Joints & Joint Movements Human Anatomy Sonya Schuh-Huerta, Ph.D.

Joints Rigid elements of the skeleton meet at joints or articulations Greek root “arthro” means joint Structure of joints Enables resistance to crushing, tearing, & other forces

Classifications of Joints Joints can be classified by function or structure Functional classification  based on amount of movement Synarthroses  immovable; common in axial skeleton Amphiarthroses  slightly movable; common in axial skeleton Diarthroses  freely movable; common in appendicular skeleton (all synovial joints)

Classifications of Joints Structural classification based on Material that binds bones together Presence or absence of a joint cavity Structural classifications include: Fibrous Cartilaginous Synovial

Classifications of Joints

Sutures – A Type of Fibrous Joint Bones are tightly bound by a minimal amount of fibrous tissue Only occur between the bones of the skull Allow bone growth so the skull can expand with brain during childhood Fibrous tissue ossifies in middle age Synostoses = closed sutures

Syndesmoses – A Type of Fibrous Joint Bones are connected exclusively by ligaments Amount of movement depends on length of fibers Tibiofibular joint = immovable synarthrosis Interosseous membrane between radius & ulna = freely movable diarthrosis

Gomphoses – A Type of Fibrous Joint Tooth in a socket Connecting ligament  the periodontal ligament

Fibrous Joints (a) Suture (b) Syndesmosis (c) Gomphosis Joint held together with very short, interconnecting fibers, and bone edges interlock. Found only in the skull. Joint held together by a ligament. Fibrous tissue can vary in length but is longer than in sutures. Peg-in-socket fibrous joint. Periodontal ligament holds tooth in socket. Socket of alveolar process Suture line Fibula Tibia Root of tooth Dense fibrous connective tissue Ligament Periodontal ligament

Cartilaginous Joints Bones are united by cartilage Lack a joint cavity 2 types Synchondroses Symphyses

Synchondroses Hyaline cartilage unites bones Epiphyseal plates Joint between first rib & manubrium (a) Synchondroses Bones united by hyaline cartilage Sternum (manubrium) Epiphyseal plate (temporary hyaline cartilage joint) Joint between first rib and sternum (immovable)

Symphyses Fibrocartilage unites bones; resists tension & compression Slightly movable joints that provide strength with flexibility Intervertebral discs Pubic symphysis Hyaline cartilage  present as articular cartilage

Symphyses (b) Symphyses Bones united by fibrocartilage Body of vertebra Fibrocartilaginous intervertebral disc Hyaline cartilage Pubic symphysis

Synovial Joints Most movable type of joint!!! All are diarthroses  what does that mean? Each contains a fluid-filled joint cavity

General Structure of Synovial Joints Articular cartilage Ends of opposing bones are covered with hyaline cartilage Absorbs compression Joint cavity (= synovial cavity) Unique to synovial joints Cavity is a potential space that holds a small amount of synovial fluid

General Structure of Synovial Joints Articular capsule  joint cavity is enclosed in a 2-layered capsule Fibrous capsule  dense irregular connective tissue, which strengthens joint Synovial membrane  loose connective tissue Lines joint capsule & covers internal joint surfaces Makes synovial fluid

General Structure of Synovial Joints Synovial fluid A viscous fluid similar to raw egg white A filtrate of blood Arises from capillaries in synovial membrane Contains glycoprotein molecules secreted by fibroblasts

General Structure of Synovial Joints Reinforcing ligaments Often are thickened parts of the fibrous capsule Sometimes are extracapsular ligaments  located outside the capsule Sometimes are intracapsular ligaments  located internal to the capsule

General Structure of Synovial Joints Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Articular capsule Synovial membrane Periosteum (a) A typical synovial joint

General Structure of Synovial Joints Richly supplied with sensory nerves Detect pain Most monitor how much the capsule is being stretched

General Structure of Synovial Joints Have a rich blood supply Most supply the synovial membrane Extensive capillary beds produce basis of synovial fluid Branches of several major nerves & blood vessels

Synovial Joints with Articular Discs Some synovial joints contain an articular disc Temporomandibular joint & Knee joint Occur in joints whose articulating bones have somewhat different shapes

How Synovial Joints Function Synovial joints  lubricating devices Friction could overheat & destroy joint tissue & bone ends Are subjected to compressive forces Fluid is squeezed out as opposing cartilages touch Cartilages ride on the slippery film

Bursae & Tendon Sheaths Bursae & tendon sheaths are not synovial joints Closed bags of lubricant Reduce friction between body elements Bursa = a flattened fibrous sac lined by a synovial membrane Tendon sheath = an elongated bursa that wraps around a tendon

Bursae & Tendon Sheaths Coracoacromial ligament Acromion of scapula Subacromial bursa Coracoacromial ligament Subacromial bursa Joint cavity containing synovial fluid Fibrous articular capsule Cavity in bursa containing synovial fluid Humerus resting Hyaline cartilage Bursa rolls and lessens friction. Tendon sheath Synovial membrane Tendon of long head of biceps brachii muscle Fibrous capsule Humerus Humerus head rolls medially as arm abducts. Humerus moving (a) Frontal section through the right shoulder joint (b) Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rub against a bone

Movements Allowed by Synovial Joints 3 basic types of movement Gliding  one bone across the surface of another Angular movement  movements change the angle between bones Rotation  movement around a bone's long axis

Gliding Joints Flat surfaces of two bones slip across each other Gliding occurs between: Carpals Articular processes of vertebrae Tarsals Gliding (a) Gliding movements at the wrist

Angular Movements Increase or decrease angle between bones Movements involve: Flexion & extension Abduction & adduction Circumduction

Angular Movements Extension Flexion (b) Angular movements: flexion & extension of the neck

Angular Movements Extension Flexion (c) Angular movements: flexion & extension of the trunk

Angular Movements Flexion Extension Flexion Extension (d) Angular movements: flexion & extension at the shoulder and knee

Angular Movements Abduction Circumduction Adduction (e) Angular movements: abduction, adduction, & circumduction of the upper limb at the shoulder

PLAY Movement of the glenohumoral joint

Rotation Involves turning movement of a bone around its long axis The only movement allowed between atlas & axis vertebrae Occurs at the neck, shoulder, elbow, hip

Rotation Rotation Lateral rotation Medial rotation (f) Rotation of the head, neck, & lower limb

Special Movements Elevation  lifting a body part superiorly Depression  moving the elevated part inferiorly Elevation of mandible Depression of mandible Elevation Depression

Special Movements Protraction  nonangular movement anteriorly Retraction  nonangular movement posteriorly Protraction of mandible Retraction of mandible Protraction Moving a body part in the anterior direction Retraction Moving a body part in the posterior direction

Special Movements Supination  forearm rotates laterally, palm faces anteriorly Pronation  forearm rotates medially, palm faces posteriorly Brings radius across the ulna

Special Movements Pronation (radius rotates over ulna) Supination (radius and ulna are parallel) Pronation (P) Rotating the forearm so the palm faces posteriorly Supination (S) Rotating the forearm so the palm faces anteriorly

Special Movements Opposition  thumb moves across the palm to touch the tips of other fingers Opposition

Special Movements Inversion & eversion Special movements at the foot Inversion  turns sole medially Eversion  turns sole laterally

Special Movements Inversion Eversion Inversion Turning the sole of the foot medially Eversion Turning the sole of the foot laterally

Special Movements Dorsiflexion & plantar flexion Up-and-down movements of the foot Dorsiflexion  lifting the foot so its superior surface approaches the shin Plantar flexion  depressing the foot, elevating the heel (ballet toe point)

Special Movements Dorsiflexion Plantar flexion Dorsiflexion Lifting the foot so its superior surface approaches the shin Plantar flexion Depressing the foot elevating the heel

PLAY Eversion of Ankle joint (5a)

Synovial Joints Classified by Shape Plane joint Articular surfaces are flat planes Short gliding movements are allowed Intertarsal & intercarpal joints Movements are nonaxial Gliding does not involve rotation around any axis

Plane Joint Nonaxial movement (a) Plane joint Metacarpals Carpals Gliding (a) Plane joint

Synovial Joints Classified by Shape Hinge joints Cylindrical end of one bone fits into a trough on another bone Angular movement is allowed in one plane Elbow, ankle, & joints between phalanges Movement is uniaxial  allows movement around one axis only

Hinge Joint Uniaxial movement Humerus Medial/ lateral axis Ulna Flexion & extension (b) Hinge joint

Synovial Joints Classified by Shape Pivot joints Classified as uniaxial – rotating bone only turns around its long axis Examples Proximal radioulnar joint Joint between atlas & axis

Pivot Joint Vertical axis Ulna Radius Rotation (c) Pivot joint

Synovial Joints Classified by Shape Condyloid joints Allow moving bone to travel: Side to side  abduction-adduction Back & forth  flexion-extension Classified as biaxial = movement occurs around 2 axes Phalanges

Condyloid Joint Biaxial movement Phalanges Anterior/ posterior axis Medial/ lateral axis Metacarpals Flexion & extension Adduction & abduction (d) Condyloid joint

Synovial Joints Classified by Shape Saddle joints Each articular surface has concave & convex surfaces Classified as biaxial joints 1st carpometacarpal joint is a good example Allows opposition of the thumb

Saddle Joint (e) Saddle joint Metacarpal 1 Medial/ lateral axis Anterior/ posterior axis Adduction and abduction Flexion and extension Trapezium (e) Saddle joint

Synovial Joints Classified by Shape Ball-and-socket joints Spherical head of one bone fits into round socket of another Classified as multiaxial  allow movement in all axes Shoulder & hip joints are examples

Ball-and-Socket Joint Multiaxial movement Scapula Medial/lateral axis Anterior/posterior axis Vertical axis Humerus Flexion and extension Adduction and abduction Rotation (f) Ball-and-socket joint

PLAY Movement of the glenohumeral joint (a)

Factors Influencing Stability of Synovial Joints Articular surfaces Shapes of articulating surfaces determine movements possible

Factors Influencing Stability of Synovial Joints Ligaments Capsules & ligaments prevent excessive motions On the medial or inferior side of a joint  prevent excessive abduction Lateral or superiorly located  resist adduction

Factors Influencing Stability of Synovial Joints Ligaments (cont…) Anterior ligaments  resist extension & lateral rotation Posterior ligaments resist flexion & medial rotation The more ligaments  usually the stronger & more stable

Factors Influencing Stability of Synovial Joints Muscle tone Helps stabilize joints by keeping tension on tendons Is important in reinforcing: Shoulder & knee joints Supporting joints in arches of the foot

Selected Joints

Selected Synovial Joints Temporomandibular Joint Is a modified hinge joint The head of the mandible articulates with the temporal bone Lateral excursion is a side-to-side movement 2 surfaces of the articular disc allow: Hinge-like movement Gliding of superior surface anteriorly

The Temporomandibular Joint Mandibular fossa Articular tubercle Zygomatic process Infratemporal fossa Mandibular fossa Articular disc Articular tubercle Articular capsule External acoustic meatus Superior joint cavity Lateral ligament Synovial membranes Articular capsule Ramus of mandible Mandibular condyle Inferior joint cavity Ramus of mandible (a) Location of the joint in the skull (b) Enlargement of a sagittal section through the joint (arrows indicate movement in each part of the joint cavity)

The Temporomandibular Joint

Selected Synovial Joints Shoulder (= Glenohumeral) joint The most freely movable joint (lacks stability!) Articular capsule is thin & loose Muscle tendons contribute to joint stability

The Shoulder Joint Acromion of scapula Glenoid labrum Coracoacromial ligament Synovial cavity of the glenoid cavity containing synovial fluid Subacromial bursa Fibrous articular capsule Hyaline cartilage Tendon sheath Synovial membrane Fibrous capsule Tendon of long head of biceps brachii muscle Humerus (a) Frontal section through right shoulder joint

The Shoulder Joint Glenoid labrum Synovial cavity of the glenoid cavity containing synovial fluid Hyaline cartilage Fibrous capsule Humerus (b) Cadaver photo corresponding to (a)

Glenohumeral Joint The rotator cuff is made up of 4 muscles & their associated tendons Supraspinatus Infraspinatus Teres minor Subscapularis  (= SITS muscles) Rotator cuff injuries are common shoulder injuries

The Shoulder Joint Articular capsule Acromion Coracoid Coracoacromial process Coracoacromial ligament Subacromial bursa Articular capsule reinforced by glenohumeral ligaments Coracohumeral ligament Greater tubercle of humerus Subscapular bursa Transverse humeral ligament Tendon of the subscapularis muscle Tendon sheath Scapula Tendon of long head of biceps brachii muscle (c) Anterior view of right shoulder joint capsule

The Shoulder Joint Acromion Coracoid process Acromion (cut) Articular capsule Glenoid cavity Glenoid cavity of scapula Head of humerus Glenoid labrum Tendon of long head of biceps brachii muscle Capsule of shoulder joint (opened) Muscle of rotator cuff (cut) Glenohumeral ligaments Tendon of the subscapularis muscle Scapula Posterior Anterior (d) Lateral view of socket of right shoulder joint, humerus removed (e) Posterior view of an opened left shoulder joint

Selected Synovial Joints Elbow joint Allows flexion & extension The humerus’ articulation with the trochlear notch of the ulna forms the hinge Tendons of biceps & triceps brachii provide stability

The Elbow Joint Synovial membrane Humerus Synovial cavity Articular capsule Synovial membrane Humerus Synovial cavity Articular cartilage Fat pad Coronoid process Tendon of triceps muscle Tendon of brachialis muscle Ulna Bursa Trochlea Articular cartilage of the trochlear notch (a) Mid-sagittal section through right elbow (lateral view)

The Elbow Joint Annular ligament Radial collateral ligament Humerus Radius Lateral epicondyle Articular capsule Radial collateral ligament Olecranon process Ulna (b) Lateral view of right elbow joint

The Elbow Joint Articular capsule Humerus Annular ligament Coronoid process Medial epicondyle Ulnar collateral ligament Radius Ulna (d) Medial view of right elbow

Wrist Joint Stabilized by numerous ligaments Composed of radiocarpal & intercarpal joint Radiocarpal joint  joint between the radius & proximal carpals (the scaphoid & lunate) Allows for flexion, extension, adduction, abduction, & circumduction Intercarpal joint  joint between the proximal & distal rows of carpals Allows for gliding movement

Wrist Joint Radius Ulna Radiocarpal Lunate joint Triquetrum Scaphoid Pisiform Capitate Hamate Trapezoid Trapezium Thumb (a) Right wrist, anterior (palmar) view

Wrist Joint Distal radioulnar joint Articular disc Ulnar collateral Radiocarpal joint Distal radioulnar joint Articular disc Radial collateral ligament Ulnar collateral ligament Intercarpal joint (b) Wrist joints, coronal section

Wrist Joint Palmar radiocarpal ligament Radius Ulna Lunate Radial collateral ligament Ulnar collateral ligament Scaphoid Intercarpal ligaments Pisiform Hamate Trapezium Carpo- metacarpal ligaments Capitate (c) Ligaments of the wrist, anterior (palmar) view

Selected Synovial Joints Hip joint A ball-and-socket joint Movements occur in all axes Limited by ligaments & acetabulum Head of femur articulates with acetabulum Stability comes chiefly from acetabulum & capsular ligaments Muscle tendons contribute somewhat to stability

PLAY Movement of the hip joint

The Hip Joint Acetabular labrum Coxal (hip) bone Articular cartilage Ligament of the head of the femur (ligamentum teres) Acetabular labrum Femur Synovial cavity Articular capsule (a) Frontal section through the right hip joint

The Hip Joint Iliofemoral Iliofemoral ligament Anterior inferior iliac spine Ischium Ischiofemoral ligament Pubofemoral ligament Greater trochanter Greater trochanter of femur (c) Posterior view of right hip joint, capsule in place (d) Anterior view of right hip joint, capsule in place

Selected Synovial Joints Knee joint The largest & most complex joint Primarily acts as a hinge joint Has some capacity for rotation when leg is flexed Structurally considered compound & bicondyloid 2 fibrocartilage menisci occur within the joint cavity Femoropatellar joint  shares the joint cavity Allows patella to glide across the distal femur

Sagittal Section of Knee Joint Tendon of quadriceps femoris Femur Suprapatellar bursa Articular capsule Patella Posterior cruciate ligament Subcutaneous prepatellar bursa Synovial cavity Lateral meniscus Lateral meniscus Anterior cruciate ligament Infrapatellar fat pad Deep infrapatellar bursa Tibia Patellar ligament (a) Sagittal section through the right knee joint

Superior View of Knee Joint Anterior Anterior cruciate ligament Articular cartilage on lateral tibial condyle Articular cartilage on medial tibial condyle Medial meniscus Lateral meniscus Posterior cruciate ligament (b) Superior view of the right tibia in the knee joint, showing the menisci and cruciate ligaments

Anterior View of Knee Quadriceps femoris muscle Tendon of quadriceps Patella Medial patellar retinaculum Lateral patellar retinaculum Tibial collateral ligament Fibular collateral ligament Patellar ligament Fibula Tibia (c) Anterior view of right knee

Knee Joint Ligaments of the knee joint: Become taut when knee is extended These extracapsular & capsular ligaments are: Fibular & tibial collateral ligaments Oblique popliteal ligament Arcuate popliteal ligament

Knee Joint Intracapsular ligaments Cruciate ligaments Cross each other like an “X” Each cruciate ligament runs from the proximal tibia to the distal femur Anterior cruciate ligament (ACL) Posterior cruciate ligament (PCL)

Anterior View of Flexed Knee Posterior cruciate ligament Fibular collateral ligament Medial condyle Medial femoral condyle Anterior cruciate ligament Medial meniscus on medial tibial Patella (f) Photograph of an opened knee joint; view similar to (e) Tibial collateral ligament Lateral condyle of femur Anterior cruciate ligament Lateral meniscus Medial meniscus Tibia Patellar ligament Fibula Patella Quadriceps tendon (e) Anterior view of flexed knee, showing the cruciate ligaments (articular capsule removed, and quadriceps tendon cut and reflected distally)

Knee Joint Intracapsular ligaments Cruciate ligaments  prevent undesirable movements at the knee Anterior cruciate ligament  prevents anterior sliding of the tibia Posterior cruciate ligament  prevents forward sliding of the femur or backward displacement of the tibia

Stabilizing function of cruciate ligaments 1 During movement of the knee the anterior cruciate prevents anterior sliding of the tibia; the posterior cruciate prevents posterior sliding of the tibia. 2 When the knee is fully extended, both cruciate ligaments are taut and the knee is locked. Quadriceps muscle Femur Anterior cruciate ligament Patella Medial condyle Anterior cruciate ligament Lateral meniscus Posterior cruciate ligament Posterior cruciate ligament Tibia (a) (b)

The “Unhappy Triad” Lateral blows to the knee can tear: Tibial collateral ligament & medial meniscus Anterior cruciate ligament Are common sports injuries!

Selected Synovial Joint Ankle joint A hinge joint between: United distal ends of tibia & fibula The talus of the foot Allows the movements of: Dorsiflexion & plantar flexion only

The Ankle Joint Medially & laterally stabilized by ligaments Medial (deltoid) ligament Lateral ligament Inferior ends of tibia & fibula are joined by ligaments Anterior & posterior tibiofibular ligaments

The Ankle Joint Tibialis posterior muscle Tibia Calcaneal tendon Ankle (talocrural) joint Talocalcaneal ligament Talus Talonavicular joint Cuneonavicular joint Tarsometatarsal joint Metatarsal bone (II) Metatarsophalangeal joint Interphalangeal joint Calcaneus Subtalar joint Navicular bone Intermediate cuneiform bone Tendon of flexor digitorum longus (a) Cadaver photo of ankle and foot, sagittal section

Ligaments of the Ankle Joint Tibia Medial malleolus Talus Medial (deltoid) ligament Navicular Sustentaculum tali 1st metatarsal Calcaneus (b) Right ankle, medial view

Ligaments of the Ankle Joint Fibula Anterior tibiofibular ligament Tibia Posterior tibiofibular ligament Lateral malleolus Anterior talofibular ligament Talus Lateral ligament Posterior talofibular ligament Metatarsals Calcaneofibular ligament Calcaneus Cuboid (c) Right ankle, lateral view

Disorders of Joints Structure of joints makes them prone to traumatic stress Function of joints makes them subject to friction and wear & tear Affected by inflammatory & degenerative processes

Joint Injuries Torn cartilage  common injury to meniscus of knee joint Sprains  ligaments of a reinforcing joint are stretched or torn Dislocation  occurs when the bones of a joint are forced out of alignment

Inflammatory & Degenerative Conditions Bursitis  inflammation of a bursa due to injury or friction Tendonitis  inflammation of a tendon sheath Swollen bursa surrounding the knee

Inflammatory & Degenerative Conditions Arthritis  describes over 100 kinds of joint-damaging diseases Osteoarthritis  most common type of “wear & tear” arthritis Rheumatoid arthritis  a chronic inflammatory disorder Gouty arthritis (gout)  uric acid build-up causes pain in joints Lyme disease  inflammatory disease often resulting in joint pain

The Joints Throughout Life Synovial joints develop from mesenchyme By week 8 of fetal development, joints resemble adult joints Outer region of mesenchyme becomes fibrous joint capsule Inner region becomes the joint cavity

The Joints Throughout Life During youth  injury may tear an epiphysis off a bone shaft; breaks near joints; dislocations Advancing age  osteoarthritis becomes more common Exercise  helps maintain joint health!

Keeping Your Joints Healthy Exercise is key – strengthens the muscles around the joints & stabilizes them; decreases injuries, joint disorders, wear-&-tear, etc. Also good: proper nutrition, hydration, & vitamins/ supplements (glucosamine a good one) The journey of a mother & daughter

Keeping Your Joints Healthy

Questions…. What’s Next Questions…? What’s Next? Lab: Finish Bones & Joints Wed Lecture: Skeletal muscle Wed Lab: Skeletal muscle tissue & muscles