PCOM DO (2025-) > MSK Week 4 > Flashcards

MSK Week 4 Flashcards

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1
Q

Strongest Hip Stabilizer Ligament

A

Iliofemoral ligament.

This ligament plays a crucial role in maintaining hip stability during movement.

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2
Q

Primary Blood Supply to Femoral Head (Basic Science Trap)

A

Medial circumflex artery. Compromise leads to AVN with intracapsular fractures.

Avascular necrosis (AVN) can occur if blood supply is interrupted.

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3
Q

Shenton’s Line Function

A

Continuous arc checked on AP hip X-ray. Disruption indicates fracture or dislocation.

Shenton’s line is an important indicator in radiological assessments.

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4
Q

Primary weight-bearing knee structure

A

Medial Femoral Condyle (It’s bigger than the lateral condyle).

The medial femoral condyle bears more weight, especially during activities.

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5
Q

Best imaging modality for Labrum/Menisci/Ligaments

A

MRI (use arthrogram/contrast for better joint evaluation).

MRI is preferred for soft tissue evaluation around joints.

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6
Q

Syndesmotic Injury Marker (Tibiofibular Clear Space)

A

Should be ≤ 6 mm on AP ankle X-ray. Increased space suggests high ankle sprain/fixation needed.

This measurement is critical for diagnosing syndesmotic injuries.

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7
Q

Modality for Occult Stress Fractures/Early Osteomyelitis

A

MRI (detects bone marrow edema not seen on initial X-ray).

MRI can reveal early signs of stress fractures that X-rays may miss.

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8
Q

Modality for Complex Tibia Plateau Fx

A

CT scan (3D visualization needed before surgery).

CT scans provide detailed imaging necessary for surgical planning.

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9
Q

Fractures Highest Risk for AVN (The Real Trap)

A

Intracapsular femoral neck fractures (Subcapital, Transcervical, Basicervical).

These fractures have a significant risk for avascular necrosis due to compromised blood supply.

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10
Q

Classification for Femoral Neck Fractures

A

Garden Classification (I: incomplete; II: nondisplaced; III: partially displaced; IV: non-engaged fragments).

This classification helps in determining treatment strategies.

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11
Q

Most Common Hip Dislocation Type

A

Posterior (85%), seen after high-velocity trauma.

Posterior dislocations are the most prevalent type following traumatic incidents.

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12
Q

Most Common Bipartite Patella Location (Trap)

A

Type 3, Superior Lateral pole (75% of cases).

Understanding the common locations can aid in diagnosis.

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13
Q

Trimalleolar Fracture definition

A

Injury to medial malleolus, lateral malleolus, and posterior aspect of the distal tibia.

This type of fracture involves multiple structures around the ankle joint.

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14
Q

Popliteal Artery formation (Anatomy Flow)

A

SFA (Femoral Artery) becomes Popliteal after traversing the adductor hiatus.

This transition is important for understanding lower limb vascular anatomy.

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15
Q

FIRST LINE Modality for DVT

A

US (Ultrasound).

Ultrasound is the primary imaging technique used for diagnosing deep vein thrombosis.

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16
Q

Defining Criterion for DVT on US

A

Failure of the vein to compress.

This criterion is a key indicator of the presence of a thrombus.

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17
Q

Standard DDH diagnostic criteria (US)

A

Alpha angle of greater than or equal to 60° and a beta angle of less than 55°.

These angles are critical in diagnosing developmental dysplasia of the hip.

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18
Q

What is the bony structure of the ankle joint formed by?

A

Tibia, Fibula (Mortise), and Talus (Trochlea)

The ankle joint is critical for foot movement and stability.

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19
Q

Which joint is primarily responsible for foot inversion and eversion?

A

Subtalar Joint

This joint allows for the side-to-side movement of the foot.

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20
Q

Where is the groove for the Flexor Hallucis Longus (FHL) located?

A

On the Calcaneus

This landmark is important for identifying the course of the FHL tendon.

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21
Q

Which lateral ligament is the weakest and most commonly injured in inversion sprains?

A

Anterior Talofibular Ligament (ATFL)

This ligament plays a crucial role in ankle stability.

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22
Q

What ligament provides crucial arch support for the head of the Talus?

A

Spring Ligament (Plantar Calcaneonavicular)

This ligament helps maintain the integrity of the medial longitudinal arch.

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23
Q

Which tendons serve as dynamic supports for the arch of the foot?

A
  • Tibialis Posterior (TP)
  • Flexor Digitorum Longus (FDL)
  • Flexor Hallucis Longus (FHL)

These tendons actively support the foot’s arch during movement.

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24
Q

What is the pathophysiology of flat foot?

A

Medial arch flattening (overpronation)

This condition leads to an inefficient gait and reduced shock absorption.

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25
Which muscles are innervated by the Deep Fibular Nerve?
* Extensor Digitorum Brevis (EDB) * Extensor Hallucis Brevis (EHB) ## Footnote These muscles are located on the dorsal aspect of the foot.
26
Which intrinsic muscles are supplied by the Medial Plantar Nerve?
LAFF: * 1st **L**umbrical * **A**bductor Hallucis (AH) * **F**lexor Digitorum Brevis (FDB) * **F**lexor Hallucis Brevis (FHB) ## Footnote This nerve primarily innervates the muscles of the medial aspect of the foot. All other muscles are innervated by the **lateral** plantar nerve.
27
The medial plantar nerve innervates the skin of?
the plantar surface of the medial 3 1/2 digits and the dorsum of the distal phalanges
28
What is the primary function of the Anterior Compartment of the leg and what is its innervation?
Dorsiflexion; Deep Fibular Nerve ## Footnote This action is essential for the swing phase to clear the foot during walking.
29
What is the primary function of the Lateral Compartment of the leg and what is its innervation?
Eversion; Superficial Fibular Nerve
30
What is the primary function of the Posterior Compartment of the leg and what is its innervation?
Plantarflexion; Tibial Nerve
31
What is the action of the Popliteus muscle?
'Unlocks' the knee joint to initiate flexion ## Footnote This muscle is important for knee mobility during the gait cycle.
32
What is the mnemonic for the Tarsal Tunnel and what does it stand for?
Tom, Dick, And A Very Nervous Henry: **T**ibialis posterior muscle Flexor **D**igitorum longus muscle Posterior Tibial **A**rtery/**V**ein/Tibial **N**erve Flexor **H**allucis longus ## Footnote This mnemonic helps recall the structures within the tarsal tunnel.
33
Where is the skin test spot for the Deep Fibular Nerve located?
In the web space between the 1st and 2nd toes ## Footnote This area is often tested for nerve function.
34
What is a common result of Deep Fibular Nerve pathology?
Loss of dorsiflexion, resulting in Foot Drop ## Footnote Foot Drop leads to difficulty in lifting the front of the foot.
35
What compensatory gait pattern occurs due to Foot Drop?
Steppage Gait ('High Step') ## Footnote This gait pattern helps to prevent dragging the foot.
36
Is pain in the sole of the foot generally caused by Deep Fibular Nerve damage?
False ## Footnote Pain in the sole is more likely due to Tibial Nerve or Tarsal Tunnel Syndrome.
37
What are the effects of Tibial Nerve intrinsic damage?
Affects plantarflexors and intrinsic muscles, potentially causing hammer/claw toe deformities ## Footnote This damage impacts foot function significantly.
38
What is the main blood supply to the femoral head?
Lateral Femoral Circumflex Artery (LFCA) ## Footnote Not the artery in the fovea.
39
What clinical pitfall is associated with the femoral head?
LFCA rupture causes avascular necrosis following fracture of the neck of the femur.
40
Which nerve exclusively innervates the gluteus maximus?
Inferior Gluteal Nerve ONLY.
41
Which nerve innervates the gluteus medius, minimus, and TFL?
Superior Gluteal Nerve.
42
What is the key rule regarding the piriformis muscle?
Superior Gluteal vessels and nerve are superior to Piriformis; Inferior Gluteal vessels/nerve, and Sciatic Nerve are inferior.
43
Does the Sciatic Nerve innervate anything in the gluteal region?
No, it is just passing through.
44
What is a clinical pitfall associated with piriformis syndrome?
Piriformis pinches the underlying Sciatic Nerve, causing pain/numbness ('sciatic cuff').
45
Describe the pathway of the pudendal nerve.
Exits Greater Sciatic Foramen → Loops deep to Sacrotuberous and superficial to Sacrospinous ligaments → Enters Lesser Sciatic Foramen.
46
What is the exception in hamstring innervation?
Biceps Femoris Short Head (BFSH) is innervated by the Common Fibular Nerve.
47
What is a pitfall regarding the Biceps Femoris Short Head?
It only crosses the knee; only does knee flexion.
48
What are the dual innervations of the adductor magnus?
Hamstring portion by Tibial Nerve; Adductor portion by Obturator Nerve.
49
What is the function of the adductor hiatus?
Femoral Vessels pass through this 'hole' in Adductor Magnus and become Popliteal Vessels.
50
In the popliteal fossa, which vessel is superficial to which?
The Popliteal Vein is superficial to the Popliteal Artery.
51
What is the action of the popliteus muscle?
'Unlocks the knee' from full extension.
52
What is the main blood supply to the femoral head in avascular necrosis?
Lateral Femoral Circumflex Artery (LFCA) ## Footnote This artery is crucial for maintaining blood supply to the femoral head.
53
What is a pitfall regarding the foveal artery?
The small artery in the round ligament is NOT the main blood supply ## Footnote It is important to recognize that the foveal artery does not supply the femoral head.
54
What muscle attaches at the lesser trochanter?
Iliopsoas muscle ## Footnote This muscle is a key flexor of the hip.
55
What is the association between the MCL and the meniscus?
MCL is closely associated/fused with the Medial Meniscus ## Footnote This relationship is important for understanding knee mechanics.
56
How are the ACL and PCL named?
Based on attachment site on the TIBIA ## Footnote The ACL prevents anterior tibial displacement.
57
What are the contents of the femoral triangle in order from lateral to medial?
Nerve, Artery, Vein, Lymphatics (NAVL) ## Footnote This order is crucial for clinical assessments and procedures.
58
What is the exception regarding the femoral nerve in relation to the femoral sheath?
The Femoral Nerve is the only NAVL component that sits OUTSIDE the Femoral Sheath ## Footnote This distinction is important for understanding nerve anatomy.
59
What is the primary function of the iliopsoas?
Major hip/trunk flexor ## Footnote It plays a crucial role in movements such as walking and running.
60
What is the innervation for the Tensor Fascia Lata (TFL)?
Superior Gluteal Nerve ## Footnote This nerve is important for hip stabilization.
61
What action does the Rectus Femoris perform?
Hip Flexion AND Knee Extension ## Footnote This muscle crosses two joints, allowing for these combined actions.
62
What is unique about the innervation of the Pectineus?
Dual Innervation: Femoral N. and Obturator N. ## Footnote This dual innervation is unusual and important for understanding its function.
63
What are the innervations of the Adductor Magnus?
Adductor portion: Obturator N.; Hamstring portion: Tibial N. ## Footnote This dual innervation is critical for its varied actions.
64
What is the 'Brevis Sandwich' regarding the Obturator Nerve?
Anterior Division is superficial to Adductor Brevis; Posterior Division is deep to Adductor Brevis ## Footnote Understanding this anatomy is important for surgical approaches.
65
What occurs at the Adductor Hiatus?
Femoral A/V exit Adductor Magnus to become Popliteal A/V ## Footnote This transition is significant for vascular anatomy.
66
What does the Saphenous Nerve provide?
Sensation to the knee/leg ## Footnote It does NOT exit through the Adductor Hiatus.
67
What is the composition of the Pes Anserinus (SGT)?
Sartorius (Ant), Gracilis (Med), SemiTendinosus (Post) ## Footnote This structure is important for knee stability.
68
What structure does cardiac muscle use at the junction?
Cardiac uses a Diad ## Footnote Skeletal muscle uses a Triad.
69
What is the mechanism of cardiac E-C coupling?
Chemical (Ca2+-Induced Ca2+ Release, CICR) ## Footnote Extracellular Ca2+ influx (30%) triggers SR release (70%).
70
True or False: Cardiac function does not depend on extracellular Ca2+ influx.
False ## Footnote Cardiac function depends on extracellular Ca2+ influx for the initial trigger.
71
What ion influx sustains the cardiac AP plateau?
Ca2+ influx through L-type Ca2+ channels (Phase 2) ## Footnote This is crucial for the cardiac action potential.
72
What is the duration of the cardiac refractory period?
Extends for the entire duration of the AP and most of the contraction ## Footnote This prevents fatal tetany.
73
What triggers contraction in cardiac muscle?
Increased cytosolic Ca2+ binds to Troponin C (TnC) ## Footnote This is essential for muscle contraction.
74
How is cardiac force modulation achieved?
By adjusting intracellular Ca2+ availability ## Footnote Cardiac muscle is a syncytium, activating partially during each beat.
75
What is the primary mechanism for cardiac relaxation?
SERCA (Sarco-endoplasmic reticulum Ca2+ ATPase) pumps Ca2+ back into the SR ## Footnote This is crucial for muscle relaxation.
76
What is the role of the NCX in cardiac muscle?
Exchanges 3Na+ for 1Ca2+ across the plasma membrane ## Footnote This is part of the Ca2+ extrusion system.
77
What does the Frank-Starling mechanism relate to?
Increased initial fiber length (stretch/preload) induces a greater subsequent contraction ## Footnote This results in increased stroke volume.
78
On which limb does the cardiac length-tension operation zone operate?
Ascending limb ## Footnote Stretching enhances the binding affinity of Ca2+ to TnC.
79
What pathway is involved in sympathetic positive inotropy?
Norepinephrine/Epi → β-AR → Gs → cAMP → PKA activation ## Footnote This enhances cardiac contractility.
80
What does PKA phosphorylate for positive lusitropy?
Troponin I (TnI) ## Footnote This speeds up relaxation by promoting Ca2+ dissociation from TnC.
81
What is the effect of PKA on Phospholamban (PLN)?
PKA phosphorylates PLN, removing its inhibition on SERCA ## Footnote This increases Ca2+ reuptake and storage.
82
What is the mechanism of Digoxin for positive inotropy?
Inhibits the Na+/K+ ATPase ## Footnote This indirectly increases intracellular Ca2+ by impairing the Na+ gradient necessary for NCX function.
83
What is the effect of Ca2+ channel blockers on contractility?
Negative inotropy by blocking L-type Ca2+ channels ## Footnote This results in less Ca2+ entry and decreased contractility.
84
What is the clinical relevance of the Crural Fascia?
Tight fascia enclosing leg; underlying cause of Compartment Syndrome ## Footnote Compartment Syndrome can lead to muscle and nerve damage due to increased pressure.
85
What is the vascular hierarchy in the Popliteal Fossa?
Popliteal Vein is superficial to the Popliteal Artery ## Footnote This relationship is important for surgical approaches and understanding vascular anatomy.
86
What nerve innervates the Anterior Compartment?
Deep Fibular Nerve ## Footnote This nerve is responsible for the motor innervation of the muscles in the anterior compartment.
87
What artery supplies the Anterior Compartment?
Anterior Tibial Artery ## Footnote This artery branches from the popliteal artery and supplies blood to the anterior compartment.
88
What is a cadaver ID tip for the EHL tendon?
Tendon goes to the hallux (big toe) ## Footnote EHL stands for Extensor Hallucis Longus.
89
What is the accessory muscle found in the anterior compartment?
Fibularis Tertius (rare) ## Footnote This muscle heads toward the base of the fifth metatarsal.
90
What nerve innervates the Lateral Compartment?
Superficial Fibular Nerve ## Footnote This nerve provides sensory and motor innervation to the lateral compartment.
91
What is a cadaver ID tip for the Fibularis Brevis tendon?
Tendon attaches to the tuberosity of the fifth metatarsal ## Footnote This attachment is key for identifying the muscle in a dissection.
92
Which tendon is most closely associated with the groove in the inferior surface of the cuboid bone?
Fibularis longus
93
What is the action of Fibularis Longus and Brevis?
Inverters of the feet ## Footnote This action is crucial for maintaining balance and stability during walking.
94
What nerve innervates the Posterior Compartment?
Tibial Nerve ## Footnote This nerve is responsible for the motor innervation of the muscles in the posterior compartment.
95
What is a common pitfall when identifying the Plantaris muscle?
Small muscle; very long, thin, white tendon commonly mistaken as a nerve ## Footnote This characteristic can lead to confusion during anatomical studies.
96
What is the name change of the Anterior Tibial Artery at the ankle?
Anterior Tibial Artery ➡️ Dorsalis Pedis Artery (DPA) ## Footnote This transition is important for understanding arterial supply to the foot.
97
What is the function of the Deep Fibular Nerve?
Provides sensory innervation to the skin of the first web space ## Footnote This area is located between the first and second toes.
98
What is the 'Dirty Double Crosser' in Layer 2 of the plantar foot?
Flexor Digitorum Longus (FDL) crosses the Flexor Hallucis Longus (FHL) ## Footnote This crossing is important for understanding muscle interactions in foot mechanics.
99
Where is the Quadratus Plantae located?
Layer 2 muscle; square-like and proximal ## Footnote This muscle assists in flexing the toes.
100
What is the appearance of the Adductor Hallucis?
Layer 3 muscle (Transverse/Oblique heads); looks like a '7' ## Footnote This muscle plays a role in adducting the big toe.
101
What key feature does the Calcaneus contain?
Sustentaculum Tali (medial process supporting the talus) ## Footnote This structure is important for the stability of the ankle joint.
102
What is a cadaver ID tip for the Cuboid?
Inferior surface has a groove containing the Fibularis Longus tendon ## Footnote This groove is significant for understanding the tendon’s path.
103
What are the deepest plantar tendons found in Layer 4?
Fibularis Longus Tendon and Tibialis Posterior Tendon ## Footnote These tendons are essential for foot stability and movement.
104
What regulates MYOSIN in smooth muscle contraction?
Ca2+ via Myosin Light Chain Kinase (MLCK) ## Footnote Key difference from skeletal muscle regulation.
105
What is the status of Troponin in smooth muscle?
Troponin ABSENT ## Footnote Tropomyosin is present.
106
How is unitary smooth muscle control achieved?
Myogenic control using extensive Gap Junctions ## Footnote This allows for propagation and syncytial function.
107
What type of control characterizes multiunit smooth muscle?
Neurogenic control with specific innervation ## Footnote Gap junctions are rare or absent.
108
What is the sequence of events in E-C coupling in smooth muscle?
Ca2+ binds Calmodulin (CaM) → activates MLCK → phosphorylates myosin regulatory site.
109
What generates action potentials in single-unit smooth muscle?
Voltage-gated Ca2+ channels (T-type/L-type), NOT Na+ channels.
110
What is the pathway for beta2 adrenergic relaxation?
Epinephrine → cAMP → PKA ## Footnote PKA phosphorylates/inactivates MLCK, allowing relaxation.
111
What does the NO/nitrate relaxation pathway activate?
sGC → cGMP → PKG1 ## Footnote PKG1 activates Myosin Phosphatase (MP) or inhibits IP3 receptors.
112
What is the role of InsP3 in the contraction pathway?
Increases intracellular Ca2+ ## Footnote Used by alpha1-AR, Angiotensin II, etc.
113
What is the significance of the latch bridge function in smooth muscle?
Stable, low-energy state allowing for Tonic Contraction or Tone.
114
What is the mechanism of PDE5 inhibitors like Sildenafil?
Inhibits breakdown of cGMP ## Footnote Maintains high cGMP/PKG1 activity leading to relaxation.
115
What does Rho-kinase activity inhibit?
Myosin Phosphatase (MP) ## Footnote Leads to contraction and Ca2+ sensitization.
116
Fill in the blank: Smooth muscle regulation focuses on MYOSIN phosphorylation by _______.
MLCK/CaM
117
True or False: Smooth muscle has Troponin.
False
118
What allows smooth muscle to achieve sustained Tonic Tone while conserving ATP?
Latch Bridge function
119
What are two ways to induce relaxation in smooth muscle?
* Block MLCK (PKA/cAMP/Beta2-AR) * Activate MP (PKG/cGMP/NO) ## Footnote Both pathways decrease MLCK activity (or increase MP activity) to lower myosin phosphorylation and induce relaxation. β 2-AR is for bronchodilation; NO/cGMP is for vasodilation.
120
What pharmacological agents rely on boosting the cGMP/PKG1 relaxation pathway?
* Sildenafil * Nitrates
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