Skeletal

Introduction to Skeletal System Lecture 5

  • Overview: This is the fifth lecture regarding the skeletal system.

  • Reminder of Previous Topics: Part two covered from the textbook pages 80-115, dense material, divided into two lectures for comprehension and application.

Upper Limb and Forearm

  • Overview of the Upper Limb: Introduction to the upper limb and forearm beginning with the humerus.

Humerus

  • Description: The largest and most proximal bone in the upper extremity.

  • Importance: Critical in understanding movement disorders related to shoulders or necks; bigger bones often function in significant ways.

  • Bone Markings:

    • Head: Proximal knob that connects to the glenoid fossa of the scapula, forming the glenohumeral joint.

    • Neck: Region connecting the head to the shaft of the humerus.

    • Greater and Lesser Tubercle:

    • Greater Tubercle: Located on the lateral side, pronounced bump.

    • Lesser Tubercle: Located on the medial side, less pronounced bump.

    • Intertubercular Groove (Bicipital Groove): Deep groove between the greater and lesser tubercles, where the tendon of the long head of the biceps passes before attaching to the scapula.

    • Deltoid Tuberosity: Attachment point for the deltoid muscle, located midway on the lateral side of the shaft of the humerus.

    • Epicondyles: Medial and lateral epicondyles located at the distal end of the bone, important for muscular attachment and acupuncture points.

    • Medial Epicondyle: Located on the medial side.

    • Lateral Epicondyle: Located on the lateral side.

    • Supracondylar Ridge: Passage above the medial and lateral epicondyles.

    • Condyles:

    • Medial Condyle (Trochlea): Has functions similar to a pulley.

    • Lateral Condyle (Capitulum): Rounded protuberance that attaches to the radii and ulna at the elbow joint.

    • Fossa: Three important depressions in the distal humerus.

    • Olecranon Fossa: Located posteriorly; the tip of the elbow.

    • Coronoid Fossa: Located anteriorly.

    • Radial Fossa: Also located anteriorly.

Radius and Ulna

  • Anatomical Position Reference: In anatomic position, radius is lateral and ulna is medial.

    • Radius:

    • Head: Round proximal tip that joins with the capitulum of the humerus.

    • Styloid Process: A needle-like projection on the distal end.

    • Ulna:

    • Head: Located at the distal end (unlike the radius).

    • Olecranon Process: The elbow's posterior knob, often referred to as the funny bone.

    • Trochlear Notch: A deep hook-like depression connecting to the trochlea of the humerus.

    • Coronoid Process: Located at the inferior lip of the trochlear notch.

    • Radial Notch: Small depression lateral to the trochlear notch where the radius connects with the ulna.

    • Interosseous Membrane: Tough fibrous connective tissue between the radius and ulna that serves as an attachment point for muscles and a stabilizing structure.

Wrist and Hand

Carpal Bones

  • Composition: Eight carpal bones arranged in proximal and distal rows.

    • Proximal Row: Pisiform, triquetral, lunate, scaphoid.

    • Distal Row: Hamate, capitate, trapezoid, trapezium.

  • Important for understanding the arrangement and potential pathologies in the wrist.

Metacarpals and Phalanges

  • Composition: Five metacarpals numbered from 1 (thumb) to 5 (little finger).

    • Base: Proximal end of metacarpals.

    • Head: Distal end of metacarpals.

  • Phalanges:

    • 2-5: Three bones each (proximal, middle, distal).

    • 1 (Thumb): Two bones (proximal, distal).

    • Knuckles: Metacarpophalangeal joints (MCP) are the joints between metacarpals and phalanges.

  • Interphalangeal Joints: Two types - Proximal Interphalangeal (PIP) and Distal Interphalangeal (DIP).

Important Clinical Applications

  • Correct identification of digits and joints is crucial for diagnosis and treatment in clinical settings.

  • Emphasized importance of knowing anatomical landmarks for acupuncture points.

Pelvic Girdle

  • Composition: Two coxal or hip bones (ischium, ilium, pubis) fused into one. The sacrum connects these two bones.

  • Obturator Foramen: Large openings in the pelvic region.

  • Iliac Crest: Upper edge of the pelvic bones, important for various anatomical landmark references.

  • Ischial Tuberosity: Major landmark on the ischium, referred to as the sit bones.

Thigh and Leg

Femur

  • Description: Longest, heaviest, and strongest bone in the body, curved anteriorly for added strength.

    • Proximal End: Knob-like head fitting into acetabulum of the hip.

    • Trochanters:

    • Greater Trochanter: Large lateral projection, significant for muscle attachment.

    • Lesser Trochanter: Smaller projection on the medial side.

  • Distal End: Medial and lateral condyles, and associated epicondyles.

    • Patellar Groove: Where the patella rests, significant in determining knee joint function.

Tibia

  • Description: Major weight-bearing bone located on the medial side, with:

    • Proximal End: Broad range of condyles (medial and lateral) and the tibial plateau for femur articulation.

    • Tibial Tuberosity: Anterior projection for quadriceps attachment.

    • Tibial Crest: Important for anatomy and acupuncture landmarks.

Fibula

  • Description: Lateral bone, thinner, nonweight-bearing.

    • Proximal Head: Located below the lateral tibial condyle.

    • Lateral Malleolus: Distal end that extends further than the tibia, contributing to ankle structure.

Ankle and Foot

Tarsal Bones

  • Composition: Seven tarsal bones (including calcaneus) akin to carpal structure in the wrist.

    • Talus: Connects directly to the tibia and fibula.

    • Navicular, Cuboid, and Cuneiform Bones: Form the structure of the medial and lateral foot regions.

Metatarsals and Phalanges

  • Similar structure to the hand; metatarsals (1-5), phalanges (similar distinctions as in hands).

  • Metatarsophalangeal joints: Points of articulation critical for movement assessment.

Joints (Articulations)

  • Definition: Places where two bones meet, allowing movement through levers and fulcrums.

  • Types of Joints:

    • Fibrous Joints: Immovable (e.g., sutures in the skull).

    • Cartilaginous Joints: Slightly movable (e.g., pubic symphysis).

    • Synovial Joints: Freely movable (e.g., knee, elbow).

Synovial Joint Categories

  • Hinge Joints: Allow movement in one plane (e.g., elbow).

  • Condyloid Joints: Allow movement in two planes (e.g., wrist).

  • Pivot Joints: Allow rotation around a single axis (e.g., atlas and axis in the cervical spine).

  • Saddle Joints: Allow movement in two planes (e.g., base of the thumb).

  • Ball-and-Socket Joints: Allow movement in all planes (e.g., shoulder, hip).

  • Gliding Joints: Limited motion seen in wrist and ankle.

Special Movements

  • Definitions: Couples of movements like inversions, plantar/dorsiflexion, elevation/depression.

  • Importance in clinical terminology and patient assessments.

Conclusion

  • Emphasis on the interplay of skeletal landmarks and functions for understanding anatomy as a whole.

  • Encouragement to review material and reinforce concepts through visual aids and anatomical models.