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Joints of the Skeletal System

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1 Joints of the Skeletal System
Chapter 8

2 What’s a Joint? Is it legal?
Functional junctions between bones Also called articulations Classified by the type of tissue that attaches the bones at the junction Also classified by the way in which they move at

3 Joints Classified by Tissue
Fibrous Joints Dense connective tissue abundant in collagenous fibers found in these joints Usually found between bones that lie very close to each other 3 types of fibrous joints: Syndesmosis, Suture and Gomphosis Cartilaginous Joints Either Hyaline cartilage or Fibrocartilage connects the bones in these joints 2 types of cartilaginous joints: Synchondrosis and Symphysis Synovial Joints The most common type of joint in the skeletal system Allow free movement More complex than fibrous or cartilaginous joints Consist of: 1) articular cartilage 2) Joint capsule 3) synovial membrane that secretes synovial fluid 6 types of synovial joints: Ball-and-socket, Condyloid, Gliding joint, Hinge joint, Pivot joint, and Saddle joint.

4 Joints Classified by Degree of Movement
Synarthrotic – immovable Amphiarthrotic – partially movable Diarthrotic – freely movable

5 Fibrous Joints Syndesmosis Amphiarthrotic (allows slight movement)
Bones in this type of joint are connected to each other with long stands of connective tissue that are collectively called an interosseous ligament (between bones) Found in places such as the distal ends of fibula and tibia, between the tarsals and carpals

6 Syndesmosis Interosseous

7 Fibrous Joints Suture Synarthrotic - immovable
Exist between flat bones of the skull only – joined by a thin layer of dense connective tissue Starts out as a fontanel – wide membranes of dense connective tissue between the skull bones, and allows compression of skull during childbirth, as well as room for growth Fontanels are replaced by sutures

8 Sutures

9 Fibrous Joints Gomphosis Synarthrotic - immovable
A strange joint that is formed when a cone-shaped process of a bone is located within a socket of another bone The root of a tooth located within the jawbone and held together by the periodontal ligament is a good example

10 Blood vessels and nerve endings
Gomphosis Tooth enamel Blood vessels and nerve endings Periodontal ligament Root of tooth Jawbone

11 Cartilaginous Joints Synchondrosis Synarthrotic – immovable
Bands of hyaline cartilage join parts of bones Much of this cartilage disappears upon maturity Example: epiphyseal plate – replaced by bone when full growth is reached (before age 25) – no more movement after this point Another example: articulation between manubrium and first rib by costal cartilage (also synarthrotic and permanent)

12 Synchondrosis

13 Cartilaginous Joints Symphysis Amphiarthrotic – slightly movable
Bones that meet at these joints have a layer of hyaline cartilage covering their ends The hyaline cartilage is also attached to a pad of fibrocartilage which allows a “spring” to movement Examples: Pubic symphasis and joints formed between adjacent vertebrae separated by intervertebral discs Intervertebral discs are also made up of fibrocartilage that surrounds a gelatinous core

14 Symphysis

15 Synovial Joints Diarthrotic – freely moving
Most common type of joint in the body More complex than fibrous and cartilaginous joints Consist of: Articular cartilage Joint capsule Synovial membrane

16 Synovial Joints Articular cartilage – made up of hyaline cartilage and cover the articular surfaces of bones in the joint – these bone ends are made up of spongy bone (like in epiphysis). The articular cartilage minimizes friction and wear Joint Capsule – Holds the bones in a synovial joint together. The outer layer of the capsule is made up of dense connective tissue and reinforced with collagenous fibers called ligaments. The outer layer attaches to the periosteum of the bones in the joint A inner layer of the joint capsule is made of a shiny vascular lining of loose connective tissue called the synovial membrane Synovial Membrane – only a few cells thick, surrounds a closed sac called the synovial cavity that is filled with synovial fluid (secreted by the cells of the synovial membrane

17 A Typical Synovial Joint

18 Some synovial joints… Are divided (partially or completely) into 2 compartments by discs of fibrocartilage called menisci or meniscus (singular). These are located between the articular surfaces of the bones Found in joints like the knee, where the menisci cushion the articulating surfaces Other synovial joints have synovial fluid filled sacs called bursae near them – usually between the skin and the bones of the synovial joint

19 Meniscus and Bursa

20 Menisci are crescent-shaped and attach to the joint capsule on its lateral sides
View of menisci from the top

21 Synovial fluid A thick, stringy fluid found in the cavities of synovial joints. With its egg-like consistency (synovial comes from Latin for “egg"), synovial fluid reduces friction between the articular cartilage and other tissues in joints to lubricate and cushion them during movement. Normal synovial fluid contains hyaluronic acid and a glycoprotein called Lubricin Synovial fluid is secreted by cells of the synovial membrane and supply nutrients to the articular cartilage (remember – the synovial membrane is made of loose connective tissue and therefore has blood vessels)

22 Arthrocentesis: extraction of synovial fluid from joint
The sample can be examined to determine the cause of joint problems

23 cloudy but translucent inflammatory synovial fluid taken from a patient with rheumatoid arthritis (left) and gout (right) respectively. pus-like fluid aspirated from a patient with acute bacterial infectious arthritis

24 colorless, clear synovial fluid from a patient with osteoarthritis accompanied by a low synovial-fluid white cell count bloody fluid aspirated from a patient with a tibial fracture into the joint space

25 Types of Synovial Joints
Hinge Joint Movement in one plane only Convex surface of one bone fits into concave surface of another Example: trochlea of humerus into trochlear notch of ulna

26 Gliding Joint Articulating surfaces of both bones in this joint are almost flat – or maybe very slightly curved Back-and-forth and twisting movements Example – carpals, tarsals, vertebrae, clavicle

27 3. Saddle Joint Between bones that have both concave as well as convex regions on their articulating surfaces 2 planes of movement Forward and back Side-to-side

28 4. Ball-and-Socket Joint
Bone with a round protrusion at the articular end fits into a cup-shaped cavity of another bone Movement in all planes Example: femur head and acetabulum of coxa

29 5. Pivot Joint Cylindrical surface of one bone rotates within another bone Examples: the dens (odontoid process) of the axis within a facet of the atlas

30 6. Condyloid Joint A condyle of one bone articulates with an elliptical cavity of another bone Example: Joints between carpals and metacarpals, Occipital condyles with facets of atlas

31 Types of Joint Movement
Flexion – Bending the lower limb at the knee or bending the hand downward at the wrist Extension – Straightening lower limb at the knee or straightening the hand at the wrist Hyperextension – Moving head upward, toward back or hand toward upper arm Dorsiflexion – bending foot upward, toward the shin Plantar Flexion – bending foot downward, toward the heel Abduction – Moving a leg away from midline, horizontally Adduction – Returning leg from horizontal position back to midline Rotation – twisting head from side to side Circumduction – moving finger in a circular motion without moving hand Supination – palms facing anteriorly Pronation – palms facing posteriorly Eversion – Pushing foot away from body laterally Inversion – Pushing foot laterally toward body (medially) Protraction – Pushing chin forward Retraction – Pulling chin back Elevation – Raising, Shrugging shoulders Depression – lowering, drooping shoulders

32 Gliding

33 Flexion

34 Supination vs. Pronation
Palm faces upward Pronation: Palm faces downward

35 Extension, Hyperextension, and Flexion
Another example: raising and lowering of hand, without moving arm

36 Dorsiflexion vs. Plantar flexion

37 Abduction, Adduction, and Circumduction

38 Rotation

39 Inversion vs. Eversion

40 Protraction vs. Retraction

41 Elevation vs. Depression
Another example: Shrugging and relaxing of shoulders

42 Opposition

43 Examples of Synovial Joints
I. Shoulder Joint – Includes the glenoid cavity of the Scapula and the head of the humerus. It is a Ball-and socket joint. The joint capsule is attached to the circumference of the glenoid cavity of the scapula and the anatomical neck of the humerus The joint capsule is reinforced by several ligaments and tendons of muscles to create a rotator cuff which supports the shoulder joint

44 Ligaments of the Shoulder Joint
Acomion process Coracohumeral – connects the coracoid process of the scapula to the greater tubercle of the humerus Greater tubercle of humerus Coracoid process Coracohumeral Ligament MADE UP OF CONNECTIVE TISSUE

45 2. Glenohumeral Ligament
Acromion Process Clavicle These 3 bands of ligament fibers extend from the edge of the glenoid cavity of the scapula to the lesser tubercle and the anatomical head of the humerus Coracoid process Glenohumeral Ligament MADE UP OF CONNECTIVE TISSUE

46 3. Transverse Humeral Ligament
Acomion process Connects the greater and lesser tubercles of the humerus Greater tubercle of humerus Coracoid process Lesser Tubercle of humerus Transverse Humeral Ligament MADE UP OF CONNECTIVE TISSUE

47 4. Glenoid Labrum Joint Capsule Attaches along the circumference of the glenoid cavity of the scapula and forms a cup-like shape with a free rim Glenoid Labrum MADE OF FIBROCARTILAGE Glenoid cavity

48 Bursae There are several bursae associated with the shoulder joint. The major ones are: Subscapular bursa Subdeltoid bursa Subacromial bursa Subcoracoid bursa

49 II. Elbow Joint Has 2 articulations:
The hinge joint between the trochlea of the humerus and the trochlear notch of the ulna The gliding joint between the capitulum of the humerus and the fovea on the head of the radius A joint capsule encloses the joint and it is reinforced by ulnar and radial ligaments and muscle fibers form the brachialis muscle

50 The Elbow Joint Capitulum Trochlea Trochlear notch

51 Ligaments of the Elbow Joint
Medial epicondyle Coronoid process of ulna Olecranon process of ulna Ulnar Collateral Ligament - Located in the medial wall of the joint capsule - thick band of dense connective tissue - anterior portion of the ligament joins the medial epicondyle of the humerus to the medial margin of the coronoid process of the ulna - The posterior portion of the ligament joins the medial epicondyle of the humerus to the olecranon process of the ulna

52 2. Radial Collateral Ligament
Located in the lateral wall of the elbow joint capsule Fibrous band that extends between the lateral epicondyle of the humerus and the annular ligament of the radius The annular ligament of the radius joins the edge of the trochlear notch of the ulna and envelopes the head of the radius Annular ligament of the radius

53 Types of Movement at the Elbow
The humerus and the ulna are a hinge joint and can only allow flexion and extension. The Radius moves freely inside the annular ligament - this allows the pronation and supination of the hand.

54 Bursa of the elbow

55 The Hip Joint Ball-and-socket joint – head of femur into acetabulum of coxa Heavy, cylindrical joint capsule surrounds the neck of the femur with the edge of the acetabulum. The joint capsule is reinforced by ligaments such as the pubofemoral ligament

56 Hip Joint Capsule

57 Ligaments of the Hip Joint
Ligamentum Capitis (ligamentum teres femoris) Attaches the pit in the femur head (fovea capitis) to the inside of the acetabulum of the coxa Carries blood vessels to the head of the femur Not very essential in holding the joint together – not known for strength

58 2. Acetabular Labrum Horse-shoe shaped ring of fibrocartilage
Attaches to the edge of the acetabulum and makes it deeper Encloses head of femur and holds it in place Remember the glenoid labrum? Similar setup to that

59 3. Iliofemoral Ligament Strongest ligament in the body!
Y-shaped band of fibers Connect the anterior inferior iliac spine of the coxa to the bony line between the greater and lesser trochanters of the femur

60 4. Pubofemoral ligament Joins the superior portion of the pubis and the iliofemoral ligament

61 5. Ischiofemoral Ligament
Connects the ischium behind the acetabulum and joins the fibers of the joint capsule

62 Iliofemoral Ligament Bursa Pubofemoral Ligament

63 Knee Joint Largest and most complex synovial joint
Medial and lateral condyles of the femur’s distal end articulate with the medial and lateral condyles of the proximal end of the tibia Femur also articulates with the patella Knee is a joint with multiple movements hinge joint - flexion and extension Condyloid - allows some rotation (between femur and tibia) and a gliding joint (between femur and patella) Joint Capsule – relatively thin, but strengthened by ligaments and tendons


65 Ligaments of the Knee Joint
Patellar Ligament The fibers of this ligament are fused with the fibers of a tendon (from the thigh muscle quadriceps femoris) Strong flat band that extends from the edge of the patella, to the tibial tuberosity Patellar Ligament

66 2. Oblique Popliteal Connects the lateral condyle of the femur to the edge of the head of the tibia (posterior side of knee) Oblique Popliteal Ligament

67 3. Arcuate Popliteal Ligament
Y-shaped ligament that extends from the lateral condyle of femur to the head of the fibula Arcuate Popliteal Ligament

68 4. Tibial(medial) Collateral Ligament
Broad, flat ligament that extends from the medial epicondyle of the femur to the medial condyle of the tibia Fibular (Lateral) Collateral Ligament Extends between lateral epicondyle of femur to head of fibula


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