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An illustration of the neurovascular bundles of the ankle and
foot on ultrasound and magnetic resonance imaging
Poster No.:
C-2429
Congress:
ECR 2010
Type:
Educational Exhibit
Topic:
Musculoskeletal
Authors:
J. Oommen; Manchester/UK
Keywords:
foot and ankle, neurovascular bundle, layers of the sole of the foot
DOI:
10.1594/ecr2010/C-2429
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Learning objectives
To illustrate the anatomical layers of the foot on ultrasound and magnetic resonance
imaging and the relationship of the neurovascular bundles in relation to the muscle layers
and the bone landmarks. The neurovascular bundle at the ankle is also illustrated.
Ultrasonography of the foot is limited by the fibrous texture of the subcutaneous tissues
and the plantar aponeurosis with increased acoustic impedence at the heel.
Identification of the muscle groups helps in the identification of the neurovascular
bundles.
Anatomically the muscles are grouped into 3 groups: the medial and lateral groups formed
by the intrinsic muscles of the big and little toe. The intermediate group consisting of the
short flexors ,the lumbericals and interossi muscles.
Images for this section:
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Fig. 1: Axial T2 weighted Magnetic resonance images.The medial muscle group bundled
on the right and the intermediate group in the centre of the Right foot.
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Fig. 2: Axial T2 weighted Magnetic resonance images.The lateral muscle group bundled
on the left and the intermediate group in the centre of the Right foot.
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Fig. 3: Axial T2 weighted Magnetic resonance images demonstrating predominantly the
intermediate group in the centre of the Right foot.
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Background
The intimate nature of the muscle groups in the foot with a paucity of inter muscular
fat deposition limits identification of the muscular layers on computed tomography. The
identification of the fine neurovascular bundle is a challenge on most imaging modalities.
Dynamic high resolution of ultrasound is able to provide soft tissue differentiation.
This is useful particularly in post operative patients with internal fixators hindering imaging
by magnetic resonance imaging or computed tomography.
The superficial layer is formed by the Abductor Hallucis, Flexor digitorum brevis and the
abductor digiti minimi from medial to lateral and extends from the calcaneal tuberosity to
the toes. This overlies the neurovascular bundle.
The second layer consist of the Flexor Hallucis longus , the Flexor Digitorum longus , the
Flexor Digitorum accessorius and the four lumberical muscles(1).
The third layer consist of the Flexor Hallucis brevis, adductor Hallucis and the flexor digiti
minimi.
The fourth layer is formed by the interossei
The neurovascular bundle separates into the medial and lateral plantar nerves deep to
the flexor retinaculum and separates further into the individual digital nerves as it leaves
the lateral border of the flexor hallucis brevis. The nerves run superficial to the flexor
digitorum longus tendons in the respective inter-metatarsal spaces.
Images for this section:
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Fig. 1: Coronal T2 Weighted Magnetic resonance image demonstrating the
neurovascular bundle at the posteromedial(left) aspect of the left ankle between the flexor
digitorum longus and the flexor hallucis longus. Note the origin of the medial muscle group
at the heel and the Flexor Hallucis brevis at the medial cortex of the calcaneum
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Fig. 2: Coronal T2 Weighted Magnetic resonance image demonstrating the
neurovascular bundle at the posteromedial(left) aspect of the left ankle between the flexor
digitorum longus and the flexor hallucis longus. Note the origin of the 1st muscle layer at
the heel and the medial cortex of the calcaneum
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Fig. 3: Coronal T2 Weighted Magnetic resonance image demonstrating the
neurovascular bundle at the inferior(left) aspect of the left ankle below th sustanticulum
tali. Note the origin of the first and second muscle layers at the heel and the flexor hallucis
brevis from the medial cortex of the calcaneum
Fig. 4: Sagittal T1Weighted Magnetic resonance image demonstrating the neurovascular
bundle at the posteromedial(left) aspect of the left ankle between the flexor digitorum
longus and the flexor hallucis longus. Note the origin of calcaneal branches and the
medial muscle group at the heel and the Flexor Hallucis brevis at the medial cortex of
the calcaneum
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Fig. 5: Sagittal T1 Weighted Magnetic resonance image demonstrating the
neurovascular bundle at the posteromedial(left) aspect of the left ankle between the flexor
digitorum longus and the flexor hallucis longus. Note the origin of the medial plantar
calcaneal branches
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Fig. 6: Coronal T2 Weighted Magnetic resonance image of the left foot demonstrating
the neurovascular bundle between the first and second layers at the level of the head of
the talus. Note the medial(left), intermediate and lateral(right) muscle groups.
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Fig. 7: Coronal T2 Weighted Magnetic resonance image of the left foot demonstrating
the medial and lateral neurovascular bundle between the first and second layers at the
level of the head of the talus. Note the medial(left), intermediate and lateral(right) muscle
groups.
Fig. 8: Coronal T2 Weighted Magnetic resonance image of the left foot demonstrating
the separated medial and lateral neurovascular bundle at the level of the bases of the
metatarsals. Note the medial(left), intermediate and lateral(right) muscle groups.
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Fig. 9: Coronal T2 Weighted Magnetic resonance image of the left foot demonstrating
the less obvious separated medial and lateral neurovascular bundle between the first and
second layers at the level of the distal shaft of the metatarsal bones. Note the smaller
medial(left margin), and lateral(right),the larger intermediate muscle groups.
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Fig. 10: Coronal T2 Weighted Magnetic resonance image of the left foot demonstrating
the separated diminished medial and lateral neurovascular bundle between the first
and second layers at the level of the shaft of the metatarsal bones. Note the small
medial(left)and lateral muscle groups (right margin), and the larger intermediate muscle
groups.
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Fig. 11: Coronal T2 Weighted Magnetic resonance image of the left foot demonstrating
the separated medial and lateral neurovascular bundle between the first and second
layers at the level of the sesamoid bones of the first metatarsal. Note the Poor distinction
between the medial(left), intermediate and lateral(right) muscle groups(tendons).
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Imaging findings OR Procedure details
A review of the structures on high resolution ultrasound images is correlated with soft
tissue layers appreciated on magnetic resonance images and referenced with anatomical
texts.
This ultrasound illustration provides a cross-sectional road map relating to the anatomical
layers.
The neurovascular bundle and their relationships are illustrated.
The bone landmarks are also identified and demonstrated here.
Images for this section:
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Fig. 1: Coronal ultrasound images showing the fat pad of the right heel and the origin of
the medial(left)and lateral(right) muscle groups from the calcaneal tuberosity.
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Fig. 2: Coronal ultrasound images showing sole of the right foot and the larger
medial(left)and the smaller lateral(right) muscle groups at the level of the mid calcaneum.
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Fig. 3: Coronal ultrasound images showing sole of the right foot and the larger
medial(left)and the smaller lateral(right) muscle groups at the level of the distal
calcaneum.
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Fig. 4: Coronal ultrasound images showing sole of the right foot at the level of the
tarsal bones. The small and separated medial and lateral plantar neurovascular bundles
are apreciated by the position of the vessels. The echogenic nerves run lateral to the
arteries. The deeper intermediate muscle group is more prominent. The muscle layers
are appreciated by toe movements.
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Fig. 5: Coronal ultrasound images showing sole of the right foot at the level of the
metatarsal bones. The small and separated medial and lateral plantar neurovascular
bundles are apreciated by the position of the vessels. The echogenic nerves run lateral
to the arteries. The deeper intermediate muscle group is more prominent. The muscle
layers are revealed by toe movements.
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Fig. 6: Coronal ultrasound images showing sole of the right foot at the level of the head
of the first metatarsal bone. The muscle tendons are revealed by toe movements.
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Fig. 7: Sagittal oblique ultrasound images showing sole of the right foot at the level of
the tarsal bones showing the medial plantar artery. The echogenic nerves run lateral to
the arteries.
Fig. 8: Sagittal oblique ultrasound images showing sole of the right foot at the level of
the tarsal bones showing the medial plantar nerves. The small and separated medial and
lateral plantar neurovascular bundles are apreciated by the position of the vessels. The
echogenic nerves run lateral to the arteries. The deeper intermediate muscle group is
more prominent. The muscle layers are revealed by toe movements.
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Fig. 9: Sagittal oblique ultrasound images showing sole of the right foot at the level of the
tarsal bones showing the lateral plantar nerves which can also be located by the position
of the vessels. The echogenic nerves run lateral to the arteries.
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Conclusion
Ultrasound can provide high resolution of soft tissue layers.
This illustration provides a cross-sectional road map for the assessment of layers of the
foot.
The course of the neurovascular bundle at the ankle and in the foot is illustrated.
This has a potential for the clinical application for foreign body localisation prior to surgical
intervention to avoid potential neurovascular injury.
Personal Information
Dr. J Oommen, Consultant Radiologist, Royal Albert Edward Infirmary, Wrightington,
Wigan and Leigh NHS Foundation Trust. Manchester, United Kingdom
References
1. Frank H Netter, Atlas of human anatomy section VII lower limb
2. Gray's Anatomy,The Anatomical basis if clinical practice, chapter111.
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