Anatomy
MBBS Anatomy question bank: general anatomy and osteology, regional gross anatomy (upper limb, lower limb, thorax, abdomen, pelvis, head and neck), neuroanatomy, histology and embryology.
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Definition
The femoral triangle is a triangular space in the upper front of the thigh that transmits the main neurovascular structures to the lower limb.
Boundaries
- Superior — inguinal ligament
- Lateral — sartorius
- Medial — adductor longus
- Floor — iliopsoas, pectineus
Contents (lateral → medial: NAVEL)
- Femoral Nerve
- Femoral Artery
- Femoral Vein
- Empty space + Lymphatics
Front of Thigh
- Quadriceps femoris (extends knee) — femoral nerve
- Sartorius
The femoral triangle carries the nerve, artery and vein into the thigh. Boundary Structure Superior Inguinal ligament Lateral Sartorius Medial Adductor longus Applied
- Femoral pulse, catheterisation
- Femoral hernia (medial to the vein)
🔑KEY POINTS TO REMEMBER- Boundaries: inguinal ligament, sartorius, adductor longus.
- Contents (lat→med): NAVEL — nerve, artery, vein, lymphatics.
- Femoral pulse & access site.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The gluteal region lies behind the pelvis and contains the muscles of hip movement and the sciatic nerve, the largest nerve in the body.
Muscles
- Gluteus maximus — extension (inferior gluteal n.)
- Gluteus medius & minimus — abduction (superior gluteal n.)
- Lateral rotators (piriformis, etc.)
Sciatic Nerve
- Largest nerve (L4–S3)
- Exits below piriformis (greater sciatic foramen)
- Supplies hamstrings + whole leg/foot (via branches)
- Divides into tibial + common peroneal
Safe Zone for IM Injection
- Upper outer quadrant of the buttock
- Avoids the sciatic nerve
The sciatic nerve leaves below piriformis and later splits into its two divisions. Nerve Muscles Superior gluteal Medius, minimus Inferior gluteal Maximus Sciatic Hamstrings, leg Applied
- Injection injury → sciatic palsy
- Trendelenburg sign (gluteus medius weakness)
🔑KEY POINTS TO REMEMBER- Gluteus maximus (extension), medius/minimus (abduction).
- Sciatic nerve (L4–S3) exits below piriformis.
- IM injection in upper outer quadrant to avoid it.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The lower limb is supplied by the lumbar and sacral plexuses; each major nerve has a characteristic lesion.
Major Nerves
- Femoral (L2–4) — quadriceps; lesion → loss of knee extension
- Obturator (L2–4) — adductors
- Sciatic (L4–S3) — hamstrings + leg
- Tibial — plantarflexors; lesion → loss of plantarflexion
- Common peroneal — dorsiflexors; lesion → foot drop
Common Sites of Injury
- Common peroneal — neck of fibula (superficial)
- Tibial — popliteal fossa / ankle
Each nerve lesion denervates set muscles, giving a typical deformity. Nerve Lesion effect Femoral Loss of knee extension Common peroneal Foot drop Tibial Loss of plantarflexion Sciatic Hamstrings + leg palsy Applied
- Foot drop → high-stepping gait
- Fibular neck fracture → common peroneal palsy
🔑KEY POINTS TO REMEMBER- Femoral → knee extension loss; common peroneal → foot drop.
- Tibial → loss of plantarflexion.
- Fibular neck fracture injures the common peroneal.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The popliteal fossa is the diamond-shaped hollow behind the knee; the leg has three fascial compartments.
Popliteal Fossa — Boundaries
- Superolateral — biceps femoris
- Superomedial — semimembranosus / semitendinosus
- Inferior — two heads of gastrocnemius
Contents (superficial → deep)
- Tibial nerve
- Popliteal vein
- Popliteal artery (deepest)
Leg Compartments
- Anterior — dorsiflexors (deep peroneal n.)
- Lateral — evertors (superficial peroneal n.)
- Posterior — plantarflexors (tibial n.)
Three compartments, each with its own action and nerve. Compartment Action Nerve Anterior Dorsiflexion Deep peroneal Lateral Eversion Sup. peroneal Posterior Plantarflexion Tibial Applied
- Popliteal aneurysm
- Compartment syndrome of the leg
🔑KEY POINTS TO REMEMBER- Popliteal contents (superficial→deep): nerve, vein, artery.
- Leg: anterior (dorsiflex), lateral (evert), posterior (plantarflex).
- Popliteal artery is the deepest structure.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The foot supports body weight and enables locomotion using its arches and the intrinsic muscles of the sole.
Arches of the Foot
- Medial longitudinal — highest, resilient
- Lateral longitudinal — low
- Transverse arch
Functions of the Arches
- Distribute body weight
- Act as shock absorbers / springs
- Protect the vessels & nerves of the sole
Sole
- Intrinsic muscles in four layers
- Plantar aponeurosis
- Medial & lateral plantar nerves (from tibial)
Arches spread weight and absorb shock during walking. Arch Feature Medial longitudinal Highest, springy Lateral longitudinal Low Transverse Side to side Applied
- Flat foot (pes planus) — fallen arch
- Plantar fasciitis
🔑KEY POINTS TO REMEMBER- Arches: medial & lateral longitudinal + transverse.
- Functions: weight distribution, shock absorption.
- Sole supplied by medial & lateral plantar nerves.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The femoral triangle is a triangular space in the upper thigh transmitting the femoral vessels and nerve.
Boundaries
- Superior — inguinal ligament
- Lateral — sartorius
- Medial — adductor longus
Contents (lateral → medial: NAVEL)
- Femoral Nerve
- Femoral Artery
- Femoral Vein
- Empty space, Lymphatics
The triangle transmits nerve, artery and vein from lateral to medial. Content Position Nerve Lateral Artery Middle Vein Medial Applied
- Femoral pulse; catheterisation
🔑KEY POINTS TO REMEMBER- Boundaries: inguinal ligament, sartorius, adductor longus.
- Contents (lat→med): NAVEL.
- Femoral access site.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The femoral sheath is a funnel of fascia enclosing the femoral vessels; its medial part, the femoral canal, is the site of femoral hernia.
Femoral Sheath — 3 Compartments
- Lateral — femoral artery
- Middle — femoral vein
- Medial — femoral canal (lymphatics)
Femoral Hernia
- Protrudes through the femoral canal
- Below & lateral to the pubic tubercle
- Commoner in females
- High risk of strangulation (narrow neck)
A femoral hernia pushes through the narrow femoral canal. Feature Femoral hernia Site Below inguinal ligament Sex Female > male Risk Strangulation Applied
- Distinguish from inguinal hernia (above/medial to tubercle)
🔑KEY POINTS TO REMEMBER- Femoral sheath: artery, vein, canal (lymphatics).
- Femoral hernia through the canal, below/lateral to pubic tubercle.
- Female > male; strangulation risk.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The sciatic nerve (L4–S3) is the largest nerve in the body, supplying the hamstrings and the entire leg and foot.
Course
- Exits the pelvis below piriformis
- Descends in the back of the thigh
- Divides into tibial + common peroneal (at the popliteal fossa)
Supplies
- Hamstring muscles
- Whole leg & foot (via branches)
The sciatic nerve runs down the thigh and splits into its two terminal nerves. Branch Supplies Tibial Posterior leg, sole Common peroneal Anterior/lateral leg, dorsum Applied
- Injection injury (use upper outer quadrant)
- Sciatica (disc prolapse)
🔑KEY POINTS TO REMEMBER- Sciatic (L4–S3) = largest nerve; below piriformis.
- Supplies hamstrings + whole leg/foot.
- Divides into tibial + common peroneal.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The common peroneal (fibular) nerve supplies the dorsiflexors and evertors; injury causes foot drop.
Course & Supply
- A branch of the sciatic nerve
- Winds around the neck of the fibula (superficial)
- Supplies the anterior + lateral compartments
Injury — Foot Drop
- Site: neck of the fibula
- Loss of dorsiflexion & eversion
- Foot drop → high-stepping gait
- Sensory loss over the dorsum of foot
Injury at the fibular neck paralyses the dorsiflexors, dropping the foot. Feature Detail Site Neck of fibula Lost Dorsiflexion, eversion Gait High-stepping Applied
- Fibular neck fracture, tight plaster cast
- Commonest cause of foot drop
🔑KEY POINTS TO REMEMBER- Common peroneal = dorsiflexors + evertors.
- Injured at the fibular neck → foot drop.
- High-stepping gait; commonest foot-drop cause.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The popliteal fossa is the diamond-shaped hollow behind the knee containing neurovascular structures.
Boundaries
- Superolateral — biceps femoris
- Superomedial — semimembranosus, semitendinosus
- Inferior — two heads of gastrocnemius
Contents (superficial → deep)
- Tibial nerve
- Popliteal vein
- Popliteal artery (deepest)
The fossa holds the tibial nerve, popliteal vein and artery, deep to superficial. Content Depth Tibial nerve Superficial Popliteal vein Middle Popliteal artery Deepest Applied
- Popliteal pulse (knee flexed)
- Popliteal aneurysm
🔑KEY POINTS TO REMEMBER- Boundaries: biceps femoris, semi-membranosus/tendinosus, gastrocnemius.
- Contents (superficial→deep): nerve, vein, artery.
- Popliteal artery is deepest.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The arches of the foot are curved bony arrangements that distribute weight and act as shock absorbers.
Types
- Medial longitudinal — highest, most important
- Lateral longitudinal — low, flat
- Transverse arch
Maintained By
- Shape of the bones
- Ligaments (spring, plantar)
- Muscles & tendons
- Plantar aponeurosis
The arches spread weight and cushion the foot during walking. Arch Height Medial longitudinal High Lateral longitudinal Low Transverse Across foot Applied
- Flat foot (pes planus)
- Pes cavus (high arch)
🔑KEY POINTS TO REMEMBER- Arches: medial & lateral longitudinal + transverse.
- Maintained by bones, ligaments, muscles, aponeurosis.
- Loss → flat foot.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.Definition
The great saphenous vein is the longest vein in the body, running up the medial side of the lower limb.
Course
- Begins at the medial end of the dorsal venous arch
- Passes in front of the medial malleolus
- Ascends the medial leg & thigh
- Drains into the femoral vein (saphenous opening)
Features
- A superficial vein
- Contains many valves
- Communicates with deep veins (perforators)
It runs constantly in front of the medial malleolus up to the femoral vein. Landmark Relation Medial malleolus In front Termination Femoral vein Applied
- Constant at the medial malleolus (venous cut-down)
- Varicose veins; used for grafts (CABG)
🔑KEY POINTS TO REMEMBER- Longest vein; runs in front of medial malleolus up medial limb.
- Drains into the femoral vein.
- Used for cut-down and bypass grafts.
📚SOURCES: BD Chaurasia’s Human Anatomy; Gray’s Anatomy; Snell’s Clinical Anatomy.