Human Anatomy & Physiology I Dr. Sullivan Unit IX Arthrology (joints) - Chapter 9

Transcription

1 Human Anatomy & Physiology I Dr. Sullivan Unit IX Arthrology (joints) - Chapter 9 I. Joints: aka Articulations a) Joints are points of contact between two or more bones. Joints may be moveable or may not be moveable. b) At a joint, the bones are held together by flexible connective tissue. c) Joint Surface: the surface of the bone that makes up the joint in question d) Arthrology: the study of articulations II. Joint Classifications a) Joints are classified by structure and function b) Structural Classification: defined by the presence or absence of a space between the bones (synovial cavity) and the type of CT holding it together. i) Fibrous Joints (Figure 9.2): bones are held together by fibrous CT. They Lack a synovial cavity and allow little or no movement. (1) Sutures (figure 9.3): Non-moveable joints binding the bones of the cranium (a) A thin layer of fibrous CT lies between the bones in a suture joint (2) Syndesmosis: Slightly more distance between the bones than in a suture joint. (a) The CT is arranged as a bundle (ligament) or a sheet (interosseus membrane) between the bones. (b) i.e. distal tibio-fibular joint and the interosseous joints between the radius/ulna & tibia/fibula. (3) Gomphoses: the fibrous joint that holds teeth to the alveolar processes of the mandible and maxilla. ii) Cartilaginous Joints (Fig. 9.4): Bones held together by cartilage and lack a synovial cavity and allows little or no movement. (1) Synchondrosis: A cartilaginous joint where the bones held together by hyaline cartilage. (2) i.e.: the junction between the metaphysis and epiphysis of growing bone. The Physis hold the two together. (3) Symphysis: The joint surfaces of the bones are covered with hyaline cartilage, but there is a fibrocartilage disc between the bones. (a) I.e. Intervertebral disc, & pubic symphysis. iii) Synovial Joints (Fig. 9.5): Synovial joints have a distinct space between the joints (synovial cavity) enclosed by a fibrous synovial capsule and filled with a lubricating synovial fluid secreted by the capsule. (1) Held together by named bundles of CT called ligaments (a) Some ligaments lie within the capsule and some outside the capsule. (2) Some Synovial joints also have articular discs or and/or meniscus (pl. menisci) to help provide shock absorption and aid in more fluid mobility. (a) i.e. Knee, TMJ (3) Tendons: tendons are the CT bundles that attach muscles to bones. As a joint moves, tendons rub against bone causing stress & strain. (a) To ease the stress or strain, some tendons are enclosed in fibrous tendon sheaths that remain stable as the tendon slides through it much like pulling a rope through a pipe. (b) Tenosynovitis: Acute or chronic inflammation of a tendon sheath. (4) Bursa: A fluid-filled sac that lies between bone and tendon to allow the tendon to slide more easily over the bone. (a) Bursitis: acute or chronic inflammation of a bursa as a result of trauma, repetitive stress, or infection. III. Synovial Joints (Figure 9.11) a) Synovial joints have many subtypes b) Monaxial: moves in one plane; Biaxial: moves in two planes; Multiaxial: moves in all three planes i) Gliding (plane) Joints: bones slide or glide along each other s joint surfaces. (1) Usually biaxial (2) i.e. intercarpals and intertarsals, sternoclavicular, acromioclavicular

2 ii) Hinge Joints: Open and close like a door along one plane of motion. (1) monaxial (2) i.e. elbow, knee, ankle, interphalangial joints iii) Pivot Joints: bones articulate with a rounded or pointed surface and rotate (1) monaxial (2) i.e. atlanto-axial joint (atlas and odontoid process) and proximal radioulnar joint. iv) Condyloid Joints: a condyle fits into a depression and allows movement along two planes of motion. (1) biaxial (2) i.e. metacarpophalangeal joints (MCP), and wrist. v) Saddle Joints: The articular surface of noe bone is a saddle shape and the other bone fits into the saddle. Allows motion along two planes of motion. (1) biaxial (2) I.e. 1 st carpo-metacarpal joint (thumb), Sternoclavicular joint vi) Ball & Socket Joint: a ball-like surface of one bone fits into a cup-like depression of another bone. Allows motion along three planes of motion. (1) multiaxial (2) i.e. Shoulder and hip c) Movements at synovial joints: different joints are capable of different movements. i) All movement are relative to anatomical position ii) Gliding: relatively flat bone surfaces move back and forth or side to side with respect to one another (1) I.e. radial and ulnar deviation of the wrist is achieved by gliding of carpal bones at the intercarpal joints. iii) Angular Movements: There is an increase or decrease between the angles of bones that make up a particular joint. (1) See animations on website and figures 9.12 through 9.22 in Saladin text. (2) Flexion: there is a decrease in the angle between articulating bones (a) i.e. bending the elbow so as to bring the hand closer to the shoulder (b) bending the knee so as to bring the foot closer to your butt (c) bending the head forward to bring the chin closer to your chest (d) bending trunk forward (e) moving the humerus forward at the shoulder (like swinging your arms) (f) moving the palm toward the forearm at the wrist (g) Bending the digits as if you re making a fist is flexion of the digits (h) Moving the femur forward at the hip joint as if you re lifting up your knee or kicking a ball (3) Extension: increasing the angle between articulating bones. Usually to restore a joint to anatomical from a flexed position. (a) Bending the head and/or trunk backward (b) Moving the humerus backward at the shoulder joint (c) Moving the palm backward at the wrist (d) Moving femur backward at the hip (e) Hyperextension: extending a joint past anatomical position (i) Hyperextension may be limited at certain joints due to the anatomical arrangement of bones & ligaments. (4) Abduction: movement of a bone away from the midline (a) moving the humerus laterally at the shoulder (b) moving the femur laterally at the hip (c) spreading the digits apart (d) radial deviation of the wrist (bending the wrist laterally) (5) Adduction: movement of a bone toward the midline (from an abducted position) (a) returning the humerus to the midline (b) returning the femur to the midline (c) lining the digits up along side each other (d) ulnar deviation of the wrist (bending the wrist medially)

3 (6) Circumduction: movement of a distal body part in a circle. (a) circumduction is a combination of flexion, extension, abduction, and adduction. (7) Lateral Flexion: movement of the trunk from side to side. (a) Lateral flexion named for left or right lateral flexion. (8) Rotation: a bone revolves around its own longitudinal axis. (a) turning the head from left to right. (b) spinning the hip & shoulder (9) Special Movements: Movements limited to certain joints (a) Opposition: movement of the 1 st metacarpal across the palm to touch the 5 th digit. (i) This trait separates us from other mammals and allows us to grasp tools. (b) Elevation: movement of a bone superiorly (i) Closing the mouth is elevation of the mandible (ii) Shrugging the shoulder is elevation of the scapulae (c) Depression: movement of a bone inferiorly (i) Opening the mouth or returning the shoulders from elevation (d) Protraction: movement of a body part anteriorly (i) Jutting your jaw out to create an underbite (ii) Crossing your arms forces you to protract your shoulders at the sternoclavicular, acromioclavicular, and scapulothoracic joints. (e) Retraction: moving a body part posteriorly (i) Usually returning to anatomical position from a protracted position. (ii) Thrusting the shoulder backward to stick out your chest. (f) Inversion (ankle): Movement of the soles of the feet medially so they face each other. (g) Eversion (ankle): movement of the soles of the feet so they face away from each other. (h) Dorsiflexion (ankle): movement of the foot supriorly so as to bring the toes closer to the tibia. (i) Plantar Flexion (ankle): movement of the foot inferiorly so as to point your toes or stand on your toes. (j) Supination (forearm): movement of the forearm at the proximal and distal radioulnar joint so that the palms of the hand face superiorly or anteriorly. (k) Pronation (forearm): movement of the forearm at the proximal and distal radioulnar joint so that the palm of the hand is facing inferiorly or posteriorly. IV. Principal Joints of the body a) Axial Skeleton i) Temporomandibular Joint (TMJ): between the mandibular condyle of condyle and the mandibular fossa of the temporal bone. (1) Forms the jaw joint, opens and closes the mouth. ii) Atlanto-occipital: joint between the occipital condyles and superior articular facets of the lateral masses of atlas (C1 vertebra) (1) flexion and extension of the head iii) Atlanto-axial: between the inferior articular facets of the lateral masses of atlas and the superior articular facets of the axis (C2 vertebra) and between the odontoid process and (1) the anterior arch of the atlas (2) rotation of the head (3) flexion, extension, lateral flexion, rotation of the spine. iv) Costovertebral joint: between the superior and inferior facets of the head of the rib and (1) the superior and inferior demi-facets of the thoracic vertebral bodies. v) Costotransverse joint: joint between the articular tubercle of the rib and the transverse (1) process of the thoracic vertebra. vi) Costochondral joint: where the bone of the rib becomes the costal cartilage. vii) Sternochondral joint: where the costal cartilage articulates with the sternum. b) Apendicular Skeleton

4 i) Sternoclavicular: between the sternal extremity of the clavicle and the manubrium of the sternum. (saddle joint) ii) limited movement in all directions iii) SHOULDER: iv) Acromioclavicular (AC) joint: between acromion of scapula and acromial extremity of the clavicle (a) Limited movement: gliding joint v) Glenohumeral: between the glenoid cavity of the scapula and the head of the humerus. (1) Ball & Socket joint allowing flexion, extension, abduction, adduction, rotation, and circumduction of the shoulder. (2) Held together by muscles of the rotator cuff. vi) ELBOW: formed by three bones (1) Trochlea of humerus articulates with the trochlar notch on the olecranon of the ulna, and the head of the radius articulates with the capitulum of the humerus to form a hinge joint. (2) Allows for flexion and extension of the elbow. vii) Proximal and distal radioulnar joints allow for rotation of the forearm. (1) Proximal: head of radius and radial notch of ulna: pivot joint (2) Distal: head of ulna and ulnar notch of radius: gliding (planar) joint. viii) WRIST: (1) Radiocarpal: between the distal surface of the radius and the scaphoid and lunate bones of the carpals. (a) A Condyloid joint that allows for flexion, extension, abduction, adduction, hyperextension, and circumduction of the wrist. (2) Intercarpal: the joints formed by the carpals coming togther. (a) Glide to assist the radiocarpal joint. ix) HAND: (1) Carpometacarpal: between the carpals and the metacarpals (a) Saddle joint that assists in all movements of the wrist. (2) Metacarpophalangeal (MCP): Condyloid joints between metacarpals and proximal phalanges (a) Flexion, extension, abduction, adduction, circumduction of the digits. (3) Proximal and Distal Interphalangeal (PIPs & DIPs): hinge joints between the proximal and distal rows of phalanges. (a) Flexion and extension of the digits x) PELVIS: (1) Sacroiliac joints: between auricular surface of sacrum and auricular surface of ilium at posterior pelvis. (a) Allows some gliding at the end of hip extension and flexion (b) Pubic Symphysis: between the two pubic bones in the anterior pelvis. xi) HIP JOINT: Femoroacetabular joint: between the acetabulum of the hip bone and the head of the femur. (1) Ball & Socket joint allowing flexion, extension, abduction, adduction, rotation, and circumduction of the thigh. xii) KNEE (FIGURE 9.14): The largest and most complex joint in the body. Three joints within a single synovial cavity. (1) The Knee moves in flexion, extension and slight rotation when flexed. (2) Lateral Tibiofemoral joint: between the lateral femoral condyle and the articular surface of the lateral tibial condyle. (a) Hinge joint for flexion and extension of the knee (b) Lateral Meniscus: a fibrocartilage, shock-absorbing, nearly-circular disc that is attached to the articular surface of the lateral tibial condyle. (3) Medial Tibiofemoral joint: between the medial femoral condyle and the articular surface of the medial tibial condyle. (a) Hinge joint for flexion and extension of the knee (b) Medial Meniscus: a fibrocartilage, shock-absorbing, semi-circular disc attached to the articular surface of the medial tibial condyle.

5 (4) Patellofemoral joint: between the posterior surface of the patella and the anterior surface of the distal femur. (a) Allows for smooth gliding of the quadriceps tendon over the knee. (5) Knee Ligaments: there are four ligament that hold the bones of the knee joint together. 2 within the joint capsule and two outside: (a) Intracapsular: (i) Anterior Cruciate Ligament (ACL): attached to the anterior tibia and posterior femur. 1. restricts hyperextension and anterior gliding of the tibia. 2. Most commonly torn knee ligament. (ii) Posterior Cruciate Ligament (PCL): attached to the anterior femur and posterior tibia. 1. restricts posterior gliding of the tibia while the knee is flexed. (b) Extracapsular: (i) Tibial (or Medial) Collateral Ligament (MCL): from the medial condyle of the femur to the medial condyle of the tibia. (ii) Prevents medial sliding of the tibia (iii) Fibular (or Lateral) Collateral Ligament (LCL): from the lateral condyle of the femur to the head of the fibula. 1. Prevents lateral sliding of the tibia xiii) ANKLE: (1) Talocrural Joint: between the distal tibia, distal fibula, and the talus. (a) Hinge joint for flexion and extension. xiv) FOOT: (1) Intertarsal joint: between the tarsal bones (a) Allow for eversion and inversion of the foot. (2) Tarsometatarsal: between cuneiforms of the trasals and the 5 metatarsal bones. (3) Metatarsophalangeal (MTP): Condyloid joints between metatarsals and proximal phalanges (a) Flexion, extension, abduction, adduction, circumduction of the digits. (4) Proximal and Distal Interphalangeal (PIPs & DIPs): hinge joints between the proximal and distal rows of phalanges. (a) Flexion and extension of the digits