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OVERVIEW OF THE COMPONENTS OF THE MSS. Dr. Nabil Khouri, MD, MSc, Ph.D, Anatomy, First lecture: Objectives: part I • Discuss the components and functions of the MSS. • Identify the major regions and compartments of upper and lower limbs. • Contrast the structural and functional classification of joints and identify factors that determine the degree of movement at a joint. • Describe the relation between bones and skeletal muscles in producing body movements. THE MUSCULOSKELETAL SYSTEM Major substructure components Are: Bone. Muscle. Tendons. Ligaments. Fascia. Cartilage. THE SKELETAL SYSTEM The Human skeletal system consists of a set of 206 bones. They support and protect the body. They work with the muscles to provide movement. The Joints – allow motion between body segments. The skeleton is divided into 2 parts: the axial and the appendicular skeleton. THE AXIAL SYSTEM The axial system is made up of the skull bones, the vertebrae, the ribs and the sternum. THE APPENDICULAR SYSTEM The appendicular system is formed by the upper and lower limbs connected to the axial skeleton through bones of pectoral (shulder) girdle and pelvic girdle. THE UPPER LIMBS BONES THE LOWER LIMBS BONES Bone: Mechanical properties • Most important properties are: – strength and stiffness of bone. • Fractures occur when the bone is loaded to failure. – Compression fractures are commonest in cancellous bone (e.g. fractured skull) – Bending and torsional fractures are commonest in cortical bone (e.g. broken tibia). The following clinical points related to the skeleton of human body are of interest for medical students. • Regions of bone sensitive to pain: • Periosteum is the outer dense membrane that covers the bone that is particularly sensitive to tearing or tension. • Fractures, tumors and infections of the bones are very painful. • The compact bone produces comparatively less sensation of pain as compared to the Periosteum and Spongy bone. • Drilling into the compact bone without anesthesia causes only dull pain or an aching sensation but drilling into spongy bone is much more painful. • Profuse blood supply of bone: • Blood supply of bone is so rich that it is very difficult to interrupt it sufficiently to kill the bone. • Passing a metal pin into the medullary cavity hardly interferes with the blood supply of the bone. • Bone fractures: Fracture is a breakage of the continuity of bone. – The fracture which is not connected with skin wound is known as simple or closed fracture. – The fracture which communicates with the skin wound is known as compound or open fracture. – A fracture requires reduction by which the alignment of broken ends is restored. Repair of fracture takes place in three stages; 1. 2. 3. Repair by granulation tissue Union by callus Consolidation by mature bone • Rickets: In Rickets (deficiency of Vitamin D) calcification of cartilage fails and ossification of the growth zone of a bone is disturbed. • Rickets affects the growing bones and therefore the disease develops during the period of most rapid growth of skeleton that is the period between the age of 3 months to 3 years • Scurvy: In Scurvy (deficiency of Vitamin C) formation of collagenous fibers and matrix is impaired. Anatomy of The Musculoskeletal System What we will study! The Muscular and Skeletal system Skeletal system: is made of Bones that is a hard supporting tissue Bones are used to make up the skeleton Found in many forms including: “small, large, long, short and flat” Bones are held together by Joints which allow and/or restrict movements. Movements are performed by Muscle upon their contractions Muscle is made of muscular tissue Types of Ordinary Body Movements Flexion – decreases angle of joint and brings two bones closer together Extension- opposite of flexion Rotation- movement of a bone in longitudinal axis, shaking head “no” Abduction/Adduction Circumduction Body Movements Abduction – moving the limb away from the midline Circumduction: coneshaped movement, proximal end doesn’t move, while distal end moves in a circleular aspect Adductionmoving toward the midline Skeletal system Objectives • • • • Divisions of the Skeleton Major bony landmarks Bone functions Classification of Bones Bones: Forms In the skeleton and are arranged into • Vertebral Column • • • • • • • • • • • • • appendicular skeleton Axial skeleton Skull Hyoid bone Ribs and sternum Appendiclular skeleton Upper Extremities Lower Extremities Auditory bones The total number of bones 26 22 1 25 ------64 62 -------6 -------206 Axial and Function of Bones – – – – – support (eg: pelvis, legs) protect (eg: skull, vertebrae) mineral storage (eg: calcium, phosphate, inorganic component) movement (eg: walk, grasp objects) blood-cell formation (eg: red bone marrow) • Cellular components include – Osteoblasts: secrete organic part of bone matrix = osteoid – Osteocytes: mature bone cells, maintain bone matrix Classification of Bones Types of Bone 1). Long bones 2). Short bones. 3). Flat bone: 4). Irregular bones 5). Sesamoid bones are special short bones: Ex: patella Long Bones • Long bones are characterized by having one shaft (the Diaphysis) that is much greater in length than width and two extremities (epiphysis). • They are comprised mostly of compact bone and lesser amounts of marrow, which is located within the medullary cavity, and spongy bone. • Most bones of the limbs, including those of the fingers and toes, are long bones. Short bones • Short bones are roughly cube-shaped, and have only a thin layer of compact bone surrounding a spongy interior . • The bones of the wrist and ankle are short bones, as are the sesamoid bones . Flat bones • Flat bones are thin and generally curved, with two parallel layers of compact bones sandwiching a layer of spongy bone . • Most of the bones of the skull are flat bones, as is the sternum . Irregular bones • Irregular bones do not fit into the above categories . • They consist of thin layers of compact bone surrounded by a spongy interior. • As implied by the name, their shapes are irregular and complicated . • The bones of the spine and hips are irregular bones . Surface Features of the Bone • 1). Projections that form joints • a). Head: The proximal articular end of the bone • b). Facet: A small, flattened articular surface • c). Condyle: A large, rounded articular process • d). Ramus: An arm-like branch off the body of a bone 2). Sites of muscle & ligament attachment. a). Tuberosity: A projection or bump with a roughened surface b). Crest: A prominent elevation or ridge c). Trochanter: A specific tuberosities located on specific bones “ Femur” d). Line e). Tubercle: A projection or bump with a roughened surface, generally smaller than a tuberosity f). Epicondyle: A projection near to a condyle but not part of the joint. g). Spine: A relatively long, thin projection or bump h). Process: A relatively large projection or prominent bump.(gen.) Surface Features of the Bone 3). Openings that allow blood vessels and nerves to pass – a). Meatus: A short canal – b). Fissure: A small or large gap between two parts of one bone – c). Foramen: An opening through a bone. – d). Sinus: Pocket (cavity) like structure within the cranial bone – e). Canal: A long, tunnel-like foramen, usually a passage for notable nerves or blood vessels 4). Depressions – a). Fossa: A broad, shallow depressed area – b). Grove: A longe depresive mark on one surface of a bone – c). Notch: A small depression The Skull • The skull, the body’s most complex bony structure, is formed by the cranium and facial bones • Cranium – – protects the brain and is the site of attachment for head and neck muscles • Facial bones – Supply the framework of the face, the sense organs, and the teeth – Provide openings for the passage of air and food – Anchor the facial muscles of expression Anatomy of the Cranium • Eight cranial bones – – – – – – – Two parietal Two temporal One frontal. One occipital One sphenoid One ethmoid • Cranial bones are thin and remarkably strong for their weight Neonatal (Fetal) Skull Parietal Bones and Major Associated Sutures • Four sutures mark the articulations of the parietal bones – Coronal suture – articulation between parietal bones and frontal bone anteriorly – Sagittal suture – where right and left parietal bones meet superiorly – Lambdoid suture – where parietal bones meet the occipital bone posteriorly – Squamous suture – where parietal and temporal bones meet • Parietal Bones: lateral aspects of the skull Frontal Bone • Forms the anterior portion of the cranium • Articulates posteriorly with the parietal bones via the coronal suture • Major markings include the supraorbital margins, the anterior cranial fossa, and the frontal sinuses (internal and lateral to the glabella) Skull – Anterior View Temporal Bone: Lateral Aspects of the Skull Temporal Bones • Form the inferolateral aspects of the skull and parts of the cranial floor • Divided into four major regions – squamous, tympanic, mastoid, and petrous Occipital Bone: Posterior view of the skull • Forms most of skull’s posterior wall and base • Major markings include the posterior cranial fossa, foramen magnum, occipital condyles, and the hypoglossal canal Occipital Bone and Its Major Markings Superior view of the skull Sphenoid Bone • Butterfly-shaped bone that spans the width of the middle cranial fossa • Forms the central wedge that articulates with all other cranial bones • Consists of a central body, greater wings, lesser wings, and pterygoid processes • Major markings: the sella turcica, hypophyseal fossa, and the pterygoid processes • Major openings include the foramina rotundum, ovale, and spinosum; the optic canals; and the superior orbital fissure Sphenoid Bone Inferior Aspect of the Skull base Med-Sagital aspects of the Skull Facial Bones • Fourteen bones of which only the mandible and vomer are unpaired • The paired bones are: – – – – – – Maxillae Zygomatics Nasals Lacrimals Palatines Inferior conchae Maxillary Bones • Medially fused bones that make up the upper jaw and the central portion of the facial skeleton Facial keystone bones that articulate with all other facial bones, except the mandible Their major markings include palatine, frontal, and zygomatic processes, the alveolar margins, inferior orbital fissure, and the maxillary sinuses Maxilla Bones Zygomatic Bones • Irregularly shapes bones (cheekbones) that form the prominences of the cheeks and the inferolateral margins of the orbits Mandible Bone • The mandible (lower jawbone) is the largest, strongest bone of the face • Its major markings include the coronoid process, mandibular condyle, the alveolar margin, and the mandibular and mental foramina Other Facial Bones • Nasal bones – thin medially fused two bones that form the bridge of the nose • Palatine bones – two bone plates that form portions of the hard palate, the posterolateral walls of the nasal cavity, and a small part of the orbits Lacrimal bones – contribute to the medial walls of the orbit and contain a deep groove called the lacrimal fossa that houses the lacrimal sac The Orbit • Bony cavities in which the eyes are firmly encased and cushioned by fatty tissue • Formed by parts of seven bones – frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid The Orbit Figure 7.9b Ethmoid Bone • Most deep of the skull bones; lies between the sphenoid and nasal bones Forms most of the bony area between the nasal cavity and the orbits Major markings include the cribriform plate, crista galli, perpendicular plate, nasal conchae, and the ethmoid sinuses Ethmoid Bone Other Facial Bones • Vomer – plow-shaped bone that forms part of the nasal septum • Inferior nasal conchae – paired, curved bones in the nasal cavity that form part of the lateral walls of the nasal cavity Nasal Cavity • Constructed of bone and hyaline cartilage • Roof – formed by the cribriform plate of the ethmoid • Lateral walls – formed by the superior and middle conchae of the ethmoid, the perpendicular plate of the palatine, and the inferior nasal conchae • Floor – formed by palatine process of the maxillae and palatine bone Nasal Cavity Paranasal Sinuses • Mucosa-lined, air-filled sacs found in five skull bones – the frontal, sphenoid, ethmoid, and paired maxillary bones • Air enters the paranasal sinuses from the nasal cavity and mucus drains into the nasal cavity from the sinuses • Lighten the skull and enhance the resonance of the voice Paranasal Sinuses Sinuses connections and drainage Hyoid Bone • Not actually part of the skull, but lies just inferior to the mandible in the anterior neck • Only bone of the body that does not articulate directly with another bone • Attachment point for neck muscles that raise and lower the larynx during swallowing and speech