PPT Notes Chapter 7 Flashcards
The Skull
Two sets of bones
Cranial bones
- Enclose the brain in the cranial cavity
- Cranial vault (calvaria)
- Cranial base: anterior, middle, and posterior cranial fossae
- Provide sites of attachment for head and neck muscles
Facial bones
- Framework of face
- Cavities for special sense organs for sight, taste, and smell
- Openings for air and food passage
- Sites of attachment for teeth and muscles of facial expression
Cranial Bones
- Frontal bone
- Parietal bones (2)
- Occipital bone
- Temporal bones (2)
- Sphenoid bone
- Ethmoid bone
- Difference between zygomatic process of temporal bone and the zygomatic bone
- Alveolar margin - where tooth and mandible meet
Frontal Bone
- Anterior portion of cranium
- Most of anterior cranial fossa
- Superior wall of orbits
- Contains air-filled frontal sinus
Parietal Bones and Major Associated Sutures
Superior and lateral aspects of cranial vault
Four sutures mark the articulations of parietal bones with frontal, occipital, and temporal bones:
- Coronal suture—between parietal bones and frontal bone
- Sagittal suture—between right and left parietal bones
- Lambdoid suture—between parietal bones and occipital bone
- Squamous (squamosal) sutures—between parietal and temporal bones on each side of skull
Occipital Bone
- Most of skull’s posterior wall and posterior cranial fossa
- Articulates with 1st vertebra
- Sites of attachment for the ligamentum nuchae and many neck and back muscles
Temporal Bones
Inferolateral aspects of skull and parts of cranial floor
Four major regions:
- Squamous
- Tympanic
- Mastoid
- Petrous
Sphenoid Bone
Complex, bat-shaped bone
Keystone bone
Articulates with all other cranial bones
Three pairs of processes:
- Greater wings
- Lesser wings
- Pterygoid processes - sharp protuberence at roof of mouth
Ethmoid Bone
- Deepest skull bone
- Superior part of nasal septum, roof of nasal cavities
- Contributes to medial wall of orbits
Sutural Bones
Tiny irregularly shaped bones that appear within sutures
Facial Bones
- Mandible
- Maxillary bones (maxillae) (2)
- Zygomatic bones (2)
- Nasal bones (2)
- Lacrimal bones (2)
- Palatine bones (2)
- Vomer
- Inferior nasal conchae (2)
Mandible
- Lower jaw
- Largest, strongest bone of face
- Temporomandibular joint: only freely movable joint in skull
Maxillary Bones
- Medially fused to form upper jaw and central portion of facial skeleton
- Keystone bones
- Articulate with all other facial bones except mandible
Zygomatic Bones
- Cheekbones
- Inferolateral margins of orbits
Nasal Bones and Lacrimal Bones
- Nasal bones
- Form bridge of nose
- Lacrimal bones
- In medial walls of orbits
- Lacrimal fossa houses lacrimal sac
- In medial walls of orbits
Palatine Bones and Vomer
- Palatine bones
- Posterior one-third of hard palate
- Posterolateral walls of the nasal cavity
- Small part of the orbits
- Vomer
- Plow shaped
- Lower part of nasal septum
Inferior Nasal Conchae
Form part of lateral walls of nasal cavity
Orbits
- Encase eyes and lacrimal glands
- Sites of attachment for eye muscles
- Formed by parts of seven bones
Nasal Cavity
Roof, lateral walls, and floor formed by parts of four bones
- Ethmoid
- Palatine bones
- Maxillary bones
- Inferior nasal conchae
Nasal septum of bone and hyaline cartilage
Ethmoid
Vomer
Anterior septal cartilage
Paranasal Sinuses
- Mucosa-lined, air-filled spaces
- Lighten the skull
- Enhance resonance of voice
- Found in frontal, sphenoid, ethmoid, and maxillary bones
Hyoid Bone
- Not a bone of the skull
- Does not articulate directly with another bone
- Site of attachment for muscles of swallowing and speech
Vertebral Column
- Transmits weight of trunk to lower limbs
- Surrounds and protects spinal cord
- Flexible curved structure containing 26 irregular bones (vertebrae)
- Cervical vertebrae (7)—vertebrae of the neck
- Thoracic vertebrae (12)—vertebrae of the thoracic cage
- Lumbar vertebrae (5)—vertebra of the lower back
- Sacrum—bone inferior to the lumbar vertebrae
- Coccyx—terminus of vertebral column
Vertebral Column: Curvatures
Increase the resilience and flexibility of the spine
- Two posteriorly concave curvatures
- Cervical and lumbar
- Two posteriorly convex curvatures
- Thoracic and sacral
Abnormal spine curvatures
Scoliosis (abnormal lateral curve)
Kyphosis (hunchback)
Lordosis (swayback)
Ligaments
- Anterior and posterior longitudinal ligaments
- From neck to sacrum
- Ligamentum flavum
- Connects adjacent vertebrae
- Short ligaments
- Connect each vertebra to those above and below
Intervertebral Discs
Cushionlike pad composed of two parts
- Nucleus pulposus
- Inner gelatinous nucleus that gives the disc its elasticity and compressibility
- Anulus fibrosus
- Outer collar composed of collagen and fibrocartilage
General Structure of Vertebrae
- Body or centrum
- Anterior weight-bearing region
- Vertebral arch
- Composed of pedicles and laminae that, along with centrum, enclose vertebral foramen
- Vertebral foramina
- Together make up vertebral canal for spinal cord
- Intervertebral foramina
- Lateral openings between adjacent vertebrae for spinal nerves
Seven processes per vertebra:
- Spinous process—projects posteriorly
- Transverse processes (2)—project laterally
- Superior articular processes (2)—protrude superiorly inferiorly
- Inferior articular processes (2)—protrude inferiorly
Cervical Vertebrae
- C1 to C7: smallest, lightest vertebrae
- C3 to C7 share the following features
- Oval body
- Spinous processes are bifid (except C7)
- Large, triangular vertebral foramen
- Transverse foramen in each transverse process
C1 (atlas) and C2 (axis) have unique features
Atlas (C1)
- No body or spinous process
- Consists of anterior and posterior arches, and two lateral masses
- Superior surfaces of lateral masses articulate with the occipital condyles
Axis (C2)
- Dens - odontoid process
- Dens projects superiorly into the anterior arch of the atlas
- Dens is a pivot for the rotation of the atlas
Thoracic Vertebrae
T1 to T12
- All articulate with ribs at facets and demifacets
- Long spinous process
- Location of articular facets allows rotation of this area of spine
Lumbar Vertebrae
L1 to L5
- Short, thick pedicles and laminae
- Flat hatchet-shaped spinous processes
- Orientation of articular facets locks lumbar vertebrae together so as to prevent rotation
Sacrum and Coccyx
Sacrum
5 fused vertebrae (S1–S5)
Forms posterior wall of pelvis
Articulates with L5 superiorly, and with auricular surfaces of the hip bones laterally
Coccyx
- Tailbone 3–5 fused vertebrae
- Articulates superiorly with sacrum
Thoracic Cage
Composed of
Thoracic vertebrae
Sternum
Ribs and their costal cartilages
Functions
- Protects vital organs of thoracic cavity
- Supports shoulder girdle and upper limbs
- Provides attachment sites for many muscles, including intercostal muscles used during breathing
Sternum (Breastbone)
Three fused bones
- Manubrium
- Articulates with clavicles and ribs 1 and 2
- Body
- Articulates with costal cartilages of ribs 2 through 7
- Xiphoid process
- Site of muscle attachment
- Not ossified until ~ age 40
Ribs and Their Attachments
12 pairs
- All attach posteriorly to thoracic vertebrae
- Pairs 1 through 7
True (vertebrosternal) ribs
Attach directly to the sternum by individual costal cartilages
Pairs 8 through12
False ribs
Pairs 8–10 also called vertebrochondral ribs
Attach indirectly to sternum by joining costal cartilage of rib above
Pairs 11–12 also called vertebral (floating) ribs
No attachment to sternum
Structure of a Typical Rib
Main parts:
- Head
- Articulates posteriorly with facets (demifacets) on bodies of two adjacent vertebrae
- Neck
- Tubercle
- Articulates posteriorly with transverse costal facet of same-numbered thoracic vertebra
- Shaft
Appendicular Skeleton
Bones of the limbs and their girdles
- Pectoral girdle attaches the upper limbs to the body trunk
- Pelvic girdle secures the lower limbs
Pectoral Girdle (Shoulder Girdle)
Clavicles and the scapulae
- Attach the upper limbs to the axial skeleton
- Provide attachment sites for muscles that move the upper limbs
Clavicles (Collarbones)
- Flattened acromial (lateral) end articulates with the scapula
- Cone-shaped sternal (medial) end articulates with the sternum
- Act as braces to hold the scapulae and arms out laterally
Scapulae (Shoulder Blades)
- Situated on the dorsal surface of rib cage, between ribs 2 and 7
- Flat and triangular, with three borders and three angles
- Seven large fossae, named according to location
The Upper Limb
30 bones form the skeletal framework of each upper limb
- Arm
- Humerus
- Forearm
- Radius and ulna
Hand
- 8 carpal bones in the wrist
- 5 metacarpal bones in the palm
- 14 phalanges in the fingers
Upper bones have both condyles and epicondyles
Humerus
- Largest, longest bone of upper limb
- Articulates superiorly with glenoid cavity of scapula
- Articulates inferiorly with radius and ulna
Trochlea
- distal end of humerus that articulates with ulna
Capitula
- distal end of humerus that articulates with another bone
Bones of the Forearm
Ulna
- Medial bone in forearm
- Forms the major portion of the elbow joint with the humerus
Radius
Lateral bone in forearm
Head articulates with capitulum of humerus and with radial notch of ulna
Interosseous membrane connects the radius and ulna along their entire length
Hand: Carpus
Eight bones in two rows
- Proximal row
- Scaphoid, lunate, triquetrum, and pisiform proximally
- Distal row
- Trapezium, trapezoid, capitate, and hamate distally
- Only scaphoid and lunate articulate with radius to form wrist joint
Hand: Metacarpus and Phalanges
Metacarpus
Five metacarpal bones (#1 to #5) form the palm
Phalanges
- Each finger (digit), except the thumb, has three phalanges—distal, middle, and proximal
- Fingers are numbered 1–5, beginning with the thumb (pollex)
- Thumb has no middle phalanx
Pelvic (Hip) Girdle
- Two hip bones (each also called coxal bone or os coxae)
- Attach the lower limbs to the axial skeleton with strong ligaments
- Transmit weight of upper body to lower limbs
- Support pelvic organs
- Each hip bone consists of three fused bones: ilium, ischium, and pubis
- Together with the sacrum and the coccyx, these bones form the bony pelvis
Hip Bone
Three regions
- Ilium
- Superior region of the coxal bone
- Auricular surface articulates with the sacrum (sacroiliac joint)
- Ischium
- Posteroinferior part of hip bone
- Pubis
- Anterior portion of hip bone
- Midline pubic symphysis joint
Comparison of Male and Female Pelves
Female pelvis
- Adapted for childbearing
- True pelvis (inferior to pelvic brim) defines birth canal
- Cavity of the true pelvis is broad, shallow, and has greater capacity
Male pelvis
- Tilted less forward
- Adapted for support of male’s heavier build and stronger muscles
- Cavity of true pelvis is narrow and deep
The Lower Limb
- Carries the weight of the body
- Subjected to exceptional forces
- Three segments of the lower limb
- Thigh: femur
- Leg: tibia and fibula
- Foot: 7 tarsal bones in the ankle, 5 metatarsal bones in the metatarsus, and 14 phalanges in the toes
Lower bones only have condyles
Femur
- Largest and strongest bone in the body
- Articulates proximally with the acetabulum of the hip and distally with the tibia and patella
Bones of the Leg
Tibia
- Medial leg bone
- Receives the weight of the body from the femur and transmits it to the foot
Fibula
Not weight bearing; no articulation with femur
Site of muscle attachment
Connected to tibia by interosseous membrane
Articulates with tibia via proximal and distal tibiofibular joints
Foot: Tarsals
- Seven tarsal bones form the posterior half of the foot
- Talus transfers most of the weight from the tibia to the calcaneus
- Other tarsal bones: cuboid, navicular, and the medial, intermediate, and lateral cuneiforms
Foot: Metatarsals and Phalanges
Metatarsals:
Five metatarsal bones (#1 to #5)
Enlarged head of metatarsal 1 forms the “ball of the foot”
Phalanges
- The 14 bones of the toes
- Each digit (except the hallux) has three phalanges
- Hallux has no middle phalanx
Arches of the Foot
- Arches are maintained by interlocking foot bones, ligaments, and tendons
- Arches allow the foot to bear weight
Three arches
- Lateral longitudinal
- Medial longitudinal
- Transverse