APPENDICULAR SKELETON

Division of the Skeleton

Pectoral (Shoulder) Girdle

• 2 pectoral girdles

• Function: attach the bones of the upper limbs to the axial skeleton

• Clavicle:

  • Anterior bone

  • Articulates with the manubrium of the sternum at the sternoclavicular joint

• Scapula:

  • Articulates with the clavicle at the acromioclavicular joint

  • Articulates with the humerus at the glenohumeral (shoulder) joint

Pectoral Girdle Components

• Clavicle

• Scapula

• Acromioclavicular joint

• Glenohumeral joint

  • Views:

    • (a) Anterior view of the pectoral girdle

    • (b) Posterior view of the pectoral girdle

Clavicle

• S-shaped

• Collar bone

• Position: horizontally across the anterior part of the thorax, superior to the first rib

• Characteristics: rougher and more curved in males

Scapula

• Also known as the shoulder blade

• Large, triangular, flat bone located in the superior part of the posterior thorax

• Position: between the levels of the second and seventh ribs

Scapula Features

• Spine

• Acromion

• Acromioclavicular joint

• Glenoid cavity

• Glenohumeral shoulder joint

• Borders: medial, lateral, inferior

• Angles and Fossae:

  • Superior angle

  • Supraspinous fossa

  • Infraspinous fossa

  • Subscapular fossa

  • Coracoid process

Upper Extremity

• Each upper limb consists of 30 bones in three main locations:

  1. Humerus in the arm

  2. Ulna and radius in the forearm

  3. 8 carpals in the wrist (carpus)

  4. 5 metacarpals in the palm (metacarpus)

  5. 14 phalanges in the hand

Humerus

• Longest and largest bone of the upper limb

• Articulations:

  • Proximal end articulates with scapula

  • Distal end articulates with ulna and radius, forming the elbow joint

Humerus Anatomy

• Major landmarks:

  • Anatomical neck

  • Greater tubercle

  • Lesser tubercle

  • Intertubercular sulcus (groove)

  • Head

  • Surgical neck

  • Deltoid tuberosity

  • Radial groove

  • Body (shaft)

  • Epicondyles: medial and lateral

Ulna and Radius

• Ulna:

  • Located on the medial aspect (little-finger side) of the forearm

  • Longer than the radius

• Radius:

  • Smaller bone located on the lateral aspect (thumb side) of the forearm

  • Narrow at proximal end, widens at distal end

• Olecranon:

  • Forms the prominence of the elbow

Hand Structure

• Carpals:

  • 8 small bones in the wrist, connected by ligaments

  • Intercarpal joints:

    • Proximal Row:

      • Scaphoid

      • Lunate

      • Triquetrum

      • Pisiform

    • Distal Row:

      • Trapezium

      • Trapezoid

      • Capitate

      • Hamate

Metacarpals and Phalanges

• Metacarpals:

  • Consist of 5 bones forming the palm

  • Each has a proximal base, shaft, and distal head

• Phalanges:

  • 14 phalanges in the five digits

  • Have proximal base, intermediate shaft, and distal head

  • Thumb (pollex) has two phalanges: proximal and distal

Pelvic Girdle

• Comprised of two hip bones (coxal bones or os coxa)

• Unite anteriorly at the pubic symphysis

• Provides support for the vertebral column and pelvic organs

• Connects lower limb bones to the axial skeleton

Pelvic Girdle Components

• Ilium:

  • Largest of the three

  • Contains the acetabulum—a socket for the head of the femur

• Ischium:

  • Inferior, posterior portion

• Pubis:

  • Anterior and inferior part of the hip bone

Pelvis Characteristics

• False pelvis vs. True pelvis:

  • Pelvic brim landmarks:

    • Sacral promontory

    • Arcuate line

    • Pectineal line

    • Pubic crest

    • Pubic symphysis

Comparison of Female and Male Pelves

• General Structure:

  • Female: Light, thin, shallow, wide, oval

  • Male: Heavy, thick, deep, narrow, heart-shaped

• Various Points of Comparison:

  • Iliac crest, acetabulum, obturator foramen, and pubic arch

  • Differences in sciatic notch and sacrum curvature

Lower Limb Structure

• 30 bones:

  1. Femur in the thigh

  2. Patella (kneecap)

  3. Tibia and Fibula in the leg

  4. 7 Tarsals in the tarsus (ankle)

  5. 5 Metatarsals

  6. 14 Phalanges

Femur

• Thigh bone; longest, heaviest, and strongest bone

• Proximal end articulates with the hip bone's acetabulum

• Distal end articulates with tibia and patella

• Body angles medially: knee joints closer to midline than hip joints

Patella

• Knee cap;

• Sesamoid bone;

• Triangular and located anterior to the knee joint

Tibia and Fibula

• Tibia:

  • Shin bone; larger, medial, weight-bearing

• Fibula:

  • Smaller than the tibia

Skeleton of the Foot

• Tarsals:

  • 7 tarsal bones in the ankle:

    1. Talus: superior tarsal bone, articulates with fibula and tibia

    2. Calcaneus: largest and strongest tarsal bone

    3. Navicular: anterior tarsal bone

    4. 3 Cuneiform bones (medial, intermediate, lateral)

    5. Cuboid

Metatarsals and Phalanges

• Metatarsus:

  • Intermediate region consisting of 5 metatarsal bones numbered I to V

• Phalanges:

  • Distal components, also numbered I to V

  • Each has proximal base, intermediate shaft, and distal head

  • Great toe has two large phalanges

Arches of the Foot

• Functions:

  • Support body weight

  • Distribute weight over foot's tissues

  • Provide leverage in walking

• Fully developed by age 12-13

• Longitudinal Arch:

  • Formed by tarsal and metatarsal bones

• Transverse Arch:

  • Formed by navicular, three cuneiforms, and bases of metatarsals