Ch-08-appendicular-skeleton-handout

Chapter 08: Appendicular Skeleton

Overview

• Appendicular skeleton includes various components:

  • Pectoral girdle (2x2)

  • Upper limbs (30x2)

  • Pelvic girdle (2)

  • Lower limbs (30x2)

• Functions of the appendicular skeleton:

  • Attaches upper limbs to the trunk

  • Attaches lower limbs to the trunk

  • Facilitates manipulation of the environment

  • Supports the weight of head, trunk, and upper limbs to the ground.

Pectoral Girdle

• Components:

  • Clavicle

  • Scapula

• Functions:

  • Joins arms to the trunk

  • Attaches to axial skeleton at the sternoclavicular joint

  • Positions the shoulder joint

  • Provides attachment for muscles that move the upper limb

Clavicle

• S-shaped long bone; only articulation between the pectoral girdle and axial skeleton.

  • Ends:

    • Lateral: Acromial end

    • Medial: Sternal end

• Functions:

  • Transmits forces from the upper limb to the trunk

  • Stabilizes and supports the scapula and upper limb

• Attachments:

  • Conoid ligament and subclavius muscle

  • Connects to acromion of scapula

  • Connects to sternum at clavicular notch

  • Costal groove for costoclavicular ligament

Scapula

• Broad, flat, triangular-shaped bone with three sides and angles:

  • Key Features:

    • Subscapular fossa

    • Coracoid process

    • Scapular spine

    • Acromion

    • Supraspinous fossa

    • Infraspinous fossa

    • Glenoid cavity/ fossa (connects with head of humerus)

    • Infra/Supra-glenoid tubercle

Upper Limb

• Each upper limb consists of 30 bones:

  • Humerus (1)

  • Radius (1)

  • Ulna (1)

  • Carpals (8)

  • Metacarpals (5)

  • Phalanges (14)

Humerus

• Regions:

  • Proximal epiphysis:

    • Head, anatomical neck, greater tubercle, lesser tubercle, intertubercular sulcus

  • Diaphysis:

    • Deltoid tuberosity

  • Distal epiphysis:

    • Condyle (capitulum, trochlea), epicondyles, fossae (anterior and posterior views)

• Connections:

  • Capitulum connects with head of radius

  • Trochlea connects with trochlear notch of the ulna

Radius and Ulna

• Radius Features:

  • Proximal: Head & neck, radial tuberosity

  • Distal: Styloid process and ulnar notch

• Ulna Features:

  • Proximal: Olecranon, trochlear notch, coronoid process, radial notch

  • Distal: Styloid process and head

• Interosseous membrane:

  • Fibrous connective tissue transferring load from distal radius to proximal ulna

Wrist and Hand

• Carpal Bones (8 total):

  • Proximal row: (lateral to medial)

    • Scaphoid, Lunate, Triquetrum, Pisiform

  • Distal row: (lateral to medial)

    • Trapezium, Trapezoid, Capitate, Hamate

• Metacarpal Bones (I-V, lateral to medial)

• Phalanges:

  • I-V (lateral to medial), with proximal, middle (except pollex), and distal phalanges

• Mnemonic: "Straight Line To Pinky, Here Comes The Thumb"

Pelvic Girdle and The Pelvis

• Pelvic Girdle: Consists of:

  • Two coxal (hip) bones (left and right)

  • Each composed of three bones: ilium, ischium, pubis

• Pelvis:

  • Comprises pelvic girdle, sacrum, and coccyx

Coxal Bones - Lateral Aspect

• Iliac Bone Features:

  • Iliac crest, gluteal lines, greater sciatic notch, iliac spines (two each)

• Ischium:

  • Ischial spine, lesser sciatic notch, ischial tuberosity (weight transfer when seated)

• Acetabulum:

  • Connects with the head of femur

Coxal Bones - Medial Aspect

• Iliac Bone Features:

  • Iliac fossa, auricular surface, greater sciatic notch

• Ischium:

  • Ischial ramus

• Pubis:

  • Superior and inferior pubic ramus, pubic crest, symphyseal surface (connecting with opposite pubis)

  • Obturator foramen present

The Pelvis

• True (lesser) Pelvis:

  • Bounded by the pelvic brim (superior boundary) and pelvic outlet (inferior boundary)

• False (greater) Pelvis:

  • Enclosed by iliac wings; defined by the pelvic inlet

• Differences Between Male and Female Pelvis:

  • Male Pelvis:

    • Narrower, heavier, narrower inlet/outlet, pubic angle < 90°, acetabuli face laterally.

  • Female Pelvis:

    • Broader, lighter, wide circular inlet/outlet, pubic angle > 100°, acetabuli face slightly anterior, sacral curvature.

Lower Limb

• Composed of:

  • Femur

  • Patella

  • Tibia

  • Fibula

  • Tarsals

  • Metatarsals

  • Hallux and other digits

Femur

• Regions:

  • Proximal epiphysis (head, fovea capitis, neck, greater/lesser trochanter, intertrochanteric crest)

  • Shaft:

    • Gluteal tuberosity, linea aspera

  • Distal epiphysis:

    • Condyles (medial and lateral), intercondylar fossa, patellar surface

Patella, Tibia, and Fibula

• Patella:

  • Large sesamoid bone protecting the knee joint

  • Features:

    • Base: attaches to quadriceps tendon

    • Apex: attaches to patellar ligament

Tibia & Fibula

• Tibia (Shinbone):

  • Proximal: condyles (medial and lateral), intercondylar eminence, tibial tuberosity

  • Distal: medial malleolus

• Fibula:

  • Proximal: fibular head

  • Distal: fibular notch, lateral malleolus

• Interosseous Membrane:

  • Fibrous connective tissue aids muscle attachments

Ankle and Foot

• Tarsal Bones (7 total):

  • Key Bones:

    • Calcaneus, Talus, Navicular, Cuneiforms (medial, intermediate, lateral), Cuboid

• Metatarsal Bones (I-V):

• Phalanges:

  • Medial to Lateral: I - V, with proximal, middle (except hallux), and distal phalanges

• Mnemonic: "Cal Told Nora Milk Is Like Cream"