A & P Lecture ~ Exam #2 (good luck...)

What are the functions of the axial skeleton? (2)

1. Creates framework for support and protection of the brain, spinal cord, and organs in the ventral body cavity

2. Provides surface area for attachment of muscles that:

• Move the head, neck, and trunk

• Perform respiration

• Stabilize elements of appendicular skeleton

Skull. Protects? Houses? How many bones? How many of those bones are cranial bones? How many of those bones are facial bones?

Protects the brain

Houses brain and sense organs for sight, smell, taste, hearing, and balance

Made up of 22 bones

• 8 form the cranium

• 14 facial bones

What does the cranium enclose? What does the thing it encloses support?

Encloses cranial cavity, chamber supporting the brain

What are the other 2 bones associated with the skull? How many of each bone? What does each bone do:?

6 auditory ossicles

• Encased by temporal bone

• Involved with sound detection

Hyoid bone

• Connected to inferior skull by pair of ligaments

The frontal bone. Forms what? What are the 2 structures related to it?

Forms the forehead and the roof of the orbits, or eye sockets

2 structures:

1. Supraorbital foramen

2. Frontal sinsuses

Supraorbital foramen. What is it?

Forms a passageway above each orbit for blood vessels and nerves

Front sinuses. What is it? Lined with? Connect with what? Function?

Air-filled cavities above the orbits

Lined with mucous membrane

•Connect with the nasal cavity

Reduce weight of the bone

Parietal bones. Paired with? Form what? Articulate with? Interlock along what forming what?

Paired bones located posterior to frontal bone

Form the roof and superior walls of the cranium

Articulate with frontal bone along coronal suture

Interlock along the midline of the cranium forming the sagittal suture

Occipital bone. Form what? Articulate with? What are the 2 structures related to this bone?

Forms the posterior and inferior portions of the cranium

Articulates with two parietal bones at the lambdoid suture

2 structures:

1. Foreman magnum

2. Occipital condyle

Foramen magnum. What is it?

Passageway surrounding the connection between the brain and the spinal cord

Occipital condyle. What is it? Articulate with?

Rounded surfaces on either side of the foramen magnum

Articulate with the first vertebra of the neck

Temporal bone. Form what? Articulate with? What is it house? Name the 4 key bone markings.

Form part of both side of the cranium and zygomatic arches

Articulate with the parietal bones at the squamous suture

House the auditory ossicles in middle ear

Key bone markings:

1. External acoustic meatus

2. Mandibular fossa

3. Mastoid process

4. Styloid process

External auditory (acoustic) meatus. What is it?

Passageway leading to the tympanic membrane or eardrum.

Mandibular fossa. What is it?

Depression that works the point of articulation with the mandible.

Mastoid process. What is it?

Attachment site for muscles which rotate and extend the head.

Styloid process. What is it?

Attachment site for ligaments that support the hyoid bone.

Sphenoid bone. Forms what and acts as what and braces what? Contains what? Wings of bone extend where and from where?

Forms part of the floor of the cranium

• Acts as bridge, uniting cranial and facial bones

• Braces sides of skull

Contains pair of sinuses (sphenoidal sinuses)

“Wings” of the bone extend laterally from a central depression, the sella turcica

Stella turcica. Function?

Houses and protects the pituitary gland

Ethmoid bone. Anterior to what? Forms what? Contributes to what? What are the 4 structures?

Anterior to the sphenoid bone

Forms part of the cranial floor

Contributes to medial surfaces of the eye orbits and forms roof and sides of the nasal cavity

4 structures:

1. Crista galli

2. Cribriform plate

3. Perpendicular plate

4. Superior and middle nasal conchae

Crista galli. Projects where?

Ridge projects above superior surface

Cribriform plate. What allows what to pass through? Carries what?

Holes in cribriform plate allow olfactory nerves to pass through, carrying sense of smell

Superior and middle nasal conchae. Projects where? Function?

Project into nasal cavity toward nasal septum

Slow airflow, allowing time to clean, moisten, and warm air before entering respiratory tract

Perpendicular plate. Extends where? Forms what?

Extends inferiorly from the crista galli between the conchae

Forms part of the nasal septum

Bones of the face. Protect and support what? Site for attachment for what? What is the only moveable bone.

Protect and support entrances to digestive and respiratory tracts

Sites for attachment of muscles for facial expression and manipulation of food

Only one (the mandible) is movable

Maxillary bones. Articulate with? How large is the bone? Form what? What are the 2 structures related with this bone?

Articulate with all other facial bones except for the mandible

Largest facial bones

Form the floor and medial parts of the orbit rims, the walls of the nasal cavity, and the anterior roof of the mouth (bony palate)

2 structures:

1. Maxillary sinuses

2. Infraorbital foramen

Maxillary sinuses. Produce what? Function?

Produce mucus that drains into nasal cavities

Lighten the weight of the maxillary bones

Infraorbital foramen. Opening for?

Opening for major sensory nerve from the face

Cleft palate. What is it?

Failure of the maxillae to fuse completely along the midline of the bony palate.

Cleft lip. What is it?

Split in the upper lip.

Palatine bones. Paired bones forms what? What shaped bone contribute to the floor of the nasal cavity and floor of each orbit? What are the sinuses and drain where?

Paired palatine bones form the posterior surface of the bony palate, or hard palate (the “roof” of the mouth)

The L-shaped bones also contribute to the floor of the nasal cavity and floor of each orbit.

Have palatine sinuses which drain into sphenoidal sinuses.

Vomer. Articulate with? Supports what?

The vomer articulates with paired palatine bones

Supports partition forming part of the nasal septum

Nasal bone. Form what? Articulate with?

Form the bridge of the nose between the orbits

Articulate with the frontal and maxillary bones

Lacrimal bone. Located where? Articulate with?

Located within the orbit on its medial surface

Articulate with the frontal, ethmoid, and maxillary bones

Inferior nasal conchae. Project where? Function?

Project from lateral walls of nasal cavity

Change airflow and deflect air toward olfactory receptors

Nasal complex. Includes what? (3)

All the bones that form the superior and lateral walls of nasal cavities

Paranasal sinuses

Nasal Septum

Paranasal sinuses drain where?

Drain into nasal cavities.

Nasal septum. Formed form what? Separate what?

Formed from perpendicular plate of ethmoid bone and vomer

Separates right and left portions of nasal cavity

Sinusitis. What is it? Caused by?

Inflammation and swelling of the mucous membrane lining the sinuses; caused by viral, bacterial or fungal infections.

Mandible. What is it? What extends where? What are the 2 processes of this bone?

Only bone of the lower jaw

Vertical process (ramus) on either side extends toward the temporal bone

Two processes: Condylar process and coronoid process

Condylar process. Ends where? Articulates with?

Ends at mandibular condyle.

Articulates with the mandibular fossa of the temporal bone.

Coronoid process. Is it anterior or posterior? Attachment point where?

Anterior process

Attachment ppoint for the temporalis muscle that closes the jaw

Zygomatic bone. Each bone articulate with and what does it form?

Each zygomatic bone articulates with the frontal bone and the maxillae, forming the lateral wall of the orbit

Temporal process of the zygomatic bone. Does what to articulate with what? What do the two process together form?

Curves laterally and posteriorly to articulate with the zygomatic process of the temporal bone

Two processes together form the zygomatic arch, or cheekbone

Hyoid bone. Shape? Where is it suspended from? Functions (2)? What happens when it factures?

Small and U-shaped

Suspended from the styloid processes of the temporal bones to the lesser horns

Functions:

Serves as base for muscles associated with the larynx (voicebox), tongue, and pharynx

Supports and stabilizes the larynx

When it factures. we have a hard time to breath, swallow, or move our own tongue.

Skull of infants and children. Skull formation begins with? What enlarges more rapidly, brain or skull? At birth cranial bones connected by what? What is the anterior fontanelle commonly known as? Function? When is do fontanelles disappear and skull growth finish?

Skull formation begins with many different centers of ossification that fuse together

Brain enlarges more rapidly than skull bones

At birth cranial bones connected by areas of fibrous connective tissue known as fontanelles

Anterior fontanelle commonly called the “soft spot”

These flexible areas allow for easier delivery of the head

Fontanelles disappear and skull growth is finished by about age four

Anterior fontanelle. Junction when?

Junction when 2 frontal + 2 parietal bones meet

Posterior fontanelle. Junction where?

Junction when 2 parietal + occipital bones meet

Vertebral column. Also called? Consists of how many bones? Consists of how many vertebrae and what else? function?

Also called the spine

Consists of 26 bones:

24 vertebrae

• The sacrum

• The coccyx, or tailbone

Provides weight-bearing column of support and protection of spinal cord

How many vertebrae in each region (Cervical, Thoracic, Lumbar)

Cervical~ 7

Thoracic~ 12

Lumbar~ 5

Primary spinal curvatures. Present when? Include?

Are present at birth

Include the thoracic and sacral curves

Secondary curves. Develop when? Include?

Develop several months after birth

Include the cervical and lumbar curves

When are all 4 spinal curves fully developed by?

10

Cervical spinal curve. Function?

Develops as the infant learns to balance the weight of the head on the vertebrae of the neck.

Thoracic spinal curve. Function?

Provide room for thoracic organs

Lumbar spinal curve. Function? Develops with what?

Balances the weight of the trunk over the lower limbs.

This curve develops with the ability to stand.

Sacral spinal curve. Function?

Provides room for various abdminopelvic organs.

Kyphosis. What is it?

Exaggerated thoracic curvature

Lordosis. What does it look like? What is it?

Bending backward

Exaggerated lumbar curvature

Scoliosis. What does it look like?

Crookedness

Abnormal lateral curvature

Vertebral body. What portion is this? Bodies of adjacent vertebrae separated from by (except where) and what is it made of?

More massive, weight-bearing portion of a vertebra

Bodies of adjacent vertebrae separated from each other by intervertebral discs (except in sacrum and coccyx or between C₁ and C₂)

• Intervertebral disc made of fibrocartilage

Vertebral arch. Forms what? Vertebral foramina of successive vertebrae forms what? Pedicles form what? Roof of arch formed by what?

Forms posterior margin of vertebral foramen

Vertebral foramina of successive vertebrae form the vertebral canal enclosing spinal cord

Pedicles form walls of arch

Roof of arch formed by laminae

Transverse process. Project from? Site for?

Project laterally or dorsolaterally from the pedicles

Sites for muscle attachment

Spinous process. Except what? Projects? Forms what?

Except C1

Projects posteriorly from the laminae

Forms bumps that can be felt along midline of back

Articular processes. Arise where? Each side of vertebra has what? Processes of successive vertebrae contact with one another at what? Gaps between pedicles form?

Arise at junction between pedicles and laminae on both sides of the vertebrae

Each side of vertebra has superior and inferior articular process

Processes of successive vertebrae contact one another at the articular facets

Gaps between pedicles form the intervertebral foramina

Intervertebral foramina. Allow what?

Allow passage of nerves to and from spinal cord

Cervical vertebrae. How does the body look like? What are the distinctive features?

Body is relatively small

Distinctive features:

• Oval, concave vertebral body

• Relatively large vertebral foramen

• Stumpy spinous process, usually with notched tip

• Round transverse foramina within transverse processes

What does the round transverse foramina with tranverse process of cervical vertebrae protect?

Protect blood vessel supplying brain

C1. What is it called? Function? Articulates with? What movement does it allow for?

Altas

Holds up the head

Articulates with the occipital condyles

Allows for a specific “nodding yes” movement

C2. What is it called? Has what projection? Allows for what movement?

Axis

Has a projection up toward the atlas, called the dens, or odontoid process

Allows for rotational “shaking the head no” movement

Thoracic vertebrae. Does the size of vertebral foramen increase or decrease while progressing through T1-T12? What about for the size of the body? What are the distinctive feature?

Size of vertebral foramen decreases, while size of body enlarges as progresses from T₁–T₁₂

Distinctive features:

Heart-shaped body; larger than cervical vertebra

Large, slender spinous process that points inferiorly

Costal facets that articulate with the heads of one or two pairs of ribs (unique thoracic)

Lumbar vertebrae. Size of vertebrae and what is the thickness of intevertbral disc? Supports what? What are the distinctive feature?

The largest vertebrae with thickest intervertebral discs; support most of body weight

Distinctive features:

Vertebral body is significantly thicker and more oval than that of thoracic vertebra

Massive, stumpy spinous process projecting posteriorly

Bladelike transverse process lacking articulations for ribs

Sacrum. Shape? Consists of how many vertebrae fused? Protects what? Has lateral articulations with what? What does the board surface provide attachment sites for?

Triangular-shaped bone

Consists of five fused vertebrae

Protects organs in pelvic cavity

Has lateral articulations with pelvic girdle

Broad surface provides attachment sites for muscles, especially those for leg movements

What is the narrow caudal area of the sacrum called?

Apex

What is the board superior surface of the sacrum called? What is the bulge of the anterior tip of the base?

Broad superior surface is the base

Bulge at anterior tip of base is the sacral promontory

The sacral canal of the sacrum extends where? What is the inferior end called?

Sacral canal extends along posterior surface

• Inferior end is the sacral hiatus

The sacral foramina of sacrum open where?

Sacral foramina open on either side of median sacral crest

Later sacral crest. Ridge formed by?

Ridge formed by the fusion of the transverse process.

Median sacral crest. Ridge formed by?

Ridge formed by fusion of spinous processes.

Coccyx. How many vertebrae. When is fusion complete? May fuse to what in elderly people? Provide attachment for?

Three to five (usually four) fused vertebrae

Fusion not complete until late in adulthood

May fuse to sacrum in elderly people

Provides attachment for muscle that closes the anal opening

Thoracic cage. Consists of what? Forms what? Protects what? What forms rib cage?

Consists of thoracic vertebrae, the ribs, and the sternum

Forms the walls of the thoracic cavity

Protects heart, lungs, and internal organs

Ribs, sternum, and costal cartilages form rib cage

Ribs. Shape? How many? What are the first 7 called? What are the 8-12 ribs called, why? 8-10, why? 11-12, why?

Long, curved, flattened bones

Twelve pairs

First seven pairs are true ribs, or vertebrosternal ribs

Connect to sternum by separate costal cartilages

Ribs 8–12 are false ribs because do not attach directly to sternum

Ribs 8–10 are vertebrochondral ribs whose costal cartilages fuse and merge together with cartilages of rib pair 7

Last two pairs (11 and 12) are floating ribs because have no connection with the sternum

The sternum. Consists of what and when do they fuse by? What are the 3 structures?

Consists of three parts that fuse by about age 25

Structures:

1. Broad, triangular manubrium

2. Elongated body

3. Xiphoid process

Manubrium of sternum. What does it articulate with? Contains what?

Articulates with the clavicles of the appendicular skeleton and cartilages of first pair of ribs

Contains shallow indentation called jugular notch

Xiphoid process. Can be broken how? What is attached?

Can be broken by impact or strong pressure such as with incorrect placement of hands during CPR

Where is the diaphragm attached

Pectoral girdle. Also called what? Connects what? Consists of what? Why are both bones important for?

Also called the shoulder girdle

Connects the upper limbs to the trunk

Consists of the clavicle and the scapula

Both bones are extremely important muscle attachment sites

Clavicle. Shape? Articulates with what at sternal end? Articulates with what at acromial end?

S-shaped bone

Articulates with manubrium at sternal end

Articulates with the acromion of the scapula at the acromial end

Scapula. Shape? Anterior surface of body bounded by? What are the 3 tips? What does the lateral angle contain and what does that articulate with to form?

Triangular bone

Anterior surface of body of scapula bounded by superior, medial, and lateral borders

The three tips are the superior, inferior, and lateral angles

Lateral angle, or head of the scapula, contains the glenoid cavity, or glenoid fossa

• Articulates with the humerus to form the shoulder joint

Subscapular fossa of scapula. What is it?

Depression in the anterior surface of the body where the subscapularis muscle attaches

Coracoid process of scapula. What is it?

Smaller, anterior projection over the glenoid cavity

Acromion of scapula. What is it? Articulate with?

Larger, posterior process that articulates with the distal end of the clavicle

Scapular spine of scapula. What is it?

Divides posterior surface of the scapula into the supraspinous fossa and the infraspinous fossa

Upper limb. Consist of what bones?

Arm

• Humerus

• Extends from the scapula to the elbow

Forearm

• The radius and ulna

Wrist and hand 

• The carpals, metacarpals, and phalanges

Humerus. Rounded head at proximal end articulates with and forms what? What is the greater and lesser tubercle? What is the deltoid tuberosity and what is it an attachment site for? What projects distally?

Rounded head at proximal end articulates with the scapula forming the shoulder joint

Greater tubercle is rounded projection on lateral surface of head

Lesser tubercle lies anterior to and is separated from greater tubercle by the intertubercular groove

Deltoid tuberosity runs along lateral border of shaft

Attachment site for deltoid muscle

Distally, the medial and lateral epicondyles project to either side

Distal end of the humerus. Smooth condyle articulates with what? Medial trochlea extends from where to where? What are the fossae? What is the capitulum? What is the shallow radial fossa proximal to and articulate with what?

Smooth condyle articulates with radius and ulna

Medial trochlea extends from coronoid fossa to olecranon  fossa

• Fossae are depressions that articulate with projections from the ulna

Capitulum forms the lateral region of the condyle

Shallow radial fossa is proximal to the capitulum

• Articulates with small projection from radius

Radius. Lies where? What does it feature?

Radius lies along lateral side of forearm or thumb.

Features:

Radial head

Neck of radius

Distal styloid process

Ulna. Lies where? What does it feature? Where does shaft end?

Ulna found on medial side or pinky.

Features:

Olecranon

Trochlear notch

Coronoid process

Shaft ends distally at disk-shaped head and short styloid process

What is the olecranon of the ulna?

Is the point of the elbow

Trochlear notch of the ulna articulates with and forms what?

Articulates with the trochlea of the humerus, forming the elbow joint

What is the coronoid process of the ulna?

Forms the inferior lip of the notch

What do the interosseous membrane connect? What is it?

Connects ulna and radius along length of bones

Fibrous sheet of connective tissue