2 The Skeletal System Parts of the skeletal system Bones (skeleton)JointsCartilagesLigamentsDivided into two divisionsAxial skeletonAppendicular skeletonIndividual bones are the organs of the skeletal system.Bone contains very active, living tissues.The skeleton can be divided into axial and appendicular portions.The axial skeleton consists of the skull, hyoid bone, vertebral column, and thoracic cage.The appendicular skeleton consists of the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.
3 Functions of Bones Support of the body Protection of soft organs Movement due to attached skeletal musclesStorage of minerals and fatsBlood cell formationFunctions of Bones1. Support and protectionSkeletal parts provide shape and form for body structures.They support and protect softer, underlying tissues.2. Body movementBones and muscles function together as levers to move the body and its parts3. Blood cell formationRed marrow functions in the production of red blood cells, white blood cells, and blood plateletsYellow marrow stores fat.4. Storage of inorganic saltsThe intercellular material of bone tissue contains large quantities of calcium phosphate.
4 Bones of the Human Body The skeleton has 206 bones Two basic types of bone tissueCompact boneSpongy boneMany open spacesCompact bone provides strength and resistance to bending.Spongy bone provides strength and reduces the weight of bone.
5 Classification of Bones Long bonesTypically longer than wideHave a shaft with heads at both endsContain mostly compact boneExamples: Femur, humerus
6 Classification of Bones Short bonesGenerally cube-shapeContain mostly spongy boneExamples: Carpals, tarsals
11 Gross Anatomy of a Long Bone DiaphysisShaftComposed of compact boneEpiphysisEnds of the boneComposed mostly of spongy bone1. Parts of a long boneEpiphyses are the ends of the bones, and are covered with articular cartilage and articulate with other bones.The shaft of a bone is called the diaphysis.
12 Structures of a Long Bone PeriosteumOutside covering of the diaphysisFibrous connective tissue membraneArteriesSupply bone cells with nutrientsExcept for the articular cartilage, a bone is covered by a periosteum.The diaphysis contains a medullary cavity filled with marrow.
13 Structures of a Long Bone Articular cartilageCovers the external surface of the epiphysesMade of hyaline cartilageDecreases friction at joint surfaces
14 Structures of a Long Bone Medullary cavityCavity of the shaftContains yellow marrow (mostly fat) in adultsContains red marrow (for blood cell formation) in infants
15 Bone GrowthEpiphyseal plates allow for growth of long bone during childhoodNew cartilage is continuously formedOlder cartilage becomes ossifiedCartilage is broken downBone replaces cartilage
16 Bone Growth Bones are remodeled and lengthened until growth stops Bones change shape somewhatBones grow in width
20 The Axial Skeleton Forms the longitudinal part of the body Divided into three partsSkullVertebral columnBony thoraxThe axial skeleton consists of the skull, hyoid bone, vertebral column, and thoracic cage.
22 The Skull Two sets of bones Bones are joined by sutures CraniumFacial bonesBones are joined by suturesOnly the mandible is attached by a freely movable jointSkullThe skull consists of 22 bones, which include 8 cranial bones,13 facial bones, and 1 mandible.1. CraniumThe cranium encloses and protects the brain.Some cranial bones contain air-filled sinuses.Cranial bones include the frontal bone, parietal bones, occipital bone, temporal bones, sphenoid bone, and ethmoid bone.2. Facial skeletonFacial bones provide the basic shape of the face and attachments for muscles.Facial bones include the maxillary bones, palatine bones, zygomatic bones, lacrimal bones, nasal bones, vomer, inferior nasal conchae, and mandible.
23 The Vertebral Column Vertebrae separated by intervertebral discs The spine has a normal curvatureEach vertebrae is given a name according to its locationVertebral ColumnThe vertebral column extends from the skull to the pelvis and protects the spinal cord.It is composed of vertebrae, separated by intervertebral disks.It has four curvatures, which give it resiliency.
24 Structure of a Typical Vertebrae A typical vertebra consists of a body and a bony arch, which surrounds the spinal cord.Notches on the lower surfaces provide intervertebral foramina, through which spinal nerves pass.
25 The Bony Thorax Forms a cage to protect major organs Thoracic Cage The thoracic cage includes the ribs, thoracic vertebrae, sternum, and costal cartilages.It supports the shoulder girdle and arms, protects visceral organs, and functions in breathing.RibsThe ribs are attached to the thoracic vertebrae.The cartilages of the true ribs join the sternum directly; those of the false ribs join it indirectly.SternumIt articulates with the clavicles.
26 The Bony ThoraxMade-up of three partsSternumRibsThoracic vertebrae
30 The Pectoral (Shoulder) Girdle Composed of two bonesClavicle – collarboneScapula – shoulder bladeThese bones allow the upper limb to have exceptionally free movementPectoral GirdleThe pectoral girdle is composed of two clavicles and two scapulae.It forms an incomplete ring that supports the arms and provides attachments for muscles.
31 Bones of the Shoulder Girdle ClaviclesThey function to hold the shoulders in place and provide attachments for muscles.
32 Bones of the Shoulder Girdle ScapulaeThe scapulae are broad, triangular bones.They articulate with the humerus and provide attachments for muscles.
33 Bones of the Upper Limb The arm is formed by a single bone Humerus provide frameworks for arms, wrists, palms, and fingers.provide attachments for muscles and function in levers that move the limb and its parts.Humerus – bone of the upper arm
34 Bones of the Upper Limb The forearm has two bones Ulna Radius Radius – one of the bones of the lower armUlna – the other bone of the lower arm
35 Bones of the Upper Limb The hand Carpals – wrist Metacarpals – palm Phalanges – fingersHandThe hand is composed of a wrist, palm, and 5 fingers.It includes carpals, metacarpals, and phalanges.
36 Bones of the Pelvic Girdle Hip bones – Coxal BonesComposed of three pair of fused bonesThe total weight of the upper body rests on the pelvisProtects several organsReproductive organsUrinary bladderPart of the large intestinePelvic GirdleThe pelvic girdle consists of two coxal bones that articulate with each other anteriorly and with the sacrum posteriorly.
37 The Pelvis The sacrum, coccyx, and pelvic girdle form the pelvis. Figure 5.23a
38 The PelvisCoxal bonesEach coxal bone consists of three bones, which are fusedThe iliumThe ischiumThe pubisFigure 5.23b
39 Gender Differences of the Pelvis The ilium – female pelvis is largerThe ischium – inlet on female largerThe pubis – pubic arch is greater than 90◦ on femaleFigure 5.23c
40 Bones of the Lower Limbs The thigh has one boneFemur – thigh boneLower LimbBones of the lower limb provide frameworks for the leg, ankle, instep, and toes.FemurThe femur extends from the knee to the hip.The patella articulates with its anterior surface
41 Bones of the Lower Limbs The leg has two bonesTibiaFibulaTibiaThe tibia is located on the medial side of the lower leg.It articulates with the talus of the ankle.FibulaThe fibula is located on the lateral side of the tibia.It articulates with the ankle, but does not bear body weight.
42 Bones of the Lower Limbs The footTarsus – ankleMetatarsals – solePhalanges – toesFootThe foot consists of an ankle, instep, and 5 toes.It includes tarsals that form the tarsus, metatarsals, and phalanges.