Skeletal System PDF

Skeletal system  HUMAN ANATOMY What is anatomy? In Greek = to cut. In Latin = to dissect. Levels of studying anatomy: 1) Macroscopic or gross: Anatomy. 2) Microscopic anatomy: Histology. 3) Radiological anatomy Other Positions of the body  Anatomical Planes...

Skeletal system  HUMAN ANATOMY What is anatomy? In Greek = to cut. In Latin = to dissect. Levels of studying anatomy: 1) Macroscopic or gross: Anatomy. 2) Microscopic anatomy: Histology. 3) Radiological anatomy Other Positions of the body  Anatomical Planes 1. Sagittal (Longitudinal) Plane: *Median plane: divides body into Rt. & Lt. halves. 2. Coronal (Frontal) Plane: divides the body into anterior & posterior parts. 3.Transverse (Axial) Plane: divides the body into upper & lower parts. Anatomical Terms of Position External (Outer) Superficial Deep Internal (Inner)  The Skeletal System Formed of: Bones Cartilages Joints  The Skeleton Represent 20% of the body weight Has two subdivisions 1) Axial skeleton, (80) bones 2) Appendicular skeleton, (126) bones  Skeletal System 1. Axial skeleton Lies along the central axis of the body, formed of: skull vertebral column bones of thoracic cage 2. Appendicular skeleton Consists of the bones of: upper limb lower limbs shoulder girdle pelvic girdle 7-8 Axial Skeleton  The Skull The skull formed of two portions 1. Cranial portion (8 bones) 2. Facial portion (14 bones) 1. Cranial portion : It is formed of 8 flat bones articulated with each other by non-mobile strong fibrous joints termed as sutures. These bones are: One frontal bones. One occipital bone. One sphenoid bone One ethmoid bone. Two parietal bones. Two temporal bones. 2. Facial portion: Is formed of 14 flat irregular bones, also joined by sutures. These bones are: Two nasal bones. Two zygomatic bones. Two maxillary bones. Two lacrimal bones. Two palatine bones. Two inferior nasal conchae. One vomer. One mandible.  The base of the skull contains a large opening called the foramen magnum that allows passage of the spinal cord It also contains multiple small foramina for passage of nerves and blood vessels.  The anterior view of the skull contains the openings and cavities for the orbit, the nose and the mouth. The fetal (and new-born baby) skull bones are not completely united but have many membranes covered areas termed the fontanels (anterior, posterior, that allow growth with age. The skull contains the (Paranasal air sinuses) Maxillary sinus Structure: Bone contains air cavity Functions: 1) Decrease the weight of skull. Clinical anatomy: sinusitis  The Vertebral Column - It is the central part of the skeleton. - It supports the head. - It encloses the spinal cord - It transmits the body weight. - It is formed of separate bones called vertebrae but some of them are fused. The number of vertebrae are 33 divided into 5 groups: 1. Cervical : 7 in number. 2. Thoracic : 12 in number. 3. Lumber: 5 in number. 4. Sacral :5 fused in a single bone called SACRUM 5. Coccygeal : 4 fused in single bone called COCCYX General features of the vertebrae - Each vertebra is formed of: Column The body: anterior. The vertebral (neural) arch: posterior. The vertebral arch is formed of two pedicles, two laminae, one spine, two transverse processes, two superior and two inferior articular processes. - Each vertebra has a vertebral foramen that allow passage of the spinal cord - The vertebrae are articulated with each other by the inter-vertebral discs,  Characteristics of vertebrae Cervial vertebra: has bifid spinous process (C1 is called atlas, C2 is axis) Thoracic vertebra : characterized by the presence of articular surfaces on its body and transverse processes for articulation with ribs. Lumbar vertebra : the largest. Has kidney shaped body  Thoracic Cage Formed of ▪ Sternum anterior ▪ 12 thoracic vertebrae posterior ▪ 12 pairs of ribs 1. Sternum It is a flat bone Has three parts 1 1. Manubruim 2. Body 2 3.Xiphoid process 3 3. Ribs They are classified into three groups: 1. True ribs (1st-7th ) articulated to the sternum anteriorly and thoracic vertebrae posteriorly. 2. False ribs (8th, 9th and 10th ) attached to each other anteriorly. articulated posteriorlly to the thoracic vertebrae 3. Floating ribs: (11th ,12th ). They articulated posteriorly to the thoracic vertebrae and anteriorly are free. Appedicular Skeleton 1. Shoulder girdle: Formed of 2 bones Clavicle anteriorly. Scapula posteriorlly. 2. Pelvic girdle: ▪ formed of right and left hip bones ▪ Each is formed of three fused bones: Ilium. Pubis. Ischium.  3. Bones of the free upper limb Humerus: in the arm HUMERUS Radius and ulna: in the forearm Carpal bones: 8 small irregular bones in the wrist RADIUS ULNA Metacarpal bones: in the hand CARPAL Phalanges: 14 short irregular bones METACARPAL in the finger PHALANGES 4. Bones of the free lower limb: ▪ Femur: in the thigh. ▪ Tibia and fibula: in the leg ▪ Tarsal bones: 7 irregular bones in the heel and ankle. ▪ Metatarsal bones: 5 bones Phalanges: 14 bones in the toes (digits).  Classification of Bones on the basic of shape 1. Long bones (humerus, femur, tibia, fibula, radius, ulna etc….). 2. Short bones (carpals and tarsals of the hands and feet etc….). 3. Irregular bones (vertebrae). 4. Flat bones (scapula, sternum, hip and bones of the skull). 5. Sesamoid bones (the largest one is the patella). Classification of Bones on the Basis of Shape Figure 5.1 Slide 5.4c  Functions of Bones Support of the body Protection of soft organs Movement due to attached skeletal muscles: “passive” Storage of minerals and fats Blood cell formation