Lecture 2: Skeletal System PDF

- Introduction - Fascia - Cartilage - Bones - joints Dr. mohamed dief allah Lecturer of anatomy & embryology Kasr alainy, Cairo university  Cartilage Hyaline Cartilage White Fibrocartilage Yellow Elastic Fibrocartilage: ...

- Introduction - Fascia - Cartilage - Bones - joints Dr. mohamed dief allah Lecturer of anatomy & embryology Kasr alainy, Cairo university  Cartilage Hyaline Cartilage White Fibrocartilage Yellow Elastic Fibrocartilage: Hyaline Cartilage Hyaline= glass Larynx (except epiglottis) Tracheal rings. During embryonic life (temporary) ❑It forms models of all bones of the skeleton In adult life (permanent) ❑Epiphyseal plates ❑Articular cartilages covering bony ends. ❑Costal cartilages. ❑Respiratory cartilages (laryngeal, tracheal rings).  Ossification in old age: Occurs in certain sites e.g. in larynx & epiphyseal cartilages.  White Fibrocartilage Sites Intervertebral discs and symphysis pubis. Symphysis pubis Ossification in old age: never occur  Yellow Elastic Fibrocartilage: Tip of nose, auricle, epiglottis & Eustachian tube. Ossification in old age: never occur  - The intervertebral disc is an example of (MCQ) A- Hyaline cartilage B- White fibrocartilage C- Yellow elastic fibrocartilage D- Synchondrosis - The Eustachian tube is an example of (MCQ) A- Hyaline cartilage B- White fibrocartilage C- Yellow elastic fibrocartilage D- Synchondrosis SKELETAL SYSTEM  Functions of Skeleton: Gives a specific shape to the body and provides it with a central axis. Protects the vital organs, the skull protects the brain, and thoracic cage protects the heart and lungs. Provides surface area for muscular attachment. Forms the joints which make the important part of the locomotor system. Transmits and supports the body weight. The vertebral column transmits the weight of the head and trunk to the bony pelvis then through the bones of lower limbs to the feet and lastly to the ground. Forms the blood elements in the bone marrow. Stores calcium salts.  Classification of Bones (Skeleton): Appendicular (peripheral) skeleton: Bones of upper and lower limbs. I- According to their position in the body: Axial skeleton: Skull, mandible, hyoid bone, sternum, ribs and vertebral column. The process of bone formation is called ossification. It is of two types: Intra-membranous ossification: Occurs in some bones, e.g. clavicle, roof of skull (skull cap). The bones are developed directly from II- According to the process of ossification: connective tissue membrane (mesenchyme). Intra-cartilaginous ossification: It occurs in long bones, vertebrae, ribs and base of skull. The connective tissue membrane (mesenchyme) is changed at first into a cartilage model, then into bones.  III. According to their shape: A- Long bones: upper and lower limbs e.g. femur and humerus. B- Short Bones: e.g. carpal bones (hand) and tarsal bones ( foot). C- Flat Bones: e.g. bones forming roof of skull, scapula and ribs. D- Irregular Bones: Bones of irregular shape e.g. vertebrae. E- Sesamoid Bones: Small nodules of bones which are embedded in some muscle tendons near their insertion or origin. Function: They diminish friction between tendons and underlying bones e.g. patella which is the largest sesamoid bone, embedded in the tendon of the quadriceps femoris muscle in front of knee joint.  Structure of long bone: - Each bone consists of two ends called epiphysis and a shaft in between called diaphysis. Growth in the length A- Ends (epiphyses): B- Shaft (diaphysis): C- Metaphysis: Part of diaphysis near epiphysis. Separated from it by epiphyseal plate. Most active part of bone.  D- Pneumatic Bones: They are bones containing air sinuses. They are present in skull bones surrounding the nose as frontal and maxillary bones, so the air sinuses are called paranasal sinuses, e.g. maxillary and frontal sinuses. Functions: 1. They decrease the weight of skull. 2. Resonance of voice. 3. They act as air bag protecting the brain and eye. 4. Warming the air. Function of the periosteum View Image 1. Responsible for the growth of long bone in width (diameter). 2. Osteoblasts form new bone in case of fractures. Joints Joint: is the contact between two bones or more Joints Fibrous joint Cartilaginous joint Synovial joint  Fibrous Joints Syndesmosis Gomphosis Suture e g inferior tibio fibular joint. e g: teeth. e g: skull. The roots of teeth are The lower ends of tibia & fibula are connected The bones of skull are connected by connected to their sockets in together by interosseous ligament the mandible & maxilla by sutural ligament. periodontal ligament. Characters: The opposed bony surfaces are connected together by fibrous tissue. There is no joint cavity. No movements are allowed. B- CARTILGENOUS JOINTS ❑ The articulating bones are connected together by a cartilage. ❑ There is no joint cavity. Characters: ❑ No (or limited) movements are allowed. Primary cartilaginous joint (synchondrosis) Secondary cartilaginous joint (symphysis): They are temporary as they disappear by ossification. They are generally permanent. A plate of hyaline cartilage connects articulating bones A disc of fibro-cartilage connects the articulating bones. No movements are allowed. Only limited movements are allowed. e.g.: epiphyseal plate of cartilage e.g.: Inter-vertebral discs. Symphysis pubis.  Synovial joints Characters:- ❑ Hyaline cartilage: covers the articulating surfaces. ❑ Fibrous capsule: connects the articulating bony ends. ❑ Synovial membrane: lines the capsule. ❑ ligaments: reinforce the capsule is externally. ❑ Synovial fluid: There is joint cavity containing. ❑ Movements: are always possible ❑ Intracapsular structures.  - Structures which may be present inside the cavity of synovial joints: 1.Articular disc: A disc of fibrocartilage which divides the joint cavity into two compartments (upper and lower) e.g. temporomandibular joint. 2.Menisci (semilunar cartilages): e.g. the two semilunar plates of fibrocartilage present inside the knee joint. 3.Ligaments: e.g. cruciate ligaments inside the knee joint. 4.Tendon: e. g. the tendon of long head of biceps muscle inside the shoulder joint. Menisci Articular disc Tendon Ligament  - Uni-axial - Bi-axial According to the axis of movements: - Poly axial - Non axial Uniaxial =single axis: hinge – pivot According to direction : a) Transverse :elbow b) Longitudinal :sup radioulnar (Sup. RA) according to shape : a) Hinge : elbow b) Pivot :Sup.RA & inf. Radio-ulnar joint.  - condylar : knee –TMJ Biaxial : 2 axes perpendicular - ellipsoid :wrist - Saddle : carpometacarpal joint of the thumb  Multiaxial : 3 axes - ball and socket : hip and shoulder Non axial joints =(plane): superior Tibiofibular  Thank you