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Flashcards in MSS 1 Exam 1 diseases Deck (64):

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
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

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

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.

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)

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

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



Tumors of connective tissue or its mesenchymal precursors are known as Sarcomas.

Most common adult soft tissue sarcoma is Malignant Fibrous Histiocytoma.

Uncertain cellular origin, but probably derived from perivascular mesenchymal cells. Tumor consists of mixture of fibroblasts, myofibroblasts, macrophages, and primitive mesenchymal cells.

The MASL1 Gene has been associated with this tumor.

Tumors typically arise in deep fascia, soft tissues of the neck or extremities, and skeletal muscle. Distant metastases may spread to lung, bone, or liver.

Treatment usually by radical resection.



Anaphylaxis is a life-threatening allergic reaction.

Starts when IgE antibodies (Abs) bind with allergens.

Mast Cell membranes incorporate receptors for IgE. When receptor-bound IgE is exposed to Antigen (Ag), Mast Cells release contents of their granules (histamine, heparin, and other stored molecules).

Histamine dilates small blood vessels & increases their permeability so that plasma leaks out. Skin appears red and edematous (swollen with fluid).

These cells also activate pathway leading to release of Prostaglandins, Leukotrienes, and Platelet-Activating Factor (PAF).

Less severe reaction, called Wheals of Urticaria, or Hives, also caused by release of histamine from mast cells.



Complex collagen synthesis can be impaired by dietary deficiency of Vitamin C (Ascorbic Acid).

Leads to Scurvy. Lack of Vitamin C causes non-hydroxylated, unstable collagen fibrils to fail to form a triple helix and have low tensile strength.

Dentine (teeth), Osteoid (bone), Connective Tissues, and Tunica Adventitia (outer walls of blood vessels) are affected, but typical hemorrhage and poor wound healing can occur anywhere.


Ehlers-Danlos Syndrome (EDS)

All forms of EDS involve a Genetic Defect in synthesis or assembly of Collagen Fibrils, results being Hyper-Elastic Skin and Hyper-Movable Joints.

Vascular EDS, the most severe, is caused by a mutation in the COL3A1 Gene that leads to abnormal Type III Collagen. Mutation in genetic structure leads to mutant enzyme production causing serious effects, including:
Aortic Rupture Perforation of Colon Retinal Detachment


Marfan Syndrome

Marfan Syndrome is an inherited connective tissue disorder caused by molecular defects in FBN1 Gene that encodes the glycoprotein fibrillin-1.

This extracellular protein is a component of microfibrils, which serve as scaffolds for elastic fiber deposition.

Abnormal Elastic Tissues in the body mark the disease.

Cardiovascular lesions, the most life-threatening, include mitral valve prolapse, and weakening of the tunica media of the aorta (which may spontaneously rupture).

Loss of connective tissue support in heart valves creates the so-called Floppy Valve that may contribute to heart failure.


Compartment syndrome

excessive pressure within a compartment

Tough deep fascia does not allow for much stretching

Buildup of fluid internally (e.g., bleeding, rhabdomyolysis) can increase pressure

May impede blood flow and/or impinge nerves within compartment


Ruptured Biceps Tendons

Can result from wear on an inflamed tendon or injury

Often “snap” or “pop” when rupture occurs

Popeye deformity occurs when muscle belly becomes displaced and forms a bulge


Supracondylar Humeral Fractures

High risk of damage to brachial artery, ulnar and median nerves, potentially to epiphyseal growth plates in children


“Golfer’s Elbow”

Medial Epicondylitis

Inflammation of common flexor tendon typically due to repetitive powerful gripping.

Common in golf, racket sports, and throwing sports (baseball, football, etc.) which require repetitive squeezing of handle or ball.

Feel pain when shaking hands, opening door, or lifting glass (movements that require digit/wrist flexion).

~90% of cases successfully treated with non-surgical approaches (rest, anti-inflammatories, physical therapy


“Tennis Elbow”

Lateral Epicondylitis

Inflammation of common extensor tendon due repetitive forceful wrist extension.

Common in tennis, or from repetitive swinging of a hammer or paint brush

Feel pain when shaking hands, opening door, or lifting glass (movements that pull on tendon)

~95% of cases successfully treated with non-surgical approaches (rest, anti-inflammatories, physical therapy)


Flexor Sheaths

Synovial sheaths which cover tendons of digit flexors.

Reduce friction during tendon movement

Ulnar Bursa
Common sheath of FDP & FDS tendons at wrist
Continues along digit 5*

Radial Bursa
Flexor pollicis longus sheath*

Digits 2-4 have separate digital sheaths

* Bursae pass through carpal tunnel into forearm. Infections can spread from digit 1 or 5 to palm and then forearm via bursae


Stenosing Tenosynovitis

“Trigger Finger”
Inflamed section (nodule) of flexor tendon gets trapped behind fibrous sheath.

Digit catches during flexion or becomes locked in flexed position.

More prevalent in patients with rheumatoid arthritis or diabetes.

Steroid injections & rest (reduce inflammation)
Surgical release (cut proximal fibrous sheath)


Extensor Sheaths

Synovial sheaths which cover tendons of digit extensors.
Do NOT extend along digits (wrist only)
Tendons insert into extensor expansions

6 sheaths (compartments)
1st: abductor pollicis longus & extensor pollicis brevis 
2nd extensor carpi radialis brevis & extensor carpi radialis longus
3rd: extensor pollicis longus
4th: extensor digitorum (4 tendons) & extensor indicis
5th: extensor digiti minimi
6th: extensor carpi ulnaris


Extensor Expansions

Extensor expansions (“hoods”)
Special connective attachments
Connect extensor tendons to phalanges
Act across MCP, PIP and DIP joints

Also attachment site for some intrinsic muscles of hand
Dorsal & Palmer interosseus muscles
Lumbrical muscles


De Quervain’s Tenosynovitis

“Gamer’s Thumb”
Thickening of 1st extensor compartment synovial sheath

Cause is unknown, but repetitive thumb abduction/extension aggravate condition

Pain & swelling limit function of abductor pollicis longus & extensor pollicis brevis 

Pain can be surgically alleviated by “release” of extensor retinaculum


Palmar Aponeurosis (Fascia)

Tough investing fascia of palm

Tensed by palmaris longus

Divides into 4 parts over metacarpals II-V.
Connect to fibrous sheaths of digits.

Transverse connections (Fasciculi) between slips prevent excessive ABduction of metacarpals


Dupuytren's Contracture

Permanent shortening of palmar aponeurosis.

Most commonly affects the 4th & 5th digits

Connection to fibrous flexor sheath of digit forces digit into flexion

Develops slowly, cause is unknown
Usually begins after age 40
20% of individuals over age 65


Dorsal Aponeurosis (Fascia)

Extensor expansions

Intertendinous connections

Extensor retinaculum


Hand Compartments

Surrounded by palmar and dorsal aponeuroses (Fascia)

Fibrous septa divides into 5 compartments


Knife attack

Adductor pollicis makes up most of soft tissue webspace between pollex and 2nd digit.

Adductor pollicis (especially transverse head) commonly injured in defensive wounds from sharp force trauma

From victim actively attempting to grab knife with hands


Hand: Deep Spaces

Deep spaces between compartments

Thenar Space
Between thenar and adductor compartments

Midpalmar Space
Between central and interosseous compartments
Continuous with forearm via carpal tunnel.
Potential pathway for movement of infections into forearm.


Triangle of Auscultation

Inferior - Latissimus Dorsi
Superior – Trapezius
Lateral - Rhomboid major

Overlies 6th intercostal space.
Floor has no large muscles.
Good place for assessing respiratory sounds with stethoscope.


Drop Arm Test

An orthopedic test of supraspinatus function (i.e., rotator cuff tear).

Examiner passively abducts the patient’s shoulder to 90 degrees. 

Examiner instructs patient to slowly lower the arm. 

Test is positive if the patient is unable to lower his or her arm in a smooth, controlled fashion (especially below 15 degrees).


Clavicular Fractures

Majority of clavicle fractures occur at midshaft

Sternocleidomastiod muscle pulls medial fragment superiorly

Weight of arm pulls lateral fragment inferiorly

Pectoralis major pulls arm and lateral fragment medially (under the medial fragment).


Winged Scapula

Inability to protract medial scapula.
Can be tested by having patient push against wall.
Damage to muscle or long thoracic n.
Usually trauma related (car accidents, mastectomy)


Rectus Sternalis m.

Rare anatomical variant (~8% of population)
Usually unilateral
May be misdiagnosed as cancerous mass during mammography


Most commonly fractured bone (~10% of all fractures)



Clavicle dysostosis

The clavicle is the only post-cranial bone to form via intramembranous ossification (like cranial bones).

Individuals with craniofacial growth abnormalities (dysostosis) often exhibit abnormal clavicles


“Shoulder” Separation

“Separated shoulder” actually damage to scapulo-clavicular ligaments

Usually from fall directly on “point” of shoulder.

Rockwood classification
3 types
Type 1 partial AC tear
Type 2 complete AC tear
Type 3 complete AC and CC tear



Superior Labrum Anterior & Posterior (SLAP) tear
Tendon of biceps brachii muscle (long head) connected to labrum.

Usually due to excessive and/or repetitive rotation during overhead throwing
Twisting tendon puts tension on labrum


Shoulder Dislocation

“Dislocated shoulder” results from displacement of humeral head from glenoid fossa. Usually from traumatic hyper-extension of abducted arm.

In 95% of shoulder dislocations the humeral head is dislocated anteriorly. Posterior and inferior dislocations are possible but rare (greater muscular support).


Nerve damage
Axillary nerve (37% of cases)
Suprascapular nerve (29% of cases)
Radial nerve (22% of cases)

Hill-Sachs Lesion-Divot created on posterior surface of humeral head from contact with glenoid rim. Interferes with rotational movement of humeral head following reduction



Inflammation of bursae, typically due to direct pressure on bursae.

Shoulder Bursitis
Usually subacromial bursa

Direct pressure of humerus on acromion process (leaning elbow on table drives humerus superiorly)

Overhead movement of humerus impinges bursa in subacromial space


“Nursemaid’s elbow”

Usually in children 1 – 6 years (small radial heads)

Rapid pull/jerk on pronated forearm

Radial head slips out of annular ligament

Child presents with limited limb motion, forearm usually held in flexed-prone position (pain upon supination)

Usually easily reduced via traction-supination or hyper-pronation techniques


Elbow Bursae

Three bursae supporting triceps brachii muscle and tendon at elbow
Subtendinous bursa
Intratendinous bursa
Olecranon bursa

Elbow Bursitis
Typically due to direct pressure on olecranon bursa from resting elbow on hard surface


Boxer’s Fracture

From punching something hard

Usually fifth metacarpal, other digits less commonly broken because force can be directly transmitted to radius


Mysasthenia gravis

* Autoimmune disease where antibodies are formed against the Ach receptors, preventing Ach binding
* Blocks normal muscle-nerve interaction resulting in progressive muscle weakness
* Mostly affects face and neck muscles


Werdnig-Hoffmann Disease

* Degradation of brain nerve cells and certain motor neurons leading to muscle weakness
* Leads to atrophy of muscle and smaller bundles under microscope


Muscular dystrophy

* Causes progressive muscle weakness and loss of muscle mass
* Caused by replacement of muscle with other tissue types



* Nematode parasitic infection caused by eating undercooked meat
* Digestion allows larva to break from the cyst and grow into adults which then invade muscle tissue including heart and diaphragm