Peripheral Nerves Flashcards
Radial nerve origins
C5-8
Pass through upper, middle and lower trunks then posterior cord of brachial plexus
Radial nerve anatomy in upper arm
As it winds around the humerus or proximal to this it innervates the tricpes.
After course in spiral groove it supplies brachioradialis and ECRL and brevis.
Bifurcates into a superifical (sensory) and deep (motor) branches
Muscles supplied by proximal branches of radial nerve
Triceps
Brachioradiailis
ECRL
ECRB
Superficial branch of radial nerve
In forearm, passes distally into the hand where it supplies skin of the radial aspect of the dorsum of the hand and dorsum of first four fingers.
Deep branch of radial nerve
Passes deep through the fibrous arch of supinator (arch of Froshe) to enter the posterior compartment of forearm
Continuous in this compartment as the purely motor posterior interosseous branch
Innervates
Supinator
Extensor digitorum
Extensor digit mini
ECU
Abductor pollicis longus
Extensor pollicis longus
Extensor pollicis brevis
Extensor indicies
Forearm muscles dupplied by posterior interosseous nerve
Supinator
Extensor digitorum
Extensor digiti minimi
ECU
Abductor pollicis longus
Extensor pollicis longus
Extensor pollicis brevis
Extensor indicis
Supinator function
Forearm supinator
Test with resisted supination
Extensor digitorum
Extensor of 2nd to 5th metacraophalangeal joints
Extensor digiti minimi function
Extensor if fifth MCP
ECU function
Ulnar extenor of the wrist
APL function
Abductor of carpometacarpal joint of thumb
EPL function
Extension of thumb interphalangeal joint
EPB function
Extensor of the MCPJ of thumb
Extensor indicies function
Extensor of index finger
Saturday night palsy
AKA radial nerve palsy
Classically associated with a drunkard who falls asleep with arm hyper abducted across a park bench
Site of compression is in the region of the spiral groove
Why is the triceps preserved in radial nerve palsy (Saturday night palsy)
Because branches of the tricpes originate proximal to spiral groove
Wrist drop
Inability to extend fingers at MCPJ
Supinator weakness
Triceps spared
Absent sensation first dorsal interosseuous
Radial nerve palsy
Compression in the spira groove of humerus/humeral fracture
Why is weakness of supination only partial in Radial nerve palsy
Because it may be accomplished with either biceps or supinator
Posterior interosseous nerve syndrome
Most common syndrome caused by compression at the arcade of Frohse (fibrous arch at the origin of supinator) which may pathologically constrict nerve
Inability to extend fingers at MCPJ, absence of wrist drop and normal sensation
Supintaor spared as branches are given off proximal to PIN entering the arcade of Frohse
Why is wrist drop absent in PIN palsy
The ECR is presreved
The ECU is innervated by PIN so there may be radial deviation of the hand on extension
Why is there no senosry deficit in PIN syndrome
It is purely motor
Inability to extend fingers at MCPJ
No wrist drop but radial deviation on extension of wrist
Presrved sensation
Preserved supinator and triceps
Posterior interosseus nerve syndrome
Arcade of Frohse associated with PIN syndrome/supinator syndrome
Roots of median nerve
C6 to T1
Pasing through upper middle and lower trunks and the lateral and medial cords of the brachial plexus
Median nerve branches proximal to the elbow
None
Median nerve at elbow
Muscles supplied
Pronator teres
Flexor carpi radialis
Palmaris longue
FDS
Prontaor teres function
Forearm pronator
FCR function
Radial wrist flexor
PL
Wrist flexor
FDS
Flexor at the IPJ for 2nd-5th fingers
Contents of the cubital fossa
Really Need Beer To Be At My Nicest
L->M
Radial nerve
Biceps tendon
Brachial artery
Median nerve
Under what is the median nerve found at the elbow?
Behind the biccipital aponeurous (lacertus fibrosus)
How does the median nerve enter the forearm
Between the two heads of pronator teres
Where is the AIN given off?
As it the median nerve passes deep to pronator teres
Anterior interosseous nerve function
Purely motor
Supplies FPL, Pronator quadratus, FDP 1 and 2
FPL function
Flexion of thumb at interphalangeal joint, key function for grip
Pronator quadratus
Pronation of forearm
Function of FDP
Flexion of DIP in 2-4th fingers
Median nerve in the hand
Passes deep to the flexor retinaculum to innervate the LOAF muscle
Lumbricals
Opponens pollicis
Abductor pollicis brevis
Palmar digital nerves-> palmar aspect of thumb, second, third and half of fourth fingers. Raedial aspect of the palm and dorsl aspect of the distal middle phalanges of the sconed, third and half of fourth fingers
Palmar cutaneous bracnh given off proximal to the carpal tunnel and supplies the median eminence and proximal palm on radial aspect of hand
Three major median nerve entrapment syndromes
Pronator teres syndrome
AIN syndrome
CTS
Pronator teres syndrome
Results from entrapment of the median nerve as it passes between the two heads of the pronator teres and under the fibrous arch of the FDS
Compression may be caused by thickened lacertus fibrosus, hypertrophied pronator teres, tight fibrous band of the FDS
Pain in forearm with weakness in hand grip and numbness and tingling in the index finger and thumb.
Similar symptoms to CTS with hand assuming a “benedicton” attitude in severe cases. Nocturnal exacerbation is absent normally
Weakness is variable but often there is no measurable weakness in median nerve innervated muscles
How to differentiate between Hand of Benediction and Ulnar Claw
Ulnar claw usually seen at rest whereas in Hand of Benediction there is weakness on active flexion in the radial three digirs
Pain in forearm
Weakness in hand attitdue
Numbness in median nerve distribution without nocturnal exacerbation
?Pronator teres syndrome
DDx
Ulnar claw or Hand of Benediction
AIN snyfrome
Most commonly due to a constricting band causing entrapment neuropathy near the origin of the nerve
FDP and FPL weakness
Abnormal pinch attitude of the hand
Weakness in pronator quadratus is usually clinically insignificant due to more powerful pronator teres.
No sensory deficit
Abnormal pinch attitude
Extension of hyperextension of the terminal phalanges of the thumb and index finger when the thumb and index finger are opposed
Abnormal pinch attitude of the hand due to weakness in FDP and FPL
Normal sensation
AIN syndrome
CTS
Caused by compression of the median nerve as it passes through the carpal tunnel
Pain anad paraesthesia in wrist and hand awakening patient from sleep
Sensory loss in te ditsirubiton of the palmar digital branches Isensory loss easiest to discern along vola tips of index and middle fingers)
Pain may also involve forearm, elbow or shoulder- classically this pain may radiate from distal to proximal and may be associated with shaking the hand to alleviate pain in contrast to cervical radiculopathy in which movement exacerbates pain.
Motor symptoms are usually late- LOAF muscles affected- weakness in abduciton, opposition and flexion of thumb.
Phalen’s positive
Function of lumbricals
Flex fingers at the MCPJ
Function of opponens pollicis
Opposition refers to the rather complex movement of the thumb which is a combination of flexion, adduction and medial rotation at the first carpometacarpal joint
Function of Abductor pollicis brevis
Abduction of thumb at MCPJ
Phalen’s test
Forcibly dosriflexing affected hand for 60 seconds
Positive test will reproduce symptoms
What is the most reliable assessment of thenar muscle function?
Abductor pollicis brevis
Nocturnal pain and paraesthesia in median distirubtion
Weakness and atrophy in LOAF muscless
Sensory loss
Carpal tunnel syndrome
Contents of carpal tunnel
9 tendons, 1 nerve
4 tendons of the FDS superifically
Median nerve
1 tendon of FPL
4 tendons of FDP
Roots of the ulnar nerve
C7/8/T1
Medial cord of the brachial plexus
Branches of ulnar nerve in arm
None
Ulnar nerve branches at the elbow
Ulnar nerve enters a groove between the medial humeral epicondyle and olecranon process
Groove covered by an aponeurosis formng an osseofibrous canal (cubital tunnel)
Two motor branches- FCU and FDP to fourth and fifth fingers
Boundaries of the cubital tunnel
Roof: Cubital tunnel retinaculum (band of Osbourne)
Laterally: Olecranon
Medially: Medial epicondyle
Floor: elbow joint capsule, posterior band of medial collateral ligament of elbow joint
Ulnar nerve in forearm
Passes between two heads of FCU to take place superifical to FDP
Two sensory branches- palmar cutaneous branch-> skin over hypothenar eminence
Dorsal cutaneous bramnch-> dorsal ulnar aspect of the hand and dorsal aspect of the fifth finger and half of fourth finger
Sensory branches of ulnar nereve in forearm
Palmar cutaneous branch
Dorsal cutaneous branch
Superficial sensory branch is given off as the ulnar nerve enters Guyon’s canal at the wrist
How does the ulnar nerve enter the hand?
Through Guyon’s canal
Borders of Guyon’s canal
Floor- transverse carpal ligament, hypothenar msucles
Roof- Volar carpal ligament
Ulnar border- Pisiform and pisohamate ligament, abductor minimimuscle belly
Radial border- Hook of hamate
Branches of the ulnar nerve in hand
Superficial sensory branch given off proximally in the canal- supplies the distal part of theulnar aspect of th eplam and the palmar aspect of the fifth and half of the fourth finger
Contineus as deep motor branch supplying:
Abductor digiti minimi
Opponens digiti minimi
Flexor digiti minimi
Lumbricals 3 and 4
Interosseous muscles
Addcutor pollicis
Flexor pollicic brevis
Action of abductor digiti minimi
Abducts and flexes 5th finger
Action of opponens digiti minimi
Opposition of the little finger with the tip of the thumb
Deepends hollow of the palm
Action of the flexor digiti minimi
Flexes little finger
Lumbricals action
Flex MCPJ and extend interphalangeals
Interosseous muscle actions function
PAD- palmar adduct
DAB- dorsal abduct
Action of adductor pollicis
Adducts CMCJ of the thumb
Flexor pollicis brevis function
Flexes thumb at MCPJ
Two major syndromes assocaited with ulnar nerve
Cubital tunnel syndrome
Guyon’s canal syndrome
What is a key differentiator between Cubital tunnel and Guyon’s canal syndrome
Dorsal cutaneous nerve which is spared in Guyon’s canal but affected in cubital tunnel
Cardinal features of cubital tunnel syndrome
Numbness and tingling of the ulnar aspect of hand
Weakness variously described as imapirment of hand grip, clumsiness or difficulty buttoning shirt
Atrophy in hypothenar eminence and first interosseous space.
Sensory loss most easily observed in the distal two phalnges of the little finger
Claw hand deformity
Froment’s sign
Claw hand
Results from simultaenous hypextension at the MCPJ and flexion at IPJ
Hyperextension at the MCPJ is due to wekness of rthe lumbricals with unopposed action of the extensor digotorum
Flexion at the IPJ is due to passive tethering pull of the flexor digitorum which occurs when the MCPJ are in extension
Froment’s sign
Due to weakness in adductor pollicis
On grasping a piece of paper between thumb and index finger and pulling
Positive when the patient attempts to compensate for lack of thumb adduction with extension of the PIPJ and felxion of the distal phalangex
Why are the FCU and FDP often spared in cubital tunnel syndrome?
Because they are situated deeply within the nerve and may be spared the more suprifically localted fibres which are compressed first
Differneces between cubital tunnel and CTS
Cubital tunnel less frequently associated with pain with weakness and atrophy early rather than late
Hypothenar wasting
Paraesthesia on medial border of hand
Weakness and clumsiness in hand
Atrophy of the dorsal interossei and hypothenar eminence
Claw hand
Froment’s sign
?Cubital tunnel syndrome
Classification of Guyon’s canal syndrome
Three types based on the site of the compression
Zone 1 to 3 based on site of compression
Guyon’s Canal Syndrome Zone 1
Mixed motor and sensory symptoms
Proximal to bifurcation of the nerve
Common causes of compression: Ganglia and hook of hamate fractures
Guyon’s Canal Syndrome
Zone 2
Surrounds deep motor branch
Predominantly motor symptoms
Common causes include ganglia and hok of hamate fractures
Guyons Canal Syndrome
Zone 3
Surrounds superifical sensory branch
Senosry symptoms only
Common caauses include ulnar artery thrombosis or aneursym
Loss of abductir digiti minimi, abductor pollicis, FDM, dorsal. interossei
Froment’s sign and claw hand
Loss of palmar sensation but not dorsal
Zone 1
Guyon’s canal syndrome
Sensory pattern is due to superifical sensory branch being affected but sparing of the dorsal cutaneous branch
Hypothenar muscles spared (abductor digiti minimi and flexor digiti minimi)
Loss of adductor pollicis and dorsal interossei
Froment’s sign and claw hand
Preserved sensation
Zone 2 Guyon’s canal syndrome
Hypothenar muscle sparing due to early origin
Sensation spared
All hand muscles spared
Loss of palmar but not dorsal sensation over ulnar border
Froment’s and Claw hand absent
Zone 3 Guyon’s canal syndrome
LFC
Direct branch of the lumbar plexus
Provides sesnosry innervation to the skin of the ventrolateral aspect of the thigh
Anatomy of the LFC
Purely sensory nerve dervied from the second and third lumbar nerves of the lumbar plexus
Emerges from lateral aspect of psoas to run obliquely and forward across iliacus
Passes across the iliac fossa medial to ASIS, enters the thigh beneath the inguinal ligament piercing the fascia lata of te lateral thigh.
Supplis the skin of the ventrolateral aspect of the thigh
Meralgia paraesthetica
Syndrome of the LFC
Usually caused by compression of the nerve in the inguinal region.
Characterised by paraesrthesia involving the ventrolateral of th e thigh.
Common in obese individuals whose abdominal girth causes excessive strain on the inguinal ligament
Fat
No motor signs
Paraesthesia in ventrolateral thigh
Meralgia paraesthetica
Saphenous nerve
Terminal branch of femoral nerve in lower limb, provides sensory innervation to the ventromedial aspect of the knee leg and foot
Anatomy of the saphenous nerve
Purely sensory branch of femoral nerve
Originatse below the inguinal ligament and enters Hunter’s canal, crossing the femoral artery from medial to laterally and exits by piercing its root
Divides into two terminal branches- infrapatellar branch supplying ventromedial aspect of the knee and a descneding branch which supplies the ventromedial aspect of the leg and ankle
Saphenous nerve compression syndrome
Occurs at exit point from adductor canal
Characterised by intense pain along medial aspect of the knee with associated numbness in this area and down medial leg.
No motor signs or symptoms
Intense pain along medial aspect of knee and leg
Numbness along medial aspect of knee and leg
Intact motor function
Saphenous nerve entrapment
What is the largest peripheral nerve in the body?
Saphenous
Anatomy of the sciatic nerve
Deirves from L4-S3
Leaves pelvis through the GSF behind the tendinous origin of piriformis
Courses laterally and downward to innervate semitendinous, semimembranosus, biceps femoris and adductor magnus.
Proceeds to popliteal fossa where it divides into terminal branches- tibial nerve and common peroneal nerve
Piriformis syndrome
Compression of the proximal segment of the sciatic nerve as it passes underneath the piriformis muscle
Cardinal features are;
Weakness in any or all of the knee flexors, ankle flexors, foot intrinsices. Sensory loss that may involve all of the foot
Can be confiused with lumbosacral radiculopathy
Weakness in any or all of the knee felxors, ankles flexors or extensors and foot intrinsics
Sensory loss involving all or part of the feet
?Piriformis syndrome
Peroneal nerve roots
L4 - S2
Anatomy of the common peroneal nerve
One of two terminal branches of the sciatic nerve taking origin in popliteal fossa.
Courses laterally winding round the neck of the fibula to divide into superficial and deep peroneal nerves
Superificial peroneal nerve
Branch of common peroneal nerve
Motor innervation to peroneus longus and brevis (foot everters)
Sensory to lower lateral leg and dorsum of the foot excluding the first dorsal webspace
Sensory supply of superficial peroneal
Lower lateral leg and dorsum of foot excluding first dorsal webspace
Deep peroneal nerve
Descends deep in anterior compartment of leg
Motor to:
Tibialis anterior, EHL, EDL, EDB
Sensory to:
First dorsal webspace
Tibialis anterior function
Deep peroneal nerve
Foot dorsiflexion and eversion
EHL function
Great toe extension
Foot dorsiflexion
Deep peroneal nerve
EDL foot function
Extensor of four lateral toes
Foot dorsiflexion
Function EDB in foot
Extenros of
Division of deep peroneal nerve
Proximal to ankle the nerve becomes superificial and divides into medial and lateral branches
Lateral (motor branch)-> EDB
Medial (sensory)-> first dorsal webspace
Most common site of peroneal nerve compression
Fibular head
Most superificial location and thus most susceptible to injury
Can be due to extrinsic compression
Deep peroneal nerve most commonly affected but common and superficial may also be
Peroneal nerve syndrome
Depends on affected branch
Ranges from common peroneal, to ddep or superficai palsy
Common peroneal palsy
Weakness of foot eversion and toe and foot dorsiflexion
Loss of sensation over dorsum of foot, toes and lateral aspect of lower leg
Deep peroneal nerve palsy
Weakness of foot and toe dorsiflexion as well as sensory loss involving the first dorsal webspace of foot
Superficial peroneal nerve palsy
Weakness of foot eversion
Loss of sensation in lateral aspect of lower leg and dorsum of foot and toes excluding first webspace
Weakness of foot eversion and toe and foot dorsiflexion
Loss of sensation over dorsum of foot, toes and lateral aspect of lower leg
Common peroneal palsy
Weakness of foot and toe dorsiflexion as well as sensory loss involving the first dorsal webspace of foot
Deep peroneal nerve palsy
Cardinal features of peroneal nerve syndrome
Weakness in foot eversion and dorsfilexion of foot and toes
Senosry loss involving lateral lower leg and dorsum of foot an toes
Weakness of foot eversion
Loss of sensation in lateral aspect of lower leg and dorsum of foot and toes excluding first webspace
Superficial peroneal nerve palsy
Tibial nerve roots
L4-S3
Terminal branch of sciatic nerve
Tibial anatomy at popliteal fossa
Distal popliteal fossa-> medial sural cutaneous nerve
Branches to gastrocnemius and then soleus passing distally in the plane between these muscles
Formation of sural nerve
Medial sural cutaneous nerve (branch of tibial at popliteal fossa) joins the lateral sural cutaneous nerve (branch of the common peroneal nerve) at the level of the Achilles tendon
Sensory to skin on the lateral heel and lateral aspect of the foot and the small toe
Tibial nerve anatomy in upper thid of leg
Motor branches to tibialis posterior, FDL, FHL
TP function
Foot invresion
FDL function
Plantar flexion
FHL
Plantar flexion of great toe
Tibial nerve anatomy at ankle
Passes caudal and dorsal to the medial malleolus and under the flexor retinaculum (tarsal tunnel)
Gives off medial calacaneal branch variably, proximal or distal to the tarsal tunnel, pure sesnory branch supplying skin of medial heel
Two terminal branches distally in tarsal tunnel:
Medial plantar nerve- motor to medial intricis, sensory to medial three and a half toes
Lateral plantar nerve- sensory to lateral one and a half toes, and lateral intrinsccs
Tarsal tunnel syndrome
Burning pain and paraesthesia in any combination of heel (calcaneal), medial sole (medial plantar), lateral sole (lateral plantar)
Weakness of foot intrinsics
Draw the cervical plexus
https://www.youtube.com/watch?v=xdrzbM8ESNA
Suprahyoid muscles
My Gravy Spoon, Darling
Mylohyoid
Geniohyoid
Stylohyoid
Digastric
Infrahyoid muscles
TOSS
Thyrohyoid
Omohyoid
Sternothyroid
Sternohyoid
Mylohyoid innervation
Supplied by the nerve to mylohyoid, a branch of the inferior alveolar nerve
From V3
Geniohyoid innervation
Innervated by a branch of ventral ramus of C1 from cervical plexus, which courses with the hypoglossal nerve into the floor of the mouth
Stylohyoid innervation
CNVII
Innervation of diagstric
anterior belly- Trigeminal
Posterior velly- CN VII
Which is the only suprahyoid muscle not supplied by a cranial nerve?
Geniohyoid, supplied by ventral rami of C1 running with hypoglossal
Location of ansa cervicalis
Behind SCM, closesly related to spinal accessory and hypoglossal nerves
Division of cervical plexus
Superificial sensory branches
Deep motor branches
Superficial sensory branches of cervial plexus
Greater occipital nerve
Lesser occipital nerve
Greater auricular nerve
Transverse cervical nerve
Supraclavicular nerve
Greater occipital nerve
C2
Supplies skin of the posterior scalp
Which segment of ansa cervicalis provides no sensory branches
C1 as it has no dorsal root
Lesser occipital nerve
C2 spinal root
Supplies skin overlying the mastoid process extending just above and below the mastoid process to include part of the lateral head and lateral neck
Greater auricular nerve
C2-3
Supplies skin overlying external ear, parotid and angle of mandible
Transvere cervical nerve
C2-3
Supplies skin overlying anterior and lateral aspects of the neck from the body of the mandible to the sternum
Supraclavicular nerve
C3-4
Supply skin just above the clavicle
Deep motor branches
Branches to the accessory nerve
Ansa cervicalis
Branches to adjacent neck muscles
Phrenic nerve
Cervical plexus
Branches to accessory nerve
Travel with CN XI to supply SCM (C2-3) and trapezius (C3-4) muscles
Ansa cervicalis
Loop formed by a superior (C1/2) and inferior root (C2/3)
Superior root fibres run with the hypoglossal enrve for a short distance
Supplies the infrahyoid muscles- head flexors including thyrohyoid, omohyoid, sternohyoid, sternothyroid and geniohyoid (suprahyoid muscle)
Cervical plexus- branches to adjacent neck mucles
Small muscular branches innervate adjacent muscles of the neck which are flexors and rotators
Include the longus anteriorly, middle scalene laterally and levator scapulae posteriorly
Phrenic nerve
C3-5
Diahphragm
Injuires to cervical plexus
Involvement of superficial senosry roots-partial numbess of head or neck
Deep motor- weakness of forward or lateral neck flexion (infrahyoid/scalenes), rotation of head (SCM), rotation of scapula (levator scapulae)
Include penetrating trauma or iatrogenic lesions or mass lesions
Unilateral phrenic nerve injury
Tolerated whilst patient at rest but may result in SOBOE
Bilateral phrenic nerve injury
Usually associated with severe ventilatory compromise at rest unless it receives an anastomotic branch from subclavian nerve
Penetrating injury, surgical injury, intrathoracic mass
Weakness in:
Lateral neck flexion
Head rotation
Head flexion
Shoulder shurg
Respiration
Deep motor branches of ansa cervicalis
Scalene (deep motor)
SCM (spinal accesory)
Infrahyoid (ansa cervicalis)
Diagphragm (Phrenic)
Trapezius (spinal accessory)
Etymology phrenic
Phren- diaphragm
Draw the brachial plexus
https://www.youtube.com/watch?v=Z_Y_kVdH9zE
Where are the roots of the brachial plexus found?
In the posterior traingle of the neck
Bordres of posterior triangle
SCM anterioly
Trapezius posteriorly
Inferiorly middle third of clavicle
Where do the branchial trunks become their divisions
In the supraclavicular fossa the three drinks give rise to anterior and posterior divisions
The posterior divisions unite to form the posterior cord
Which trunks of the brachial plexus form the lateral cord?
anterior divsions of the upper and middle trunk
Which trunks form the medial cord
Anterior division of the lower trunk
How do the brachial plexus cords leave the posterior traingle of the neck
Through te otulet between the first rib and clavicle to enter the axilla
What are the branches from the roots of the brachial plexusD
Dorsal scapular
LTN
Function of LTN
Serratus anterior
Pulls scapula forward around thorax.
Palsy results in winging of scapula
Function of dorsal scapular nerve
Supplies rhomboids
Scapular retraction around the scapularthoracic joint
Levator scapulae:
The levator scapulae functions to elevate the scapula and tilt the glenoid cavity inferiorly by rotating the scapula downward. If the scapula is fixed, a contraction of the levator scapulae leads to the lateral flexion of the cervical vertebral column to the side and stabilizes the vertebral column during rotation.
Nerve roots dorsal scapular
C5
Nerve roots LTN
C5, 6, 7
Branches from the trunk of the brachial plexus
Nerve to subclavius
Suprascapular nerve
Both from upper trunk
Nerve to subclavius
From upper trunk of brachial plexus
Supplies subclavius muscle but may also contain accessory nerve fibres that join the phrenic nerve in the mediastinum
Suprascapular nerve
Infraspinatus- external rotation
Supraspinatus- abduction
Branches from divisions of brachial plexus
None
Branches of lateral cord of brachial plexus
Lateral pectoral
Muscultocutaneous
Lateral root of median nerve
Lateral pectroal nerve
Supplies pec major
Musculocutaneous nerve
BBC
and
Lateral cutaneous nerve of forearm
Branches of medial cord of brachial plexus
Medial pectroal
Medial brachial cutaneous
Medial antebrachial cutnaeous
Ulnar
Medial root of median nerve
Medial pectroal nerve
Pectoralis major and minor
Medial brachial cutaneous nerve
Sensory to skin on medial aspect of forearm
Medial antebrachial cutaneous nerve
Skin on medial aspect of the forearm
Branches of posterior cord of brachial plexus
Upper subscapular
Thoracodorsal
Lower subscapular
Termiantes as axillary and raidal nerves
Upper subscapular
Supplies upper part of subscapularis
Lower subscapular nerve
Lower part of subscapularis
Thoracodorsal nerve
Supplies lat dorsi
Axillary nerve
Supplies delotid and skin overlying muscle (regimental patch)
Common brachial plexus klesions
Traumatic:
Erb-Duchenne
Dejerine Klumpke
Entire plexus
Isolated lateral, medial, posterior cords
Non-traumatic:
Throacic outlet syndrome
Radiation brachial plexoparhy
Neuralgic amyotrophy
Describe Erb-Ducheenne Brachial plexus injury
Upper brachial plexus, traction on the C5/6 roots, excessive lateral displacement of the head to contralateral side or downward displacement of ipsilateral shoulder e.g. fall on shoulder
Arm internally rotated and adducted, forearm extend and pronated. Palm faces out and backwards-> waiter’s tip
Impairment of shoulder abduction (deltoid and supraspinatius)
Impariment of elbow flexion (Biceps, BR and brachialis involvement)
Impairment of external rotation of arm (infraspinatus involvement)
Impairment of supination (biceps)
Sensory loss limited to sin over deltoid
Depressed or absent biceps and BR reflexes
Arm internally rotated and adducted, elbow extended and pronated, palm faces out and back. Numbness over regimental patch
Upper brachial plexus injury
Erb-Duchenne
Impairment of shoulder abduction (deltoid and supraspinatus)
Impariment of elbow flexion (Biceps, BR and brachialis involvement)
Impairment of external rotation of arm (infraspinatus involvement)
Impairment of supination (biceps)
Sensory loss limited to sin over deltoid
Depressed or absent biceps and BR reflexes
Describe Dejerine-Klumpke brachial plexus injury
Lower brachial plexus injury involving traction on C8 and T1 roots, associated with hyperabduction of the arm.
Claw hand deformity with sesnosry loss in the ulnar distribution of hand and forearm +/- ipsilateral Horners
Deep tendon reflexes intact
Claw hand deformity with sesnosry loss in the ulnar distribution of hand and forearm +/- ipsilateral Horners
Deep tendon reflexes intact
?Klumpke’s
Explain the ulnar claw
Fingers extended at MCPJ due to unopposed action of the extensor digitorum (radial), flexed and IPJ due to unopposed action of the FD muscles (median)
Lumbricals and interossei normally provide flexion atthe MCPJ and extension at teh IPJ
Describe complete brachial plexus injury
Rare
High speed vehicular accident
Completely paralysed, asensate, areflexic limb
Describe lateral cord palsy
Loss of function of the median and musculocutaneous nerves
Impairment in elbow flexion and supination and impairment of forearm pronation, radial wrist flexion, wrist flexion, PIP flexion, a distal phalanx of thumb flexion, 2nd and 3rd DIP flexion impairment, impaired forearm supination.
Numbness in the lateral forearm
Biceps hyporeflexia
Impairment in elbow flexion and supination and impairment of forearm pronation, radial wrist flexion, wrist flexion, PIP flexion, a distal phalanx of thumb flexion, 2nd and 3rd DIP flexion impairment, impaired forearm supination.
Numbness in the lateral forearm
Biceps hyporeflexia
Lateral cord palsy
Describe medial cord palsy
Primarily affect the ulnar and median nerve
Impairment of ulnar wrist flexion, impairment of DIPJ flexion 3 and 4, finger abduction
Impairment of thumb abduction, opposition, proximal phalanx flexion
Sensory loss in the medial aspect of arm and forearm.
Deep tendon reflexes intact
Impairment of ulnar wrist flexion, impairment of DIPJ flexion 3 and 4, finger abduction
Impairment of thumb abduction, opposition, proximal phalanx flexion
Sensory loss in the medial aspect of arm and forearm.
Deep tendon reflexes intact
Medial cord palsy
Describe posterior cord palsy
Subscapular, thoracodorsal, axillary and radial nerves
Impairment of internal rotation of humerus (subscapular)
Impaired adduction of elevated arm (TD)
Impaired abduction (supraspinatus)
Impairment of elbow extension, wrist extension, forearm supination, finger extension
Sensory loss over entire extensor surface of the arm and forearm, dorsum of hand and first four finger
Absent or depressed triceps reflex
mpairment of internal rotation of humerus (subscapular)
Impaired adduction of elevated arm (TD)
Impaired abduction (supraspinatus)
Impairment of elbow extension, wrist extension, forearm supination, finger extension
Sensory loss over entire extensor surface of the arm and forearm, dorsum of hand and first four finger
Absent or depressed triceps reflex
Posterior cord lesion
Vascular thoracic outlet syndrome
Compression of subclavian artery or vein
Neurogenic thoracic outlet syndrome
Medial or lateral tunrk of brahcial plexus compression
Causes of thoracic outlet syndrome
Usually due to several anatomic anomalies in the region, most common is an incomplete cervical rib with a fascial band extending from the tip to the first rib.
Elongated C7 transverse process
Complete cervical rib
Anomalous insertion of anterior and medial scalene muscles
Shoulder and arm pain
Slight wasting and weakness of the hypothenar, interosseous, adductor pollicis and deep flexor muscles of fourth and fifth fingers
Numbness and tingling along the medial aspect of the forearm and hand
Thoracic outlet syndrome
Describe thoracic outlet syndrom
Vascular or neurogenic compression of the subclavian artery/vein or medial cord or lateral trunk of brachial plexus
Shoulder and arm pain
Slight wasting and weakness of the hypothenar, interosseous, adductor pollicis and deep flexor muscles of the fourth and fifth fingers
Reflexes usually preserved
May complain of numbness and tingling along medial aspect of forearm and hand
Apical lung tumour syndrome
Pancoast’s tumour, usually SCC in the superior sulcus of lung
May compress or envelope lower brachial plexus
May have symptoms similar to thoracic outlet syndrome with posterior cord involvement including weakness of triceps
May precede diagnosis of tumour
Pevious Breast Ca, RTx
Delayed onset intrinsic hand weakness associated with distal paraesthesias and sensory loss.
Atrophy
Radiation plexopathy
Severe pain as a presenting symptom may point to malignant infiltration of the plexus
Tends to be >1y post-irradiation.
Parsonage-Turner Syndrome
Abrupt onset of shoulder girdle or scapular pain
Followed by prominent weakness and atrophy of the upper arm muscle.
Movement or activity of the shoulder muscles tends to aggravate the pain, which is usually quite severe
May be preceded by infectious events
Pain persists for up to 2/52 5then abates, weakness and atrophy usually appear when pain disppaers.
Abrupt onset of shoulder girdle or scapular pain
Followed by prominent weakness and atrophy of the upper arm muscle.
Movement or activity of the shoulder muscles tends to aggravate the pain, which is usually quite severe
May be preceded by infectious events
Parsonage-Turner Syndrome
Draw the lumbosacral plexus
https://www.youtube.com/watch?v=T_GlJu0dxkA
Anatomy of lumbar plexus
Union of the ventral rami of T12 to L4
Upper part- T12-L2, 3 nerves with sensory branches
Lower part L2-4, 2 mixed nerves femoral and obturator, 1 sensory nerve LFC)
After leaving the psoas muscle, the upper nerves of the lumbar plexus each run parallel to the lower intercostal nerves where they help supply the transverse and olbique abdominal muscles
Iliohypogastric
T12-L2
Two cutaneous branches, anterior and lateral
Anterior- skin over anterior wall about pubis
Lateral- skin over outer buttock and hip
Ilioinguinal nerve
L1
Skin of medial thigh below the IL and skin of symphysis pubis and external genitalia
Genitofemoral nerve
L1-2
Two branches
Genital- Skin over scrotum
Femoral- skin over femoral triangle
Motor to cremaster
Nerve roots of femoral nerve
L2-L4
Anatomical course of femoral nerve
Mixed motor/sensory nerve that arises within psoas
Runs in the groove between the psoas and iliacus (hip flexors), which it supplies
Descends behind the inguinal ligament to enter the femoral triangle and divide into anterior and posterior divisions
Innervation of psoas major
Direct branches of ventral rami from lumbar plexus L1-3
Innervation of iliacus
Femoral nerve L2-4
Anterior division of the femoral nerve
Supplies a muscular branch to sartorius (external rotator of thigh)
Sensory to skin of the anterior and medial aspects of thigh- the anterior cutaneous nerve of thigh
Supplies a muscular branch to sartorius (external rotator of thigh)
Sensory to skin of the anterior and medial aspects of thigh- the anterior cutaneous nerve of thigh
Anterior division of femoral nerve
Posterior division of femoral nerve
Supplies a muscular branch to quadriceps (extensor)
Sensory to skin over medial aspect of leg and foot (saphenous nerve)
Supplies a muscular branch to quadriceps (extensor)
Sensory to skin over medial aspect of leg and foot (saphenous nerve)
Posterior division of femoral nerve
Function of femoral nerve
Hip extension
External rotation
Leg extension
Sensation of anteromedial thigh and medial leg and foot
Obutrator nerve roots
L2-4
Anatomical course of obturator
Mixed motor/sensory nerve that arises within psoas and passes through the obturator canal, descending into the medial thigh.
Motor to adductor muscles of the thigh
Sensory to the skin over the medial aspect of the thigh
Mixed motor/sensory nerve that arises within psoas and passes through the obturator canal, descending into the medial thigh.
Motor to adductor muscles of the thigh
Sensory to the skin over the medial aspect of the thigh
Obturator nerve
What is the only muscle of the medial compartment of thigh not supplied by obturator
Hamstring portion of adductor magnus (tibial portion of sacral)
What are the four groups of nerves formed by the sacral plexus
Motor gluteal nerves
Posterior femoral cutaneous nerve (sensory)
Pudendal (mixed)
Sciatic (mixed)
Superior gluteal nerve roots
L4-S1
Anatomical course of superior gluteal nerve
Passes above piriformis to supply glkuteus medius, gluteus minimus and TFL which are abductors and internal rotators of the thigh
Inferior gluteal nerve roots
L5-S2
Anatomical course of inferior gluteal nerve
Passes below piriformis to supply gluteus maximus, major hip extensor
Posterior femoral cutaneous nerve roots
S1-S3
Anatomical course of PFC
Sensory nerve leaves the pelvis to enter buttock via the greater sciatic notch
Supplies skin of posterior thigh and popliteal fossa
Pudendal nerve roots
S2-4
Anatomical course of pudendla nerve
mixed leaves pelvis to enter perineum via the greater sciatic notch
Motor to perineal muscles and external anal sphincter
Sensory to skin of perineum, penis, scrotum and anus
Features of lesions of the lumbar plexus
Usually incomplete, abdominal pathology
Motor: weakness in hip flexion, leg extension, thigh external rotation and thigh adduction
Sensory loss to the inguinal and genital region, lateral thigh, anterior and medial thigh, medial leg and foot
Absent femoral or genitofemoral reflexes
Usually incomplete, abdominal pathology
Motor: weakness in hip flexion, leg extension, thigh external rotation and thigh adduction
Sensory loss to the inguinal and genital region, lateral thigh, anterior and medial thigh, medial leg and foot
Absent femoral or genitofemoral reflexes
Lumbar plexus lesion
Sacral plexus lesions
Usually incomplete
Pelvic
Weakness in the abduction and internal rotation of the thigh, hip extension, knee flexion and all muscles of leg and foot
Sensory loss in posterior thigh and most of leg and foot except medial aspect
Absent achilles
Bowel and bladder control compromised
Neurotransmitter of postganglionic SNS
NAdr except for adrenal medulla (Adr) and sweat glands (NACh)
What causes the functional divergence of the symapthetic nervous system
Preganglionic SNS fibres characteristically synapse on several postganglionic neurones
In contrast to PNS in which the ganglionic innervation is relatively discrete
Afferent sympathetic fibres
Pass through sympathetic ganglia without synapsing
Enter spinal nerves via white communicating rami and synapse in thoracolumbar DRG
Afferent fibres carrying visercal pain related impulse run in
Sympathetic fibfes
In contrast to other visceral afferent stimuli which travel with parasympathetics
Hering-Bruer reflex
Ventilatory reflex protecting lung from hyperinflatoin
As lung inflates afferent impulses are sent to expiratory centre through relay in nucleus of the solitary tract
expiratory centre in turn inhibits the inspiratory centre and promotes passive expirration.
Termination of autonomic afferent fibres from baroreceptors
In the nucleus solitarius
