Comprehensive Study Notes: Knee, Foot, and Ankle Anatomy (Lectures 10.x)
Knee, Foot, and Ankle Anatomy: Comprehensive Notes
Overview context
This lecture walkthrough covers knee menisci with horns, cruciate ligaments, and an in-depth tour of the foot and ankle bones, joints, and supporting ligaments, ending with leg vascular anatomy and practical image references (figures 10.59, 10.74, 10.118, 10.125, 10.145, 10.169).
Emphasis on how bone relationships determine ligament names and joint mechanics, and on common radiographic landmarks used to identify structures.
Knee anatomy: Meniscus and cruciate ligaments
Meniscus horns (anatomy and views)
In sagittal view, the meniscus shows anterior horn and posterior horn as the dark triangular areas at the ends.
In coronal views, the meniscus presents as medial horn and lateral horn.
The horns are the dark spaces within the meniscus on the respective view.
Intercondylar region and cruciate ligaments
The intercondylar fossa sits between the femoral condyles where the cruciate ligaments reside.
Cruciate ligaments provide key anterior-posterior stability.
Attachment-based naming:
If a ligament attaches from the medial femoral condyle to the posterior tibia, it is the posterior cruciate ligament (PCL).
If a ligament attaches from the lateral femoral condyle to the anterior tibial plateau, it is the anterior cruciate ligament (ACL).
Practical mnemonic: the attachment location essentially tells you the name of the ligament (posterior tibia = PCL; anterior tibia = ACL).
Quick cross-reference from image 10.74 (revisit 10.59):
The image shows the same concepts with the cruciate-labels and horn terminology.
When identifying ligaments, use the attachment site (medial condyle to posterior tibia → PCL; lateral condyle to anterior tibia → ACL).
Pelvic/femur-related context (not shown here but relevant to knee mechanics)
The menisci sit between the femoral condyles and tibial plateau, helping load distribution and shock absorption during knee flexion/extension.
Coronal view of the knee and surrounding anatomy
Coronal perspective of the knee shows:
The horns of the menisci in their respective positions (medial/lateral ho rns).
The surrounding musculature and fibular/peroneal positioning to orient left vs right sides.
Distal fibula and fibular alignment influence lateral knee anatomy and are important for later ankle discussion.
Transition to the foot and ankle: distal tibia/fibula–talus articulation
Three primary bone groups of the foot
There are three groups (as in the hand), but named differently:
Tarsals (the seven ankle bones) –
Metatarsals –
Phalanges (toes) –
Note: The foot has one fewer bone than the hand (the hand has carpals; the foot has tarsals).
Key image: 10.118 (superior view of the tarsals).
The talus is the tarsal bone that articulates with the tibia and fibula to form the ankle joint; it’s the bone that sits most superiorly and is involved in transmitting weight to the foot.
Talus and ankle joint mechanics
The distal tibia and fibula form the ankle joint with the talus, creating the ankle mortise (technical name for the ankle joint): .
The talus has three parts: body, neck, head.
The talus is the only tarsal that articulates with the tibia and fibula, making it critical for weight transfer into the foot.
Inferior to the talus sits the calcaneus (heel bone, also called os calcis): .
Between the talus and calcaneus lies the sinus tarsi, a natural gap through which tendons pass; its presence is normal.
Distal tibia/fibula relationship
The distal tibia and fibula sit side-by-side, connected by the interosseous membrane to prevent drift.
The fibula’s proximal tip includes a styloid process (a pointed projection) similar to the wrist.
Major ankle landmarks
Medial malleolus: a prominent, medial projection of the distal tibia.
Lateral malleolus: the corresponding outer projection of the distal fibula.
These malleoli form the sides of the ankle joint and help stabilize the talus.
Detailed talus anatomy for articulation with the leg
The body of the talus articulates with the tibia/fibula to form the ankle joint.
The neck of the talus connects the body to the head; the head articulates with the navicular bone on the medial side.
Weight transmission role of the talus
The talus is crucial for weight distribution from the leg to the foot due to its articulation with the tibia and calcaneus.
Significance of the calcaneus and tendon attachments
The Achilles tendon (gastrocnemius and soleus muscle group) attaches to the calcaneus, near the heel.
Summary of radiographic landmarks for ankle region
The talus sits between the tibia and fibula; the mortise is formed by these bones.
The calcaneus sits inferior to the talus.
Sinus tarsi lies between the talus and calcaneus.
The distal tibia’s medial malleolus and fibula’s lateral malleolus form the ankle’s medial and lateral borders.
The talus–navicular–cuboid region and the other tarsal bones
The sequence moving distally from the talus
After the talus, the next tarsal bone anteriorly on the medial side is the navicular; it is the medial tarsal bone.
Lateral to the navicular is the cuboid; it is the lateral tarsal bone.
Mnemonics and memory cues for the tarsals
Navicular (N) is medial; Cuboid (C) is lateral. A simple cue: M and N can help recall medial orientation (M for medial, N for navicular). Cuboid can be remembered with a pool-side cue (side pocket) to reinforce lateral position.
The other three tarsals are the three cuneiforms: medial, intermediate, and lateral.
Medial cuneiform
Intermediate cuneiform
Lateral cuneiform
The three groups of tarsals reaffirm the three-bone layering: talus on top, navicular/cuboid on the mid-foot, and the three cuneiforms adjacent to the big toe side (medial) of the foot.
Metatarsals and their junctions
Metatarsals form the instep and arch of the foot.
Articulations: tarso-metatarsal joints (between tarsals and metatarsals).
Base vs. head anatomy:
Base: articulates with the tarsals.
Head: articulates with the proximal phalanges.
There are metatarsals, numbered I to V, with I associated with the big toe.
The head ends show a subtle lucency indicating a sesamoid bone near the first metatarsal head (some individuals have two sesamoids at this location).
The patella is the largest sesamoid bone in the body; another common sesamoid is near the first metatarsal head in the foot.
Phalanges: toes
The digits (toes) are numbered I through V, with I being the big toe.
Phalanges anatomy
The first digit (hallux) has two phalanges: proximal and distal.
Digits II–V have three phalanges: proximal, middle, distal.
Joints in the digits
Distal Interphalangeal joints (DIP): between the distal and middle phalanges.
Proximal Interphalangeal joints (PIP): between the middle and proximal phalanges.
Metatarsophalangeal joints (MTP): between the metatarsal bases/heads and the proximal phalanges.
Summary of the foot anatomy figures
Figure 10.118 (superior view of the tarsals, including the talus, navicular, cuboid, and cuneiforms).
Metatarsal and phalangeal relationships are described alongside MTP and interphalangeal joints.
Ligaments and tendons around the ankle
Ligaments named by attachments
If a ligament connects the fibula to the talus, it is a type of talofibular ligament (anterior or posterior).
If a ligament connects the tibia to the talus, it is a tibio-talar ligament; the tibio-talar ligament is also known as the deltoid ligament when discussing its multiple-band composition.
The tibia–talus linkage near the medial malleolus is a key component of the deltoid (tibiotalar) ligament complex.
The fibula–talus linkage is the talofibular ligament (anterior or posterior).
Specific ligaments during axial views (image 10.125 and 10.145 references)
Anterior talofibular ligament: located anterior to the ankle, between the tibia/fibula and talus.
Posterior talofibular ligament: located posterior to the ankle, between the tibia/fibula and talus.
Posterior tibiofibular ligament: connects the tibia and fibula posteriorly, contributing to the stability of the distal tibiofibular joint.
Deltoid ligament: a group of ligaments on the medial side (tibia–talus connections), sometimes labeled as tibio-talar ligaments; multiple bands present.
Other key tendinous structures around the ankle
Extensor retinaculum: a supportive band on the anterior aspect that covers the extensor tendons and holds them in place.
Flexor digitorum longus tendon: located near the medial malleolus; attachment point can be traced straight downward from the medial malleolus.
Peroneus longus tendon: located near the lateral malleolus; attachment path runs downward from that region.
Visual cues for orientation on axial views
Patient is typically supine; anterior structures are at the top of the image, posterior structures at the bottom.
Lateral malleolus (fibula) tends to appear more rounded; the medial malleolus (tibia) is more pointed.
Practical radiology note
The extensor retinaculum and surrounding tendons are key to identifying tendon paths and ligament relationships on axial views.
Vascular anatomy of the leg (angiography context)
Arterial path from the aorta to the leg
Abdominal aorta gives rise to the bifurcation around the level of the iliac crest to form the common iliac artery.
The common iliac divides into:
Internal iliac artery
External iliac artery
As the external iliac artery travels into the thigh, it becomes the femoral artery.
Branches off the femoral artery
Circumflex arteries: branches that wrap around the bone/spiral around the thigh.
Profunda femoris artery (deep femoral): a deeper branch off the femoral artery.
The femoral artery travels down the thigh and becomes the popliteal artery as it passes behind the knee.
The knee and leg behind the knee
Popliteal artery: the continuation behind the knee; this region supplies the posterior knee and lower leg.
Figure reference and clinical note
Figure 10.169 shows an angiogram with the aorta, common iliac, internal and external iliac, femoral, profunda femoris, circumflex, and the popliteal artery.
The patient in the image shows some hip degeneration at the acetabulum; this is noted as part of the radiographic context.
A practical clinical note: the femoral artery is a common place to palpate a pulse and has historical use in angiography via catheterization.
Summary of the vascular pathway
Aorta → Common iliac → Internal iliac + External iliac → External iliac becomes Femoral artery → Profunda femoris + Circumflex arteries → Popliteal artery (behind knee).
Image references recap for study planning
Knee images:
10.59 and 10.74 cover knee anatomy (menisci horns, intercondylar fossa, cruciate ligaments).
Foot and ankle images:
10.118: Superior view of tarsals (talus, navicular, cuboid, cuneiforms).
10.125: Axial view of the ankle showing malleoli, ligaments, extensor retinaculum, and tendon paths.
10.145: Axial view detailing lateral/medial malleoli, extensor retinaculum, flexor digitorum longus tendon, peroneus longus tendon, and posterior tibiofibular ligaments.
10.169: Angiogram illustrating the aorta, common/internal/external iliac, femoral, profunda femoris, circumflex, and popliteal arteries.
Other anatomical cues to remember
Os calcis = calcaneus (heel bone).
Sinus tarsi: small space between talus and calcaneus on imaging.
The calcaneal tendon (Achilles tendon) attaches to the calcaneus.
The medial malleolus belongs to the tibia; the lateral malleolus belongs to the fibula.
The ankle mortise is the joint formed by the distal tibia, fibula, and talus.
Foundational concepts and practical implications
Anatomy-to-name principle
Ligaments are named for their bony attachments (tibia–talus, fibula–talus, etc.), aiding in rapid identification during imaging and surgical planning.
Weight transfer mechanics
The talus plays a pivotal role in distributing body weight from the leg to the foot due to its articulation with both bones of the leg and the calcaneus.
Radiologic orientation cues
An understanding of anterior vs posterior, medial vs lateral, and superior vs inferior helps interpret radiographs and axial CT/MRI slices quickly.
Memory aids and clinical relevance
Mnemonic cues (e.g., Cuboid = lateral; Navicular = medial; Cuboid sounds like “cubed”/side pocket; M and N for medial/navicular) can aid exam recall).
Practical clinical notes
Common fracture-prone areas include the base of the 5th metatarsal and the first MTP region due to sesamoid presence; awareness of these regions helps in rapid assessment.
Week 10 wrap-up guidance
Review knee images (10.59, 10.74) and foot/ankle images (10.118, 10.125, 10.145, 10.169) to reinforce the relationships described and ensure comfortable identification of landmarks.
Quick reference: key terms and concepts
Horns: anterior horn, posterior horn (sagittal); medial horn, lateral horn (coronal).
Intercondylar fossa; cruciate ligaments (PCL, ACL).
Ankle mortise; talus as weight-transmitter; calcaneus; sinus tarsi.
Tarsals: bones (talus, navicular, cuboid, and three cuneiforms).
Metatarsals: bones; base and head; first metatarsal may have sesamoids near its head.
Phalanges: bones total; hallux with 2 phalanges; digits II–V with 3 phalanges each.
Joints: tarso-metatarsal, metatarsophalangeal (MTP), proximal interphalangeal (PIP), distal interphalangeal (DIP).
Ligaments: talofibular (anterior and posterior), tibio-talar (deltoid) ligaments; posterior tibiofibular ligament.
Tendons around the ankle: extensor retinaculum; flexor digitorum longus; peroneus longus.
Vascular path: Aorta → Common Iliac → Internal/External Iliac → External becomes Femoral → Profunda Femoris and Circumflex branches → Popliteal.
Os calcis = calcaneus; osseous landmarks: medial malleolus (tibia), lateral malleolus (fibula).
Imaging cues: anterior vs posterior, superior vs inferior orientation; sinus tarsi.