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Lower Extremity Anatomy > Osteology (Part 6): Ossification Centers & Accessory Ossicles > Flashcards

Osteology (Part 6): Ossification Centers & Accessory Ossicles Flashcards

(43 cards)

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1
Q

Talus primary ossification center

A
  • Center of talar body

- Appears by 6-7th fetal month

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2
Q

Talus secondary ossification center

A
  • Not always present
  • Posterior process
  • Os Trigonum results if it does not fuse
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3
Q

Calcaneus ossification

A
  • Consistently has 2 ossification centers
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4
Q

Calcaneus primary ossification center

A
  • Center of calcaneus

- Appears 4-6th fetal month

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5
Q

Calcaneus secondary ossification center

A
  • Calcaneal apophysis
  • Contributes to calcaneal tuberosity and posterior surface
  • Appears around age 6-8
  • Fuses between 14-18
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6
Q

Cuboid ossification

A
  • Single primary center

- Usually present at birth (9th month)

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7
Q

Navicular ossification

A
  • Last foot bone to begin ossifiying
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8
Q

Navicular primary ossification center

A
  • Appears at the center around age 3
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9
Q

Navicular secondary ossification center

A
  • Not always present
  • Forms medial bone
  • Results in bipartite navicular if present and fails to fuse
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10
Q

Medial cuneiform primary ossification center

A
  • Appears at the center around age 2
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11
Q

Medial cuneiform secondary ossification ceneter

A
  • Plantar in location

- Not always present

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12
Q

Intermediate cuneiform primary ossification center

A
  • Appears at the center around age 3
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13
Q

Lateral cuneiform primary ossification center

A
  • Appears at the center around age 1
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14
Q

1st metatarsal ossification

A
  • 1⁰: appears in the shaft during 10th intrauterine week
  • 2⁰: appears in the base around age 3 (proximal growth plate)
  • Fuses ~ 18 years of age
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15
Q

2nd, 3rd, and 4th metatarsal ossification

A
  • 1⁰: appears in the shaft during 9th intrauterine week
  • 2⁰: appears at the head between 3 and 4 years of age (distal growth plate)
  • Fuses ~ 18
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16
Q

5th metatarsal ossification

A
  • 1⁰: appears in the shaft during the 10th intrauterine week
  • 2⁰ : appears at the head between 3 and 4 years of age (distal growth plate)
  • Fuses ~ 18
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17
Q

5th metatarsal secondary ossification

A
  • Can be another 2⁰ in the styloid process

- Lack of fusion results in an os Vesalianum within the fibularis brevis tendon

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18
Q

Phalanges ossification

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A
  • Considered long bongs
  • Develop by endochondral ossification
  • Except for tufts of the distal phalanges (intramembranous ossification)
19
Q

Phalanges primary ossification center

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A
  • Appears in the shaft of distal (9-12 intrauterine week)
  • Proximal (11th – 15th intrauterine week)
  • Middle (after 15th intrauterine week)
20
Q

Phalanges secondary ossification center

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A
  • Appear in the base between ages 2-8 (age 3 is average)

- Fuse by age 18

21
Q

1st MTPJ Sesamoid bones

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A
  • Begin ossification between years 7-8

- Medial sesamoid is usually larger than the lateral sesamoid of the 1st MTP joint

22
Q

Tarsal bones present at birth

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A
  • Talus
  • Cuboid
  • Calcaneus
23
Q

Tarsal bones present by 1 year of age

Study These Flashcards
A
  • Talus
  • Cuboid
  • Calcaneus
  • Lateral cuneiform
24
Q

Tarsal bones present by 2 years of age

Study These Flashcards
A
  • Talus
  • Cuboid
  • Calcaneus
  • Lateral cuneiform
  • Medial cuneiform
25
Tarsal bones present by 3 years of age
- Talus - Cuboid - Calcaneus - Lateral cuneiform - Medial cuneiform - Intermediate cuneiform - Navicular
26
Accessory ossicles are found within
- Tendons - Joint capsules - High pressure areas
27
Accessory ossicles
- Easily mistaken for fractures - Some are derived from failure of union of 2ᵒ ossification center - Usually asymptomatic - Can become symptomatic
28
Symptomatic accessory ossicles usually invovle
- Fracture - Dislocation - Degeneration - AVN - Impingement
29
Accessory navicular (4-21%)
- Lack of fusion of a secondary ossification center of navicular tuberosity (type I and II)
30
Type I accessory navicular (os tibiale externum, os navicular secundum)
- Within posterior tibialis tendon at the insertion | - Proximal to navicular tuberosity
31
Type II accessory navicular (prehallux, bifurcate hallux)
- Connected to navicular tuberosity by cartilaginous bridge - Often bilateral - Large, located near navicular tuberosity
32
Type III accessory navicular
- Prominent navicular tuberosity (cornuate navicular | - A fused type II
33
Os supranaviculare (1-3.5%)
- Also called Piries bone, os talonavicular dorsale | - Located proximal dorsal aspect of navicular
34
Os Peroneum (20-70%)
- Located within the tendon of peroneus longus (lateral to fibular sulcus/groove of cuboid, lateral to cuboid) - Commonly bilateral - Can cause degeneration of peroneus longus tendon - Can form joint with cuboid tuberosity
35
Os Vesalinum (0.1-1%)
- Found within tendon of peroneus brevis at insertion on styloid process of 5th metatarsal - Unfused secondary ossification center - Seen on AP and medial oblique xray
36
Os Trigonum (7-25%)
- Located posterior to talus - Lack of fusion of secondary ossification center of the lateral tubercle - Can cause posterior impingement and tenosynovitis of FHL
37
Os sustentaculi (0.3-1%)
- Located on posterior aspect of sustentaculum tali
38
Os calcaneum secundarius (~1%)
- Located at anterior process of calcaneus | - Can mimic bifurcate ligament avulsion fracture
39
Os subtibiale (rare)
- Near posterior colliculus of medial malleolus
40
Os Supratalare/os astraglus (~1%)
- Located dorsal to neck of talus
41
Os Intercuneiforme (1-2%)
- Located between cuneiforms dorsally | - Usually between medial and intermediate
42
Os Intermetatarseum (~4-5%)
- Between bases of metatarsals - Most common between 1st and 2nd; 4th and 5th - Can form a synovial joint with neighboring bone or fuse to them
43
Accessory sesamoid bones
- Most common at the IPJ of the hallux and the MTPJ of the 5th digit

Lower Extremity Anatomy (35 decks)

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