Upper Limb Flashcards
Pectoral girdle:
- consists of the clavicle and scapula
- suspends the humerus and the upper limb away from the axial skeleton to increase range of movement
- can be elevated, depressed, protracted, and retracted
- elevated (shoulders to ears)
- depressed (shoulders down)
- protracted (horizontal movement - butterfly stroke bringing hands together)
- retracted (butterfly stroke hands apart) on the chest wall
sternoclavicular joint:
- where the medial end of the clavicle articulates with the sternum
- this is the ONLY articulation between the axial skeleton and the upper limb
- it contains an articular disk that divides the joint into 2 joint cavities
- at the joint between the articular disk and the sternum the clavicle can be protracted (arch forward bringing clavicles closer) and retracted (bringing scapula medial and clavicle out)
- at the joint between the articular disk and the medial end of the clavicle the clavicle can be elevated and depressed
acromioclavicular joint
-where the lateral end of the clavicle articulates with the acromion process of the scapula
Clavicular fractures:
- most commonly occur at the weakest point between the middle 1/3 and lateral 1/3
- medial 2/3 of the clavicle may be elevated by the sternocleidomastoid muscle
- lateral 1/3 may be depressed by weight of limb or aDDucted by the pectoralis major
- ventral rami of C8-T1 in the medial cord of the brachial plexus may be lacerated as a result of the fracture
Shoulder trauma to the acromioclavicular joint:
-may cause subluxation (displacement) of the acromion process at the joint
coracoclavicular ligament
- extends from the acromion to coracoid
- prevents dislocation at the acromioclavicular joint
glenohumeral joint:
- ball in socket joint that articulates the head of the humerus with the glenoid fossa of the scapula
- permits flexion and extension
- abduction and adduction
- medial and lateral rotation
Association between humerus and scapula movement
- when the humerus aBducts, the scapula laterally rotates along the chest wall
- when the humerus aDDucts, the scapula medially rotates along the chest wall
- aBduction: for every 2 degrees of abduction of the arm at the glenohemoral joint there is a 1 degree lateral rotation of the scapula
(ie) for every 180 degrees of full aBduction there is 120 degrees of rotation of the humerus and 60 of the scapula
Tendons of the rotator cuff:
- strengthen the articular capsule of the glenohumeral joint
- includes: supraspinatus, infraspinatus, teres minor and subscapularis (SITS)
Inflammation of the rotator cuff:
- tendons may become torn or inflamed
- most commonly affects tendon of supraspinatus
- patients experience pain anterior and superior to the glenohumeral joint during aBduction
Capsule of the glenohumeral joint:
- strengthened by ligaments
- glenohumeral bands: strengthen anterior aspects of the joint
- coracohumeral ligament: strengthens the superior aspect of the joint
- coracoacromial ligament: prevents superior displacement of the head of the humerus
humeral dislocation:
- dislocation of the humerus at the glenohumeral joint most commonly displaces the head of the humerus inferiorly and then anteriorly
- becomes positioned just inferior to the coracoid process
- may stretch the axillary nerve or the radial nerve
humeral fracture of the surgical neck of the humerus
-the axillary nerve may be lesioned and the posterior circumflex humeral artery may be lacerated
humeral fracture of the greater tubercle of the humerus:
- may result in avulsion of the greater tubercle and detachment of the rotator cuff muscles from the humerus
- in these patients the remaining rotator cuff muscle. the subscapularis, medially rotates the humerus at the glenohumeral joint
transverse fracture of the humerus:
- distal to the deltoid tuberosity
- may result in aBduction of the proximal fragment by the deltoid muscle
midshaft fracture of humerus:
- the radial nerve may be lesioned
- profunda brachial artery may be lacerated
supracondylar fracture of humerus:
- contractions of the triceps and the brachialis may shorten the arm
- median nerve may be lesioned as a result of intercondylar or supracondylar fracture of the distal end of the humerus
Elbow joints:
- humeroradial joint, humeroulnar joint, and proximal radioulnar joint
- humeroradial and humeroulnar joints are hinge joints that permit flexion and extension
humeroradial joint:
head of the radius articulates with the capitulum of the humerus
humeroulnar joint:
-trochlear notch of the ulna articulates with the trochlea of the humerus
proximal radioulnar joint:
- the radial notch of the ulna articulates with the head of the radius
- pronation and supination occur at this joint and at the distal radioulnar joint
Lateral Epicondylitis:
- tennis elbow
- an inflammation of the common extensor tendon that results from forced extension and flexion of the forearm at the elbow
- patients exhibit pain over the lateral epicondyl (may radiate down the posterior aspect of the forearm)
Medial epicondylitis:
- golfer’s elbow
- an inflammation of the common flexor tendon that results from repetitive flexion and pronation of the forearm at the elbow
Fracture of the medial epicondyle of the humerus:
-ulnar nerve may be lesioned
Articulations of the wrist:
- proximally with the radius at radiocarpal and ulna at ulnocarpal joints
- distally with the metacarpels at caropmetacarpal joints
What forms the radiocarpal joint?
-distal end of the radius, scaphoid, and lunate
What forms the ulnocarpel joint?
-formed by the distal end of the ulna, an articular disk, and the triquetrum
What do the radiocarpal and ulnocarpel joints allow?
- flexion/extension
- aBduction (radial deviation wave hi wrist towards thumb)
- aDDuction (ulnar deviation wave hi wrist towards pinky)
Colles’ Fracture
- fracture of the distal radius
- may result in avulsion of the styloid process from the shaft of the radius
- radius may be shortened and styloid process of the ulna may project further distally than the styloid process of the radius
- fracture of the distal radius, forearm, or hand may exhibit a “dinner fork” deformity as a result of the posterior displacement of the distal part of the radius
How many carpel bones are there?
8
Arrangement of the carpel bones
-into 2 loosely arranged rows: proximal and distal
Proximal row:
- contains (lateral to medial) scaphoid, lunate, triquetrum, and pisiform bones
- pisiform is anterior to triquetrum
- pisiform is a sesamoid bone that is embedded in the tendon of the flexor carpi ulnaris
Distal row:
-contains (lateral to medial) trapezium, trapezoid, capitate, and hamate bones
Lunate dislocation:
- lunate is most commonly dislocated carpal bone
- it is typically dislocated anteriorly into the carpal tunnel
- dislocation may cause carpel tunnel syndrome
carpal tunnel formed by:
- formed posteriorly by the 8 carpel bones
- anteriorly by the flexor retinaculum which attaches medially to the pisiform and hamate, laterally to the tubercles of the scaphoid and trapezium
carpel tunnel contains:
-median nerve and 9 tendons that arise from the 3 flexor muscles
3 flexor muscles of the forearm:
in the anterior forearm:
- flexor digitorum superficialis
- profundus
- flexor pollicis longus
Canal of Guyon:
- situated between the pisiform and the hook of the hamate superficial to the carpel tunnel
- ulnar nerve, artery, and vein cross the wrist and pass into the hand after transversing it
Joints in each of the 4 fingers:
- formed by a metacarpel and 3 phalanges
- metacarpophalangeal (MP) joint
- proximal interphalangeal (PIP) joint
- distal interphalangeal (DIP) joint
MP Joint:
- metacarpels articulate with the proximal phalanges
- MP joints are condyloid joints: permit flexion, extension, aBduction, and aDDuction
PIP Joint:
- proximal phalanges articulate with the middle phalanges
- hinge joint: permits flexion and extension
DIP joint:
- middle phalanges articulate with the distal phalanges
- hinge joint: permits flexion and extension
Thumb joints:
- 3 joints
- carpometacarpal
- MP joint
- interphalangeal joint
- MP and interphalangeal joints of the thumb have actions similar to those in the fingers
Carpometacarpel joint:
- formed by the first metacarpel and by the trapezium
- saddle joint: permits flexion, extension, aBduction, aDDuction, and rotation
Anatomic Snuffbox:
- small region on the posterolateral part of the wrist
- formed by the tendons of the 2 extensor muscles of the thumb and the aBductor pollicis longus
- lateral border: extensor pollicis brevis and aBductor pollicis longus
- Medial border: extensor pollicis longus
What is in the floor of the snuffbox:
-scaphoid and trapezium bones
Blood supply/innervation in snuffbox:
- radial artery passes through the snuffbox
- superficial branch of the radial nerve innervates the skin over the snuffbox
Scaphoid fracture:
- most commonly fractured carpal bone
- patient exhibit pain and tenderness localized over the snuffbox
- proximal part of the scaphoid may undergo avascular necrosis because the blood supply to the bone supplies the distal part first and then the proximal part
Humeral fracture nerves affected:
ARM fracture:
From superior to inferior:
Axillary: head of humerus
Radial: mid shaft
Median: supracondular
Subclavian artery branches:
- arises from the brachiocephalic artery on the right and the arch of the aorta on the left
- becomes the axillary artery at lateral border of the first rib
Thyrocervical trunk of the subclavian:
-gives rise to the suprascapular and transverse cervical arteries which supply muscles that attach to the scapula
suprascapular artery:
- crosses posterior to the triangle of the neck
- passes over the transverse scapular ligament
- supplies the supraspinatus and infraspinatus on the posterior aspect of the scapula
- to remember think Air force = ABOVE while navy = BELOW
- artery is above the suprascapular ligament, nerve is below
transverse cervical artery
- crosses the posterior triangle of the neck
- divides into a superficial branch that supplies the trapezius
- divides into a deep branch (dorsal scapular artery) that supplies the rhomboids and the levator scapulae
- runs with accessory nerve
axillary artery:
-divided into 3 parts by the pec minor and has 6 branchs:
1 from the first, 2 from the second, and 3 from the third
"Screw The Lawyer Save A Patient": Superior thoracic Thoracoacromiol Lateral thoracic Subscapular Anterior circumflex humeral Posterior circumflex humeral
first part of the axillary artery:
-contains the superior thoracic artery which supplies the first 2 intercostal spaces and the serratus anterior
second part of the axillary artery:
- thoracoacromial artery: supplies the anterior wall of the axilla (including the pecs, deltoid, clavicle, and acromioclavicular joint)
- lateral thoracic artery: courses with the long thoracic nerve and supplies the serratus anterior, the pecs, and the breast
third part of the axillary artery:
- subscapular artery: largest branch of the axillary artery which gives rise to the circumflex scapular artery (courses around the lateral border of the scapula to supply the teres minor, major, and infraspinatus) and the thoracodorsal artery (supplies the latissimus dorsi)
- posterior circumflex humeral artery: arises adjacent to the subscapular artery and courses with the axillary nerve through the quadrangular space around the surgical neck of the humerus
- anterior circumflex humeral artery: smaller than the posterior circumflex humeral and supplies the muscles in the anterior arm
Axillary artery occlusion:
- if the first or second part of the axillary artery (or the subclavian artery) are occluded then the circumflex scapular and thoracodorsal branches of the subscapular artery contribute to collateral circulation to bypass the block
- anastomoses may develop superior and posterior to the scapula between the thoracodorsal and circumflex scapular branches of the subscapular artery and the suprascauplar, dorsal scapular, and posterior intercostal arteries
Brachial artery:
- continues from the axillary at the lower border of the teres major tendon and supplies the anterior/posterior aspect of the arm
- branches into profunda brachial artery
- also branches into the radial artery and ulnar artery in the cubital fossa (they supply the forearm and hand)
profunda brachial artery:
- spirals around the midshaft of the humerus with the radial nerve
- supplies the triceps brachii muscle and contribute to collateral circulation around the elbow
Volkmann’s Ischemic Contracture:
- caused by supracondylar fracture of the humerus
- displacement of the humerus due to this fracture may compress the brachial artery and result in ischemia of the forearm and hand
- patients have a hand that is severely flexed at the wrist and fingers that are severely flexed at the interphalangeal joints
Dupuytren’s contracture:
- caused by fibrosis and shortening of the palmar aponeurosis
- thickening and shortening of the bands of the aponeurosis over the flexor tendons results in flexion of the ring and little fingers
Ulnar artery:
- supplies the medial side of the forearm and the hand
- branches into the common interosseous artery, superficial arch, and deep branches
common interosseous artery
arises from the ulnar artery in the cubital fossa
-branches into an anterior interosseous artery and a posterior branch which supply the deep muscles in the anterior and posterior forearm
superficial arch:
- continuation of the ulnar artery
- forms the superficial palmar arch in the palm of the hand and branches into palmar metacarpal arteries which supply the hand and digits
Deep branches of the ulnar artery:
-anastomoses with the medial part of the deep palmar arch
Radial artery:
- supplies the lateral side of the forearm and the hand
- has superficial branch and distal part
superficial branch of the radial artery:
- arises from the radial artery at the wrist
- anastomoses with the lateral part of the superficial palmar arch
distal part of the radial artery:
- courses dorsal to the wrist and crosses the floor of the anatomic snuffbox
- enters the deep part of the palm after passing between the 2 heads of the first dorsal interosseous muscle
- forms the deep palmar arch that branches into dorsal metacarpal arteries which supply the hand and digits
Superficial veins of the arm:
- cephalic and basilic veins
- arise from a venous network on the dorsal aspect of the hand
Cephalic vein:
- arises from the lateral aspect of the venous network
- courses on the anterolateral aspect of the forearm and arm
- passes between the deltoid and pectoralis major
- drains into the axillary vein
Basilic vein:
- arises from the medial aspect of the venous network
- courses on the medial aspect of the forearm
- courses with the brachial artery in the arm
- joints with the brachial vein to form the axillary vein
Ventral rami that form the brachial plexus:
- C5-T1 spinal nerves
- provides innervation of the upper limb
- every nerve coming out of the brachial plexus contains at least 2 spinal cord segments (so every muscle in the upper limb innervated by one of these nerves is being innervated by at least 2 spinal cord segments which protects against spinal cord lesions)
Branching pattern of the ventral rami of the brachial plexus:
Roots (5)
Trunks (3)
Divisions (6)
Cords (3)
(10) branches
Terminal Nerves (5)
Rob Thompson Drinks Cold Beer Tuesday
Cubital fossa contents:
“My Bottoms Turned Red”
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medial to lateral
Median nerve
Brachial artery
Tendon of biceps
Radial nerve
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What rotation do the upper limbs undergo during development?
-lateral rotation
The axilla triangular boundaries:
The armpit, between the pec major and minor: contains blood supply/innervation of the upper limb
Posterior wall: humerus, teres major, latissimus dorsi, subscapularis, scapula
Medial wall: serratus anterior and rib
Anterior wall: pectoralis major and minor
Superior Trunk of Brachial Plexus:
- formed by the ventral rami of C5 and 6
- nerves from the superior rami innervate proximal muscles in the upper limb (pectoral girdle and shoulder)
Middle trunk of the brachial plexus:
- formed by the ventral rami of C7
- nerves that contain fibers in the intermediate rami innervate muscles that act mainly at the elbow and wrist
inferior trunk of the brachial plexus:
- formed by the ventral rami of C8 and T1
- nerves that contain fibers from the inferior rami innervate distal muscles such as those in the hand
Gradient of innervation in the brachial plexus:
-ventral rami of the brachial plexus exhibit a proximal to distal gradient of innervation
Anterior and posterior divisions of the brachial plexus:
- 6 divisions are formed when each trunk divides into anterior and posterior fibers
- FIVE final terminal nerves:
- 3 anterior (form the “M”): musculocutaneous nerve (lateral), median nerve, and ulnar nerve (medial)
- 2 posterior: Axillary (lateral branch of the radial), Radial, and
Anterior division fibers:
- innervate the muscles in the anterior arm, forearm, and hand
- FLEXORS
- musculocutaneous, ulnar, median, lateral, and medial pectoral nerves
Posterior division fibers
- innervate the muscles in the posterior forearm and arm
- EXTENSORS
- axillary, radial, upper, middle, lower subscapular nerves
Three cords:
- formed when the anterior fibers join together and when the posterior fibers join
- cords named for their relationship to the axillary artery
Lateral cord: superior and middle trunks of the anterior division fibers
Medial cord: inferior trunk of the anterior division fibers
Posterior cord: posterior divisions of all 3 trunks
Ten collateral nerves:
10 collateral nerves come off roots of big 5 – mainly innervating muscles around the shoulder
C5 - Dorsal Scapular
C5, C6, C7 – Long thoracic
Upper trunk – Suprascapular
Lateral cord – Lateral pectoral
Medial Cord – Medial Pectoral, Medial Brachial Cutaneous, Medial Antebrachial Cutaneous
Posterior – Subscapular (lower and upper), Thoracodorsal (Middle Subscapular)
Five terminal nerves:
musculocutaneous, ulnar, and median form the M and arise from the lateral and medial cords
radial and axillary arise from the posterior cord
Preplexus injuries:
-affect the ventral rami or the trunks of the brachial plexus proximal to the formation and branching of terminal and collateral nerves and have a more widespread effect than lesions in individual collateral or terminal nerves
Erb-Duchenne Syndrome:
CAUSES:
-results from a lesion of the C5 and 6 ventral rami in the superior trunk of the plexus
EFFECTS:
- proximal musculature in the upper limb is mainly affected, muscles acting at the shoulder and elbow will be weakened
- C5 and 6 dermatomes of the lateral arm, forearm, thumb, and index finger may experience altered sensation
SYMPTOMS:
- upper limb is held in “waiter’s tip” position due to a loss of aBduction and weakness of flexion and lateral rotation at the glenohumeral joint (arm remains aDDucted, extended, and medially rotated)
- elbow flexion, supination, and wrist extension may also be weakened. Forearm remains pronated and carpal flexors flex the hand at the wrist
- rhomboid muscles, levator scapular, and serratus anterior muscle remain unaffected because the nerves that innervate them arise from ventral rami proximal to the lesion
Klumpke’s Paralysis:
CAUSES:
- results from compression of C8 and T1 ventral rami in the inferior trunk of the plexus
- may be due to compression of the inferior trunk by a cervical rib or by a pancoast tumor in the apical part of a lung. May be seen in conjunction with other symptoms of thoracic outlet syndrome.
EFFECTS:
- distal muscles in the upper limb affected
- altered sensations in skin of C8-T1 dermatomes in the medial hand, ring, and little fingers and medial forearm
- patients experience weakness of the intrinsic muscles of the hand innervated by C8 or T1 fibers in the median and ulnar nerves
SYMPTOMS:
- patients present with ape hand and a claw hand
- patients may have difficulty making a fist due to weakness in muscles that flex at the MP and interphalangeal joints of the fingers
- Muscles that act at the shoulder and elbow remain unaffected
suprascapular nerve:
- C5 and 6
- arises from the upper trunk and crosses the posterior triangle of the neck deep to trapezius
- passes through the scapular notch under the superior transverse scapular ligament through the supraspinatus fossa around the spine of the scapula and into the infraspinous fossa
SUPPLIES:
-supraspinatus and infraspinatus
NEUROVASCULAR BUNDLE:
-exists as VAN
Suprascapular nerve lesions:
CAUSES:
-may be compressed as it courses through the scapular notch
EFFECTS:
-shoulder pain, weakness in aBduction of the arm at the glenohumeral joint and in lateral rotation at this joint
Lateral pectoral nerve:
- C5-7
- arises from the lateral cord
SUPPLIES:
-pectoralis major (its clavicular head)
Medial pectoral nerve:
- C8, T!
- airses from the medial cord
SUPPLIES:
- pectoralis minor
- passes through pec minor to innervate the pec major
brachial cutaneous nerve:
- C8, T1
- arises from the medial cord
SUPPLIES:
-skin on the medial aspect of the arm
Medial antebrachial cutaneous nerve:
- C8, T1
- arises from the medial cord distal to the medial brachial cutaneous
SUPPLIES:
skin on the medial aspect of the forearm
upper subscapular nerve:
- C5, 6
- arises from the posterior cord
SUPPLIES:
-upper part of the subscapularis
Thoracodorsal nerve:
- C6-8
- arises from the posterior cord between the upper and lower subscapular nerves
SUPPLIES:
latissimus dorsi
Thoracodorsal nerve lesions:
CAUSES:
-surgical procedure of the axilla may lesion
EFFECTS:
- difficulty in elevating the trunk (as if attempting to climb or do a push up)
- may have difficulty using a crutch
Lower subscapular nerve:
- C5-6
- arises from the posterior cord
SUPPLIES:
-lower part of the subscapularis muscle and teres major
dorsal scapular nerve:
- C5
- arises from the C5 ventral ramus of the plexus
- courses through the substance of the scalenus medius muscle and crosses the posterior triangle of the neck
- passes deep to the vertebral border of the scapula
SUPPLIES:
- levator scapulae
- rhomboid major
- rhomboid minor
NEUROVASCULAR BUNDLE:
-VAN
long thoracic nerve:
- C5, 6, 7
- arises from the superior 3 ventral rami
- passes posterior to the C8 and T1 ventral rami and then courses superficially on the lateral thoracic wall with the lateral thoracic artery
SUPPLIES:
-serratus anterior muscle
Long thoracic nerve lesions:
-most commonly injured since it courses superficial to the serratus anterior on the lateral wall of the thorax
SYMPTOMS:
- patients cannot hold the vertebral border of the scapula flat against the back and have a winging of the vertebral border of the scapula (medial winged scapula)
- also may experience weakness in ability to protract the scapula and difficulty raising arm above the head
Musculocutaneous nerve:
- terminal nerve
- C5-7
- contains anterior division fibers from the superior 3 ventral rami
- continues from the lateral cord and passes through the coracobrachialis muscles into the anterior compartment of the arm
- courses between the biceps and the brachialis muscles, emerging lateral to the tendon of the biceps
SUPPLIES:
- coracobrachialis, biceps brachii, and brachialis muscles
- continues as the lateral antebrachial cutaneous nerve (supplies skin of the lateral aspect of the forearm)
Musculocutaneous nerve lesions:
- uncommon
- nerve may be compresses as it passes through the coracobrachialis muscle
- patients may experience weakness in flexion of the forearm at the elbow and weakness in supination
median nerve:
- C6-T1
- contains anterior division fibers from all of the ventral rami EXCEPT C5
- formed by the lateral and medial cords uniting anterior to the axillary artery
- courses medial to the tendon of the biceps and the brachial artery in the arm. Reaches forearm after passing anterior to the elbow and deep to the bicipital aponeurosis
- passes through the carpal tunnel at the wrist between the flexor reticulum and the flexor tendons
In the FOREARM: passes between the 2 heads of the pronator teres and courses between the flexor digitorum superficialis and flexor digitorum profundus muscles to reach the wrist
SUPPLIES:
-superficial muscles in the anterior forearm (flexor carpi radialis, palmar longus, flexor digitorum superficialis, and pronator teres muscle)
What does the median nerve give rise to:
- anterior interosseous nerve in the cubital fossa
- recurrent branches distal to the carpal tunnel
- muscular branches distal to the carpal tunnel
- common palmar digital nerves
- proper digital cutaneous nerves
- palmar cutaneous branch proximal to the carpal tunnel
anterior interosseous nerve:
- in the cubital fossa which supplies deep muscles in the anterior forearm (lateral half of the flexor digitorum profundus, flexor pollicis longus, and pronator quadratus)
- only muscle in the anterior forearm NOT supplied by the median nerve are the brachioradialis (radial), flexor carpi ulnaris (ulnar), and the medial half of the flexor digistorum profundus (ulnar)
muscles in the anterior forearm NOT supplied by the median nerve:
- brachioradialis (radial)
- flexor carpi ulnaris (ulnar)
- medial half of the flexor digistorum profundus (ulnar)
recurrent branches of the median nerve:
-supply the 3 thenar muscles
muscular branches of the median nerve:
-supply the lumbricals to the index and middle fingers
common palmar digital and proper digital cutaneous nerves:
-supply the palmar aspects and sides of the radial 3 1/2 digits (thumb, index, middle and half of ring) and the nail beds of 2 1/2 digests
palmar cutaneous branch:
-crosses superficial to the flexor retinaculum and supplies skin of the palm up to the base of the lateral digits
Median nerve lesion - carpal tunnel:
CAUSES:
-carpal tunnel syndrome the median nerve is compressed as it courses through the carpal tunnel between the flexor tendons and flexor retinaculum
SYMPTOMS:
- numbness and pain (particularly at night) over the palmar aspect of the thumb, index, and middle fingers
- cutaneous sensation from the lateral aspect of the palm may be spared because the palmar branch of the median nerve does NOT transverse the carpal tunnel
- weakness of thenar muscles may be evident resulting in ape hand where the thumb cannot be opposed and is aDDucted/extended
- lateral 2 lumbricals weakened, results in slight clawing of the index and middle fingers due to reduced ability to flex the MP joints and extend the interphalangeal joints
Median nerve lesions - cubital fossa:
CAUSES:
- may be compressed proximal to the cubital fossa in a supracondylar fracture of the humerus
- ordistal to the cubital fossa as it passes between the 2 heads of the pronator trees
SYMPTOMS:
- altered sensation in the lateral part of the hand
- loss of thumb opposition
- weakness in pronation
- weakness in ability to flex the thumb, PIP and DIP joints of the index and middle fingers, and PIP joints of the ring and little fingers
- both lesions result in “hand of benediction”: index and middle fingers remain extended when the patient tries to flex those digits (tries to make a fist)
Median nerve lesions - recurrent branch:
CAUSES:
-recurrent branch may be lesioned distal to the carpal tunnel as a result of laceration of the nerve adjacent to the thenar eminence
SYMPTOMS:
-affects the thenar muscles and results in ape hand (no cutaneous deficits)
anterior interosesseous nerve lesions:
CAUSES:
-may be compressed near the interosesseous membrane deep in the anterior forearm
SYMPTOMS:
- weakness of pronation (pronator quadratus)
- weakness in flexion at the index and middle fingers at the DIP joints
- weakness in the ability to flex the distal phalanx of the thumb (flexor pollicis longus)
- inability to form the letter o by touching the tip of the thumb to the tip of the index finger
Ulnar nerve:
- C8 and T1
- consists of the anterior division fibers of the C8 and T1 ventral rami (continue from the medial cord)
- courses medially in the arm and reaches the forearm after passing posterior to the elbow through a groove between the olecranon and the medial epicondyle of the humerus
- passes between the 2 heads of the flexor carpi ulnaris in the anterior forearm and courses between the flexor carpi digitorum profundus muscles to reach the wrist
- passes through the canal of Guyon between the pisiform bone and the hook of the hamate and anterior to the carpal tunnel
INNERVATES:
1 1/2 muscles in the anterior forearm (flexor carpi ulnaris and the medial half of the flexor digitorum profundus)
Branches of the ulnar nerve:
- palmar cutaneous branch
- dorsal cutaneous branch
- superficial branch
- deep branch
palmar cutaneous branch of the ulnar nerve:
- passes anterior to the flexor retinaculum
- supplies the medial aspect of the palm of the hand
dorsal cutaneous branch of the ulnar nerve:
- divides into dorsal digital nerves
- supply the sin of the dorsum of the hand at the bases of the little finger and medial side of the ring finger
superficial branch of the ulnar nerve:
-innervates the palmaris brevis and the skin of the medial side of the palm and dorsum of the hand, dorsal and palmar aspects of the little finger, and the medial half of the ring finger
deep branch of the ulnar nerve:
- innervates the 3 muscles of the hypothenar eminence
- innervates the 2 lumbricals to the ring and little finger
- passes deep into the palm between the flexor digiti minimi and the aBductor digit minimi muscles
- innervates the aDDuctor pollicis and 7 interosseous muscles
Ulnar nerve lesions:
CAUSES:
- may be compressed at the wrist as it passes between the hook of the hamate and the pisiform bone in Guyon’s canal
- most commonly lesioned at the elbow as it courses adjacent to the medial epicondyle of the humerus
- may also be compressed between the 2 heads of the flexor carpi ulnaris (cubital tunnel syndrome)
- may be lesioned at the hook of the hamate
SYMPTOMS:
- ulnar claw hand caused by a weakeness of the medial 2 lumbricals that flex at the MP joints and extend at the interphalangeal joints of the ring and little fingers
- weakness in the ability to aBduct or aDDuct the thumb at the MP joints (intersesseous muscles and aDDuctor pollicis) making patients unable to hold a piece of paper between the thumb and the index finger or between adjacent fingers
- Weakness of the intersesseous muscles results in clawing of the index and middle fingers (lateral 2 lumbricals innervated by the median nerve remain unaffected)
- muscles in the hypothenar eminence may be effected resulting in weakness in flexion, aBduction, and opposition of the 5th finger
- altered sensation to the skin in the medial aspects of the hand and medial digits
- weakness in the ability to flex the DIP joints of the ring and little fingers
- weakness in the ability to flex the hand at the wrist
- pain and paresthesia in the medial 1 1/2 digits
SUMMARY:
- ulnar claw hand
- weakness in aBduction and aDDuction of the digits
Axillary nerve:
- C5 and C6
- consists of the posterior division fibers
- courses through the quadrangular space around the surgical neck of the humerus
INNERVATES:
- deltoid and teres minor
- skin of the arm covering the attachment of the deltoid to the humerus
NEUROVASCULAR BUNDLE:
-runs with posterior humeral circumflex artery
Axillary nerve lesions:
CAUSES:
- dislocation of the head of the humerus from the glenoid fossa
- fracture of the surgical neck of the humerus
SYMPTOMS:
- weakness in aBduction of the arm at the glenohumeral joint due to loss of the deltoid
- altered sensation of the skin covering the deltoid
- deltoid may undergo atrophy resulting in a loss of the rounded contour of the shoulder
- may be weakness in lateral rotation due to weakness of the teres minor muscle
radial nerve:
- C5 - T1
- consists of the posterior division fibers from the posterior cord
- crosses the tendon of the latissimus dorsi posterior to the axillary artery then courses around the posterior aspect of the shaft of the humerus between the medial and lateral heads of the triceps
- enters the forearm anterior to the lateral epicondyle of the humerus
INNERVATES:
- the 3 heads of the triceps brachii muscle
- brachioradialis
- extensor carpi radialis longus muscles
- skin of the posterior arm
NEUROVASCULAR BUNDLE:
-runs with deep brachial artery
Divisions of the radial nerve:
-in the proximal part of the forearm it divides into superficial cutaneous branch and a deep muscular branch
superficial cutaneous branch of the radial nerve:
INNERVATES:
- skin over the lateral side of the forearm
- lateral side of the dorsal aspect of the hand
- dorsal aspect of the lateral 3 1/2 digits to the PIP joints
deep branch of the radial nerve:
-passes posteriorly around the proximal part of the radius within the supinator muscle and into the posterior forearm
INNERVATES - muscles of the posterior forearm:
- extensor carpi radialis brevis
- extensor carpi ulnaris
- extensor pollicis longus
- extensor pollicis brevis
- aBductor pollicis longus
- extensor digiti minimi
- extensor indicis muscles
Radial nerve lesions:
CAUSES:
-commonly due to a spiral fracture of the midshaft of the humerus
SYMPTOMS:
- “wristdrop” weakness in the ability to xtend the hand at the wrist and loss of extension at the MP joints of ALL digits
- supination may be weakened but not lost (biceps brachii which the the other supinator and innervated by the MC nerve will be unaffected)
- extension of the forearm at the elbow is spared because the triceps receives its innervation proximal to the fracture
- pain and paresthesi in skin over the first dorsal interosseus muscle between the thumb and index
Radial nerve lesion distal to the elbow:
-deep branch of the radial nerve may be lesioned as it courses through the supinator by a subluxation of the head of the radius
SYMPTOMS:
- wristdrop
- weakness in the ability to extend the MP joints
NO SENSORY DEFICITS
Characteristics of nerve compression in upper limb:
- sensory signs precede motor weakness
- proximal nerve lesions will have more signs and symptoms than a distal lesion
Rotator cuff nerves:
- axillary
- musculocutaneous
- radial
Upper trunk lesions
-waiters tip
pre-plexus injuries:
- affect the ventral rami or trunks of the brachial plexus proximal to the formation and branching of terminal and collateral nerves
- have more widespread effects than lesions to individual collateral or terminal nerves
SITS/AEI
- supraspinatus: aBduction
- infraspinatus: external rotation
- teres minor: external rotation
- subscapularis: internal rotation
rotator cuff tear
- A rotator cuff tear is a tear of the tendons of the rotator cuff muscles, and this can happen acutely or over time with overuse.
- The tendon of the supraspinatus muscle is the most commonly affected tendon in a rotator cuff tear.
Shoulder dislocation:
- dislocation of the humerus at the glenohumeral joint
- Most typically, the head of the humerus moves out inferiorly then anteriorly out of the glenoumeral joint
- Posterior dislocations of the humerus can also occur.
NERVES AFFECTED:
- stretch the axillary nerve (innervates the deltoid muscle, which contributes to nearly every movement at the glenohumeral joint - abduction, medial/lateral rotation, and flexion/extension)
- the axillary nerve also innervates the teres minor (contributes to lateral rotation at the glenohumeral joint)
- may also stretch the radial nerve (innervates muscles that control flexion (i.e. brachioradialis) and extension (i.e. triceps brachii) of the forearm)
