Skeletal System: Module 4
Overview of the Skeletal System and Joints
Focus of Study: Skeletal system and joints (Unit 4)
Learning Outcome: Explain structure and functions of the skeletal system and joints
Importance: Study unit requires significant time investment for mastery
Composition of the Skeletal System
Components: Comprised of bones, cartilages, and joints
Function: Forms a strong, flexible framework for the body
Supports body weight daily
Characteristics of Bones
Definition: Bones are mineralized structures
Matrix Contains: Calcium phosphate
Importance: Essential for hardness and strength
Function:
Provides protection for soft tissues and organs
Allows movement through muscular attachment
Joints
Definition: Joints (articulations) form where two or more bones meet
Movement: Movement occurs at joints; single bones cannot bend without fracturing
Example: Elbow joint allows bending between upper arm and forearm
Roles of the Skeleton
Support
Provides shape and structure to the body
Acts as a scaffold: Supports limbs and vertebral column
**Specifics: **Mandible and maxilla support teeth; rib cage and pelvis support viscera
Protection
Encloses critical organs
Brain, spinal cord, heart, lungs
Protects pelvic viscera and bone marrow
Movement
Muscles pull on bones to enable limb movement and breathing
Bones provide attachment surfaces for muscles; muscle contractions lead to joint movements
Reference: Human biology press sources for additional animated explanations
Hematopoiesis (Blood Formation)
Definition: Red bone marrow is the main producer of blood cells, including immune system cells
Location: Found in bones such as femurs, pelvis, ribs, and vertebral bodies
Function: Synthesizes red and white blood cells, and platelets
Terminology:
“Hema” or “haemato” refers to blood
Mineral Storage
Crucial for electrolyte and acid-base balance
Stores: Calcium and phosphate; releases ions into blood as needed
Calcium: Essential for nerve impulses and muscle contractions
Acid-base balance: Buffers blood pH through absorption and release of alkaline salts
Bones absorb or release minerals as required
Energy Storage
Yellow bone marrow in long bone shafts contains fat (adipose tissue)
Adipocytes store triglycerides as a potential energy source
Role of Cartilage in the Skeletal System
Function: Provides smooth surfaces at joints, supports soft tissues
Example: Tip of the nose and external ear contain cartilage
Flexibility: Cartilage allows more flexibility compared to bones
Example: Easy movement of the tip of the nose
Characteristics: Avascular (no blood vessels or nerves)
Nutrition and waste removal occur through diffusion, leading to slow healing processes after injury
Types of Cartilage
Hyaline Cartilage
Clear, smooth, and contains moderate collagen fibers
Location: Covers articular surfaces of joints (e.g., hip joint)
Elastic Cartilage
Contains collagen and numerous elastic fibers
More flexible; found in structures like the outer ear
Fibrocartilage
Contains limited cells and dense collagen fibers
Provides more stability and less flexibility
Location: Between vertebrae (intervertebral discs) and pubic bones
Bone Structure and Types
Osteology: Study of bone
Bone as Living Tissue:
Contains blood and nerve supply
Dynamic: Continuously remodels and interacts with organ systems
Bone Types:
Compact bone vs. Spongy bone
Compact Bone: Dense, has no visible spaces
Spongy Bone: Fills heads of long bones; more porous and lighter
Bone Classification Based on Shape
Flat Bones
Thin, curved plates (e.g., cranial bones, ribs, sternum)
Structure: Two compact bone plates with spongy bone in between
Long Bones
Longer than broad, crucial for movement (e.g., femur, humerus)
Functions as levers for muscles
Short Bones
Similar width and breadth (e.g., carpal and tarsal bones)
Typically cube-shaped
Irregular Bones
Complex shapes (e.g., vertebrae)
Does not fit into other categories
Sesamoid Bones
Rounded or oval, usually found within ligaments
Example: Patella (largest sesamoid bone); pisiform bone
Long Bones: Structure and Features
Principles:
Shaft known as diaphysis
Ends of diaphysis called epiphyses
Hollow center known as medullary cavity filled with yellow marrow
Epiphyseal Plate:
Growth zone made of hyaline cartilage; allows bone elongation
Critical for growth until replaced by bone tissue
Endosteum: Layer lining the internal marrow cavity
Bone Marrow
Definition: Soft tissue filling marrow cavity of long bones
Types of Bone Marrow:
Red Bone Marrow: Produces blood cells; primarily found in children
Yellow Bone Marrow: Fatty tissue in adults; can revert to red during severe anemia
Chemical Composition of Bone
Composition:
15% water
30% collagen
55% mineral salts (calcium and phosphorus)
Microscopic Structure:
Organized into Haversian systems with a central canal surrounded by lamellae
Blood Supply: Through central canals; essential for bone cell nourishment
Bone Cells
Osteoblasts:
Build new bone; mature into osteocytes
Osteocytes:
Mature bone cells trapped in lacunae
Maintain bone matrix
Osteoclasts:
Break down bone tissue; resorb old or unwanted bone
Nutrient Supply to Bone
Nutrient Foramen: Rounded holes allowing nutrient supply to bone cells
Vascular Structures: (arteries, veins) enter through nutrient foramen to nourish bone cells
Conclusion
The skeletal system is complex and serves multiple functions critical for bodily support, protection, movement, blood formation, mineral storage, and energy.
Understanding the structure and function of bones and joints is essential for comprehending how the human body operates effectively.
Explore additional resources and illustrations to strengthen understanding of these concepts.
Anatomy and Physiology: Skeletal System - Week 4 Notes
Objectives of the Lesson
Focus on Objectives Five and Six: related to the skeletal system.
Bone Formation: Ossification or Osteogenesis
Definition: The process of laying down new bone by osteoblasts.
Two Main Processes of Bone Formation:
1. Intramembranous Ossification
Definition: Direct laying down of bone without cartilage.
Importance: Essential during fetal development and natural healing of bone fractures.
Steps Involved in Intramembranous Ossification:
Mesenchymal cells cluster and differentiate into osteoblasts that form an ossification center.
Osteoblasts produce osteoid and deposit it to mineralize extracellular matrix. Some become entrapped as osteocytes.
Spongy bone and periosteum forms; blood vessels enter, promoting growth.
Compact bone forms beneath the periosteum, surrounding the spongy bone.
2. Endochondral Ossification
Definition: Involves cartilage as a precursor before replacing it with bone tissue.
Importance: Essential for the formation of long bones and their growth in length.
Steps Involved in Endochondral Ossification:
Formation of periosteum; perichondrium becomes periosteum.
Formation of a bone collar around the primary ossification center.
Calcification of matrix begins, allowing osteoprogenitor cells to secrete osteoids to form bone trabeculae.
Appearance of the secondary ossification center at epiphysis after birth; epiphyseal plate remains until growth concludes.
Growth Plate (Epiphyseal Plate)
Definition: A strip of cartilage between primary and secondary ossification centers that allows for lengthening of bones until about age 20.
Observation: When it ossifies, it leaves the epiphyseal line visible on x-rays.
Bone Growth Mechanisms
Growth in Length:
Achieved through changes in the epiphyseal plate.
Cartilage growth through multiplication of chondrocytes and new matrix deposition (Interstitial growth).
Excessive deformation can lead to disorders such as dwarfism due to failure of cartilage growth.
Growth in Width (Appositional Growth):
Involves the deposition of new tissue at the bone surface rather than internal growth.
Osteoblasts in the periosteum lay down new bone tissue on the outer surface, making bone thicker.
Bone Remodeling
Definition: The continuous process of bone tissue replacement, involving absorption and deposition of new bone.
Importance:
Reparative, mineral release, adaptation to stress from usage or disuse.
Key Players:
Osteoblasts: Deposit new bone.
Osteoclasts: Absorb old bone.
Balanced Remodeling:
Necessary for maintaining bone health; imbalances could lead to diseases like osteoporosis.
Bone Resorption and Mineral Release
Definition: The process of dissolving bone to release minerals into circulation.
Mechanism: Osteoclasts respond to low calcium levels by breaking down bone tissue.
Practical Application: Notable implications in dental corrections using braces and adaptations of the mandible due to loss of teeth.
Fractures
Types of Fractures:
Stress Fracture: Caused by abnormal trauma.
Pathological Fracture: Resulting from underlying diseases.
Classification Based on Skin Breach, Fracture Line Direction, and Displacement:
Closed (Simple) Fracture: Skin remains intact.
Open (Compound) Fracture: Skin is broken.
Transverse, Oblique, Spiral, Comminuted, and Greenstick Fractures.
Non-displaced vs. Displaced Fractures:
Non-displaced: Bone pieces remain aligned.
Displaced: Pieces shift out of anatomical alignment.
Phases of Bone Repair
Three Stages:
Reactive Phase: Inflammatory response and hematoma formation.
Reparative Phase: Formation of a fibrocartilaginous callus, leading to a bony callus.
Remodeling Phase: Reshaping of the bone over months to years post-injury.
Osteoporosis
Definition: Severe loss of bone density, leading to porous bones.
Impact: High susceptibility to fractures, particularly in the hip, wrist, and spinal vertebrae.
Pathophysiology: Estrogen deficiency post-menopause accelerates osteoclast activity above osteoblast activity.
Prevention: Importance of diet and exercise during critical bone density accumulation years (ages 25-40).
Conclusion
Emphasis on Continuous Learning:
Review the course content and prescribed readings.
Note any questions for further clarification.
Maintain adherence to the schedule provided for continued education progression in Anatomy and Physiology.
Overview of the Skeletal System
Introduction by Renee Fermceau
Focus: Locating and naming all bones in the body including key principles of the skeletal system.
Total Number of Bones: Two hundred six (206) in the adult skeleton.
Note: This number varies with age.
At Birth: Approximately 270 bones present, some of these bones fuse during childhood.
Age-Related Changes in Bone Number
Bones Fuse, Reducing Count:
Child Pelvic Girdle:
Three distinct bones: ilium, ischium, pubis.
In Adults: These fuse to form a single hip bone called os coxa.
Skull Bones:
At birth: Numerous separate bones.
In adults: Bones fused into a single casing protecting the brain.
Example Encountered: Fontanelles in fetal skull, which are open spaces filled with dense connective tissue that allow for growth and adaptability during birth.
Definitions and Explanations:
Fontanelle: Spaces allowing flexibility in the fetal skull.
Anterior Fontanelle: Last to close by age two, crucial for skull shape adjustment during childbirth and continued brain growth afterward.
Recommended Reading: Section on fontanelles from noted text (not specified here).
Divisions of the Human Skeleton
Two Principal Divisions:
Axial Skeleton (80 bones):
Central supporting axis of the body.
Components Include:
Skull
Auditory ossicles (three pairs, six total).
Hyoid bone (in the neck).
Vertebral column (spine).
Thoracic cage, including ribs and sternum.
Appendicular Skeleton (126 bones):
Comprises bones of the upper and lower limbs along with the corresponding girdles:
Pectoral girdle (attaches upper limb to axial skeleton).
Pelvic girdle (attaches lower limb to vertebral column).
Classification of Skull Bones
Total of 22 Skull Bones (excludes the six auditory ossicles):
Cranial Bones vs. Facial Bones:
Cranial Bones:
Function: Enclose cavity housing the brain.
Categories:
Flat bones forming the cranium.
Serve as casing for brain and inner ear structures.
Facial Bones:
Support facial features and house sensory organs (eyes, nose, etc.).
Identification of Specific Cranial Bones
Cranial Bones:
Frontal Bone (orange):
Forms forehead and upper eye sockets.
Parietal Bones (dark green, two):
Form roof and sides of the skull.
Temporal Bones (light green, two):
Located at temples, enclosing outer ear and cheek arch.
Sphenoid Bone (dark orange):
Butterfly-shaped, connects cranial and facial bones.
Ethmoid Bone (two):
Role includes structure of nasal cavity.
Identification of Specific Facial Bones
Maxillae (light purple/pink):
Forms upper jaw, palate, nose, and eye socket floor.
Zygomatic Bones:
Comprises cheekbone structure, forming arch and part of the eye socket.
Nasal Bones:
Foundation for the nose's structure.
Mandible:
Lower jawbone, connects with temporal bone at the jaw joint.
Vomer (green):
Forms part of nasal septum separating nasal cavity.
Lacrimal Bone (neon green):
Located in medial wall of eye socket; relates to tear production.
Detailed Examination of Skull Orientation
Importance of Orientation:
Identify anterior (front) vs. posterior (back) sides.
Recognize medial (towards the center) vs. lateral (towards the side) positions.
Distinction necessary for understanding each bone's relationship in the skull.
Description of the Occipital Bone and General Skull Structure
Occipital Bone (yellow):
Forms the back and base of the skull.
Review Different Views of the Skull: To understand spatial orientation of bones.
Palatine Bone (brown):
Part of the palate where upper teeth are anchored.
Inferior Nasal Concha:
Located within the nasal cavity walls, noted for eventual discussion in context with sense organs.
Paranasal Sinuses
Function and Importance:
Help reduce skull weight, play role in resonance, trap particles.
Locations of Different Sinuses:
Frontal Sinus:
Deep to superciliary arches, within frontal bone.
Maxillary Sinus:
Largest, located in maxilla body.
Sphenoid Sinus:
Found in the sphenoid bone.
Ethmoidal Sinuses:
Numerous small pockets (air cells) between the nose and eye area, difficult to visualize.
Clinical Relevance of the Sinuses
Understanding Sinuses:
Essential to comprehend symptoms during illnesses like cold or flu:
Pressure or pain related to sinusitis.
Changes in voice due to resonance alterations with blocked sinuses.
Ear Structures
Auditory Ossicles:
Located in middle ear within temporal bone:
Malleus (green): Connects to the eardrum.
Incus: Intermediate bone.
Stapes: Connects to inner ear structures.
Hyoid Bone:
Thin, fragile bone in neck, shaped like a 'U'.
Associated with potential strangulation injuries (fracturing).
Comprises central body and two greater horns; includes smaller lesser horns.
Conclusion
Summary: Focuses on anatomy of the skull and structures related to hearing.
Introduction to the Skeletal System
Focus on the Vertebral Column in Unit Four.
Objectives: Understand the regions, curvatures, and vertebral characteristics of the spine.
Overview of the Vertebral Column
Alternate Name: Spinal column.
Composition:
33 vertebrae, each separated by intervertebral cartilage discs.
Forms a flexible column supporting body weight as the central axis.
Functions Include:
Absorbing stresses from activities such as walking and jumping.
Protecting the spinal cord housed within the vertebral column.
Intervertebral Discs
Functions:
Cushion of fibrocartilage forming joints between vertebrae.
Allows movement between adjacent vertebral bodies.
Absorbs shock and transmits loads through the vertebral column.
Structure:
Composed of:
Annulus Fibrosus: Outer layer – strong and fibrous.
Nucleus Pulposus: Inner layer – gelatinous and shock-absorbing.
Structural Regions of the Vertebral Column
Subdivided into Five Regions:
Cervical Region:
Contains 7 cervical vertebrae (C1 through C7).
Thoracic Region:
Contains 12 thoracic vertebrae (T1 through T12).
Lumbar Region:
Contains 5 lumbar vertebrae (L1 through L5).
Sacral Region:
Sacral vertebrae fused into one bone called the sacrum.
Coccygeal Region:
Contains 4 fused vertebrae forming the coccyx.
Curvatures of the Vertebral Column
Natural Bends:
Four natural curvatures:
Cervical curvature (secondary curve).
Thoracic curvature (primary curve).
Lumbar curvature (secondary curve).
Sacrococcygeal curvature (primary curve).
Primary Curves:
Develop during fetal development: Thoracic and sacrococcygeal curves.
Secondary Curves:
Develop after birth:
Cervical develops first (due to head lifting).
Lumbar develops from walking.
Abnormalities in Curvatures:
Kyphosis: Excessive outward curve in thoracic area (hunchback).
Lordosis: Excessive inward curve in lumbar region (sway back; common in pregnant women).
Scoliosis: Lateral curvature of the spine (can occur left, right, or both).
Anatomy of Individual Vertebrae
General Structure of Vertebrae:
Vertebral body (anterior part).
Vertebral foramen (opening for the spinal cord).
Arch of bone bordering the vertebral foramen (pedicle and lamina).
Key Components:
Vertebral body (blue).
Vertebral foramen (opening inside vertebra).
Spinous process (posterior projection, can be felt along the back).
Transverse processes (lateral projections first seen from the side).
Articular processes and facets for articulation with adjacent vertebrae.
Formation of Channels:
When vertebrae stack, they form:
Intervertebral foramina (where spinal nerves exit).
Vertebral canal (where spinal cord is protected).
Differences between Vertebral Regions:
Cervical Vertebrae:
Small vertebral bodies; foramina in transverse processes for blood vessels.
Spinous processes split (bifid).
C1 (Atlas): No body, supports skull, ring-shaped, articulates with occipital condyles.
C2 (Axis): Contains the dens or odontoid process for head rotation.
Thoracic Vertebrae:
Larger, heart-shaped bodies; articulate with ribs.
Costal facets on vertebral bodies and transverse processes.
Lumbar Vertebrae:
Largest of the spine, thickest bodies, designed for weight bearing.
Location for lumbar punctures due to non-overlapping laminae.
Sacrum:
Composed of five fused vertebrae by the age of 20.
Curvature posteriorly and anteriorly; connects axial and appendicular skeleton.
Anterior surface has transverse ridges; posterior surface features median crest and sacral foramina (for spinal nerves).
Coccyx:
Formed from 4-5 fused coccygeal vertebrae; complete fusion by age 20-30.
Serves as an attachment for pelvic floor muscles.
Can be fractured during childbirth or from falls.
Conclusion
Students should now be able to:
Identify regions of the vertebral column.
Explain the curvatures of the vertebral column.
Identify the characteristics of all vertebrae of the spine.
Introduction to the Thoracic Cage
Recording presented by Missus Van Sail.
Focus: Unit four, the skeletal system, specifically the thoracic cage.
Learning Objective: By the end of this session, students should be able to identify the bones of the thoracic cage.
Overview of the Thorax
Definition: The thorax is defined as the entire chest region.
Bones Composing the Thoracic Cage Include:
Sternum
Ribs
Costal cartilages
Thoracic vertebrae (complete the cage posteriorly)
Functions of the Thoracic Cage
Protection:
Protects vital organs such as:
Heart
Lungs
Major blood vessels
Breathing:
Plays a crucial role in the mechanics of breathing.
Support:
Acts as the anchoring point for:
Pectoral girdle
Upper appendicular skeleton
Articulation:
Joints between these structures are essential for movement and stability.
Detailed Anatomy of the Sternum
General Structure of the Sternum:
Composed of three major elements in adults:
Manubrium (upper section)
Body (middle section)
Xiphoid process (lower section)
Joints of the Sternum:
Manubriosternal Joint:
Junction between manubrium and body of the sternum.
Projects slightly anterior; is palpable through the skin.
Known as the sternal angle, it indicates the level of the second rib.
Xiphisternal Joint: Joint between the body of the sternum and xiphoid process.
Manubrium Articulation:
Articulates with the clavicles at the clavicular notches.
Articulates with costal cartilages along lateral margins.
Jugular Notch:
Indent on the superior margin of the manubrium.
Can be felt at the base of your neck.
Bones of the Ribs
General Information:
There are 12 pairs of ribs.
Every rib articulates with thoracic vertebrae posteriorly and ends anteriorly in costal cartilage.
Rib Structure and Orientation:
Ribs angle anteroinferiorly from the vertebrae to the sternum.
Posterior aspect of the ribs is positioned higher than the anterior aspect.
Classification of Ribs
Ribs Categorized Into:
True Ribs:
First seven pairs.
Their cartilage directly connects to the sternum.
False Ribs:
Next five pairs.
Their cartilage connects indirectly to the sternum.
Forms a Structure: Costal margin, which can be traced by pulling in the stomach.
Floating Ribs:
Last two pairs (ribs eleven and twelve).
Not attached to the sternum.
Characteristics of Ribs
Typical vs. Atypical Ribs:
Focus will be on typical ribs (ribs resembling the standard structure).
Most ribs are typical and possess similar features:
Head: Articulates with thoracic vertebrae.
Curved Shaft:
Sharp Inferior Border:
Costal Groove:
A groove for arteries, veins, and nerves.
Anterior End:
Joins with costal cartilage to anchor to sternum.
Details of Rib Articulation:
Tubercle of the Rib:
For articulation with the transverse costal facet of the thoracic vertebra.
Tubercle faces externally and posteriorly.
Head of the Rib:
Connects to two adjacent vertebrae, allowing for flexibility and movement.
Summary
All essential details regarding the bones of the thoracic wall have been covered.
Transition: Students should now move on to the study of the bones of the appendicular skeleton.
Week 4: Skeletal System - Appendicular Skeleton
Introduction to the Appendicular Skeleton
Definition: The appendicular skeleton is a segment of the skeletal system focused on limbs and their attachments.
Main Components Include:
Pectoral girdle and upper limbs, among others.
Pectoral Girdle (Shoulder Girdle)
Definition: Composed of two bones - the clavicle and the scapula.
Layman's Terms: Commonly known as the collarbone (clavicle) and shoulder blade (scapula).
Bones of the Pectoral Girdle
Clavicle (Collarbone):
Description: Thin, curved bone that serves as a significant anchor point for the upper limb to the trunk.
Articulation:
Medial Side: Articulates with the sternum (manubrium).
Lateral Side: Articulates with the scapula (at the acromion).
Surface Anatomy:
Medial End: Called the sternal end; thickened area that articulates with the sternum.
Lateral End: Known as the acromial end; this end is flattened from top to bottom.
Surface Features:
Superior surface is smooth, while the inferior surface is rough for muscle attachment and neurovascular pathways.
Palpability: Clavicle can be traced from the medial aspect (sternum) to lateral (tip of the shoulder), making it easily palpable due to its superficial location.
Curvature: Clavicle exhibits a unique shape: convex medial curvature transitioning to concave lateral curvature.
Scapula (Shoulder Blade):
Description: A large, flat, triangular bone that connects the humerus (upper arm bone) with the clavicle.
Movement: Glides across the rib cage when the arm moves, allowing for mobility of the shoulder joint.
Surfaces:
Costal Surface: Facing the ribs serves as the anterior surface of the scapula.
Posterior Surface: Not smooth; divided by a prominent ridge (spine of the scapula) into upper (supraspinous) and lower (infraspinous) regions.
Key Features:
Fossa: An indented region of bone, specifically:
Subscapular Fossa: Located on the costal surface, deep to the scapula.
Borders: Three distinct edges:
Superior Border: Top edge of the scapula.
Medial Border: Adjacent to the vertebral column.
Lateral Border: Angled border facilitating the attachment of various muscles.
Glenoid Cavity (Glenoid Fossa):
A hollowed-out area where the head of the humerus articulates, critical for shoulder joint functionality.
Coracoid Process:
An anteriorly projecting structure serving as a point of attachment for muscles (e.g., biceps brachii).
Posterior View of the Scapula
Features:
The posterior surface features the spine of the scapula which separates the supraspinous fossa (above) from the infraspinous fossa (below).
The acromion is a significant bone projection seen in both anterior and lateral views, forming the tip of the shoulder and articulating with the acromial end of the clavicle.
Conclusion
Overview of the Pectoral Girdle Concludes: Allowing transition to anatomical study of the bones of the upper limb.
Understanding Structure and Function: Pectoral girdle is essential for comprehending upper limb movement and anatomy.
Introduction to the Skeletal System
Focus on Unit 4: The Skeletal System.
Objective Seven: Discussing bones of the upper limb.
Overview of the Upper Appendicular Skeleton
Includes: Pectoral girdle and the upper limbs.
Breakdown of Bone Regions:
Arm (Brachium):
Contains a single bone: Humerus.
Forearm (Antebrachium):
Located between the elbow and wrist joints.
Contains two bones: Radius and Ulna.
Carpal Region:
Contains 27 bones in total per hand:
8 Carpals (wrist bones)
5 Metacarpals (bones of the palm)
14 Phalanges (finger bones)
Humerus: Anatomy and Key Features
Proximal End:
Articulates with the glenoid cavity of the scapula to form the shoulder joint.
Features:
Head: Half-spherical structure projecting medially in the anatomical position.
Surgical Neck: Located below the tubercles; named a common fracture site.
Distal End:
Forms the elbow joint.
Features:
Condyles:
Capitulum: Lateral condyle that articulates with the radius.
Trochlea: Medial condyle, larger, articulates with the ulna.
Epicondyles:
Medial Epicondyle: More projecting than lateral, palpable on oneself.
Lateral Epicondyle.
Olecranon Fossa: A depression on the posterior aspect that accommodates the olecranon process of the ulna when elbow is extended.
Radius and Ulna: Structure and Function
Radius:
Orientation: Lies laterally in the forearm.
Proximal End:
Head: Distinct thick disc-shaped structure concave to articulate with the capitulum of the humerus.
Notch: Accommodates the ulna at the margin.
Distal End Features:
Styloid Process: Bony point palpable near the thumb.
Articular Facets:
Triangular Facet: Articulates with scaphoid (triangular in shape).
Quadrangular Facet: Articulates with lunate (quadrangular shape).
Ulnar Notch: Indented region conveying articulation with the ulna.
Ulna:
Orientation: Lies medially to the radius.
Proximal End Features:
Trochlear Notch: Deep C-shaped notch that wraps around the humerus's trochlea.
Olecranon: Palpable tip of the elbow.
Coronoid Process: Lesser projection at the anterior edge of the trochlear notch.
Radial Notch: Faces the radius posteriorly, accommodating the edge of the radius head.
Distal End:
Styloid Process: Medially located, opposite to the radial styloid process.
Osteology of the Hand
Numbering of Bones in Hand:
Carpal Bones: 8 total, divided into two rows:
Proximal Row: 4 bones (Scaphoid, Lunate, Triquetrum, Pisiform).
Distal Row: 4 bones (Trapezium, Trapezoid, Capitate, Hamate).
Pisiform Bone: A sesamoid bone resting on the triangular bone, only visible anteriorly.
Features of Distal Row Carpal Bones:
Each articulates with metacarpal bones.
Hamate known for the prominent hook (hamulus).
Orientation Tips:
Identify the lateral side by locating the thumb or the broader distal end of the radius.
Carpal bones form an arch.
Carpal Tunnel and Carpal Tunnel Syndrome
Carpal Tunnel:
Enclosed tunnel formed by the flexor retinaculum.
Passage for:
Flexor tendons of the fingers.
Median nerve.
Carpal Tunnel Syndrome:
Caused by entrapment of the median nerve due to pressure from tendons or swelling leading to pain and weakness in hand muscles.
Metacarpal and Phalanges Structure
Metacarpals: 5 elongated bones in the palm.
Structure: Base, shaft, head (with knuckles visible)
Phalanges: Bones of the fingers (Digits).
Structure: Each digit has three phalanges (proximal, middle, distal) except the thumb has two.
Numbering System: Start laterally with the thumb (1) to pinky (5).
Conclusion
The complexity of the skeletal system in the upper limb is significant, and understanding each component is crucial for comprehensive knowledge in this study unit.
Introduction to the Overview of Lower Limb Anatomy
Components of the Lower Limb:
Thigh, leg, and foot; key bones and landmarks discussed are crucial for understanding the skeletal framework.
Structure of the Lower Limb
Thigh: Made up of a single bone, the femur.
Leg: Composed of two long bones:
Tibia (yellow)
Fibula (green)
Patella: A sesamoid bone serving as the kneecap (orange).
Foot: Composed of:
7 Tarsal Bones: (ankle)
5 Metatarsals: (light blue)
14 Phalanges: (toes)
Differences in Terminology
Phalanges in the Foot: Same structure as the hand; termed tarsals in place of carpals and metatarsals instead of metacarpals.
Mnemonic: "T for Toes" for tarsals and metatarsals.
Detailed Anatomy of the Femur
Longest Bone in the Body: Located in the thigh.
Divided into Three Parts:
Proximal End:
Contains a distinct head fitting into the acetabulum of the pelvis.
Features a pit called the fovea for ligament attachment.
Distal to the head is the neck of the femur.
Shaft: Contains major projections for muscle/ligament attachments.
Greater Trochanter: Major projection, with a smaller lesser trochanter nearby.
Distal End:
More features posteriorly (back) than anteriorly (front).
Condyles (medial and lateral): Smooth articular surfaces participating in joint movement.
Epicondyles: Slightly above condyles; do not articulate in joints.
Intercondylar Fossa
Deep Indent: Between medial and lateral condyles.
Location for Attachment of:
Anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL).
Patella (Kneecap)
Description: Flat triangular bone, largest sesamoid bone; lies within quadriceps tendon.
Function: Protects anterior knee joint and has rounded edges.
Articulates with: The femur at the patellar surface - important for knee function.
Anatomy of the Leg
Definition: The leg is between the knee and ankle, with tibia being the larger bone involved in the knee joint.
Proximal End of the Tibia Includes:
Condyles: Flattened, articulating surfaces with the femur for knee joint.
Intercondylar Eminence: Region for attachment of ligaments (cruciate ligaments, meniscus).
Tibial Landmarks
Tibial Tuberosity: Roughened area on the anterior aspect for patellar tendon attachment. Felt below the kneecap.
Medial Malleolus: Bony protrusion on the medial ankle, palpable.
Fibular Notch: Notch on the lateral side for articulation with fibula.
Articular Facet for Talus: Inferior surface of the tibia articulates with the tarsal bone, talus.
Anatomy of the Fibula
Location: Laterally in the leg, not involved in weight bearing.
Head: Proximal end with a styloid process, articulating with the tibia.
Lateral Malleolus: Bony protrusion on the lateral ankle, palpable.
Bones of the Foot
Comprised of: Tarsal bones (7), metatarsal bones (5), and phalanges (14).
Tarsal Bones
Proximal Group:
Talus: Superior bone articulating with tibia and fibula at the ankle joint.
Calcaneus: Largest tarsal bone forming the heel.
Distal Group:
Cuboid: Most lateral.
Cuneiform Bones: Medial, intermediate, and lateral cuneiforms.
Metatarsals and Phalanges
Metatarsals: 5, numbered medially starting from the big toe (hallux).
Phalanges: Similar structure to hand; each toe has proximal, middle, and distal phalanges, except the hallux, which has two (proximal and distal).
Flat Feet and Arches of the Foot
Flat Feet (Pes Planus):
Condition where foot arches flatten, causing the soles to touch the ground. Affects approximately 30% of the population.
Can be corrected by proper footwear or physical therapy.
Foot Arches:
Two longitudinal (medial and lateral) and one transverse arch.
The medial longitudinal arch is the highest, formed by the calcaneus extending to the great toe.
Transverse arch is formed by the distal row of tarsal bones.
Function of Arches: Support the body’s weight effectively and are maintained by ligaments and tendons.
Conclusion
Understanding Anatomy of the Lower Limb:
Crucial for further study of joints and their functions.
Seek clarification or engage in discussions during live sessions for deeper comprehension.
Appendicular Skeleton
Instructor: Rainette Van Sail
Focus: Components and features of the lower appendicular skeleton
The Pelvic Girdle
Definition: A complete ring that anchors the lower limbs to the skeleton.
Composition: Consists of three bones:
Two Coxal (Hip) Bones
Sacrum (also part of the vertebral column)
Note: The sacrum will not be discussed in detail.
The Os Coxae (Hip Bone)
Composition: Each hip bone (os coxae) comprises three fused bones:
Ilium
Ischium
Pubis
Articulation: The right and left os coxae meet at a joint called the pubic symphysis, located at the midline (indicated by a green box in illustrations).
Description of the Cartilage Disc at this Joint: Made of fibrocartilage.
Pelvic Inlet
Definition: Defined by a ridge along the area of the red line in illustrations.
Pelvic Inlet: Refers specifically to this ridge.
Structure and Orientation of the Hip Bone
Complex Shape and Orientation: Recommended resource for visual aid: Anatomy TV.
Views of the Pelvic Girdle:
Anterior view
Lateral view
Posterolateral view
Medial (internal) view
Illustration of Encasing Girdle When Articulated.
Characteristics of Os Coxa Components
Ilium
Location: Flared superior section of the os coxae; primarily located in the abdominal cavity rather than the pelvic cavity.
Features:
Iliac Crest:
Extends from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS).
ASIS: Sharp anterior projection palpable through the skin.
PSIS: Often seen as dimples on lower back.
Anterior Inferior Iliac Spine (AIIS) and Posterior Inferior Iliac Spine (PIIS): Less prominent than the superior spines.
Ischium
Location: Inferoposterior portion of the hip bone.
Features:
Ischial Spine: Projects outward posteriorly.
Lesser Sciatic Notch: Indentation inferior to the ischial spine, clinically relevant.
Ischial Tuberosity: Large, rough surface that supports the body while sitting; feeling these surfaces when someone sits on your lap.
Ischial Ramus: Joins with the inferior ramus of the pubis to form the ischial-pubic ramus.
Pubis
Description: The smallest component of the pelvis, consisting of two ramus (sheets of bone).
Features:
Superior Pubic Ramus and Inferior Pubic Ramus join to form the body of the pubis.
Pubic Tubercle: Small, rounded projection of bone on the superior edge where the rami meet.
Pectineal Line: Running laterally from the pubic tubercle, it forms part of the pelvic brim.
Acetabulum and Obturator Foramen
Acetabulum: Important for the femur's integration to form the hip joint; composed of contributions from the ilium, ischium, and pubis.
Obturator Foramen: Large triangular hole formed between the ischium and pubis.
Pelvic Anatomy and Sexual Dimorphism
Sexual Dimorphism in the Pelvis:
Noted as the most sexually dimorphic part of the skeleton—differences in anatomy between males and females are most pronounced here.
Characteristics:
Male Pelvis: More robust, thicker and heavy structure, designed to support larger muscles and body build.
Female Pelvis: Adapted for pregnancy and childbirth, wider, shallower, and features larger pelvic inlet and outlet.
Identification of Sex from Pelvic Features
Pelvic Inlet Shape:
Female: Circular or oval-shaped
Male: Heart-shaped due to an anterior projection from the sacrum.
Sub Pubic Angle:
Female: Larger than 80 degrees
Male: Smaller than 70 degrees.
Acetabulum Size:
Larger in males due to larger femur size.
Greater Sciatic Notch:
Broader in females and narrower in males, less than 70 degrees.
Summary and Resources
Importance of Visual Aids: Tables and pictures enhance understanding of the anatomical differences.
Recommended reading: Refer to Table 8.1 in prescribed materials.
Reminder for Students: Attend live revision sessions for clarity and focus on anatomy and physiology.
Introduction to Joints
Recording Covers: The final chapter of Unit 4, focusing on the joints of the body.
Learning Outcomes Include:
Identification of all joints in the body.
Description of the classification, composition, and functions of joints.
Explanation of the structural characteristics and movements of specific synovial joints.
Definition and Overview of Joints
Articulations or Joints: Connect the bones of the skeletal system, creating a functional system:
Supports the body.
Permits effective movement.
Protects softer organs.
Definition of Joint: A joint is any point where two bones meet (mobile or immobile).
Naming Convention: Joint names typically derive from the bones involved (e.g., sternoclavicular joint = sternum + clavicle).
Classification of Joints
Structural Classification Based On:
Presence of a joint cavity.
Type of connective tissue involved.
Divided Into Three Categories:
Fibrous Joints
Cartilaginous Joints
Synovial Joints
1. Fibrous Joints
Definition: Adjacent bones united by fibrous connective tissue.
Mobility: Generally immobile.
Types Include:
Sutures:
Immobile/slightly movable joints binding skull bones.
Examples: coronal suture, sagittal suture, lamboid suture.
Syndesmosis:
Two bones bound by long collagenous fibers.
More mobility than sutures.
Example: radial ulnar syndesmosis between radius and ulna.
Gomphosis:
Tooth socket joints in the mandible/maxilla, analogous to nails in wood.
2. Cartilaginous Joints
Definition: Bones joined by hyaline cartilage or fibrocartilage.
Mobility: More mobile than fibrous joints, less than synovial joints.
Types Include:
Synchondroses:
Bound by hyaline cartilage.
Examples: epiphyseal plates in children, ribs to sternum via costal cartilages.
Symphysis:
Bones joined by fibrocartilage.
Examples: intervertebral discs between vertebrae, pubic symphysis.
3. Synovial Joints
Definition: Most common, highly mobile joints.
Features:
Articulating bones are not directly connected.
Joint cavity filled with synovial fluid.
Ends of bones are covered by articular cartilage to minimize friction.
Joint Capsule: Retains synovial fluid:
Outer fibrous capsule connected to periosteum of bones.
Inner synovial membrane.
Accessory Structures Include:
Tendons: Attach muscles to bones.
Ligaments: Stabilize joints.
Bursae: Reduce friction.
Functional Classification
Based on the Degree of Movement:
Synarthrosis: Immobile joints.
Amphiarthrosis: Slightly movable joints.
Diarthrosis: Freely movable joints.
Types of Synovial Joints
Six Fundamental Types Distinguished by Shapes and Degrees of Freedom:
Ball and Socket Joints (Multiaxial)
Condyloid Joints (Biaxial)
Saddle Joints (Biaxial)
Hinge Joints (Uniaxial)
Pivot Joints (Uniaxial)
Plane or Gliding Joints (Biaxial)
Uniaxial Joints
Pivot Joint
Allows rotational motion without gliding.
Example: Radial ulnar joints:
The head of the radius fits into the radial notch of the ulna, held by the annular ligament.
Allows pronation and supination of the forearm.
Hinge Joint
Allows flexion and extension; no sliding.
Example: Elbow joint between humerus and ulna:
Actions include bending (flexion) and straightening (extension).
Stabilized by radial and ulnar collateral ligaments.
Biaxial Joints
Plane or Gliding Joint
Smooth movement in several directions along a plane.
Examples:
Intercarpal joints in the wrist.
Tarsal bones in the feet.
Condyloid/ Ellipsoid Joints
Irregular surface where bones fit together like nested bowls.
Examples:
Metacarpophalangeal joints (knuckles).
Radiocarpal joint at the wrist.
Allows flexion, extension, abduction, adduction, and circumduction.
Saddle Joint
Similar to condyloid but with greater range of motion.
Example: Joint between trapezium bone and base of the first metacarpal (thumb).
Multiaxial Joints
Ball and Socket Joint
Allows movement in multiple directions, including rotation.
Examples:
Shoulder joint (glenohumeral joint): head of humerus into glenoid cavity.
Hip joint (acetabulum with femur head).
Stability vs. Mobility: Increased mobility comes at the expense of stability; ligaments assist in stabilization.
In the shoulder, glenoid labrum deepens socket stability.
Conclusion and Study Tips
Understanding Joint Movements and Classifications: Enhances comprehension of body mechanics during actions.
Reference: Provided PDF for additional terms and images for clarification on joint movements.