Neuro Anatomy Flashcards
What sensations are carried by the spinothalamic tract
Pain, temperature, crude touch
Where are the spinothalamic tracts located
Anterior spinothalamic - anterior to ventral horn
Lateral spinothalamic - lateral to the grey matter
What sensations are carried in the dorsal columns
Light touch, vibrations, joint position sense.
What are the two dorsal column tracts
Fasciculus cunatus (lateral) Fasciculus gracilis (medial)
What is the major descending motor pathway in the spine?
Lateral corticospinal (pyramidal tract)
What is brown sequard syndrome and what is the distribution of neuronal symptoms
Hemisection if the spinal cord
Ipsilateral paralysis, loss of joint position, light touch and pressure/vibration
Contralateral loss of pain, temperature and crude touch
What is the route of decent of the corticospinal tract
Cortex
Internal capsule
Medulla - decussates with majority crossing and descending as lateral corticospinal and minority (10%) remaining ipsilateral and descending as anterior corticospinal.
What would be the effect of an infarct in the internal capsule
Contralateral paralysis
What is the pathway of the spinothalamic tract
1st order neurones enter via the dorsal horn and synapse.
2nd order neurones decussate within a few spinal levels and ascend to the ventroposterior nucleus of the thalamus and synapse
3rd order neurones path to the somatosensory cortex
What is the route of the dorsal column
First order neurones enter via the dorsal horn and ascend ipsilaterally in the Fasciculus cuneatus and gracilis and synapse in the medulla
Second order neurones decussate and ascend to the ventroposterior nuculus of the thalamus and synapse
Third order neurones pass to the somatosensory cortex.
What is the blood supply to the spinal cord and where does it arise?
Anterior spinal artery arising from the vertebral arteries at foremen magnum
2 posterior spinal arteries arising from posterior inferior cerebellar artery at level of foremen magnum
Which artery supplies most of the spinal cord
Anterior spinal artery
What is the venous drainage of the spine
Posterior spinal vein
Posterior lateral spinal vein
Internal vertebral venous plexus in epidural space
How is spinal arterial blood flow supported
Which is the key vessel in this
Radicular arteries arise from local vessels at each spinal level and feed the spinal arteries
The most important is the adamkiewicz artery from the lower thoracic upper segmental segmental arteries
What nerves typically form the roots of the brachial plexus?
What variations are there?
Anterior primary rami of Spinal nerves C5-T1
Sometimes C4 or T2
What are the segments of the brachial plexus termed
Roots - spinal nerves Trunks Divisions Cords Branches - end nerves
What makes the brachial plexus vulnerable to injury
When are risks of injury?
It is superficial in the neck
Trauma, childbirth, GA,
What are the trunks of the brachial plexus? Which roots form which?
Which nerve branch arises from which trunk?
Upper - c5+6
Middle - c7
Lower - c8+t1
Suprascapular nerve from the upper trunk
What are the cords of the brachial plexus?
Lateral
Posterior
Medial
Where does the radial nerve from from in the brachial plexus?
The posterior cord
Where does the medial nerve arise in the brachial plexus
Combination of the medial and lateral cords
Where does the ulnar nerve arise in the brachial plexus
From the medial cord
Where does the musculocutanious nerve arise from in the brachial plexus
The lateral cord
Where do the brachial plexus nerve roots emerge
Emerge from the intervertebral foremina then between scalenous anterior and saclenous medius. They pass inferior laterally across the first rib then posterior to the subclavian artery
What nerves arise directly from the brachial plexus roots
Nerve to scalene
Nerve to subclavian
Dorsal scapular nerve
Long thoracic nerve
Where are the brachial plexus divisions located
Anterior to the first rib posterior to the subclavian artery
Where are the brachial plexus divisions located
Beneath the clavicle and in the axilla around the axillary artery
What are the divisions of the brachial plexus (in relation to the trunks?)
Anterior and posterior divisions of each trunk
What divisions form the posterior cord
What branches does it produce?
Posterior divisions of all three trunks
Axillary nerve
Deltoid nerves
Radial nerve
What divisions form the lateral cord of the brachial plexus
What branches does it produce?
Anterior divisions of upper and middle trunks
Lateral pectoral nerve
Musculocutanious nerve
Part of median nerve
What divisions form the medial cord in the brachial plexus
What branches does it give off
Anterior division of the lower trunk Medial pectoral nerve Median cutaneous nerve to arm and forearm Ulnar nerve Contributes to median nerve
Where does the axillary nerve arise? What does it supply? Action of the muscles?
Posterior cord of Brachial Plexus
Sensation over sergeants patch
Motor to deltoid and teres minor
Arm abduction and external rotation
Where does the radial nerve arise? What does it supply? Action of the muscles?
Posterior cord
Sensation - dorsum of thumb and lateral 1.5 fingers, branches to posterior arm and forearm
Motor - triceps, wrist extensors
Arm and wrist extension
What is the route of the radial nerve
From the posterior cord descends posteriomedially then anteriolaterally passing anterior to lateral epicondyle. Crosses acf forming a superficial sensory and deep motor branch.
Superficial branch descends under brachioradialis. Deep branch descends to posterior compartment
Where does the musculocutanious nerve arise? What does it supply? Action of the muscles?
Lateral cord
Innervates arm flexors
Gives off sensory branch - lateral cutaneous nerve of the forearm
Where does the median nerve arise? What does it supply? Action of the muscles?
Lateral and medial cords of the plexus
Innervates for arm flexors and muscles of the thenar eminence + 1st and 2nd lumbericles
Sensation to lateral palmar aspect of hand
Route of median nerve
From the combination of lateral and medial cords travels with the artery into the arm
Passes between forearm flexors giving off palmar branch before going through carpel tunnel into hand
Where does the ulnar nerve arise? What does it supply? Action of the muscles?
Medial cord
Innervates flexor carpi ulnaris and half of flexor digitorum profundus + hypothenar eminance, lateral lumbericles and adductor pollicis
Sensation to dorsal and palmer side of the medial aspect of the hand
Route of the ulnar nerve
From the medial cord
Posterior to medial epicondyle
Cubital tunnel
Descends anterior compartment of forearm
Enters and superficial to carpel tunnel in ulnar tunnel
What nerve provides sensation to the shoulder, what is its origin roots?
Supraclavicular (C3-4)
What nerve provides sensation to the proximal lateral upper arm, what is its origin roots?
superior lateral cutaneous (c5-6), branch of the axillary
What nerves provides sensation to the axilla and proximal medial upper arm , what is its origin roots? What nerve supplies below it and posteriorly
Intercostobrachial T2
Posterior cutaneous nerve of the arm c5-8, radial branch
What nerveS provides sensation to the distal lateral upper arm and posteriolateral element of the forearm, what are their origin roots?
Inferior lateral cutaneous nerve of the arm
Posterior cutaneous nerve of the forearm
All C6-8, branches of the radial
What nerve provides sensation to the medial forearm what is its origin roots?
Medial cutaneous nerve of the forearm
C8-t1
What nerve provides sensation to the lateral forearm, what is its origin roots?
Lateral cutaneous nerve of the forearm
C5-6
Musculocutanious
What nerves provides sensation to the hand?
Medial dorsal and palmer surfaces (1.5 digits) Lateral palmer and dorsal fingertips (3.5 digits) median Lateral dorsal (except fingertips) (3.5 digits) radial
What nerves form the lumbar plexus
What contributes in 50%
L1-3 and part of L4
In 50% a branch of t12 is involved
How is the femoral nerve formed in the lumbar plexus
The dorsal divisions of L2,3 and 4
What forms the lateral cutaneous nerve of the thigh in the lumbar plexus
Dorsal divisions of L2 and 3
What forms the obturator nerve in the lumbar plexus
Ventral divisions of L2,3, and 4
What nerves are formed by the higher lumbar plexus (l1/2 +/- t12j
Subcostal
Iliohypogastric
Ilioinguinal
Genitofemoral
Where do the femoral and lateral cutaneous nerve of the thigh emerge in relation to musculature
Posteriolateral edge of the psoas
What lumbar plexus nerves arise on the medial border of psoas major
Obturator and accessory obturator
How does the genitofemoral nerve emerge from the lumbar plexus with respect to musculature
Pieces psoas appearing anteriorly to it
What is the route of the femoral nerve
Emerges lateral psoas
Runs inferiorly between psoas and iliacus
Passes beneath inguinal ligament into thigh
Lies lateral to the femoral artery (separated by iliac fascia ie NOT in femoral sheath)
Divides into terminal branches
What muscles does the femoral nerve supply with which branches
What sensation does it provide
Anterior division:
Sartorius
Intermediate and medial cutaneous nerve of the thigh (anterior and medial thigh)
Posterior division
Quadriceps
Nerves to recuts femoris and vastus (medialis, intermedius, lateralis)
Saphenous nerve
What is the route of the saphenous nerve
What does it supply
Arises in femoral triangle
Descends lateral to the femoral vessels
Enters adductor canal
Crosses vessels to lie on medial side in front of lower adductor Magnus
In the lower adductor canal pieces fascia lata between sartorius and gracilis becoming subcutaneous.
Passes along tibial side of leg with great saphenous vein
Descends with vein to great toe.
Sensation to skin to front and medial leg and proximal medial foot.
What is the route of the o trust or nerve
What does it supply
Arises medial border psoas at pelvic brim
Enters thigh via obturator canal dividing into a+p branches
Anterior provides articular branches to the hip and communicates with medial cutaneous nerve to the leg and saphenous nerve forming the subsartorial plexus supplying medial thigh sensation
Posterior branch provides articular branch to knee
What connects the lumbar and sacral plexuses
Origins and route
The lumbosacral trunk (L4/5)
From medial psoas runs over pelvic brim joining S1
What nerve roots form sacral plexus
S1 to S5 and coccygeal nerve
What are the main nerves from sacral plexus and their origin roots
The posterior cutanious nerve of the thigh - S1-3
The nerve to quadratus femoris from anterior rami L4-S1
Sciatic nerve - L4 to S3
What nerve provides sensation to the posterior thigh, leg and peroneum?
Posterior cutanious nerve of the thigh
What does the nerve to quadratus femoris supply?
Articular branch to hip joint
Inner action to quadratus femoris and gemellius inferior
Route of sciatic nerve
Leaves pelvis through greater thoracic foramen
Enters buttock under glut maximum
Runs midway between greater trochanter of femur and ischial tuberosity
Passes into back of thigh and runs down to apex of popliteal fossa between semitendinous and biceps femoris tendons
Here divides into 2 - tibial nerve and common peroneal nerve (though this division can occur anywhere from the sacral plexus to the popliteal fossa)