BIO 004 · Human Anatomy
The Lower Extremity
Appendicular Skeleton, Lower Extremity
A reference for the lower extremity video and lab. This page covers the pelvic girdle that carries the body's weight to the legs, and the bones of the thigh, leg, and foot, each bone broken out with its key markings.
How to use this sheet
Notes prints the full reference for review.
Study prints as a fill-in-the-blank worksheet to complete while you watch the video or read.
Quiz me is on-screen practice: type the term, or click Reveal to check yourself.
The tables and sequences respond to Study and Quiz too, with a Reveal button on each row.
- Name the three bones that fuse to form the hip bone, and describe the pelvis.
- Identify the key markings of the hip bone, including the acetabulum.
- Identify the key markings of the femur, patella, tibia, and fibula.
- Name the bones of the foot, including the seven tarsal bones and the arches.
Your pre-work
Work through these the evening before class. None of it is turned in. It is how you learn the material and build your spaced recall.
This is more than a checklist. Ticking these boxes is the start, not the finish. Committing this material to memory and being able to apply it takes considerable time and repeated effort. You are not done when the boxes are checked. Put in the real hours, and keep coming back for frequent recall and review until the material is genuinely yours.
The Lower Extremity, an Overview
The lower limb is built heavier than the upper limb because it carries the body's weight. Compare its four parts, proximal to distal.
| Part | Region it spans | Bones |
|---|---|---|
| Pelvic girdle | attaches the lower limb to the axial skeleton | the two hip bones |
| Thigh | hip to knee | femur (and the patella at the knee) |
| Leg | knee to ankle | tibia and fibula |
| Foot | ankle to toes | tarsals, metatarsals, and phalanges |
The Pelvic Girdle
Each hip bone, the os coxae, begins as three separate bones that fuse at the acetabulum: the ilium, the ischium, and the pubis.
Ilium
- Iliumthe large, fan-shaped superior part of the hip bone
- Iliac crestthe curved upper ridge, the rim you rest your hands on
- Anterior superior iliac spinethe prominent point at the front of the crest, a palpable landmark
- Posterior superior iliac spinethe point at the back of the iliac crest
- Iliac fossathe smooth, concave inner surface
- Auricular surfacethe ear-shaped surface that joins the sacrum at the sacroiliac joint
- Greater sciatic notchthe deep notch on the posterior border; the sciatic nerve, the largest nerve in the body, passes through it
Ischium
- Ischiumthe posteroinferior part of the hip bone
- Ischial tuberositythe strong, roughened knob you sit on
- Ischial spinethe pointed projection above the tuberosity
Pubis
- Pubisthe anteromedial part of the hip bone
- Pubic symphysisthe cartilage joint where the two pubic bones meet in front
- Pubic crestthe ridge along the upper border of the pubis
- Pubic ramithe superior and inferior bars of bone extending from the body
The acetabulum and the pelvis
- Acetabulumthe deep cup where the three bones meet, the socket for the head of the femur
- Obturator foramenthe large opening framed by the ischium and the pubis
- The bony pelvisthe two hip bones together with the sacrum and the coccyx
- True and false pelvisthe false pelvis is the wide flare above the pelvic brim, the true pelvis is the narrower ring below it
- Sex differencesthe female pelvis is wider and shallower, with a broader pubic angle and a larger outlet, adapted for childbirth
The Thigh and Knee
Femur
- Femurthe thigh bone, the longest and strongest bone in the body
- Headthe ball at the proximal end that fits into the acetabulum
- Fovea capitisthe small pit on the head that anchors a ligament to the acetabulum
- Neckthe narrow region just below the head, a common fracture site
- Greater trochanterthe large lateral projection, a major muscle attachment
- Lesser trochanterthe smaller projection on the medial side
- Linea asperathe rough ridge down the posterior shaft, a muscle attachment line
- Medial and lateral condylesthe rounded distal knobs that articulate with the tibia
- Medial and lateral epicondylesthe projections just above the condyles
- Intercondylar fossathe notch between the condyles on the posterior surface
Patella
- Patellathe kneecap, a sesamoid bone formed within the quadriceps tendon
- Basethe broad superior border of the patella
- Apexthe pointed inferior tip
The Leg
The leg bones, tibia and fibula
The two leg bones differ in side and in whether they bear weight. Compare them side by side.
| Bone | Side and weight | Proximal (knee) end | Distal (ankle) end |
|---|---|---|---|
| Tibia | medial, the shin bone, the weight-bearing bone of the leg | medial and lateral condyles articulate with the femur; tibial tuberosity on the front anchors the patellar ligament; sharp anterior border felt as the shin | medial malleolus, the medial bump of the ankle |
| Fibula | lateral, slender, does not bear body weight | head, the knob at the proximal end | lateral malleolus, the lateral bump of the ankle |
The Foot
Tarsals, the ankle
- Tarsalsseven bones forming the ankle and the back of the foot
- Talusthe tarsal that articulates with the tibia and fibula and receives the body's weight
- Calcaneusthe heel bone, the largest tarsal
- Other tarsalsthe navicular, the cuboid, and the three cuneiform bones
Metatarsals, phalanges, and arches
- Metatarsalsfive bones forming the sole, numbered 1 to 5 from the great toe
- Phalangesthe toe bones, fourteen in each foot
- Great toethe hallux, has two phalanges, the other toes have three each
- Arches of the footthe medial and lateral longitudinal arches and the transverse arch, which spread body weight
See also: The Upper Extremity, the other appendicular region, and Bone Histology for the bone tissue.
Build the word
Term breakdown
Lower limb bones are named for cups, hammers, and pins. The roots also tell you the three bones that fuse to form the hip.
- ili-flankilium
- ischi-hipischium
- pub-pubispubis
- acetabulumvinegar cupacetabulum (hip socket)
- femor-thighfemur
- trochanterrunnergreater and lesser trochanters
- patellasmall pan, platepatella (kneecap)
- tibi-shinbone, flutetibia
- fibulapin, broochfibula
- malleoluslittle hammermedial and lateral malleoli
- tars-ankletarsals, metatarsals
- calcane-heelcalcaneus
- talusankle bonetalus
- condyle (kondylos)knucklemedial and lateral condyles
- halluxgreat toehallux
Draw it from memory Sketch and label before you check
Work on blank paper, from memory, before you look back at the figures. The lower limb carries weight, so note which landmarks are the big weight-bearing ones as you draw.
- Draw the os coxae (hip bone) and label the ilium, ischium, and pubis, and the acetabulum where the three meet.
- Draw the femur, patella, tibia, and fibula. Label the head, neck, and greater and lesser trochanters of the femur; the medial and lateral condyles and tibial tuberosity of the tibia; and the head and lateral malleolus of the fibula.
- Draw the foot from above. Label the seven tarsals (talus, calcaneus, navicular, cuboid, three cuneiforms), the five metatarsals, and the phalanges; mark the hallux.
Then check yourself. Compare your drawings against the figures above. Whatever you missed is tonight's study list. Redraw it until the hip, leg, and foot bones come out right without looking.
Study questions
Work on answering these in writing, in your own words. They are the questions to bring to class, and good practice for the reasoning the exams ask for.
- Name the three bones that fuse to form the hip bone, and the point where all three meet.
- Trace the bones of the lower limb from hip to toes in order, naming each.
- Compare the tibia and the fibula by which one bears weight and how you would tell them apart.
- Name the arches of the foot and explain what they contribute to standing and walking.
Step 2 . Retrieval check
Now explain it back, in your own words.
In 60 words or more, pull together what the video just taught you. Include the key concepts. This is the point where the learning actually sticks. After you submit, your spaced-recall cards for this topic unlock.