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MF5 > Lower Limb > Flashcards

Lower Limb Flashcards

1
Q

What is the MSK system derived from?

A
  • Almost all of the connective tissues of the MSK system is dervied from the mesoderm.
  • Each tissue type (i.e., cartilage, bone, muscle) goes through different mechanisms of differentiation
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2
Q

Somite

A
  • Bilaterally paried blocks of mesoderm
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3
Q

Limb Development

A
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4
Q

Stages of Limb Axis Formation

A
  1. Limb Initiation - Fibroblast growth factor (FGF) starts initiation of limb bud. Limb identity may be regulated by tranascription growth factors (T-box genes).
  2. Proximodistal Axis (from distal aspect of appendage to proximal) - Apical ectodermal ridge (AER) froms at distal end of limb bud. AER and limb mesenchyme contine to communicate with each other via FGF to direct future limb development.
  3. Anteroposterior axis (from head to toe) - Under the control of the -Zone of polarixing activity (ZPA)- an area of mesenchyme that contains signals that instruct limb bud to form along anterior posterior axis. Under regulation of sonic Hedgehod (shh) genes.
  4. Dorosoventrical Axis (from spinal colum to belly) - important for patterning of muscles. Under the control of both mesoderm and ectoderm of limb bud depending on the stage of development. (Mesoderm first controls the axis, but later ectodermal orientation becomes prominant.) Under regulation of Wnt genes, expressed in the dorsal part of the progress zone.
  • Limb enlargement occurs due to interaction between AER and progress zone.
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5
Q

Differences between a newborn and adult foot

A
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6
Q

Common Congential Foot Abnormalities

A
  • Metartsus Adductus
  • Clubfoot Deformitiy
  • Calcaneovalgus (Flexible flatfoot)
  • Congenital Vertical Talus
  • Multiple Digital Deformities
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7
Q

Metatarus Adductus (MTA)

A
  • One of the most common foot deformities
  • Transverse plane deformity in Lisfranc’s (tarsometatarsal) joints
  • Toes angle abruptly towards the midline - creates a curved foot shape
  • Mild MTA requries no treatment. Moderate can be treated with stretching. Severe requires bracing and casting in order to prevent formation of bunions and hammer toes.
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8
Q

Clubfoot/ Talipes Equinovarus

A
  • Congenital deformity with 4 main components
    1. Cavus Midfoot
    2. Forefoot Adductus
    3. Subtalar Varus
    4. Hindfoot Equinus
  • Multifactorial deformity with genetic and intrauterine factors
  • Foot appears “down and in. Medial border of foot is concave with deep medial skin furrow and lateral border is highly convex.
  • On exam there is tightness of Achillar tendon with little dorsiflexion
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9
Q

Types of Clubfoot

A
  • There are 2 types of clubfoot (type determines treatment)
    • Extrinsic (supple) type - A severe positional or soft tissue deformity. Can be treated with casting.
    • Intrinsic (rigid) type - Manual reduction is impossibe. May require surgery, but casting should be attempted first.
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10
Q

Pathogenesis of Clubfoot

A
  • During pregnancy, foot remains in physiological clubfoot position up to the 11th week as fibula growth is faster than tibial growth up to this point.
  • Clubfoot is a deformity that involves the entire foot.
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11
Q

Main anatomical changes observed in clubfoot

A
  1. Talus - primary deformity is a deviation of the anterior section of the talus in medial and plantar direction. See a greater angle between the trochlea of the talus an the talar neck. Talar neck is also shortened and the typical shoulder is not present.
  2. Calcaneus - Deformity of the calcaneus is less pronounced then the talus. See a slight medical deviation.
  3. Metatarsal and forefoot bones - they are slightly hypoplastic (shortened but normal width).
  4. Tibia - shows slight internal rotation (it is masked by posterior displacement of the fibula giving impression leg is externally rotated).
  5. Ankle joint - Talus is pushed forward out of ankle mortise
  6. Subtalar joint - Calcaneus is rotated medially and tilted ventrocaudally in relation to the talus resulting in absence of normal upward slope in dorsal to ventral direction.
  7. Talonvicular joint - Navicular bone is displaced in medial and plantar direction in relation to the talus.
  8. Soft tissue changes - soft tissue of anteromedial and posterolateral sides of the talus are shortened.
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12
Q

Calcaneovalgus

A
  • Deformity at tibiotalar joint so that foot is positioned in extreme hyperextension.
  • Associated with external rotation of the calcaneus, an overstretched Achilles tendon, and tight anterior leg musculature.
  • On exam foot has “up and out” appearance with dorsum of foot almost touching anterior ankle. Ankle can usually only be planter flexed to 900 or less
  • Treatment includes stretching exercises and splinting
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13
Q

Congential Vertical Talus/ Rocker-Bottom Foot

A
  • Rigid deformity where hindfoot is in equinus position with talus and calcaneus pointing downward and the forefoot is dorisflexed.
  • Results in dislocation of midtarsal bones on head and neck of talus
  • Foot exam reveals rigid foot with “reversed” arch, a convex plantar surface, and a deep crease on the lateral dorsal side of the foot. Ankle joint is plantarflexed while midfoot and forefoot are extended upward.
  • Surgery is needed in most cases
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14
Q

Foot bone anatomy

A
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15
Q

Digital Deformities

A
  • There are multiple types of digital deformities:
    • Polydactyly
    • Syndactyly - webbed toes
    • Overlapping toes
    • Amniotic (annular) bands - produced by thin bands of amniotic membrane wrapping around various parts of the extremity in uterus
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16
Q
  1. Equinus
  2. Adduction and valgus
  3. Abducted and varus
  4. Dorsiflexion
  5. Supination
  6. Pronation
A
  1. Describes a plantar flexion –foot pointing down.
  2. Describes defects toward the midline.
  3. Describes defects away from the midline.
  4. Describes the situation where the dorsal surface of the foot is in proximity to the dorsum of the
    tibia.
  5. Weight placed on outside of foot (more accurate to say inversion)
  6. Weight placed on inside of foot (more acurate to say eversion)
17
Q

Fingers and Toes Formation

A
  • Fingers and toes are formed when cell death in the AER separates this ridge into 5 parts → further formation of digits depends on continued outgrowth under influence of 5 segments of ridge ectoderm, condensation of mesenchyme to form cartilaginous digital rays, and death of internvening tissues between rays.
18
Q

Components of Peripheral nerves

A
  1. Axons - elongated cell processes of neurons which propagate nerve action potentials.
  2. Schwann cells - ensheathe axonal processes in myelin
  3. Connective tiessue matrix - Composed of epineurium, perinerium, and endoneurium
19
Q

Femoral Nerve

A
  • Location: Leg near the groin
  • Innervation: L2-L4 (origin - lumar plexus)
  • Function:
    • Forms largest branch of lumar plexus.
    • Has both motor and sensory function.
      • Motor - Motor innervation to anterior compartment of thigh
      • Sensory - Sensory innervation of skin of the anterior thigh and lower part of the leg below the knee.
20
Q

Obturator Nerve

A
  • Location: Descends through fibers of psoas muscle and emerges from medial border, running posterioly to common iliac ateries and laterally along pelvic wall to obturator foramen. It enters through the obturator canal and splits into anterior and posteror divisions.
  • Innervation: L2-L4 (origin - lumbar plexus)
  • Function:
    • Motor - innervates all the muscles in the medial comprtment of the thigh (except hamstring part of adductor magnus).
    • Sensory - Cutaneous branch supplies skin of middle part of medial thigh
      *
21
Q

Superior Gluteal Nerve

A
  • Location: Leaves the pelvis via greater sciatic foramen, entering gluteal region superiorly to piriformis muscle.
  • Innervation: L4-S1 (origin - sacral plexus)
  • Function:
    • Motor: Innervates gluteus minimus, gluteus medius, and tensor fascia lata.
    • Sensory: None
22
Q

Inferior Gluteal Nerve

A
  • Location: Leaves plevis via greater sciatic formen, entering gluteal region inferiorly to piriformis muscle.
  • Innervation: L5-S2 (origin - sacral plexus)
  • Function:
    • Motor: Innervates gluteus maximus
    • Sensory: None
23
Q

Sciatic Nerve

A
  • Location: Leaves pelvis and enters gluteal region via greater sciatic foramen. It emerges inferiorly to piriformis and descends in an inferolateral direction. (Divides into Femoral and Tibial division)
  • Innervation: L4-S3 (origin - sacral plexus)
  • Function:
    • Motor: Innervates biceps foramis, semitendinosus, semimembranosus, and medial part of adductor magnus.
    • Sensory: Does not have direct cutaneous function, but provides indirect sensory innervation via terminal branches.
24
Q

Deep Fibular Nerve

A
  • Location: Originates from sciatic nerve - bifurcates into common fibular and tibial nerve at apex of poplitea fossa. Comon fibular nerve wraps around neck of fibula, moving anterolaterally and gives rise to superifical and deep fibular nerve.
  • Innervation: L4-S1 (orgin - common fibular nerve)
  • Function:
    • Motor: Innervates muscles in anterior compartment of leg and some instrinsic muscles of the foot.
    • Sensory: Supplies triangular region of skin between 1st and 2nd toe.
25
Q

Superifical Fibular Nerve

A
  • Location: Terminal branch of common fibular nerve. Arises at neck of fibula and descends between fibularis and lateral side of extensoru digitorum longus.
  • Innervation: L4-S1 (Origin - common fibular nerve)
  • Function:
    • Motor: Supplies fibularis longus and fibularis brevis. Works to evert the foot at subtalar joint and weakly contributes to plantarflexion.
    • Sensory: Innervates skin over anterolateral leg and dorsum of foot (except webbed space between 1st and 2nd toes).
26
Q

Tibial Nerve

A
  • Location: Branch of sciatic nerve that arises at the apex of the popliteal fossa. It continues down the leg posterior to the tibia and passes posteriorly and inferiorly to the medial malleolus through the tarsal tunnel where it then terminates.
  • Innervation: L4-S3
  • Function:
    • Motor: Innervates posterior compartment of the leg
    • Sensory: Innervates skin of posterolateral side of leg, lateral side of foot, and sole of foot
27
Q

Types of Peripheral Nerve Injury

A
  • Neuropraxic injury - least severe form of injury. A tempory interruption of conduction without loss of axonal continuity. There is a physiological block of nerve conduction in affected axions. Because nerve retains its physical integrity the prognosis for spontaneous recovery is good. Generally see clinical improvement within a few hours - day.
  • Axonotmetric - More severe form of injru. Axon is disrupted with degeneration of distal stump, but surroudning support structures remain in tact to varying degree. This leaves in place a conduit-guiding axonal outgrowth to appropriate rennervation of target organs. Quality of recovery depends of damage of support structures. (Loss of continuity of axon and myelin covering, but preservation of connective tissues).
  • Neurotmesis - Most severe form of injury. Severence or disruption of entrie nerve fiber, either from internal scarring or by physical transection.
28
Q

Signs and Symptoms of Peripheral Nerve Disease

A
  • Sensory disturbances - All modalities of cutaneous sensibility are lost only over the autonomous zone (area exclusively supplied by the nerve).
    • With peripheral nerve lesions area of light touch sensory loss is greater than pinprick sensory loss
    • While pain and parethesia can help to localize a lesion, they tend to radiate beyond the distribution of the damaged nerve.
  • Motor distrubances - Interruption of motor fibers in a motor or mixed nerve results in lower motor neuron paress or paralysis or the muscles innervated by that nerve. Muscles will atrophy and may become hypotonic (decreased resistance to passive motion).
  • Muscle stretch reflex disturbances - can result in decreased or absent muscle stretch reflex
  • Vasomotor, sudomotor, and trophic disturbances
    • Skin served by affected nerve may become thin and scaly; dry and inelastic; cease to sweat
    • May see retardation of nail and hair growth in affected area
    • More liable to injury - ulcers may form
29
Q
  1. Autonomous Zone
  2. Intermediate Zone
  3. Maximal Zone
A
  1. Autonomous zone (area exclusively supplied by the nerve).
  2. Autonomous zone is surrounded by intermediate zone (where one nerves territory overlaps with sensory area supplied by adjacent nerves).
  3. Maxmial zone - Autonomous + Intermediate zone
30
Q

Fractues Types

A
  • Comminuted -Bone fragments into 3 or more pieces. More common in the elderly with brittle bones.
  • Spiral - Ragged break occurs when excessive twisting forces are applied to a bone. Common sports fracture.
  • Depressed - Broekn bone portion is pressed inward. Typical of a skull fracture.
  • Compression - Bone is crushed. Common is porous bones subjected to extreme trauma, as in a fall.
  • Epiphyseal - Epiphysis separates from the diaphysis along the epiphyseal plate. Tends to occur where catilage cells are dying and calcification of the matric is occuring.
  • Greenstick - Bone breaks incompletely - only one side of the shaft breaks; the other side bends. Common in children whose bones have relatively more orgnic matric and are more flexible than adults.
31
Q

Main Hip

  1. Flexor
  2. Extensor
A
  1. lliopsoas (L2, L3)
  2. Gluteus Maximus (L5-S1)
32
Q

Main Hip

  1. Abductors
  2. Adductors
A

1.

  • Glutues Medius (L4-S1)
  • Gluteus Maximus (S1-S2)
  • Tensor Fascia Lata

2.

  • Adductor magnus, longus and brevis
  • Pectineus
  • Gracilis
33
Q

Main Hip

  1. External Rotators
  2. Internal Rotators
A

1.

  • Piriformis
  • Obturator externus
  • Obturator Internus
  • Gemilli
  • Quadratus Femoris

2.

  • Gluteus medius
  • Glutues minimus
  • Tensor fascia lata

MF5 (15 decks)

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