Appendicular+Skeleton

Appendicular Skeleton Overview

  • Comprises:

    • Shoulder Girdle

    • Upper Limbs

    • Pelvic Girdle

    • Lower Limbs

Bones in the Appendicular Skeleton

Shoulder Girdle and Upper Limbs

  • Bones Include:

    • Clavicle

    • Scapula

    • Humerus

    • Radius

    • Ulna

    • Carpals

    • Metacarpals

    • Phalanges

Shoulder Girdle

  • Also known as the Pectoral Girdle.

  • Composed of:

    • Clavicle

    • Scapula

  • Provides free movement of the upper limb but is prone to dislocation.

Clavicle (Collarbone)

  • Attaches medially to the sternum and laterally to the scapula.

  • Acts as a brace for the shoulder, preventing dislocation.

  • A broken clavicle shows its importance as it causes the shoulder region to cave in.

Scapula (Shoulder Blade)

  • Not directly attached to the axial skeleton; supported by trunk muscles.

  • Key features:

    • Acromion: Connects with the clavicle at the acromio-clavicular joint.

    • Coracoid Process: Anchors muscles of the arm.

Upper Limb

Arm

  • Humerus: Long bone with a rounded head fitting into the scapula's glenoid cavity.

Forearm

  • Radius: Lateral bone (thumb side).

  • Ulna: Medial bone (little finger side), connected by interosseous membrane.

Hand

  • Carpals: 8 bones in 2 rows of 4, bound by ligaments.

  • Metacarpals: Five bones, numbered 1-5 from thumb to little finger. These form the knuckles when the hand is clenched.

  • Phalanges: 3 per finger, 2 for the thumb.

Pelvic Girdle

  • Formed by two coxal bones.

  • Functions:

    • Weight bearing

    • Protects reproductive organs, bladder, and part of the large intestine.

  • Each coxal bone is formed from:

    • Ilium

    • Ischium

    • Pubis

Ilium

  • Largest part of the hip bone.

  • Connects to the sacrum at the iliosacral joint.

Ischium and Pubis

  • Ischium: Known as the "sit down bone".

  • Pubis: Forms the anterior part of the coxal bone.

Acetabulum

  • Deep socket receiving the head of the thigh bone, formed by ilium, ischium, and pubis.

Lower Limb

  • Stronger bones to support body weight.

  • Consists of:

    • Thigh

    • Leg

    • Foot

Thigh

  • Femur: Strongest bone; articulates with acetabulum at proximal end.

Leg

  • Tibia: Shinbone; forms knee joint with femur.

  • Fibula: Lateral to tibia, does not form knee joint.

  • Both bones are connected by an interosseous membrane.

Foot

  • Designed to support body weight.

  • Tarsals: 7 bones; weight carried by calcaneus (heel) and talus (between tibia and calcaneus).

  • Metatarsals: Form the sole of the foot.

  • Phalanges: 3 per toe except for the great toe, which has 2.