Skeletal System PDF

SKELETAL SYSTEM Prepared By Doppalapudi Sandeep M. Pharmacy, Assistant Professor Department of Physiology & Pharmacology Chebrolu Hanumaiah Institute of Pharmaceutical Sciences, Chandramoulipuram, Chowdavaram, Guntur, Andhra Pradesh, India – 52...

SKELETAL SYSTEM Prepared By Doppalapudi Sandeep M. Pharmacy, Assistant Professor Department of Physiology & Pharmacology Chebrolu Hanumaiah Institute of Pharmaceutical Sciences, Chandramoulipuram, Chowdavaram, Guntur, Andhra Pradesh, India – 522019  The Skeletal System Parts of the skeletal system include: – Bones (skeleton) – Joints – Cartilages – Ligaments Divided into two divisions: 1. Axial skeleton – 80 bones 2. Appendicular skeleton – 126 bones  Functions of Bones Framework – Supports muscle, fat and skin Protection – Surrounds vital organs like skull, ribs, pelvis Movement – Muscles attach to bones to provide movement Mineral homeostasis – Stores and maintain minerals (Calcium & phosphorus) Production of blood cells – Red bone marrow – produes Red and white blood cells and platelets Storage – Calcium – Yellow bone marrow – has adipocytes – stores fat.  Classification of Bones Long bones – Typically longer than wide – Have a shaft with heads at both ends – Contain mostly compact bone Examples: Femur, humerus Short bones – Generally cube-shape – Contain mostly spongy bone Examples: Carpals, tarsals  Classification of Bones Flat bones – Thin and flattened, usually curved – Thin layers of compact bone around a layer of spongy bone Examples: Skull, ribs, sternum Irregular bones – Irregular in shape – Do not fit into other bone classification categories Example: Vertebrae and hip  Gross Anatomy of a Long Bone Diaphysis – Shaft – Composed of compact bone Epiphysis – Ends of the bone – Composed mostly of spongy bone Divisions of the Skeletal System  The Axial Skeleton Forms the longitudinal part of the body Divided into three parts – Skull – Vertebral column – Bony thorax  Skull (Cranium) Consists of 22 bones Bones of the skull are grouped into two categories: – Cranial bones - Eight cranial bones form the cranial cavity – Frontal bone, – two parietal bones, – two temporal bones, – the occipital bone, – the sphenoid bone, – ethmoid bone – Facial bones - Fourteen facial bones form the face – Two nasal bones, – two maxillae, – two zygomatic bones, – the mandible, – two lacrimal bones, – two palatine bones, – two inferior nasal conchae and vomer  Skull The cranial and facial bones protect and support special sense organs and the brain. Besides forming the large cranial cavity, the skull also forms several smaller cavities – Nasal cavity – Orbits (eye sockets) – Paranasal sinuses – Small cavities which house organs involved in hearing and equilibrium Bones of the Skull  Skull Immovable joints called sutures fuse most of the skull bones together. The skull provides large areas of attachment for muscles that move various parts of the head. Skull and facial bones provide attachment for muscles that produce facial expressions. The facial bones form the framework of the face and provide support for the entrances to the digestive and respiratory systems.  Skull (Cranial Bones) Frontal Bone – Forms the forehead Parietal Bones – Form the sides and roof of the cranial cavity Temporal Bones – Form the lateral aspects and floor of the cranium Occipital Bone – Forms the posterior part and most of the base of the cranium Sphenoid Bone – Lies at the middle part of the base of the skull Ethmoid Bone – Located on the midline in the anterior part of the cranial floor medial to the orbits – A major superior supporting structure of the nasal cavity – Contain thin projections called conchae which are lined by mucous membranes – Increased surface area in the nasal cavity helps to humidify inhaled air trapping inhaled particles Posterior View  Skull (Facial Bones) Nasal Bones – Form the bridge of the nose Maxillae – Form the upper jawbone and most of the hard palate – Separates the nasal cavity from the oral cavity Zygomatic Bones (Cheek bones) – form the prominences of the cheeks Lacrimal Bones – Form a part of the medial wall of each orbit Palatine Bones – Form the posterior portion of the hard palate Inferior Nasal Conchae – Form a part of the inferior lateral wall of the nasal cavity  Skull (Facial Bones) Vomer – Forms the inferior portion of the nasal septum Mandible – Lower jawbone and the only movable skull bone – The largest, strongest facial bone Nasal Septum – Divides the interior of the nasal cavity into right and left sides Orbits – Eye socket Foramina – Openings for blood vessels, nerves or ligaments of the skull Sphenoid Bone Ethmoid Bone & Vomer Mandible  Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity Functions: – Lighten the skull – Give resonance and amplification to voice – Warm and moisten air  The Hyoid Bone The only bone that does not articulate with another bone Serves as a moveable base for the tongue The hyoid bone also helps to keep the larynx (voice box) open at all times  Vertebral Column Also called the spine, backbone, or spinal column Functions: – Protect the spinal cord – Support the head – Serve as a point of attachment for the ribs, pelvic girdle, and muscles The vertebral column is curved to varying degrees in different locations – Curves increase the column strength – Help maintain balance in the upright position – Absorb shocks during walking, and help protect the vertebrae from fracture  Vertebral Column Composed of a series of bones called vertebrae (Adult=26) – 7 cervical are in the neck region – 12 thoracic are posterior to the thoracic cavity – 5 lumbar support the lower back – 1 sacrum consists of five fused sacral vertebrae – 1 coccyx consists of four fused coccygeal vertebrae  Vertebral Column Cervical Vertebrae(7) Thoracic Vertebrae (12) Lumbar Vertebrae (5) Sacrum Coccyx  Intervertebral Discs Found between the bodies of adjacent vertebrae Functions to: – Form strong joints – Permit various movements of the vertebral column – Absorb vertical shock Vertebrae typically consist of: – A Body (weight bearing) – A vertebral arch (surrounds the spinal cord) – Several processes (points of attachment for muscles)  Vertebral Column (Regions) Cervical Region – Cervical vertebrae (C1–C7) – The atlas (C1) is the first cervical vertebra – The axis (C2) is the second cervical vertebra Thoracic Region – Thoracic vertebrae (T1–T12) – Articulate with the ribs Lumbar Region – Lumbar vertebrae (L1–L5) – Provide for the attachment of the large back muscles Sacrum – The sacrum is a triangular bone formed by the union of five sacral vertebrae (S1–S5) – Serves as a strong foundation for the pelvic girdle Coccyx – The coccyx, like the sacrum, is triangular in shape – It is formed by the fusion of usually four coccygeal vertebrae Cervical Thoracic Vertebrae Vertebrae Comparison of Vertebrae Sacrum & Coccyx  Thorax Thoracic cage is formed by the: – Sternum – Ribs – Costal cartilages – Thoracic vertebrae Functions to: – Enclose and protect the organs in the thoracic and abdominal cavities – Provide support for the bones of the upper limbs – Play a role in breathing  Thorax Sternum – “Breastbone” located in the center of the thoracic wall – Consists of the manubrium, body, xiphoid process Ribs – Twelve pairs of ribs give structural support to the sides of the thoracic cavity – True ribs (7 pairs), False ribs (3 Pairs) and floating ribs(2 pairs). Costal cartilages – Costal cartilages contribute to the elasticity of the thoracic cage THORAX Rib Sternum Three parts – Manubrium – Body – Xiphoid process  The Appendicular Skeleton Limbs (appendages) Pectoral girdle Pelvic girdle  Upper Limb The pectoral girdle consists of two bones, the scapula and the clavicle The free part has 30 bones 1 humerus (arm) 1 ulna (forearm) 1 radius (forearm) 8 carpals (wrist) 19 metacarpal and phalanges (hand)  The Pectoral (Shoulder) Girdle Composed of two bones – Clavicle – collarbone – Scapula – shoulder blade These bones allow the upper limb to have exceptionally free movement. The clavicle is convex in shape anteriorly near the sternal junction The clavicle is concave anteriorly on its lateral edge near the acromion Bones of the Shoulder Girdle  Pectoral Girdle - Scapula Also called the shoulder blade Triangular in shape Most notable features include the spine, acromion, coracoid process and the glenoid cavity Bones of the Shoulder Girdle  Features on the Scapula Spine - a large process on the posterior of the scapula that ends laterally as the acromion Acromion - the flattened lateral portion of the spine of the scapula Coracoid process - a protruding projection on the anterior surface just inferior to the lateral aspect of the clavicle Glenoid cavity - shallow concavity that articulates with the head of the humerus  Skeleton of the Arm - Humerus Longest and largest bone of the free part of the upper limb The proximal ball-shaped end articulates with the glenoid cavity of the scapula The distal end articulates at the elbow with the radius and ulna  Bones of the Upper Limb The arm is formed by a single bone- Humerus  Skeleton of the Forearm - Ulna The longer of the two forearm bones Located medial to the radius Olecranon - the large, prominent proximal end, the “tip of your elbow” Coronoid process - the anterior “lip” of the proximal ulna Trochlear notch - the deep fossa that receives the trochlea of the humerus during elbow flexion Styloid process - the thin cylindrical projection on the posterior side of the ulna’s head  Radius Lies lateral to the ulna (thumb side of the forearm) The head (disc-shaped) and neck are at the proximal end The head articulates with the capitulum of the humerus and the radial notch of the ulna Radial tuberosity - medial and inferior to neck, attachment site for biceps brachii muscle Styloid process - large distal projection on lateral side of radius Radius & Ulna  Bones of the Upper Limb The hand – Carpals – wrist – Metacarpals – palm – Phalanges – fingers  Skeleton of the Hand The carpus (wrist) consists of 8 small bones (carpals) Two rows of carpal bones Proximal row - scaphoid, lunate, triquetrum, pisiform Distal row - trapezium, trapezoid, capitate, hamate Scaphoid - most commonly fractured Carpal tunnel - space between carpal bones and flexor retinaculum  Metacarpals and Phalanges Five metacarpals - numbered I-V, lateral to medial 14 phalanges - two in the thumb (pollex) and three in each of the other fingers Each phalanx has a base, shaft, and head Joints - carpometacarpal, metacarpophalangeal, interphalangeal  Bones of the Pelvic Girdle Hip bones Composed of three pair of fused bones – Ilium – Ischium – Pubic bone The total weight of the upper body rests on the pelvis Protects several organs – Reproductive organs – Urinary bladder – Part of the large intestine The Pelvis The Pelvis: Right Coxal Bone  The Ilium Largest of the three hip bones Ilium is the superior part of the hip bone Consists of a superior ala and inferior body which forms the acetabulum (socket for head of the femur) Superior border - iliac crest Hip pointer - occurs at anterior superior iliac spine Greater sciatic notch - allows passage of sciatic nerve  Ischium and Pubis Ischium - inferior and posterior part of the hip bone Most prominent feature is the ischial tuberosity, it is the part that meets the chair when you are sitting Pubis - inferior and anterior part of the hip bone Superior and inferior rami and body Comparing Male and Female Pelves FEMUR  Skeleton of the Thigh - Femur and Patella Femur - longest, heaviest, and strongest bone in the body Proximally, the head articulates with the acetabulum of the hip bone forming the hip (coxal) joint Neck - distal to head, common site of fracture Distally, the medial and lateral condyles articulate with the condyles of the tibia forming the knee joint Also articulates with patella  Patella Largest sesamoid bone in the body Forms the patellofemoral joint Superior surface is the base Inferior, narrower surface is the apex Thick articular cartilage lines the posterior surface Increases the leverage of the quadriceps femoris muscle TIBIA & FIBULA  Tibia (shin bone) The larger, medial weight-bearing bone of leg The lateral and medial condyles at the proximal end articulate with the femur It articulates distally with the talus and fibula Tibial tuberosity - attachment site for the patellar ligament Medial malleolus - medial surface of distal end (medial surface of ankle joint)  Fibula The smaller, laterally placed bone of leg Non-weight bearing The head forms the proximal tibiofibular joint Lateral malleolus - distal end, articulates with the tibia and the talus at the ankle  Bones of Lower Limbs The foot – Tarsus – ankle – Metatarsals – sole – Phalanges – toes  Skeleton of the Foot - Tarsals, Metatarsals & Phalanges Seven tarsal bones - talus (articulates with tibia and fibula), calcaneus (the heel bone, the largest and strongest), navicular, cuboid and three cuneiforms Five metatarsals - (I-V) base, shaft, head 14 phalanges (big toe is the hallux) Tarsus = ankle