The Axial and Appendicular Skeletons

Chapter 7 and 8

Objectives

• Be able to differentiate between the axial and appendicular skeleton

• Be able to describe and recognize the bones of the axial and appendicular skeletons

• Know the terminology indicative of the various bone features that will be studied

The Skeletal System

• Divided into:– Axial• Axis of the body

– Skull, vertebrae, sternum and rib cage

– Appendicular• Appendages

– Pectoral and pelvic girdles, arms and legs aclasta.co.nz

Articulations

• Condyle – rounded knob that articulates with another bone

• Facet – smooth flat, slightly concave or convex surface

• Head – prominent expanded end of the bone, maybe rounded

Extensions and Projections• Epicondyle – projection superior to a condyle

• Lines – slightly raised, elongated ridge

• Process – bony prominence

• Protuberance – bony outgrowth

• Spine – Sharp, slender, or narrow process

• Trochanter – two large processes associated with femur

• Tubercle – small rounded process

• Tuberosity – rough elevated surface

Depressions

• Alveolus – socket

• Fossa – shallow, broad, or elongated basin

• Fovea – small pit

• Sulcus – groove for blood vessel, nerve, or tendon

Passages and Cavities

• Canal – tunnel in a bone

• Foramen – hole through bone

• Fissure – slit through a bone

• Meatus – opening into canal

• Sinus – air-filled space in bone

Skull• Composed of 22 bones– Cranial

• Direct contact with meninges and brain – Facial

• No contact with meninges or brain

• Most articulate at sutures– Coronal, sagittal, squamous, lambdoid

– Contains various cavities and sinuses• Cranial, orbits, nasal, oral• Frontal, sphenoid, ethmoid, maxillary

Cranial Bones• Cranium composed of 8 bones

– Frontal, parietal (2), temporal (2), occipital, sphenoid, ethmoid

– Temporal bone• Mastoid and styloid processes• Stylomastoid and mastoid foramen

– Occipital• Foramen magnum, occipital condyles, hypoglossal canal, external occipital protuberance

and nuchal line

– Sphenoid• Superior orbital fissure and optic foramen• Sella turcica – hypophyseal fossa• Foramen rotundum and ovale – nerve passage• Foramen spinosum – blood vessel passage

– Ethmoid• Contributes to medial wall of orbit, roof and walls of nasal cavity, and nasal septum• Crista galli, cribiform plate and cribiform foramen• Perpendicular plate and middle nasal conchae• Ethmoid sinus

Facial Bones• Give shape to face and hold teeth

– Form parts of nasal and orbital cavities, provide sites for muscle attachment

– 14 bones• (2 each) maxillae, nasal, palatine, inf. nasal conchae, zygomatic,

lacrimal• (1 each) vomer, mandible

– Maxillae• Alveolar processes and alveolus• Infraorbital foramen – blood vessel and nerve passage

– Mandible• Strongest bone of skull, develops as two bones• Mental protuberance, body, angle, ramus• Coronoid process, mandibular notch, condylar process• Mental foramen and mandibular foramen – blood vessels and nerves

Bones Associated with Skull

• Auditory ossicles– Malleus, incus, and stapes

• Hyoid– U-shaped bone between chin and larynx– Does not articulate with any other bone– Attached to styloid process – Body, lesser and greater horns

Skull: Infancy and Childhood

• Skull bone are not yet fused

• Fontanels – spaces between cranial bones– Anterior, posterior, sphenoid, mastoid

• Frontal and mandible are two separate halves at birth

• Skull grows more rapidly than rest of skeleton

Vertebral Column• Functions

– Support, protection of spinal cord, shock absorption

• Composed of 33 vertebrae– 7 cervical– 12 thoracic– 5 lumbar– 5 sacral– 4 coccygeal

• Slight S-shape with four bends– Cervical, thoracic, lumbar, and pelvic

• Intervertebral discs– Core of gelatinous nucleus pulposus surrounded by a fibrocartilage

ring, anulus fibrosus– 23 discs, start between C2 and C3, end between L5 and sacrum

Cervical Vertebrae

• Cervical– Atlas and axis, C1 and C2– C2 – C6 have a bifurcated

spinous process– C7 spinous process long • Vertebral prominens

– All cervical vertebrae have transverse foramen• Blood vessels

physioweb.org

Thoracic Vertebrae

• 12 thoracic vertebrae

• Spinous processes are more pointed and angled down

• Body of all T vertebrae contain costal facets

• Transverse process of T1 – T10 contain transverse costal facets

spineuniverse.com

Lumbar, Sacral, Coccyx

• Lumbar– Large prominent bodies and blunt square spinous

process

• Sacral– Bones fuse by third decade of life– Median sacral crest and lateral sacral crest– Sacral foramina – passage of nerves and blood vessels

• Coccyx

Thoracic cage

• Consists of the thoracic vertebrae, sternum, and ribs

• Encloses the heart and lung and provides attachment for the pectoral girdle– Costal margin – downward arc of ribs

Thoracic Cage• Sternum

– Bony plate anterior to heart – Three regions

• Manubrium, gladiolus (body), xiphoid process

• Ribs– Attached proximally to the vertebrae, distally to the sternum via

costal cartilage– Head, neck , tubercle– Shaft – where rib flattens and widens– Angle – curve– Costal groove – inferior margin of rib, blood vessels and nerves– True ribs 1-7, direct connection to sternum– False ribs 8-12, no direct connection

• 11-12 floating ribs

Disorders of the Axial Skeleton• Cleft Palate– Right and left halves of palate fail to join– Results in no separation of oral and nasal cavities

• Stenosis of lumbar spine

• Abnormal Spinal curvatures– Scoliosis– Kyphosis– Lordosis

Pectoral Girdle• Supports the arm

– Consists of two bones on each side of body• Clavicle and scapula

• Clavicle– S-shaped bone– Sternal and acromial ends

• sternoclavicular and acromioclavicular joints• Conoid tubercle – attachment of ligament, acromial end

• Scapula– Flat, triangular bone that lies posterior to the ribs– Three sides: superior, medial, and lateral borders

• Angles: superior, medial, and lateral– Subscapular fossa – broad anterior surface– Spine – transverse ridge on posterior surface

• Suprasinous fossa and infraspinous fossa– Acromion process

• Apex of shoulder, articulates with clavicle– Coracoid process– Glenoid cavity

abcopro.com

Upper Limb• Divided into four regions, 30 bones per limb

• Brachium– Shoulder to elbow, arm proper– Humerus

• Antebrachium– Elbow to wrist– Radius and ulna

• Carpus– Wrist– Proximal row, thumb side: scaphoid, lunate, triquetrium, pisiform– Distal row, thumb side: trapezium, trapezoid, capitate, hamate

• Manus– Hand– 5 metacarpals

• Proximall– base, body, head– 14 phalanges

• 2 in pollex, 3 in other digits

cliffsnotes.com

Humerus

rci.rutgers.edu

Ulna and Radius

rci.rutgers.edu

Pelvic Girdle• Consists of three bones

– Sacrum, 2 coxal bones (hip bones)

• Three distinctive features– Iliac crest– Acetabulum– Obturator foramen

• Hip bones– Fusion of three bones

• Ilium– Anterior and posterior superior spines– Anterior and posterior inferior spines– Greater sciatic notch– Iliac fossa

• Ischium– Ischial tuberosity

• Pubis– Superior and inferior ramus– Pubic symphysis

cliffsnotes.com

Lower Limb• Divide into 4 regions, 30 bones per limb

• Femoral region– Thigh, extends from hip to knee– Femur

• Crural region– Leg proper, extend from knee to ankle– Tibia (medial) and fibula (lateral)

• Tarsal region– Ankle– Union of crural region with foot

• Pedal region– Foot– 7 tarsal bones

• Proximal row hallux side: navicular, tallus, calcaneous• Distal row hallux side: medial, intermediate, lateral cuniform, cuboid

– 5 metatarsals – 14 phalanges

• Hallux contains only two bones, all other toes contain three

cliffsnotes.com

Femur

gmchyderabad.blogspot.com

Tibia and Fibula

edoctoronline.com