MSS 1 Exam 1 diseases Flashcards
Long Thoracic nerve palsy
Winged scapula from paralysis of left serratus anterior m. following mastectomy
Long thoracic n. surrounded by axillary lymph nodes, can easily be damaged during lymph node removal during radical mastectomies
Axillary nerve (C5-C6) innervation and pathology
Motor: Deltoid, teres minor
Sensory: Superior arm (lateral)
Potential for axillary nerve damage during fractures of surgical neck of humerus
causes: Weakened abduction of arm between 15-90 degrees (Deltoid). Sensory loss to lateral surface of superior arm.
Radial nerve (C5-T1) innervation and pathology
Motor: Posterior compartment muscles arm & forearm
Sensory: posterior/lateral arm, posterior forearm, lateral dorsum hand.
Splits in forearm
Superficial branch: sensory to posterior hand (lateral side)
Deep branch: Muscles of posterior forearm compartment
Pierces supinator muscle, emerges as posterior interosseous n.
Deficits depend on location
Axilla: Usually from compression (crutch use, sleeping in chair). Loss of all extensors in arm and forearm. Inability to extend elbow, wrist, CMC and MCP joints. Sensory deficits entire length of distribution.
Radial groove of humerus: Usually from humeral midshaft fracture. Triceps unaffected. Inability to extend wrist, CMC and MCP joints. Sensory loss in forearm and hand.
Distal forearm/Wrist: Usually from compression of superficial branch (wearing a watch too tight, etc.). Motor unaffected. Sensory loss in dorsal hand.
Musculocutaneous nerve (C5-C7) innervation and pathology
Motor: muscles of anterior compartment of arm
Sensory: Lateral forearm
Pierces coracobrachialis on way to innervate biceps and brachialis.
Nerve lesion is rare, usually direct trauma to anterior arm
Weakened shoulder/elbow flexion
Weakened supination
Sensory loss to lateral forearm
Median nerve (C5-T1) innervation and pathology
Motor: most muscles of anterior forearm and lateral hand.
Sensory: lateral palm, digits I-III and lateral ½ of digit IV.
No function in shoulder or arm.
Crosses elbow joint anteriorly (medial side).
Runs between 2 heads of pronator teres m.
Innervates most anterior forearm muscles
Gives off Anterior interosseous n.
Innervates deep anterior compartment muscles (lateral ½ flex. dig. profundus, flexor pollicis longus, pronator quadratus).
Enters hand via carpal tunnel.
Innervates thenar muscles (except deep head of FPB) and lumbricals 1 & 2.
Pronator Teres Syndrome
Hypertrophy of pronator teres muscle from repetitive strenuous pronation
Compresses median nerve between humeral and ulnar heads of muscle
Results in weakened motor function and sensory parenthesia
“Hand of Benediction”
Median n. damage at elbow (or more proximal).
Patient attempts to make fist, cannot flex digits I-III
Lost:
flexor digitorum superficialis (Digit I-V flexion)
lateral ½ flexor digitorum profundus (Digit I & II flexion)
lateral 2 lumbricals (Digit I & II flexion)
thenar muscles (Digit I flexion, abduction)
Kiloh-Nevin Syndrome
Anterior interosseous nerve syndrome)
Median nerve damage usually due to fractures of radius or ulna
Deficits:
Motor: Pronator quadratus, flexor pollicis longus, lateral ½ of flexor digitorum profundus
Sensory: none
Loss of flexor pollicis longus and lateral ½ of flexor digitorum profundus prevents flexion of distal phalanges of digits I-III
“Pinch” sign indicating ant. Interosseous n. damage (unable to flex distal phalange to produce OK)
Carpal Tunnel Syndrome
Compression of median nerve in carpal tunnel by inflammation of flexor tendons
Deficits
Motor: thenar muscles and lumbricals 1 & 2
Sensory: parenthesia of lateral palm, digits I-III and lateral ½ of digit IV.
Ulnar nerve (C8-T1) innervation and pathology
Motor: 1 & ½ muscles in forearm; hypothenar and most deep muscles of hand
Sensory: medial hand (anterior and posterior) including digit V and medial side of digit IV.
No function in shoulder or arm.
Crosses elbow joint posteriorly (medial side).
“funny bone”
Runs between and innervates flexor carpi ulnaris and medial ½ of flexor dig. profundus
Enters hand via Guyon’s canal.
Innervates muscles of hypothenar, adductor, interosseous compartments; lumbricals 3-4
Cubital Tunnel Syndrome
Compression of Ulnar n. from entrapment in cubital tunnel (passage through fascia and flexor tendons at ulnar groove).
Can be caused by direct pressure, hypertrophy of forearm flexors, or tension on nerve from extended flexion of elbow (while sleeping, etc).
Motor deficits in forearm and hand, sensory deficits of medial hand and digits IV & V.
“Claw Hand”
Ulnar n. damage at elbow (or more proximal).
Digit I: loses adduction (adductor pollicis)
Digit II-III: lose adduction & abduction (palmar & dorsal interossei mm.)
Digit IV-V: lose all flexors except flexor digitorum superficialis (median n.)
Lose finger adduction & abduction (Cant hold paper between fingers)
Froment’s Test: A test of pollex adduction. Patient with ulnar n. damage cannot adduct thump to hold a piece of paper. Must flex thumb to maintain grip.
Ulnar tunnel syndrome
(Handlebar palsy)
Compression of Ulnar n. from direct pressure on Guyon Canal.
Common in cyclists
Deficits restricted to hand
weakness of intrinsic hand muscles
parenthesia of skin on medial hand and digits IV-V
Erbs-Duchenne’s Palsy
Injury to upper trunk of brachial plexus (C5-C6)
Generally from forced increase in angle between head & neck.
Deficits
Nerves & Muscles
Axillary n. (Deltoid, teres minor)
Suprascapular n. (Supraspinatus, infraspinatus)
Musculocutaneous n. (coracobrachialis, biceps brachii, ½ brachialis)
Radial n. (C5-C6 fibers to posterior forearm)
Actions
Paralysis of abductors (deltoid, supraspinatus)
Weakened lateral rotation (deltoid, infraspinatus, teres minor)
Weakened elbow flexion and supination (biceps brachii, brachialis)
Weakened wrist extensors
Loss of sensation in C5-6 dermatomes (lateral upper limb)
“Waiter’s tip” hand: Arm adducted and medially rotated, weakened elbow flexion & supination, flexed wrist
Klumpke’s Palsy
Injury to lower trunk of brachial plexus (C8-T1)
Generally from excessive upward pull on upper limb.
C8-T1 fibers lost in Radial, Median and Ulnar nerves.
All intrinsic muscles of the hand lost
All fingers “clawed”
Damage to T1 can impact sympathetic innervation
Horner’s syndrome: loss of sympathetics to head
Dermatomes of upper limb
C5 & C6 above axial line (Lateral)
C7 along axial line (Central)
C8 & T1 below axial line (Medial)
Upper limb test points
C5 lateral cubital fossa
C6 thumb
C7 middle finger
C8 5th finger
T1 Medial cubital fossa
Retroesophogeal Subclavian a.
Common variant in which right subclavian a. (RCA) passes posterior to esophagus.
May result in dysphagia (difficulty swallowing).
May result in right upper limb ischemia due to compression of RCA between esophagus and vertebrae.
Clavicle Fracture Complications
clavicle fracture can lead to rupture of subclavian artery due to the proximity of the artery to the inferior midshaft
Compartment Syndrome: Forearm
Usually from laceration of artery during supracondylar fractures of humerus, radius or ulna shafts.
Both Compartments
Brachial artery
Common interosseous artery
Anterior compartment
Radial artery
Ulnar artery (distal)
Anterior interosseous artery
Posterior Compartment
Post. Interosseous artery
Fascia restricts swelling, compressing muscles and neurovasculature within compartment.
Volkmann’s Ischemic Contracture
Permanent shortening of anterior and posterior forearm muscles due to undiagnosed/untreated compartment syndrome.
Usually from brachial artery laceration.
Volkmann’s Sign
“Clawed” appearance of hand with:
Wrist Flexion (more flexors than extensors)
MCP hyperextension (extensor digitorum overpowers lumbricals)
PIP flexion (Flexor digitorum superficialis)
DIP flexion (Flexor digitorum profundus)
Allen’s Test
Ensures sufficient anastomotic supply of blood to hand by Ulnar a. prior to catheterization of Radial a.
Scaphoid Fracture
Blood to scaphoid supplied distally from radial a.
Fracture can result in necrosis of proximal fragment
Pain in response to palpation of anatomical snuffbox
Lateral wrist between extensor pollicis longus and brevis tendons
Cubital Fossa location
Triangular depression on anterior elbow
Boundaries
Superior: Medial & Lateral epicondyles
Lateral: Brachioradialis m.
Medial: Pronator teres m.
Post-Mastectomy Lymphedema
Removal of axillary lymph nodes disrupts lymph drainage from upper limb
Treated via exercise, compression bandages, and massage