Skeleton & Joints The Skeletal System • Overview of the skeleton • The skull • The vertebral column and thoracic cage • The pectoral girdle and upper limb • The pelvic girdle and lower limb • Adaptations to Bipedalism Overview of the Skeleton • Regions of the skeleton – axial skeleton = central axis – appendicular skeleton = limbs and girdles • Number of bones – 206 in typical adult skeleton Surface Features of Bones Axial and Appendicular Skeleton • Axial skeleton • Appendicular skeleton Major Skull Cavities The Skull • 22 bones joined together by sutures • Cranial bones surround cranial cavity – 8 bones in contact with meninges • Facial bones support teeth and form nasal cavity and orbit – 14 bones with no direct contact with brain or meninges – attachment of facial and jaw muscles Frontal Bone • Forms forehead • Forms roof of the orbit Parietal Bone • Cranial roof and part of its lateral walls • Temporal lines of temporalis muscle Temporal lines Temporal Bone • Lateral wall and part of floor of cranial cavity – squamous part – tympanic part – mastoid part – petrous portion Petrous Portion of Temporal Bone • Part of cranial floor • Houses middle and inner ear cavities Occipital Bone • Rear and base of skull • Foramen magnum • Skull rests on atlas Sphenoid Bone • Body of the sphenoid • Lesser wing • Greater wing Maxillary Bones • Forms upper jaw • Forms inferomedial wall of orbit • Forms anterior 2/3’s of hard palate Nasal Bones • Forms bridge of nose and supports cartilages of nose Mandible • Only movable bone • Holds the lower teeth • Attachment of muscles of mastication • Mandibular foramen • Mental foramen Ramus, Angle and Body of Mandible The Vertebral Column Newborn Spinal Curvature • Spine exhibits one continuous C- shaped curve Adult Spinal Curvatures • S-shaped vertebral column with 4 curvatures • Secondary curvatures develop after birth – Cervical curvature – Lumbar curvature Abnormal Spinal Curvatures • Scoliosis • Kyphosis • Lordosis Typical Cervical Vertebrae • Small body and larger vertebral foramen • Transverse process short with transverse foramen for protection of vertebral arteries • Bifid or forked spinous process in C2 to C6 Typical Thoracic Vertebrae • Spinous processes pointed and angled downward • Rib attachment Lumbar Vertebrae • Thick, stout body and blunt, squarish spinous process Thoracic Cage • Attachment site • Protection • Involved in respiration True and False Ribs • True ribs (1 to 7) • False ribs (8-12) • 12 pairs of ribs in both sexes Pectoral Girdle • Attaches upper extremity to the body • Scapula and clavicle • Clavicle attaches medially to the sternum and laterally to the scapula • Scapula articulates with the humerus Clavicle • S-shaped bone, flattened dorsoventrally Scapula • Triangular plate overlies ribs 2 to 7 Upper Limb • 30 bones per limb • Brachium • Antebrachium • Carpus • Manus Brachium and Antebrachium Carpal Bones • Form wrist • 2 rows (4 bones each) Metacarpals and Phalanges • Phalanges are bones of the fingers • Metacarpals are bones of the palm Sesamoid Bone Pelvic Girdle • Girdle • Pelvis • Supports trunk on the legs and protects viscera Os Coxae (Hip Bone) • Acetabulum is hip joint socket • Ilium • Pubis • Ischium Comparison of Male and Female • Female lighter, shallower pubic arch( >100 degrees), and pubic inlet round or oval • Male heavier, upper pelvis nearly vertical, coccyx more vertical, and pelvic inlet heart-shaped Femur and Patella Tibia • Tibia is thick, weight- bearing bone (medial) • Broad superior head with 2 flat articular surfaces Fibula • Slender lateral strut stabilizes ankle • Does not bear any body weight • Joined to tibia by interosseous membrane The Ankle and Foot • Tarsal bones are shaped and arranged differently from carpal bones • Talus • Calcaneus • Distal row of tarsal bones The Foot • Remaining bones of foot are similar in name and arrangement to the hand • Metatarsal I is proximal to the great toe (hallux) • Phalanges – 2 in great toe – 3 in all other toes Bipedalism and Limb Adaptations Bipedalism and Upright Stance Bipedalism and Head Position The Skeletal System Summary • Overview of the skeleton • The skull • The vertebral column and thoracic cage • The pectoral girdle and upper limb • The pelvic girdle and lower limb • Adaptations to Bipedalism Joints • Joints Classification – bony – fibrous – cartilaginous • Synovial joints • Types of Movement • Anatomy of Some Joints – Humeroscapular – Elbow – Coxal – Knee • Joint Disease Joints Classification • Arthrology • Kinesiology Joints Classification • Classified by freedom of movement – diarthrosis – amphiarthrosis – Synarthrosis • Classified how adjacent bones are joined – fibrous, cartilaginous, bony or synovial Bony Joint • Gap between two bones ossifies • Can occur in either fibrous or cartilaginous joint Fibrous Joints • Collagen fibers span the space between bones – sutures, gomphoses and syndesmoses Fibrous Joint -- Sutures • Immovable fibrous joints • Serrate - interlocking lines Fibrous Joint -- Sutures • Lap - overlapping beveled edges • Plane - straight, nonoverlapping edges Types of Sutures Fibrous Joint -- Gomphoses • Attachment of a tooth to its socket • Held in place by fibrous periodontal ligament • Some movement while chewing Fibrous Joint -- Syndesmosis • Two bones bound by ligament only • Most movable of fibrous joints Cartilaginous Joint • Bones are joined by hyaline cartilage Cartilaginous Joint -- Symphysis • 2 bones joined by fibrocartilage • Only slight amount of movement is possible Synovial Joint • Joint in which two bones are separated by a space called a joint cavity General Anatomy • Articular capsule encloses joint cavity • Synovial fluid = slippery fluid; feeds cartilages General Anatomy • Articular cartilage = hyaline cartilage covering the joint surfaces • Articular discs and menisci • Tendon • Ligament Tendon Sheaths and Bursae • Bursa • Tendon sheaths Components of a Lever • A lever is a rigid object that rotates around a fixed point called a fulcrum • Rotation occurs when effort overcomes resistance Mechanical Advantage of a Lever • Two kinds of levers – lever that helps increase output of force – lever move object further and faster Mechanical Advantage • Mechanical advantage is calculated from the length of the effort arm (Muscle moment) divided by the length of the resistance arm (Joint moment) First-Class Lever • Has fulcrum in the middle between effort and resistance Second-Class Lever • Resistance between fulcrum and effort Third-Class Lever • Effort between the resistance and the fulcrum Range of Motion • Degrees through which a joint can move • Determined by – structure of the articular surfaces – strength and tautness of ligaments, tendons and capsule – action of the muscles and tendons Axes of Rotation • Shoulder joint has 3 degrees of freedom = multiaxial joint • Other joints – monoaxial or biaxial Types of Synovial Joints Types of Synovial Joints Ball-and-Socket Joints • Smooth hemispherical head fits within a cuplike depression • Multiaxial joint Condyloid (ellipsoid) Joints • Oval convex surface on one bone fits into a similarly shaped depression on the next • Biaxial joints Saddle Joints • Each articular surface is shaped like a saddle, concave in one direction and convex in the other • Biaxial joint Gliding Joints • Flat articular surfaces in which bones slide over each other • Limited monoaxial joint Hinge Joints • One bone with convex surface that fits into a concave depression on other bone • Monoaxial joint Pivot Joints • One bone has a projection that fits into a ringlike ligament of another • First bone rotates on its longitudinal axis relative to the other Types of Movement Flexion, Extension and Hyperextension • Flexion • Extension • Hyperextension Flexion, Extension and Hyperextension Abduction and Adduction • Abduction – Hyperabduction • Adduction Elevation and Depression • Elevation • Depression Protraction and Retraction • Protraction • Retraction Circumduction Rotation • Medial rotation • Lateral rotation Supination and Pronation • In the forearm and foot • Supination • Pronation Movements of Head and Trunk • Flexion, hyperextension and lateral flexion of vertebral column Rotation of Trunk and Head • Right rotation of trunk; rotation of head Movements of Mandible • Lateral excursion • Medial excursion • Protraction Movement of Hand and Digits • Radial and ulnar flexion • Abduction of fingers and thumb • Opposition is movement of the thumb to approach or touch the fingertips • Reposition is movement back to the anatomical position Movements of the Foot • Dorsiflexion is raising of the toes as when you swing the foot forward to take a step (heel strike) • Plantarflexion is extension of the foot so that the toes point downward as in standing on tiptoe • Inversion is a movement in which the soles are turned medially • Eversion is a turning of the soles to face laterally Shoulder Joint The Humeroscapular Joint • Most freely movable joint in the body – shallowness and looseness • Supported by ligaments and tendons – 3 glenohumeral, coracohumeral, transverse humeral and biceps tendon The Humeroscapular Joint • Supported by rotator cuff musculature • 4 Bursae associated with shoulder joint Stabilizers of the Shoulder Joint Tendons of Rotator Cuff Muscles Dissection of Shoulder Joint Elbow Joint The Elbow Joint • Single joint capsule enclosing the humeroulnar and humeroradial joints Elbow Joint Hip Joint The Coaxal (hip) Joint • Head of femur articulates with acetabulum Hip Joint Dissection of Hip Joint Knee Joint The Knee Joint • Most