Unit 2 STRX Flashcards
Boundaries of the axilla
Anterior Wall - Pectoralis major, pectoralis minor, clavipectoral fascia
Medial Wall - Serratus anterior, ribs 1-4
Posterior Wall - Scapula, Teres Major, Subscapularis, Latissimus dorsi
Lateral Wall - Intertubercular Sulcus of Humerus
Apex - Cervicoaxillary canal, 1st rib, clavicle, scapula
What are the contents of the axillary sheath?
Which of these are most anterior?
Cords of the brachial plexus, axillary artery, axillary vein, fat, lymphatics
Axillary vein
How many parts does the Axillary a. have and what are the borders that separate them?
3 parts
Subclavian a. |inferior border of 1st rib| Axillary a. part 1
Axillary a. part 1 |Pec minor (proximal border)| Axillary a. part 2
Axillary a. part 2 |Pec minor (distal border)| Axillary a. part 3
Axillary a. part 3 |inferior border Teres Minor| Brachial a.
Name the parts of the Axillary artery and their corresponding branches
Part 1 - Superior thoracic a
Part 2 - Thoracoacromial trunk, Lateral thoracic a.
Part 3 - Anterior and Posterior Circumflex, Subscapular
Subscapular –> Circumflex scap and thoracodorsal a.
What is the origin of the Axillary v?
Basilic and Brachial veins
What major vein drains into the axillary vein?
Cephalic v
What nerves come from the Roots of the Brachial plexus?
Dorsal Scapular n (C5)
Phrenic n (C5)
Long thoracic n (C5-C7)
What nerves come from the Trunks of the Brachial Plexus?
Suprascapular (C5-C6)
N to Subclavius (C5-C6)
What nerves come from the Divisions of the Brachial Plexus?
None
What nerves come from the Cords of the Brachial Plexus?
Lateral: Lateral Pectoral (C5-7)
Posterior: Upper subscapular (C5-6)
Lower subscapular (C5-6)
Thoracodorsal (C6-8)
Medial: Medial Pectoral (C8-T1)
Medial cutaneous of the arm (T1)
Medial cutaneous of the forearm (C8)
What are the Terminal Branches of the Brachial Plexus?
Musculocutaneous (C5-C7)
Median (C5-T1)
Axillary (C5-6)
Radial (C5-T1)
Ulnar (C8-T1)
What is this a common sign of?
winged scapula - C5, C6, C7 Long thoracic n. injury
Describe the common signs of Erb’s Palsy and the nerves associated with it
Arm hanging by their side and medially rotated
Forearm extended and pronated - “Waiter’s tip hand”
Damage to the upper plexus (C5-C6)
Pt presents with this symptom, along with supinated forearm. What has been damaged?
Lower plexus (C8-T1)
Identify what nerve dysfunction causes these signs as well as Ape Hand and Wrist Drop
Ulnar Claw - Distal ulnar n
Hand of Benediction - Proximal Median n
Median Claw - Distal Median n
“OK” guesture - Proximal Ulnar n
Ape Hand - Distal Median n
Wrist drop - Radial n
The epidermis arises from ___________ while the dermis arises from ______________
Ectoderm
Mesoderm
Identify the layers of the _________
Epidermis
Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
What are Keratohyaline granules and their function?
Granules that contain filaggrin that promote keratin fiber cross-linking
Creates impermeable barrier in stratum corneum to prevent pathogen crossing
What are Odland bodies and their function?
Granules that release glycophospholipid-rich contents (via exocytosis) into intercellular spaces of stratum granulosum around individual keratinocytes
Makes epidermis impermeable to water loss from skin
What type of cells are in the epidermis and what are their functions?
Merkel cells - oval shaped mechanoreceptors that detect light touch
Langerhans cells - first defense, dendritic immune cells that destroy pathogens and use Birbeck granules for antigen presentation to T-regulatory cells
Melanocytes - produces melanin which is packed into melanosomes –> sent to keratinocytes through cytoplasmic projections
Keratinocytes - form protective layer on epidermis (stratum corneum)
What are the layers of the dermis and what are they composed of?
Papillary layer - loose connective tissue
Reticular layer - dense connective tissue
List the sensory receptors found in the dermis and their functions
Meissner corpuscles - light touch receptors in the papillary layer
Pacinian corpuscles - phasic receptors - deep pressure, vibration
Ruffini endings - tonic receptors - pressure (skin stretch), deformations within joints
Identify the structure indicated
Pacinian corpuscle
Differentiate acanthosis from ancatholysis
Acanthosis is hyperplasia of the stratum spinosum
Acantholysis is the breakdown of desmosome attachment (in the stratum spinosum)
Differentiate dyskeratosis from spongiosis and parakeratosis
Dyskeratosis are cells coming apart and show hyperpigmented nuclei
Spongiosis is when there is intercellular edema pushing cells apart
Parakeratosis is abnormal keratin production and maturation
Identify the structure indicated by the yellow arrows.
By the blue arrows.
Langerhans cells
Cytoplasmic projections
Interpret the histological findings and the skin abnormality
Nodule
The mass is in the epidermis and dermis, and it’s raising the epidermis more superficially
Interpret the histological findings and the skin abnormality
Pustule
Abundance of dead neutrophils in the epidermis
Interpret the histological findings and the skin abnormality
Vesicle or Bulla - size unknown
Histology shows intraepidermal fluid-filled space that appears unstained, with the layers of the epidermis separated from each other.
Interpret the histological findings and the skin abnormality
Erosion
Histology shows an incomplete loss of epidermis; the stratum spinosum and basal layer seem to be untouched.
Interpret the histological findings and the skin abnormality
Ulcer
Histology shows a complete loss of epidermis and partial loss of dermis; if it had been contained to the epidermis it would have been erosion
Interpret the histological findings and the skin abnormality
Acanthosis
Diffuse epidermal hyperplasia; pathology shows exaggerated rete ridges and dermal papilla
Identify the skin abnormality and it’s pathophysiology
Wheals
Brought on by type I hypersensitivity reactions - IgE responds to allergen and mediates mast cell degranulation, releasing potent vasodilators
Interpret the histological findings and the skin abnormality
Parakeratosis
Histology shows nuclei in the stratum corneum
Interpret the histological findings and the skin abnormality
Hyperkeratosis
Histology shows excessive hyperplasia of the stratum corneum
Identify the cells indicated by the red arrows
Eosinophils
Red staining
Identify the circled cells
Neutrophils
Interpret the histological findings and identify the skin abnormality
Spongiosis
Histology shows intraepidermal intercellular edema
Patient presents with small, lichenified, scaly mass.
Interpret the histological findings and explain the pathogenesis of the likely diagnosis
Actinic keratosis - squamous cell carcinoma precursor
Histology shows parakeratosis and dysplastic keratinocytes; the encircled section shows a keratinized pearl indicative of Actinic keratosis
Pathogenesis: DNA damage from UV rays results in mutations in p53 and/or RAS
Patient presents with macule.
Interpret the histological findings and identify the skin abnormality
Nevi
Histology shows linear pattern of melanocyte proliferation within epidermis
Patient presents with scaling.
Interpret the histological findings and explain the pathogenesis of the likely diagnosis
Psoriasis
Histology shows parakeratosis, hyperkeratosis, and acanthosis; loss of stratum granulosum; dilated capillaries; neutrophils in dermal papillae
Pathogenesis: Inheritable HLA-C, upregulation of CARD14, mutation in IL-12, or mutation in IL-23 –> leads to predisposition of keratinocyte production
Pathophysiology: Irritation/trauma activate inflammatory factors –> IL-23 stimulates CD4 T-cell differentiation–> release of IL17 –> binding of IL-17 to IL-17R on epithelial and stromal cells –> secretion of CXCL8 –> lead to neutrophil recruitment
Overall secretion of IL-17, TNF-a, IFN-y, IL-22 stimulates survival and proliferation
Sustained inflammatory response + predisposition of keratinocyte differentiation –> psoriasis
Patient presents with pearly telangiectatic papule.
Interpret the histological findings and explain the pathogenesis of the likely diagnosis
Basal cell carcinoma
Histology shows palisading arrangement of cells with elongated hyperchromatic nuclei around a nodule in stratum basale
Pathogenesis: DNA damage results in activation of SHH signaling pathway –> inhibits PTCH patched protein allowing SMO smoothened protein to detach –> SMO travels to nucleus and activates glioma-associated oncogene (GLI) transcription factors –> increased cell proliferation
Explain each step of the melanocytic nevus progression
A. Normal skin with scatted melanocytes
B. Junctional Nevus - nests of nevus cells along the epidermis-dermis junction
C. Compound nevus - nests of nevus cells within the dermis and along the epidermis-dermis junction
D. Dermal nevus - nests of nevus cells only in the dermis
E. Dermal nevus with neurotization - spindle-shaped cells in wave-like orientations that have lost their ability to produce melanin
Identify what stage of nevus progression this is and justify your findings
Junctional - nests of nevus cells along dermis-epidermis junction
Identify what stage of nevus progression this is and justify your findings
Compound - nests of nevus cells within the dermis and along the epidermis-dermis junction
Identify what stage of nevus progression this is and justify your findings
Dermal - nests of nevus cells only in the dermis
Identify what stage of nevus progression this is and justify your findings
Dermal with neurotization - spindle-shaped cells are seen in the dermis
Explain each step of the progression from dysplastic nevus to melanoma
A. Lentiginous melanocytic hyperplasia
B. Lentiginous junctional nevus
C. Dysplastic lentiginous compound nevus
D. Early melanoma
E. Advanced melanoma
Identify what stage of dysplastic nevus –> melanoma progression this is and justify your findings
Dysplastic compound nevus
3 arrows show hyperchromatic, atypical nuclei
2 arrows show perinuclear halos
Double-headed arrow shows lamella fibrosis
Identify what stage of dysplastic nevus –> melanoma progression this is and justify your findings
Early melanoma
Histology shows radial growth phase - horizontal spreading of melanoma in epidermis and dermis
Identify what stage of dysplastic nevus progression –> melanoma this is and justify your findings
Advanced melanoma
Histology shows vertical growth phase - vertical spread of melanoma into dermis, subQ and possibly vasculature
What are the borders of the triangular space of the shoulder region?
How does this differ from the triangular interval?
Triangular space borders:
Superior - Teres minor
Inferior - Teres major
Lateral - Long head of the tricep
Triangular interval borders:
Superior - Teres major
Medial - Long head of the tricep
Lateral - Surgical neck of the humerus
What are the borders of the quadrangular space of the shoulder region?
Superior - Teres minor
Inferior - Teres major
Medial - Long head of triceps
Lateral - Surgical neck of humerus
Explain the Empty Can test and what it’s testing for.
Testing for ruptured supraspinatus tendon
Pt places straight arm 90 degrees of abduction and 30 degrees forward flexion
Internally rotates the arm completely
Pt then resists examiners attempts to depress arm
Identify the following structures
A. Suspensory Ligaments
B. Fat lobule
C. Lactiferous Sinus
D. Lactiferous Ducts
E. Pectoral Fascia
F. Retromammary space (bursa)
What arteries supply blood to the breast?
What veins drain the breast?
Arteries:
Pectoral branch of the thoracoacromial trunk
Internal thoracic a.
Lateral mammary branches of lateral thoracic a.
Medial mammary branches of internal thoracic a.
Veins:
Axillary vein
Internal thoracic vein
What nerves innervate the breast?
Lateral cutaneous branches of the 4th and 5th intercostal nerves
What are the different pathways of lymph drainage from the nipple, areola, and mammary glands in the breast?
subareolar plexus –> parasternal –> bronchomediastinal
subareolar plexus –> pectoral –> central –> apical –> infraclavicular –> supraclavicular
subareolar plexus –> subscapular –> central –> …
Subareolar plexus –> abdominal
What are the different pathways of lymph drainage from the skin of the breast?
IM, orientation, and body part
Axillary radiograph of the left shoulder
IM, orientation, body part
radiographic “Y” view of left shoulder/scapula
What are the orientations of these X-rays?
Top: AP
Bottom: Lateral
Compare and contrast these two imaging modalities.
Both are MRIs
Top is T-1 weighted
Bottom is T-2 weighted
What structures are contained in the Triangular interval?
Radial n.
Deep radial a. (profunda a.)
Which nerve provides sensory cutaneous innervation to the regions noted?
Pink - Radial n
Green - Musculocutaneous n
Yellow - Median n
Purple - Medial cutaneous n of the forearm
Blue - Ulnar n.
How can you tell the difference between a myopathic injury from a neurogenic injury in a group of muscle tissue cells?
A neurogenic injury would show fiber type grouping after reinnervation –> nerves to cells die –> motor units around it take over those cells and reassign to that fiber type –> form groups of motor units instead of the randomly distributed
A myopathic injury would maintain the random distribution of motor units but would likely atrophy in groups, show inflammation, repair of damage portioned of cell
What are the classic histological findings of Dermatomyositis, and the clinical presentation?
Perifascicular atrophy + inflammation of tissue cells
CP: Muscle pain, proximal muscle weakness (getting out of chairs, climbing stairs, picking up things), erythematous skin changes around eyes, red thickened skin on knuckles and knees
How do you differentiate between Dermatomyositis and Polymyositis?
Similar musculoskeletal symptoms and presentation
Polymyositis doesn’t present with skin changes - diagnosis of exclusion
How do X-linked Muscular Dystrophies result in the clinical presentations seen?
Loss of function mutation with DAG (dystrophin-associated glycoprotein)
DAG links sarcolemma to ECM –> transmits force out of actin/myosin in cell into ECM –> culminates contraction, prevents damage to cell during contraction
No DAG –> no link –> damage to cells faster than repair can keep up
Explain the histological differences between skeletal, cardiac, and smooth muscle tissue
Skeletal muscle: latitudinal striations, multiple peripheral nuclei, elongated cells
Cardiac muscle: longitudinal striations, single central nucleus, intercalated disks
Smooth muscle: non-striated, homogenous pink background, single central nucleus, fusiform cells
How is skeletal muscle developed and repaired?
Developed: mesoderm –> mesenchymal cells –> myoblasts –> myotubes –> differentiation to muscle fiber
Regeneration: satellites stem cells
Function of the glenohumeral ligaments
Strengthen the anterior aspect of the joint capsule
Function of coracohumeral ligament
Strengthens the joint capsule superiorly
Structures and function of coraco-acromial arch
Coracoid process, acromion, coracoacromial ligament
Form protective arch that overlies humeral head, prevents superior displacement from glenoid cavity
Blood supply and innervation of the glenohumeral joint
Anterior and posterior circumflex humeral a
Branches of suprascapular a
Suprascapular n
Axillary n
Lateral pectoral n
Blood supply and innervation of the acromioclavicular joint
Suprascapular a
Thoraco-acromial a
Lateral pectoral n
Axillary n
Grading of Acromioclavicular separation
Grade 1 - ligaments bruised/strained, no actual separation of joint
Grade 2 - Partial tear or stretching of AC ligaments with slight joint separation
Grade 3 - both AC ligaments and coracoclavicular ligaments are torn, clavicle and acromion completely separated
What is the function of the transverse humeral ligament?
Hold the long head of the biceps tendon in place
What is the location and function of the conoid ligament?
Attaches the coracoid process to the clavicle
Helps prevent dislocation of the acromioclavicular joint
What is the function of the superior transverse scapular ligament?
Bridges the scapular notch and allows passage for the suprascapular nerve
Function of the coracoacromial ligament
Prevents upward dislocation of the shoulder joint
The three bones that make up the shoulder
Humerus, scapula, clavicle
What is the name of the coracoclavicular ligament that connects the clavicle to the coracoid process?
Trapezoid ligament
What type of joint is the glenohumeral joint?
Synovial
Shoulder dislocations may injure what nerve, resulting in what sensory and motor dysfunctions?
Axillary nerve
Sensory loss of lateral part of upper arm
Motor loss of deltoid - difficulty abducting arm
What structures limit elbow extension?
Olecranon fossa of the humerus and olecranon process
What structures limit elbow flexion?
Coranoid process and coranoid fossa
What structure keeps the head of the radius tight against the capitulum of the humerus while allowing for rotation to occur during pronation and supination?
Annular ligament
The elbow joint is weakest ____________ and strengthened by _________
anteriorly and posteriorly
collateral ligaments on the sides
“Golfer’s elbow” refers to…
Repetitive use injury, typically excessive ulnar deviation
irritation of the medial epicondyle leading to inflammation of the muscles originating from it
“Tennis elbow” is caused by…
Repetitive use injury, typically excessive extension of the wrist
irritation of the lateral epicondyle leading to inflammation of the muscles originating from it
What bones articulate in the radiocarpal joint?
Radius, scaphoid, lunate
Which ligaments play a role in limiting movement at the CMC and IM joints of the hand?
Superficial and deep transverse metacarpal ligaments
What is the clinical presentation of lymphangitis?
localized pain and muscle aches, red streaks along drainage channel, systemic symptoms
Risk of septicemia if not treated
What are the boundaries and structures that run through the cubital fossa?
Lateral - brachioradialis
Medial - pronator teres
Floor - brachialis
Superior - imaginary line connecting epicondyles
Structures lateral to medial - TAN
Tendon of biceps brachii
Artery, brachial
Nerve, median
The medial cubital vein is tributary to what vein?
Basilic v
What nerve travels with the cephalic v at the level of the cubital fossa?
Lateral antebrachial cutaneous n
What is the role of arrector pili in sweat glands?
Muscle that causes hair to become erect and compresses sebaceous gland which then secretes sebum into shaft
What is the role of sebum secreted by sebaceous glands?
Protect and hydrate the skin
Explain the significance of a BRAF mutation in melanoma
BRAF is a proto-oncogene caused by a missense mutation
- responsible for MEK phosphorylation
Gain of function mutation results in kinase activity 500x higher than normal –> uncontrolled proliferation
Most nevi are docile until UV radiation causes further mutations
Explain the significance of a RAS mutation in melanoma
Gain of function mutation in RAS would cause unregulated phosphorylation of BRAF –> MEK –> MAPK/ERK –> melanocyte cell proliferation
Clinical presentation: slowly progressive muscle weakness in distal extremities.
Muscle biopsy: patchy mononuclear inflammatory cells rich in CD8+ T cells, focal invasion of abnormal appearing myofibers, “rimmed vacuoles”
Inclusion body myositis
What structures create the carpal tunnel?
Hook of hamate and pisiform
Trapezium and scaphoid
What structures pass through carpal tunnel?
Median n
FPL
FDP x4
FDS x4
What structures create the ulnar canal?
Pisiform, hook of hamate, pisohamate ligaments
Explain how regeneration is different from scar formation
Regeneration is the complete restoration to a normal state by differentiated cells and stem cells
Scar formation occurs when there is severe damage and loss of progenitor cells; the damage is replaced by connective tissue
What determines a tissues ability to repair itself?
- Type of tissue: labile, stable, permanent
- extracellular matrix integrity
- factors produced at site of injury: macrophages, stromal cells, etc
- Integrins
How is liver regenerated?
Kupffer cells (liver macrophages) recruit cytokines by autocrine releasing TNF –> it paracrine releases IL6 to act on hepatocytes –> stimulates hepatocytes from G0 to G1 –> growth factors released from the injury site bind to hepatocyte receptors –> cell proliferation –> TGF-B initiates termination when there is enough
What are the steps of scar formation?
Platelet – fibroblasts, macrophages, neutrophils
Eschar - granulation tissue, new blood vessels
Collagen scar
Healing by first intention
24 hrs: Neutrophil accumulation
24-48: Epithelial cells close wound
3 days: neutrophils replaced by macrophages to clear debris; granulation tissue invades
5 days: neovascularization peaks; fibroblasts migrate/proliferate
2 weeks: decrease in leukocyte infiltrate
4 weeks: essentially normal epidermis
Healing by second intention
Severe wound –> necrotic debris –> more inflammation –> more granulation tissue made of fibrin, plasma fibronectin, type III collagen –> loss of dermal appendages –> scar by end of 1 month
Dupuytren’s Contracture pathophysiology and clinical presentation
Hypoxia of the muscle in the hand + HLA-T cell interaction –> inflammatory response –> fibroblasts proliferate –> fibromatosis (excessive ECM deposition) –> tissue fibrosis and thickening/shortening of palmar fascia
Presents as firm nodule on palm of hand proximal to metacarpophalangeal joint
Achondroplasia pathophysiology and clinical features
AD mutation by gain of function FGFR3 gene
Defective FGFR3 gene –> continuous receptor stimulation by FGF –> inhibited chondrocyte proliferation –> decreased lengthening of bone during endochondral ossification
Clinical features
- disproportionately large heads, short stature, normal torso
Osteogenesis imperfecta pathophysiolog
AD in COL1A1 or COL1A2 –> decreased formation of hydrogen and disulfide bonds between type I precollagen molecules –> decreased triple helix formation –> decreased synthesis of normal type I collagen –> impaired bone matrix formation
Osteogenesis Imperfecta type I and type II clinical features
Type I - mildest, most common
- growth delay, skeletal deformities, brittle bones, blue sclerae, progressive hearing loss
Type II - most severe, usually fatal in first year of life
- multiple intrauterine fractures
- underdeveloped lungs
Osteopetrosis pathophysiology and clinical features
gene mutation –> inability of osteoclasts to generate acidic environment –> decreased bone resorption –> overgrowth of bone with pathological bone composition
Clinical features
- recurrent fractures - bones dense but brittle from poor remodeling
- cranial nerve disorders
- pancytopenia
Briefly distinguish between osteoporosis, osteogenesis imperfecta, and osteopetrosis
Osteoporosis: increased osteoclastic activity –> increased bone resorption
Osteogenesis imperfecta: inability of osteoclasts to generate acidic environment –> decreased bone resorption
Osteopetrosis: decreased osteoclastic activity –> bone overgrowth
Difference between bull rider’s thumb and skier’s thumb
Bull rider’s thumb is a torn ulnar collateral ligament of the thumb
Skier’s thumb is a torn radial collateral ligament of the thumb
