Anatomy & Physiology Study Guide: Bones, Joints, and Muscles of the Upper and Lower Limbs

Bones, Joints, and Muscles of the Upper and Lower Limbs

Articulations and Joints of the Limbs

Articulations, or joints, are connections between bones that allow for varying degrees of movement. The upper and lower limbs contain several important synovial joints, each with specific structural and functional characteristics.

• Synovial Joints: Freely movable joints characterized by a synovial cavity and articular cartilage.

• Types in Limbs:

  • Acromioclavicular (AC) joint: gliding

  • Glenohumeral (shoulder) joint: ball and socket

  • Elbow joint: hinge

  • Radioulnar joint: pivot

  • Intercarpal and intertarsal joints: gliding

  • Hip joint: ball and socket

  • Knee joint: hinge

  • Ankle joint: hinge

Upper Limb Bones and Landmarks

Clavicle

• Function: Acts as a strut between the sternum and scapula, providing support for shoulder movement.

Scapula

• Key Landmarks:

  • Acromion & coracoid processes

  • Spine of scapula

  • Supraspinous, infraspinous, and subscapular fossae

  • Glenoid fossa (cavity)

  • Lateral (axillary) & vertebral (medial) borders

Humerus

• Key Landmarks:

  • Head, surgical neck, anatomical neck

  • Greater and lesser tubercles

  • Deltoid tuberosity

  • Intertubercular sulcus (groove)

  • Medial & lateral epicondyles

  • Olecranon & coronoid fossae

Ulna and Radius

• Ulna: Olecranon process, coronoid process, trochlear notch, radial notch, styloid process

• Radius: Head, neck, radial tuberosity, styloid process

Carpals, Metacarpals, and Phalanges

• Carpals (8): Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate

• Metacarpals: 5 bones (palm)

• Phalanges: Proximal, middle, distal (fingers)

Muscles Acting on the Shoulder (Insert on the Humerus)

The shoulder joint is a triaxial (ball and socket) joint, allowing for a wide range of motion. Several muscles originate from the trunk or scapula and insert on the humerus to produce movement at the shoulder.

Muscle	Origin	Insertion	Action at Shoulder (Humerus)
Pectoralis Major	Medial clavicle & sternum	Humerus	Flexion, Adduction, Internal Rotation
Latissimus dorsi	Thoracic & lumbar vertebrae, sacrum, iliac crest	Anterior humerus	Extension, Adduction, Internal Rotation
Coracobrachialis	Coracoid process	Humerus	Flexion
Subscapularis	Subscapular fossa	Humerus	Internal rotation
Supraspinatus	Supraspinous fossa	Humerus	Abduction
Infraspinatus	Infraspinous fossa	Humerus	External rotation
Teres minor	Lateral (axillary) border of scapula	Humerus	External rotation

Muscles Acting on the Elbow and Wrist

The elbow is a uniaxial hinge joint, while the wrist is a condyloid joint allowing flexion, extension, abduction, and adduction. Muscles crossing these joints produce movement at both the elbow and wrist.

Muscle	Action at Elbow	Action at Wrist
Brachialis	Flexion
Brachioradialis	Flexion
Pronator teres	Pronation
Flexor carpi radialis		Flexion & abduction
Flexor carpi ulnaris		Flexion & adduction
Palmaris longus		Flexion
Extensor carpi radialis longus		Extension & abduction
Extensor carpi radialis brevis		Extension & abduction
Extensor carpi ulnaris		Extension & adduction

Lower Limb Bones and Landmarks

Pelvic Girdle and Femur

• Pelvic Bones: Ilium, ischium, pubis (fused in adults)

• Femur: Head, neck, greater/lesser trochanter, linea aspera, medial/lateral condyles

• Patella: Sesamoid bone within the quadriceps tendon

• Tibia: Medial bone of the leg, tibial tuberosity, medial/lateral condyles

• Fibula: Lateral bone of the leg

Knee Joint

• Type: Hinge joint

• Ligaments: Medial (tibial) and lateral (fibular) collateral ligaments, anterior and posterior cruciate ligaments

• Menisci: Medial and lateral meniscus (fibrocartilage pads)

Muscles Acting on the Hip (Insert on the Femur)

The hip joint is a triaxial (ball and socket) joint, allowing for flexion, extension, abduction, adduction, and rotation. Muscles originating from the pelvis or vertebral column insert on the femur to produce these movements.

Muscle	Origin	Insertion	Action at Hip (Femur) and/or Knee
Iliopsoas group (psoas major, iliacus)	n/a	n/a	Flexion of the hip
Gluteus maximus	n/a	n/a	Extension & external rotation of hip
Gluteus medius & minimus	n/a	n/a	Abduction of hip
Tensor fascia latae (TFL)	Iliac crest	IT Band	Stabilizes knee
Piriformis	Sacrum	Femur	Abduction and external rotation of hip
Quadratus femoris	n/a	n/a	External rotation of hip
Pectineus	Pubis	Femur	Flexion & adduction of hip
Adductor magnus, longus, brevis	Pubis	Linea aspera	Adduction of hip
Gracilis	Pubis	Tibia	Adduction of hip, flexion of knee
Sartorius	ASIS	Tibia	Flexion, abduction, external rotation of hip; flexion of knee
Quadriceps femoris (Rectus femoris)	Rectus: AIIS	Tibial tuberosity via patella	Flexion of hip (rectus femoris), extension of knee (all quadriceps)
Hamstrings (Biceps femoris, Semitendinosus, Semimembranosus)	Ischial tuberosity	Fibula (biceps), tibia (semis)	Extension of hip, flexion of knee

Muscles Acting on the Ankle

The ankle is a uniaxial hinge joint, allowing dorsiflexion and plantar flexion. Muscles in the lower leg control these movements and also contribute to inversion and eversion of the foot.

Muscle	Action at Ankle
Tibialis anterior	Dorsiflexion
Tibialis posterior	Plantar flexion
Peroneus (fibularis) longus	Eversion & plantar flexion
Peroneus (fibularis) brevis	Eversion & plantar flexion
Gastrocnemius	Flexion of knee & plantar flexion (inserts on calcaneus via Achilles tendon)
Soleus	Plantar flexion (inserts on calcaneus via Achilles tendon)
Extensor digitorum longus	Extends toes

Key Definitions

• Flexion: Decreasing the angle between two bones (e.g., bending the elbow)

• Extension: Increasing the angle between two bones (e.g., straightening the knee)

• Abduction: Movement away from the midline

• Adduction: Movement toward the midline

• Internal (Medial) Rotation: Rotation toward the midline

• External (Lateral) Rotation: Rotation away from the midline

• Dorsiflexion: Lifting the foot upward toward the shin

• Plantar Flexion: Pointing the foot downward

• Eversion: Turning the sole of the foot outward

• Inversion: Turning the sole of the foot inward

Additional info:

• Some muscle origins and insertions were marked as "n/a" in the original notes; standard anatomical knowledge was used to clarify their general locations.

• Tables were reconstructed for clarity and completeness.