supplying a myotome? What muscle are you testing?
Finger FLEX
Flexor digitorium superficialis
How do you clinically test the T1 motor axons, supplying a myotome? What muscle are you testing?
Finger ABD
Dorsal interossei
How do you clinically test the L3 motor axons, supplying a myotome? What muscle are you testing?
Knee EXT
Quadriceps femoris
How do you clinically test the L4 motor axons, supplying a myotome? What muscle are you testing?
Ankle DF
Tibialis anterior
How do you clinically test the L5 motor axons, supplying a myotome? What muscle are you testing?
Great toe EXT
Extensor hallucis longis
How do you clinically test the S1 motor axons, supplying a myotome? What muscle are you testing?
Ankle PF
Gastrocneumius
How do you clinically test the S2 motor axons, supplying a myotome? What muscle are you testing?
Knee FLEX
Biceps femoris
Describe the route of a somato-motor action potential from the primary somatomotor cortex (UMN) to skeletal muscle.
Primary somatosensory cortex
AP continues onto UMN axons of CST
AP continues onto anterior horn of L3 spinal cord
UMN synapse with L3 LMN
AP continues to L3 spinal nerve
AP continues onto L3 posterior or anterior ramus
AP enters the lumbar plexus of named nerve and reaches NMJ of supplied nerve
What is a reflex? Describe the patellar reflex
Involuntary response to stimulus
Patella senses stretch, activates APs in femoral nerves and sensory APs to dorsal horn of L3 axons
Axons synapse on LMNs in femoral nerve
Reach quadriceps NMJ and extension occurs
What is a monosynaptic reflex? What does it indicated?
Occurs each time a skeletal muscle is stretched
Normal muscle tone
Reflex muscle contractions are controlled by…
Descending pathways
What sign would suggest an UMN lesions versus a LMN lesion?
Spasticity
Flaccidity
Which axons are activated when testing the tendon jerk of biceps brachii?
C5, C6
Which axons are activated when testing the tendon jerk of brachioradialis?
C6
Which axons are activated when testing the tendon jerk of triceps brachii?
C7, C8
Which axons are activated when testing the knee jerk reflex?
L3, L4
Which axons are activated when testing the ankle jerk reflex?
S1, S2
Anterior roots contain only sensory/motor axons, whilst posterior roots contain only sensory/ motor axons?
Motor
Sensory
The space in the middle of the grey matter in the spinal cord is known as the?
Spinal canal
For CNI, give it’s extracranial and intracranial course and connection with CNS (if applicable)
In olfactory mucosa in nasal cavity
Synapse in olfactory bulb, and pass to olfactory tract
NO CONNECTION
Outline how you would go about testing CNI
Smell while covering contralateral side
For CNII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Neurones of retina travel posteriorly via optic nerve to the orbit
Pass from the optic chiasm to the optic tract
Diencephalon
Outline how you would go about testing CNII
Visual acuity (Snellen) Colour (Ishihara plates) Fields (4 quadrants) Reflexes (Pupillary light reflexes) Fundoscopy
For CNIII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
SOF into orbit and supply all extraocular muscles except 2, PSs synapse in ciliary ganglion
Lateral wall of cavernous sinus (orbit)
Mesencephalon (midbrain)
Outline how you would go about testing CNIII
Light reflexes via a torch (PS)
For CNIV, give it’s extracranial and intracranial course and connection with CNS (if applicable)
SOF into orbit and supply SO muscle
Lateral wall of cavernous sinus (orbit)
Mesencephalon (midbrain)
Outline how you would go about testing CNIV
H test (in and down)
For CNVI, give it’s extracranial and intracranial course and connection with CNS (if applicable)
SOF into orbit and supply LR muscle
Cavernous sinus to orbit
Pontomedullary junction
Outline how you would go about testing CNVI
H test (out)
For CNVIII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Axons from cochlear and vestibular apparatus
Posteromedially from IAM to PM junction
Pontomedullary junction
Outline how you would go about testing CNVIII
Rinnie and Weber tests
For CNXI, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Axons supply SCMD, travel across posterior triangle to trapezius
Foramen magnum to jugular foramen
Cervical spinal cord
Outline how you would go about testing CNXI
Shrug shoulders (and resist) - TRAPEZIUS Turn head to flex neck (and resist) - SCMD
For CNXII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Descends lateral to carotid sheath (at hyoid turns anteriorly to tongue)
Pass anteriorly to hypoglossal canal
Many rootlets lateral to pyramids of medulla
Outline how you would go about testing CNXII
Stick tongue out and move side-side
Tip of tongue will point towards side of pathology
For CNV, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Sensory passes superficial to deep structures of face posteriorly to foramen
Motor from CNV3 travels from f. ovale to skeletal muscle
Inferior to tentorium cerebelli
Pons!
Give the superficial sensory divisions for the trigeminal supply to the face
CNVI: upper eyelid to tip of nose to forehead
CNV2: Lower eyelid to upper lip and nostril
CNV3: Lower lip and chin to TMJ/ mandible (except angle)
What gives sensory supply to the angle of mandible, and what are the roots of this nerve?
Great auricular nerve (C2, C3)
Give the deep sensory divisions for the trigeminal supply to the face
CNV1: orbit (not floor or lower eyelid), upper anterior nasal cavity, paranasal sinuses (not maxillary), anterior and posterior CF
CNV2: lower posterior nasal cavity, maxillary sinus, maxilla, floor of nasal cavity/ palate, maxillary teeth, soft tissues
CNV3: Middle CF, mandible A 2/3 of tongue, floor of mouth, buccal mucosa, mandibular teeth
Outline how you would go about testing the sensory divisons of CNV
Close eyes
Cotton wool - ‘Say when you feel me touching you’
Compare sides
Which nerve is the 1st part of afferent limb of blink/ corneal reflex?
Long ciliary nerve
Outline how you would go about testing the motor division of CNX
Palpate strength of masseter (clench teeth)
Open jaw against resistance
For CNVII, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Somatic motor fibres to parotid gland and then facial expression muscles (1 out of 5)
Directly to IAM
Pontomedullary junction
The facial canal is located within what part of the temporal bone?
Petrous part
What is the function of chorda tympani, a branch of CNVII?
Taste to A 2/3 of tongue
PS to submandibular and sublingual glands (salvation)
What is the tiniest SkM in the body?
Stapedius
What is the role of the stapedius muscle, and what happens when you damage it?
Reduces stapes movement to dampen down excessive noise
Hyperacuisis
Outline how you would go about testing CNVII
Test the muscles of facial expression - raise eyebrows, close eyes tightly, smile, puff out cheeks and hold air
List the muscles of facial expression
Frontalis
Orbicularis oculi
Elevators of lips
Orbicularis oris
For CNIX, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Descends in pharynx in mouth to stylopharyngeus, parotid gland, pharyngeal muscosa, carotid body and sinus, posterior 1/3 of tongue
Directly to jugular foramen
Medulla oblongata
Outline how you would go about testing CNIX
Elicit afferent limb of gag reflex
What is the only muscle supplied by CNIX
Stylopharyngeus
Which muscles are supplied with motor innervation from CNV?
Tensor tympani
Tensor veli palatini
1 pair of jaw closing muscles - lateral pterygoid
3 pairs of jaw opening muscles - masseter, temporalis, medial pterygoid
For CNX, give it’s extracranial and intracranial course and connection with CNS (if applicable)
Structures between pallate and midgut
Directly into jugular foramen
Medulla oblongata
Why is pain often referred from pharynx to ear and vice versa?
Both supplied by glosopharyngeal nerve
What two vessels is the carotid sheath located between?
CCA and IJV
The left recurrent laryngeal nerve, branch of CNX, passes under…
Arch of aorta
The right recurrent laryngeal nerve, branch of CNX, passes under…
Right subclavian artery
Outline the route taken by both vagus nerves from the chest to abdomen
RIGHT: Lateral aspect of trachea LEFT: Lateral aspect of aortic arch Pass posterior to lung root on oesophagus Pass through diaphragm with oesophagus Pass onto surface of stomach Branches and travels to organs
List the branches of the vagus nerve in the abdomen
Celiac and superior mesenteric ganglia Foregut Renal Midgut (on mesenteries) Splenic Pancreatic
What vertebral level do the oesophagus and vagus nerve pass through the diaphragm?
T10
Where do the vagus nerves very last PS axons pass onto?
Splenic flexure of colon
Outline how you would go about testing CNX
MUSCLES OF PALATE (motor) - Say ‘aaah’ - uvula deviates to side that is functioning
PHARYNGEAL MUSCLES - Swallow water and see if they splutter
LARYNGEAL MUSCLES - Listen to speech and see if any hoarseness
What is a space-occupying lesion, and what are the two main types?
Abnormal tissue taking up space
Acute or subacute
What are the layers of the scalp?
SCALP Skin CT (artery-rich) Aponeurosis (tendon) Loose CT (thinnest) Pericranium (periostum - outer membrane of bone)
Why do scalp lacerations and incisions bleed excessively?
Scalp arteries form a rich anastomotic network just deep to skin
What two arteries do scalp arteries branch from?
Internal and external carotid
What is the thinnest part of the skull? What type of joint is it? What artery courses just deep to it?
Pterion
Fibrous joint - suture (H shape)
Middle meningeal artery
List the borders of each of the cranial fossa; anterior, middle and posterior?
Frontal bone - wings of sphenoid
WIngs of sphenoid - petrous temporal bone
Petrous temporal bone - occipital bone
What is the name for the protective coverings of the brain and spinal cord?
Meninges
List the 3 layers of membrane covering the brain and spinal cord, from superficial to deep
Dura matter ‘hard matter’ (ADHERENT TO SKULL)
Arachnoid matter ‘spidery mother’
(Subarachnoid space)
Pia matter ‘faithful matter’ (ADHERENT TO BRAIN)
What CN is the sensory supply to the dura?
CNV
Which layer of the meninges encloses the dural venous sinuses? What are the main three types?
Dura matter
DIaphragm sellae, tentorium cerebelli, falx cerebri
What is the diaphragm sellae? What does it sit upon?
Tough sheet of dura matter forming a roof over pituitary fossa (on sella turcica)
What is the tentorium cerebelli?
Tough sheet of dura matter tenting over cerebellum, which attaches to ridges of petrous temporal bone
What is the falx cerebri? What are the attachments to the deep aspect of skull?
Midline structure of dura matter that seperates the cerebral hemispheres
Crista galli of ethmoid bone, internal sagittal suture, internal occipital protuberance
Where do the cerebral veins drain into?
Dural venous sinuses
List the main dural venous sinuses that drain blood from the brain
Sigmoid sinus ‘S shape’
Superior sagittal sinus
Inferior sagittal sinus
Where does the sigmoid sinus drain and to what foramen?
IJV at jugular foramen
Where is the confluence of sinuses?
In midline at internal occipital protuberance
What is the danger triangle of the face?
Venous spread of infection from superficial to deep - ophthalmic vein has no valves and can leak backwards = CAVERNOUS SINUS THROMBOSIS
Outline the arterial supply to the brain
- ICA (branch of CCA)
- ECA (branch of CCA)
- VA (branch of SCA)
What route does the vertebral artery take to reach the cranial cavity?
Through transverse foraminae in cervical vertebrae
Through foramen magnum
Outline the branches of the Circle of Willis from bottom to top
Vertebral arteries (connected by anterior spinal)
Basilar artery (anastomosis of two VAs)
(Pontine arteries)
Posterior cerebral arteries (division of basillar artery)
ICAs (connected to PCAs by posterior communicating arteries)
1. Ophthalmic arteries
2. Branch of ICAs = Anterior cerebral arteries (connected by anterior communicating artery)
MCAs (continuation of ICAs)
Which arteries supply the medial, lateral and posterior aspects of the cerebral hemispheres respectively?
ACAs
MCAs
PCAs
Where can the Circle of Willis be found?
Inferior to midbrain, close to the pituitary stalk and optic chiasm in subarachnoid space
What circulates within the subarachnoid space?
CSF
Where does the subarachnoid space terminate?
S2 part of the sacrum
Outline the route taken by CSF from production to reabsorption
- Secreted by choroid plexus
- From right and left lateral ventricles
(via Foraminae of Munro - ONE FOR EACH) - Into midline 3rd ventricle
(Cerebral aqueduct) - Into 4th ventricle
- Into subarachnoid space of brain and cord (and some into central canal)
- Reabsorbed into dural venous sinuses
Where are the lateral ventricles, 3rd ventricle and 4th ventricle located, respectivelly?
Cerebral hemispheres
Diencephalon
Between cerebellum and pons
What reabsorbs CSF back into the dural venous sinuses?
Arachnoid granulations
What is hydrocephalus? How is it managed?
Excess production, obstruction to flow or inadequate reabsorption leading to increased CSF volume
Ventricular peritoneal shunt (connects ventricles to peritoneal cavity)
List the types of bleeding that can occur within the cranial cavity and what causes each of them
EXTRADURAL HAEMORRHAGE (between bone and dura) due to ruptured middle meningeal artery (damage to pterior)
SUBDURAL HAEMORRHAGE (seperates dura from arachnoid) due to torn cerebral veins
SUBARACHNOID HAEMORRHAGE (into CSF of subarachnoid space) due to ruptured CIrcle of WIllis ‘Berry aneurysm’
What can happen if you sustain damage to the extradural venous plexuses?
Epidural haematoma compressing spinal cord or cauda equina
Where is the needle inserted in epidural anaesthesia? Why?
Subarachnoid space where it surrounds cauda equina (spinal nerves not as easily damaged as conus medullaris and vertebrae not fused)
Typically L3/4
What are the four common types of supratentorial herniation?
Cingulate (under falx cerebri)
Central (through tentorium cerebelli)
Uncal (uncus = medial temporal lobe, inferior to tentorium cerebelli)
Transcalvarial (fracture of cranial cavity)
What nerve can be compressed in uncal supratentorial herniation? What is the effect?
Oculomotor nerve
Fixed dilated pupil (ipsilateral)
What are the two common types of infratentorial herniation?
Upward (over tentorium cerebelli)
Downward/ tonsillar herniation (of cerebral tonsils into foramen magnum)
Where is the cerebral aqueduct located anatomically?
In the midbrain
Which cranial nerve is located in the anterior midline of the midbrain?
Oculomotor nerve
Which CN is the only nerve to exit the brainstem posteriorly?
Trochlear nerve - EXIT POSTERIOR MIDBRAIN AT JUNCTION WITH PONS
What is different about cervical spinal nerves compared to other spinal nerves?
Cervical spinal nerves exit above the vertebrae but all others exit below
If a patient has reduced sensation unilaterally on the face, including the forehead and lip, what does this suggest?
More likely involves peripheral facial nerve (Bell’s palsy) than a centrallesion (forehead sparing)
How do you clinically test the L2 motor axons, supplying a myotome? What muscle are you testing?
Hip FLEX
Iliopsoas
What pathology is often associated with Horner’s syndrome, due to the sympathetic nervous system travelling close to the site of damage?
Internal carotid dissection
