Axial Skeleton

Friday, December 2nd

Skull Bones Review

Mental Foramen

The Teeth• Human teeth show a morphology mainly

differentiated by :– 1. The shape of their upper surface = crown– 2. The number of tooth roots– 3. The purpose of each tooth type

• Cutting• Shredding• Grinding

The Teeth

The Teeth• Incisors

– Cutting teeth– 8 incisors– Very front of the mouth– Rather flat surfaces– A straight sharp horizontal edge for cutting

and biting– 1 long conical root

The Teeth• Canines

– 4– Very strong, pointed

corner teeth– Used for tearing and shredding– Larger and stronger than the incisors– 1 single root– Upper canines are sometimes called

“eyeteeth”

The Teeth• Premolars

– 8– Used for chewing foot– Placed lateral to and behind the canine

teeth– Flat upper surface– 1-2 roots– Crown has 2 cusps

The Teeth• Molars

– 12 – Back of the mouth– Large and flat upper surface– 2-4 roots– Largest of the permanent teeth– Used for final chewing and grinding before

swallowing– 3rd molars = Wisdom teeth

The Auditory Ossicles• 3 smallest bones in the body• Ossicles mean “tiny bones”• Contained within the middle ear space • Serve to transmit sounds from the air

• In order from the eardrum to the inner ear (superficial to deep)– 1. Malleus– 2. Incus– 3. Stapes

The Auditory Ossicles• Malleus – Hammer

– Articulates with the incus and is attached to the eardrum (or tympanic membrane)

• Incus – Anvil– Connected to the other ear bones

• Stapes – Stirrup– Articulates with the incus

The Auditory Ossicles

Malleus

Incus

The Auditory Ossicles

Stapes

The Auditory Ossicles

The Vertebral Column• Major Functions

– Cervical – Support the weight of the head and trunk

– Thoracic – Protect spinal cord

– Lumbar – Allow spinal nerves to exit spinal cord

– Sacral – Site for muscle attachment

The Vertebral Column• Abormalities

– Scoliosis• Lateral curvature of

spine (usually inchildren)

The Vertebral Column• Abormalities

– Lordosis• Exaggerated anterior curve of lumbar

spine (barrel chest)

The Vertebral Column• Abormalities

– Kyphosis• Exaggerated posterior curve of thoracic

spine (humpback)

The Vertebral Column• Each bone consists of:

– A body– An arch– Several processes

The Vertebral Column• Body

– Weight bearing portion

• Vertebral arch– Surround vertebral foramen– Formed from joining

laminae and pedicales

• Vertebral foramen– All form the vertebral canal =

spinal cord

The Vertebral Column• Transverse Process

– Extends laterally from each side of the arch between the pedicle and lamina

• 2 Laminae– Extend from

transverse processes to spinous process

The Vertebral Column• Articular Processes

– Where vertebrae articulates with each other

• Spinous Process– Extends dorsally from 2

laminae

The Vertebral Column• Intervertebral discs

– Dense fibrous connective tissue– Drying along with the weakening of ligaments of

the vertebral column• Predisposes older people to herniated discs –

slipped discs

The Vertebral Column• Cervical - 7

– 1st – Atlas• “Yes” motion• No body

– 2nd – Axis• “No” motion

The Vertebral Column• Cervical

– Small bodies– Each transverse process has transverse foramen

– Whiplash – hyperextension of the cervical vertebrae

The Vertebral Column

• Thoracic - 12–Long, thin spinous processes–Articulates with the ribs

The Vertebral Column• Lumbar - 5

– Large, thick bodies– Heavy rectangular transverse and spinous

processes– Sturdiest of the vertebrae

The Vertebral Column

• Sacrum– Alae – wings– Articulates with

the hip bones– 5 fused

vertebrae

The Vertebral Column

• Coccyx– Tailbone– Usually 4 fused

vertebrae– Very reduced

bodies– No foramina or

processes

The Bony Thorax• The Rib Cage

– Bony and cartilaginous structure– Supports the pectoral girdle– Provides attachments for the muscles of the neck,

thorax, upper abdomen and back– Consists of

• 24 ribs• The sternum• 12 thoracic vertebrae

The Bony Thorax• The rib parts:

– Head – end of the rib closest to the vertebral column

– Neck - is the flattened portion which extends lateralward

– Tubercle - articulates with the transverse process– Angle – bending portion

The Bony Thorax• Manubrium

– the broad, upper part of the sternum

– articulates with the clavicles and first 2 ribs

• Body– The lengthier and

narrow part of the sternum

– Below the manubrium

The Bony Thorax

• Xiphoid Process– Small cartilaginous

process of the lower sternum

– Ossified in adults

• Costal Cartilage– Bars of hyaline cartilage– Push ribs forward– Contribute to the

elasticity of the rib cage

The Bony Thorax• Vertebrosternal or “True Ribs”

– Upper 7 ribs– Attached to the sternum (costal cartilage)– Allow movement (breathing)

• False ribs– 5 sets of ribs below true ribs– Has no direct attachment to the sternum

The Bony Thorax• Vertebrocostal ribs

– Those ribs connected to the lower thoracic vertebrae with costal cartilage

– Ribs 7 or 8 down to rib 10

– Each rib is attached to the costal cartilage of the rib located superiorly to it (above it)

– AKA “False ribs” because their costal cartilage does not attach directly to the sternum