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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’sof hard palate
Nasal Bones• Forms bridge of
nose and supports cartilages of nose
• Only movable bone
• Holds the lower teeth
• Attachment of muscles of mastication
• Mandibular foramen
• Mental foramen
Mandible
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, squarishspinous 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 legsand 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 interosseousmembrane
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
• Immovable fibrous joints
• Serrate - interlocking lines
Fibrous Joint -- Sutures
• Lap - overlapping beveled edges
• Plane - straight, nonoverlapping edges
Fibrous Joint -- Sutures
Types of Sutures
Fibrous Joint -- Gomphoses
• Attachment of a tooth to its socket
• Held in place by fibrous periodontal ligament
• Some movement while chewing
• Two bones bound by ligament only
• Most movable of fibrous joints
Fibrous Joint -- Syndesmosis
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 complex diarthrosis
– Patellofemoral
– Tibiofemoral
The Knee Joint• Joint capsule anteriorly
consists of patella and extensions of quadriceps femoris tendon
Knee Joint – Sagittal Section
Knee Joint – Anterior and Posterior Views
• Anterior and lateral cruciate ligaments
• Medial and lateral collateral ligaments
Knee Joint – Superior View
• Medial and lateral meniscus absorb shock and shape joint
Dissection of Knee Joint
Joint Disease
Arthritis
• Arthritis is a broad term for pain and inflammation
Arthritis
• Osteoarthritis results from years of joint wear
Arthritis• Rheumatoid arthritis is autoimmune
attack on joint
Rheumatoid Arthritis
Summary• Joints Classification
– bony– fibrous– cartilaginous
• Synovial joints• Anatomy of Some Joints
– Humeroscapular– Elbow– Coxal– Knee
• Joint Disease
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