A&P - Skeletal System (Bones)

Upper Extremity Anatomy

Introduction to Upper Extremity

  • Understanding anatomical terms:

    • Distal: Further from the point of attachment

    • Proximal: Closer to the point of attachment

  • Key proximal bones:

    • Scapula and Clavicle (proximal)

    • Humerus, Radius, Ulna (distal)

Humerus

  • The longest bone of the upper extremity, located in the upper arm above the elbow.

  • Proximal connection: Glenoid fossa of the scapula forms the shoulder joint.

  • Distal connection: Humerus connects to radius and ulna at the elbow.

Key Portions of the Humerus

  • Capitulum: Connects to the radius at the elbow.

  • Trochlea: Connects to the ulna.

  • Epicondyles: Muscle attachment points located on the distal ends of the humerus.

    • Medial Epicondyle: Attachment for wrist flexors (muscles that flex the wrist).

    • Lateral Epicondyle: Attachment for wrist extensors (muscles that extend the wrist).

    • Conditions:

      • Lateral Epicondylitis (Tennis Elbow): Inflammation from repeated wrist extension.

      • Medial Epicondylitis (Golfer's Elbow): Inflammation from wrist flexion against resistance.

Forearm Anatomy

  • Bones: Radius and Ulna

  • Ulna:

    • Medial bone (toward the little finger) in the forearm.

    • Larger at the elbow and articulates with the humerus.

  • Radius:

    • Lateral bone (toward the thumb) in the forearm.

    • Larger at the wrist, connects with carpal bones.

  • Movement at the wrist involves pronation and supination (rotation around the forearm).

Elbow Joint Mechanics

  • Olecranon process (part of the ulna):

    • Prominent bump of the elbow.

    • Fits into the olecranon fossa on the humerus when elbow is extended.

Wrist Anatomy

  • Carpal bones:

    • Two rows of four bones forming the wrist:

    • Proximal Row: Pisiform, Triquetrum, Lunate, Scaphoid.

    • Distal Row: Hamate, Capitate, Trapezoid, Trapezium.

  • Function: Allow for flexion and extension of the wrist.

  • Mnemonic for remembering the carpal bones: "Some Lovers Try Positions That They Can't Handle" (From proximal to distal).

Injury Considerations in the Wrist

  • Scaphoid: Most commonly fractured carpal bone.

    • Often from a FOOSH injury (Fall On Outstretched Hand).

    • Risk of avascular necrosis if blood supply is compromised.

  • Carpal Tunnel Syndrome: Compression of nerves due to repetitive motion (e.g., typing).

Hand Anatomy

  • Metacarpals: Form the framework of the hand, connect to carpal bones proximally and to phalanges distally.

  • Phalanges: Bones of the fingers.

    • Three in each finger (proximal, middle, distal) and two in the thumb.

Lower Extremity Anatomy

Introduction to Lower Extremity

  • Bones include the hip, thigh, leg, ankle, and foot; connect with the axial skeleton.

Pelvic Girdle

  • Composed of:

    • Coxal bones (hip bones) and sacrum.

    • Strong support for the torso and attachment for lower limbs.

    • Coxal Bone Structure:

      • Ilium (uppermost part),

      • Ischium (posterior/inferior),

      • Pubis (anterior).

  • Acetabulum: Socket for the femur, forming the hip joint.

Femur

  • Longest and heaviest bone in the body, located in the thigh.

  • Connects proximally to the acetabulum of the pelvis and distally to the tibia at the knee joint.

Tibia and Fibula

  • Tibia: Larger, medial bone of the lower leg, connects with femur to form knee joint.

  • Fibula: Smaller, lateral bone of the lower leg, mainly providing support, not directly involved in the knee joint.

Patella

  • Patella (kneecap): Largest sesamoid bone, located in the patellar tendon connecting quadriceps to tibia.

Ankle and Foot

  • Similar structure to the hand: tarsals, metatarsals, and phalanges.

  • Tarsals: Include Talus (ankle joint) and Calcaneus (heel).

  • Arches of the Foot:

    • Medial and lateral longitudinal arches support body weight and facilitate movement.

    • Flat feet (pes planus) occur when arches fail to provide proper support.