Anatomy & Physiology Study Notes: Lower and Upper Limb

Lower Limb Anatomy

Lower Limb Regions

The lower extremity provides support, locomotion, and balance, organized into six functional regions:

• Gluteal (buttocks)

• Femoral (thigh)

• Knee

• Leg (shin/calf)

• Ankle (talocrural)

• Foot (pedal)

Skeletal Anatomy of the Lower Limb

• Pelvic Girdle & Ilium

  • Pelvic bones: ilium, ischium, pubis (form the bony pelvis)

  • Key landmark: ASIS – anterior superior iliac spine

• Femur

  • Major landmarks:

    • Head & neck

    • Greater & lesser trochanters

    • Linea aspera

    • Medial & lateral condyles

  • Functional points:

    • Hip joint: articulation, site of major muscle attachment (e.g., gluteus medius/minimus)

    • Knee joint: distal femur with tibia and patella; medial/lateral condyles serve as attachment sites for ligaments and menisci

• Tibia & Fibula

  • Tibia: medial, weight-bearing bone; key features include tibial tuberosity, medial & lateral condyles, and medial malleolus

  • Fibula: lateral, slender bone for lateral stabilization; not weight-bearing; lateral malleolus forms the outer ankle

  • Proximal & distal tibiofibular joints: connect the bones

• Foot

  • Tarsals: 7 bones (talus, calcaneus, cuboid, navicular, three cuneiforms)

  • Metatarsals: 5 (numbered medial to lateral)

  • Phalanges: 14 (proximal, middle, distal)

Surface Anatomy & Fascia

• Superficial fascia: contains fat, cutaneous nerves, superficial veins, and lymphatics

• Deep fascia (fascia lata): surrounds muscles, forms compartments

• Key compartments of the thigh (deep fascia):

  1. Anterior compartment: hip flexors & knee extensors (femoral nerve)

  2. Medial compartment: thigh adductors (obturator nerve)

  3. Posterior compartment: hip extensors & knee flexors (sciatic nerve)

Venous Systems of the Lower Limb

• Superficial veins: great saphenous vein (medial), small saphenous vein (posterior calf)

• Deep veins: accompany arteries, have valves to prevent backflow

Lymphatic Drainage

• Superficial lymphatics follow veins to superficial inguinal nodes

• Deep lymphatics follow arteries to deep inguinal nodes

Cutaneous Nerves of the Lower Limb

Region	Primary Cutaneous Nerve(s)	Origin (plexus)
Anterior thigh	Lateral cutaneous n. of thigh, femoral cutaneous branches	Lumbar plexus (L2-4)
Medial thigh	Obturator n. cutaneous branches	Lumbar plexus (L2-4)
Leg (anterolateral)	Superficial fibular (peroneal) n.	Common fibular nerve (L4-S2)
Leg (posterolateral)	Sural n.	Tibial & common fibular branches (S1-S2)
Foot (dorsal)	Superficial fibular & saphenous	Tibial nerve (L4-S3)
Foot (plantar)	Medial & lateral plantar nn.	Tibial nerve (L4-S3)

Muscle Innervation & Myotomes

• L2-L4: Hip flexion, knee extension

• L4-L5: Ankle dorsiflexion

• L5-S1: Hip extension, knee flexion, ankle plantarflexion

• S1-S2: Toe flexion/extension

Muscles of the Lower Limb

Muscles are organized by compartment and function. Key examples:

Muscle	Proximal Attachment	Distal Attachment	Innervation	Main Action
Rectus femoris	AIIS & acetabulum	Patellar tendon	Femoral n. (L2-4)	Knee extension, hip flexion
Vastus lateralis	Greater trochanter	Patellar tendon	Femoral n. (L2-4)	Knee extension
Adductor longus	Body of pubis	Linea aspera	Obturator n. (L2-4)	Hip adduction
Gluteus maximus	Ilium, sacrum, coccyx	Gluteal tuberosity, IT band	Inferior gluteal n. (L5-S2)	Hip extension, lateral rotation
Biceps femoris (long head)	Ischial tuberosity	Head of fibula	Sciatic n. (tibial division)	Knee flexion, hip extension

Key Vascular Relationships

Vessel	Origin	Course through Lower Limb	Major Branches
Femoral a.	External iliac a.	Enters femoral triangle, continues down thigh	Profunda femoris, superficial epigastric
Popliteal a.	Continuation of femoral a.	Posterior knee, divides into anterior & posterior tibial aa.	Genicular branches
Anterior tibial a.	Popliteal a.	Passes anterior to interosseous membrane	Dorsalis pedis (foot)
Posterior tibial a.	Popliteal a.	Travels posterior to medial malleolus	Medial & lateral plantar aa.

Foot Architecture & Plantar Compartments

• The foot's rigid architecture is created by a layered fascial system and multiple muscle compartments, supporting body weight, maintaining the arches, and enabling complex locomotion.

• Landmarks: calcaneus, navicular, medial/lateral malleolus, tarsal tunnel

• Muscle layers: plantar muscles organized into four layers, each with specific actions (e.g., toe flexion, abduction, adduction)

Upper Limb Anatomy

Overview of Upper Limb Bones

• Clavicle: Sternal and acromial ends; articulates with sternum and scapula

• Scapula: Spine, acromion, coracoid process, glenoid cavity

• Humerus: Head, greater/lesser tubercles, deltoid tuberosity, medial/lateral epicondyles

• Forearm: Radius (lateral, thumb side), ulna (medial, pinky side)

• Carpals: 8 wrist bones (scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate)

• Metacarpals & Phalanges: 5 metacarpals, 14 phalanges (proximal, middle, distal)

Muscle Groups of the Upper Limb

Muscle	Proximal Attachment	Distal Attachment	Innervation	Main Action
Biceps brachii	Scapula (coracoid & supraglenoid tubercle)	Radial tuberosity	Musculocutaneous n. (C5-7)	Elbow flexion, supination
Triceps brachii	Scapula & humerus	Olecranon process	Radial n. (C6-8)	Elbow extension
Deltoid	Clavicle, acromion, spine of scapula	Deltoid tuberosity	Axillary n. (C5-6)	Shoulder abduction
Flexor carpi radialis	Medial epicondyle of humerus	Base of 2nd metacarpal	Median n. (C6-7)	Wrist flexion, abduction
Extensor digitorum	Lateral epicondyle of humerus	Extensor expansions of digits 2-5	Radial n. (C7-8)	Finger extension

Major Nerves of the Upper Limb

Nerve	Origin (Cord)	Primary Motor Target	Primary Sensory Regions
Musculocutaneous	Lateral	Anterior arm flexors	Lateral forearm
Median	Lateral & medial	Anterior forearm, thenar muscles	Medial palm, digits 1-3
Ulnar	Medial	Intrinsic hand muscles	Medial palm, digit 4.5
Radial	Posterior	Posterior arm, forearm extensors	Posterior arm, forearm, hand
Axillary	Posterior	Deltoid & teres minor	Lateral shoulder region

Key Joints and Movements

• Shoulder (glenohumeral) joint: Ball-and-socket, allows flexion, extension, abduction, adduction, rotation

• Elbow joint: Hinge, allows flexion and extension

• Wrist joint: Condyloid, allows flexion, extension, abduction, adduction

• Hand joints: Metacarpophalangeal (MCP), proximal interphalangeal (PIP), distal interphalangeal (DIP)

Vascular Supply of the Upper Limb

Artery	Origin	Major Branches / Distribution
Subclavian	Aorta (R) or brachiocephalic trunk (L)	Axillary, vertebral, internal thoracic
Axillary	Continuation of subclavian	Brachial, circumflex humeral
Brachial	Continuation of axillary	Radial, ulnar
Radial	Brachial	Deep palmar arch
Ulnar	Brachial	Superficial palmar arch

Summary Table: Hand Compartments & Muscles

Compartment	Muscles Included	Primary Action
Thenar	Opponens pollicis, abductor pollicis brevis, flexor pollicis brevis	Thumb opposition, flexion, abduction
Hypothenar	Opponens digiti minimi, abductor digiti minimi, flexor digiti minimi	Little finger opposition, flexion, abduction
Central	Lumbricals, palmar & dorsal interossei	Flex MCP joints, extend IP joints, finger ab/adduction
Adductor (deep)	Adductor pollicis	Thumb adduction

Example: Clinical Application

• Injury to the common fibular nerve at the fibular neck can cause foot drop due to loss of dorsiflexion and eversion.

• Carpal tunnel syndrome results from compression of the median nerve at the wrist, causing numbness and weakness in the lateral hand.

Additional info: Tables and content have been expanded and reorganized for clarity and completeness. Some details (e.g., clinical applications, summary tables) are inferred from standard anatomy curricula.