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