Chapter 7 The Skeleton Flashcards
What Skeletal System includes?
- includes bones, cartilage and ligaments
* framework that help maintain body shape and allow movement
Bones of Skeleton
- approximately 206 bones in adult skeleton
* two major sub-divisions: axial and appendicular skeleton
Axial Skeleton
- 3 major regions: skull, vertebral column and thoracic cage
* protect brain and spinal cord and vital organs within the thorax
Axial Skeleton: Skull
o contains 22 separate bones – cranial and facial bones
o cranium - protects brain
o houses special sense organs for vision, hearing, smell, equilibrium and taste
o calvaria (cranial vault) = top of the skull (skull cap)
o cranial base = skull inferior aspect
o mandible detaches readily from rest of the skull
o brain sits in cranial cavity, has ear, nasal and oral cavities, and orbits (Fig. 7.3)
Name the 8 Cranium bones?
o Frontal bone most anterior o Parietal bones (2) in middle o Occipital bone posteriorly located o Temporal bones (2) o Sphenoid bone o Ethmoid bone
Cranium: Frontal bone
Frontal bone most anterior
* joined to parietal bones by coronal suture * forms the supraorbital margins * contains the frontal sinuses
Cranium: Parietal bones
Parietal bones (2) in middle
* two halves joined together at sagittal suture * form most of the superior and lateral aspects of the skull
Cranium: Occipital bone
Occipital bone posteriorly located
*joined to parietal bones by lamboid suture
*external occipital protuberance – median protrusion
• site of attachment of ligamentum nuchae – elastic ligament that attaches the vertebrae of the neck to the skull and for several neck muscles
*foramen magnum = large hole where medulla oblongata (inferior portion of brain) connects with spinal cord
*occipital condyles – found on each side of foramen magnum and articulate with first cervical vertebrae
Cranium: Temporal bones
- Lateral portion of skull
- joined to parietal bone by squamous suture
- external acoustic meatus (canal) – transmits sound waves toward tympanic membrane of ear
- mastoid process –projection of bone filled with air cavities that connect to middle ear
- zygomatic process (anterior projecting) of the temporal bone joins with the temporal process of zygomatic bone to form zygomatic arch
Cranium: Sphenoid bone
o Sphenoid bone – forms interior middle floor of cranium
* articulates with all other cranial bones * contains sphenoidal sinuses * sella tursica – snug enclosure for the pituitary gland * optic canal and superior orbital fissure – passageway for nerves - from eye and to muscles of eye
Cranium: Ethmoid bone
- Ethmoid bone – anterior to sphenoid bone in floor of cranium
- articulates with nasal bones of face
- cribriform plates = located on superior surface - has tiny holes that allow filaments of the olfactory nerve to pass into brain
- lateral masses contain ethmoidal air cells (sinuses)
Cranium: Facial Bones
Facial bones (14 bones) all paired except mandible and vomer bones o Mandible o Maxilla o Zygomatic bones o Nasal bones o Lacrimal bones o Palatine bones o Vomer o Inferior Nasal Conchae o orbits o nasal cavity o paranasal sinuses
Cranium - Facial Bones: Mandible
- Lower jaw – inferior to maxilla and articulates posteriorly with temporal bone
- condylar process – articulates with mandibular fossa of temporal bone
- coronoid process – attachment point for temporalis muscle
- alveolar process – contains inferior set of teeth
Cranium - Facial Bones: Maxilla
- Upper jaw – fused medially
- articulates with all facial bones except the mandible
- alveolar process – contains superior set of teeth
- maxillary sinuses – on either side of the nasal cavity
Cranium - Facial Bones: Zygomatic bones
cheek bones
Cranium - Facial Bones: Nasal bones
Fused medially and form bridge of nose
Cranium - Facial Bones: Lacrimal bones
Form part of the medial wall of the orbit
Cranium - Facial Bones: Palatine bones
Fused medially – forms posterior part of hard palate and part of the wall of the nasal cavity
Cranium - Facial Bones: Vomer
Forms nasal septum
Cranium - Facial Bones: Inferior Nasal Conchae
- Project medially from lateral walls of nasal cavity
* increase air turbulence of inspired air
Cranium - Facial Bones: orbits
- Cone-shaped fossas
- protect eyes, cushioned by fatty tissue, and has attachment points for muscles that rotate them
- wall formed by parts of seven bones
Cranium - Facial Bones: nasal cavity
- Pear-shaped opening anteriorly in mid-line of face
* constructed of bone and hyaline cartilage
Cranium - Facial Bones: paranasal sinuses
- Several bones of the face with mucosa-lined air-filled cavities that open into the nasal cavity
- located within frontal, sphenoid, ethmoid and maxillary bones
- act as resonance chambers during voice production
- warm and humidify inspired air
Hyoid Bone
Hyoid Bone – not part of the adult skull
* only bone in the body that does not articulate with another bone * anterior and superior aspect of neck just below the mandible * attachment point of tongue and neck muscles that elevate the larynx during speech and swallowing
Axial Skeleton: Vertebral Column general functions
26 bones - vertebrae
* supports weight of head and trunk * protects spinal cord * site for rib and muscle attachment * anterior and posterior ligaments, support vertebral column
Axial Skeleton: Features of Vertebrae
- Regional differences but all have:
- body = bony disk that is weight-bearing portion
- vertebral arch – projects posteriorly from body
- vertebral foramen = large opening surrounded by arch and together with foramina of other vertebrae forms vertebral canal – contains the spinal cord and cauda equine
- transverse process extends laterally from each side of the arch
- spinous process extends posteriorly from the arch
Axial Skeleton - Vertebral column: Intervertebral discs
- fibrocartilage – located between bodies of adjacent vertebrae
- have external annulus fibrosus and internal gelatinous nucleus pulposus
- Provide additional support and prevent vertebral bodies from rubbing against each other
- compress with age so distance between vertebrae decreases – overall height of individual decreases, and more prone to herniation
Axial Skeleton - Vertebral column: Herniated disc
- Rupture of the annulus fibrosus and protrusion of nucleus pulposa through the annulus
- if presses on spinal cord or on spinal nerves existing cord – produces numbness and pain
- treated with moderate exercise, massage, heat therapy and painkillers
- surgical treatment = removal of disc and bone graft to fuse adjoining vertebrae
Vertebral Column Regions:
- Has 5 regions and four major curvatures
- Cervical region – concave
- Thoracic region – convex
- Lumbar region – concave
- Sacral and coccygeal regions
Vertebral Column Regions: Cervical
Cervical region – concave
7 cervical vertebrae (C1-C7)
whiplash = traumatic hyperextension of the cervical vertebrae
-May result in fracture of spinous processes or herniated disc putting posterior pressure on spinal cord, spinal nerves, muscles, tendons and ligaments
Vertebral Column Regions: Thoracic
*Thoracic region – convex
12 thoracic vertebrae (T1-T12)
Vertebral Column Regions: Lumbar
Lumbar region – concave
5 lumbar vertebrae (L1-L5)
Vertebral Column Regions: Sacral and coccygeal bone
Sacral and coccygeal regions – together convex
1 sacrum – adult = 5 fused sacral vertebrae from developing embryo
1 coccygeal bone – adult = 4-5 fused coccygeal vertebrae
Abnormal spinal curvatures – due to disease or congenital defect : Kyphosis
- Kyphosis = exaggerated concave curvature of thoracic region
- most common in post-menopausal women (“dowager’s hump”)
Abnormal spinal curvatures – due to disease or congenital defect : Lordosis
- Lordosis = exaggeration of convex curve of lumbar region
* seen in pregnant women, those with pot-bellies
Abnormal spinal curvatures – due to disease or congenital defect : Scoliosis
- Scoliosis = “twisted” - lateral and rotational curvature of the vertebral column
- more common in girls in late childhood
- treated with body braces or surgically to prevent permanent deformity and breathing difficulties
Axial Skeleton - Thoracic Cage
-Semi-rigid chamber that protects vital organs in thorax
= thoracic vertebrae, ribs and associated costal cartilages and sternum
*increases and decreases in volume during respiration
Parts:
*Articulate with the thoracic vertebrae (12 pairs of ribs)
*true ribs (7 pairs) – attach directly via their costal cartilages to the sternum
* false ribs (5 pairs)
- floating ribs
*sternum
Thoracic Cage: Articulate with the thoracic vertebrae
12 pairs of ribs - articulate with the thoracic vertebrae
* head – articulates with bodies of two adjacent vertebrae
* tubercle – articulates with transverse process of inferior vertebra
* body (shaft) = main part of rib,
- angle = point of greatest curvature and weakest point that can be fractured in crushing injury
- sternal end = attaches to costal cartilage
Thoracic Cage: True ribs
-True ribs (7 pairs) – attach directly via their costal cartilages to the sternum
Thoracic Cage: False ribs
- False ribs (5 pairs) – 8th, 9th, 10th attach by common cartilage to the seventh ribs
- floating ribs – 11th and 12th do not attach to sternum
Thoracic Cage: Sternum
-Sternum – has three parts:
*manubrium – most cranial portion - articulates with clavicle and 1st rib
• jugular notch – located on superior margin and easily palpated
• sternal angle –prominence where inferior margin of manubrium and body of sternum meet (2nd rib attaches here)
* body – middle portion * xiphoid process - most caudal portion and no ribs attach here
Appendicular Skeleton
Appendicular Skeleton = bones of upper limbs, lower limbs and pectoral and pelvic girdles
Appendicular Skeleton is divided?
- Pectoral Girdle and Upper Limb (Arm, Forearm and Hand)
- Pelvic Girdle and Lower Limb (Thigh, Leg, Foot)
- bones generally thicker, longer and heavier than upper limb
Appendicular Skeleton: Pectoral Girdle
scapula and clavicle
* calvicle (collar bone) ventrally located long bone with slight sigmoid (s-shaped) curve
* scapula (shoulder blade) – dorsally located
- Glenoid cavity – cranially located on lateral surface – articulates with head of humerous
Appendicular Skeleton: Arm
Arm = upper limb from shoulder to elbow
- Humerus – only bone of arm
* distal end articulates
- laterally with radius
- medially with ulna
Appendicular Skeleton: Forearm
- ulna – on medial side of forearm
- radius – on lateral side (thumb-side) of forearm
- Colles fracture = common fracture distal end of radius when person falls and attempts to break fall with outstretched hands - articulate with each other proximally and distally
- connected along entire length by interosseous membrane
- radius – on lateral side (thumb-side) of forearm
Appendicular Skeleton: Hand
*Carpus (Wrist)
Carpals bones (8) = two rows of four bones
Carpal tunnel – formed by at ligament that stretches across the anterior surface of the carpals bones
-tendons, nerves and blood vessels pass through tunnel to enter the hand
-carpal tunnel syndrome – edema or connective tissue deposition within carpal tunnel resulting in tingling, burning and numbness of the hand
*Metacarpus (Palm)
Metacarpals – numbered 1-5 from lateral (thumb side) to medial
*Phalanges (Fingers)
Phalanges (14) that make up the digits – thumb (2) and 4 fingers (3)
Appendicular Skeleton: Hand
*Carpus (Wrist)
Carpal tunnel
*Metacarpus (Palm)
*Phalanges (Fingers)
Appendicular Skeleton: Pelvic Girdle
Pelvic Girdle – right and left coxal bones and sacrum
* coxal bones – right and left halves join anteriorly to each other at the pubis and posteriorly with sacrum - formed from the fusion of three bones: ilium, ishium and pubis - acetabulum = deep hemispherical socket on lateral surface
Appendicular Skeleton: Thigh
Thigh
* Femur (Fig. 7.33) = the only bone
* proximal end articulates with acetabulum of coxal bone
* distal end articulates with tibia
- patellar surface – articulates with patella
*patella = large sesamoid bone located within the tendon of the quadriceps femoris muscle group
Appendicular Skeleton: Leg
- Lower limb between the knee and ankle
- tibia – larger bone and supports most of the weight of the leg
- medial malleolus – forms medial side of ankle joint
- fibula – does not articulate with femur - articulates with the tibia
- lateral malleolus - forms lateral side of ankle joint
- Potts fracture – distal end of fibula, tibia, or both
Appendicular Skeleton: Foot
Foot – tarsal bones, metatarsal bones, phalanges
o *tarsal bones (7) – proximal bones of foot – larger than carpal bones of wrist
-talus – articulates with tibia and fibula to form ankle joint
-calcaneous = largest and strongest bone of the foot = heel
*metatarsals (5) – form the dorsal and plantar surfaces of the foot * phalanges (14) – arranged in similar manner to phalanges of hand * three major arches distribute weight between ball and heel of foot during standing and walking - higher on the medial side than the lateral side
Developmental Aspects of Skeleton
- Fontanelles = unossified remnants of fibrous membranes between skull bones
- anterior fontanelle = largest (between frontal and parietal bones) ossifies by about 2 years of age
- Spinal curvatures
- C-shaped as newborn and other curvatures develop as baby starts to lift head then walk
Developmental Aspects of Skeleton: Congenital Abnormalities
Congenital abnormalities
* cleft palate – occurs when palantine processes of maxillary bones don’t fuse with one another - produces opening between oral and nasal cavities making it difficult to eat, drink or speak * dysplasia of hip (1%) of infants – acetabulum incompletely formed or ligaments of hip are loose - head of femur slips out of socket - treatment by split or harness to hold femur in place or surgery to tighten ligaments
