JOINTS AND RELATED TERMS Dr. Farhat Aamir

At the end of this session, the student should be able to: Identify sub division of skeletal system. Identify structural, functional and regional classification of joints. Define and describe the structure of cartilaginous, fibrous and synovial joints. Identify common terms related to like tendon, ligament, bursae, aponeurosis and raphe. Identify clinical applications.

Sub divisions of skeletal system The axial skeleton Eighty bones The appendicular skeleton. Total one twenty six bones

Axial skeleton Skull  Cranium 8  Face 14  Auditory ossicles 6  Hyoid 1  Vertebrae (including sacrum and coccyx) 26  Sternum 1  Ribs 24

Appendicular skeleton Shoulder girdles Clavicle 2 Scapula 2 Upper extremities Humerus 2 Radius 2 Ulna 2 Carpals 16 Metacarpals 10 Phalanges 28 Pelvic girdle Hip bone 2 Lower extremities Femur 2 Patella 2 Fibula 2 Tibia 2 Tarsals 14 Metatarsals 10 Phalanges 28

Joints Articulation between two or more bones is defined as joints. Structurally three subtypes: Fibrous Cartilaginous joint Synovial joint

Joints On the basis of movement Synarthrosis (Immovable)  Fibrous joint Amphiarthrosis (slightly movable)  Cartilaginous joint Diarthrosis (Freely movable joint)  Synovial joint

Fibrous joint Connected by collagen fibers Three types Sutures: skull Syndesmosis Gomphosis: present between teeth and mandible/maxilla

Cartilaginous joints Two types Primary and secondary cartilaginous joints Primary also known as Synchondrosis. Between epiphysis and diaphysis First rib and manubrium Joined by plate of hyaline cartilage

Cartilaginous joints Secondary cartilaginous joint is termed as symphysis. Bones are connected by a plate of fibrocartilage and the articular surfaces of the bones are covered by a thin layer of hyaline cartilage. Examples: joints between the vertebral bodies and the symphysis pubis.

Synovial Joints The articular surfaces covered by a thin layer of hyaline cartilage separated by a joint cavity Permits a great degree of freedom of movement. The cavity of the joint is lined by synovial membrane Outside synovial membrane is lined by thick membrane known as capsule

Synovial Joints Articular surfaces are lubricated with fluid known as synovial fluid Ligaments present within the capsule are intracapsular. For example: cruciate ligament in knee joint. Ligament present outside the capsule are extracapsular.

Synovial Joints Divided on the base of shape Plane, hinge, pivot, bicondylar, condylar (ellipsoid), saddle, and ball and socket Divided on the basis of movement as uniaxial, biaxial and multiaxial.

Synovial Joints Plane joints: articular surfaces are flat Permits sliding movement For example: intercarpal joints, intertarsal joints Hinge joints: like of the door Examples are elbow and ankle joint

Synovial Joints Pivot joints: central bony pivot is present Surrounded by bony ring Rotatory movement present Atlantoaxial joint and superior radioulnar joint.

Synovial Joints Ellipsoid joint/condyloid joint: elliptical convex articular surfaces fit with elliptical concave surfaces Flexion, extension, abduction and adduction Small circumduction Wrist joint Ball and socket joint: Permits maximum movement Shoulder joint and hip joint

Synovial Joints Bicondylar joints: movement in one axis with limited rotation Two condyles articulates with concave surface Flexion, extension, abduction and adduction with slight rotation Knee joint Saddle joint: reciprocally concavoconvex Resembles saddle Carpometacarpal joint of thumb

Ligaments and bursae Ligament: Cord or band of connective tissue joining two bones Mainly composed of collagen fibers Bursa: closed fibrous sac lined with smooth membrane Commonly present close to the joints

Synovial sheath, aponeurosis and raphe Synovial sheath: tubular bursa surrounding tendons. Present where tendons passes through retinaculum or osseo- fibrous tunnels. Reduce friction between tendons and surrounding structures. Aponeurosis: modification of tendon. Thin strong sheet of fibers Raphe: interdigitation of tendinous ends of fibers of flat muscles.

Clinical correlations Arthritis: Inflammatory condition of the joints Damage to the articular surface of joints Cartilage becomes fragile Formation of nodules known as osteophytes

Clinical correlations Arthroscopy: Technique of visualizing joints by using small telescope Joints are approached through small incision in skin. Ligaments are prone to stretch injuries Termed as sprain Pain, swelling and loss of movement

Clinical correlations Trauma and infection can lead to inflammation of synovial sheath and bursa Bursitis is the term used for inflammation of bursa

Summary Sub types of skeleton Definition of joints Types Examples Subtypes of synovial joints Definition of ligament, bursa, aponeurosis Clinical correlations

References  Gray’s anatomy for students, 2 nd edition, chapter 1, body systems, page