Axial Skeleton II and Appendicular Skeleton

I. Facial Bones: 14 Bones

 

 

 

A. Unpaired

1. Mandible

2. Vomer

B. Paired

1. Maxillae

2. Zygomatics

3. Nasals

3. Lacrimals

4. Palatines

5. Inferior conchae

C. Mandible: U-shaped lower jaw

 

1. Structure

            a. Ramus (branch)

            b. Body

2. Landmarks

            a. Mandibular notch

            b. Mandibular condyle (rounded articular projection)

            c. Mandibular angle

            d. Coronoid process

                        i. Attachment for temporalis muscle

            e. Alveolar margin        

                        i. Holds teeth

D. Maxillay bones (Maxillae): Upper jaw and central portion of facial skeleton

 

1. Keystone—all other facial bones articulate with maxillae

2. Landmarks

            a. Aveolar margins

            b. Palatine processes

                        i. Posterior projection

                        ii. Anterior 2/3’s of hard palate

            c. Frontal processes

                        i. Superior projection to frontal bone

            d. Zygomatic processes

                        i. Articualtions with zygomatic bones

E. Zygomatic bones: Cheek bones

 

1. Interolateral margins of orbits

F. Nasal bones

1. Bridge of nose

2. Articulations

            a. Superior: frontal bone

            b. Lateral: maxillae

            c. Posterior: ethmoid bone

G. Lacrimal bones

 

1. Medial walls of each orbit

2. Articulations

            a. Superior: frontal bones

            b. Posterior: ethmoid bone

H. Palatine bones

1. Posterior part of the hard palate

I. Vomer: Nasal septum

J. Inferior nasal conchae

1. Part of the lateral wall of nasal cavity

K. Hyoid bone: Acts as moveable base for tongues

 

1. Not part of skull

2. Does not articulate with any other bones

3. Raise and lower larynx during swallowing

 

II. Vertebral Column (Spine)

 

A. General characteristics

1. 26 irregular bones

2. Transfers weight of trunk to lower limbs

3. Protects the spinal cord

4. Attachment point for ribs

5. Attachment point for muscles of back

B. Divisions (5)

1. Cervical curvature

            a. 7 vertebrae (C1-C7)

            b. Concave posteriorly

2. Thoracic vertebrae

            a. 12 vertebrae (T1-T12)

            b. Convex posteriorly

3. Lumbar curvature

a. 5 vertebrae (L1-L5)

b. Concave posteriorly

4. Sacrum: 5 fused vertebrae

            a. Convex posteriorly

5. Coccyx: 4 fused vertebrae

C. Ligaments

1. Anterior and posterior ligaments

D. Intervertebral discs (shock absorbers)

 

1. Functions as a cushion-like pad between vertebrae

2. Two parts

            a. Nucleus pulposus—semi-fluid

                        i. Gives elasticity and compressibility

            b. Annulus fibrous

                        i. Forms outer collar to limit expansion

                        ii. Connects successive vertebrae

                        iii. Rupture: herniated disc (slipped disc)

 

 

 

E. General structure of vertebrae

 

1. Body (centrum)

2. Vertebral arch

            a. Pedicle

            b. Transverse process

            c. Superior articular process

            d. Laminae

            e. Transverse process

            f. Vertebral foramen

                        i. Successive foramen form vertebral canal

            g. Intervertebral foramina

                        i. Spinal nerves pass through laterally

 

III. Thoracic Cage

 

A. Elements

1. Dorsal (posterior): Vertebrae

2. Lateral: Ribs

3. Anterior: Sternum and costal cartilages

B. Function

1. Protective cage for vital organs

2. Attachment for muscle

3. Supports shoulders girdle and upper limbs

4. Participates in breathing

B. Sternum (fusion of three bones)

1. Manubrium, body and xiphoid process

2. Articulations

            a. Manubrium

i. Clavicles: clavicular notches

ii. First two pairs of ribs

            b. Body (bulk of sternum)

                        i. Cartilages of ribs 2-7

            c. Xiphoid

                        i. Body of sternum

3. Landmarks

            a. Jugular notch

                        i. Common carotid artery issues from aorta

                        ii. Level of second and third vertebrae

            b. Sternal angle

                        i. Level of second rib

                        ii. Disc between fourth and fifth thoracic vertebrae

            c. Xiphisternal joint

                        i. Ninth thoracic vertebra

C. Ribs

1. Nomenclature based on Attachments

            a. Posterior: thoracic vertebrae

            b. Anterior

i. VertebrosternalTrue(7 pairs): sternum via intercostals cartilages

ii. VertebrochondralFalse (3 pairs): indirect attachment to sternum via costal cartilage

iii. Vertebral—Floating (2 pairs): no anterior attachment

2. Size:

            a. Increase from 1-7

            b. Decrease from 8-12

3. Structure

            a. Head of rib: articulates with same-numbered thoracic vertebra

            b. Neck

c. Tubercle: articulates with transverse process of same-numbered thoracic vertebra

d. Shaft: bulk of rib

 

IV. Appendicular Skeleton

A. General characteristics

1. Limbs and girdles

2. Pectoral girdle: attaches upper limbs to body trunk

3. Pelvic girdle: attached lower limbs to body trunk

4. Limb fundamental plan

            a. Three segments connected by moveable joints

B. Pectoral girdle (not really a girdle—not connected posteriorly)

1. Bones (2)

            a. Clavicle

                        i. Anterior

            b. Scapula

                        i. Posterior

2. Characteristics

            a. Only clavicle attaches to thoracic

            b. Scapula is free to move across thorax

                        i. Arm very mobile

            c. Socket of shoulder joint (glenoid cavity of scapula)

                        i. Shallow and poorly reinforced

                        ii. Does not restrict movement of humerous

3. Clavicle—double curve

 

            a. Sternal end

                        i. Articulates sternum (manubrium)

            b. Acromial end

                        i. Articulates scapula

            c. Function

                        i. Restricts medial movement of arms

                        ii. Attachment for thoracic and shoulder muscles

            d. Fracture

                        i. Curvature promotes anterior displacement

4. Scapula

 

            a. Structure (triangle; three sides and angles)

                        i. Acromion—anterior projection of spine; articulation with clavicle

ii. Coracoid process—anterior projection of superior scapular border; anchors bicep muscle

                        iii. Glenoid cavity—articulates with humerous

                        iv. Suprascapular notch—nerve passage

                        v. Superior, lateral and inferior angles

                        vi. Spine—posterior surface

vii. Infraspinous, supraspinous and subscapular fossa—shallow depressions

                        viii. Superior, medial and lateral borders

 

V. Upper Limb (30 bones)

 

A. Arm: shoulder to elbow

1. Structure of the humerus

 

            a. Head

            b. Anatomical neck

            c. Greater and lesser tubercles

                        i. Separated by intertubercle groove

            d. Surgical neck (most likely site of fracture)

            e. Deltoid tuberosity

                        i. Attachment site of deltoid muscle

            f. Radial groove           

                        i. Course of radial nerve

            g. Condyles

                        i. Trochlea (medial): articulates with ulna

                        ii. Capitulum: articulates with radius

B. Forearm (antebrachium)

1. General considerations

 

            a. Two parallel long bones: ulna and radius

            b. Articulations

                        i. Proximal: humerus

                        ii. Distal: bones of wrist

                        iii. Radioulnar joints: radius and ulna both proximally and distally

2. Ulna: forms elbow joint with humerus; wide at proximal end, narrow at distal

            a. Olecranon and coronoid processes

                        i. Grip trochlea of humerus to form a stable hinge joint

                        ii. At full extension, olecranon process locks to prevent hyperextension

            b. Radial notch: articulates with radius

            c. Head (wrist end): articulates with radius

            d. Styloid process: attachment for wrist ligaments

3. Radius: narrow proximally, wide distally

            a. Head (humerus end)

i. Superior surface articulates with capitulum of humerus

ii. Medial surface articulates with ulna

            b. Radial tuberosity: anchors biceps muscle

            c. Styloid process: attachment for wrist ligaments

C. Hand

 

1. Carpus: proximal structure of hand

            a. Group of 8 bones (carpals) tied together with ligaments

            b. Two irregular rows of four bones each

                        i. Proximal row: scaphoid, lunate, triquetral and pisiform

                        ii. Distal row: Trapezium, trapezoid, capitate and hamate

2. Metacarpus (5 wrist-like spokes)

            a. No names; numbers (1-5) instead; 1 on thumb side

            b. Articulations

                        i. Bases with carpals

                        ii. Heads with phalanges

3. Phalanges (fingers or digits): 14 bones

            a. Numbered 1-5 beginning with pollex (thumb)

            b. Distal, middle and proximal phalanges for each digit

            c. No middle phalanx for pollex

 

VI. Pelvic Girdle

A. Paired coxal (hip) bones

 

1. Coxal bones unite anteriorly

2. Coxal bones unite with sacrum posteriorly

3. Regions of coxal bone (fused during childhood)

            a. Ilium

            b. Ischium

            c. Pubis

B. Ilium: majority of the coxal bone

 

1. Body

2. Ala (winglike)

            A. Superior margins—Iliac creasts

3. Posteriolateral surface

            a. Attachment of gluteal muscle

C. Ischium: posteriorinferior part of hip bone

1. Ishial body

2. Ishial ramus

3. Ishial tuberosity (where we sit)

D. Pubis (pubic bone)

1. Superior and inferior rami

2. Body

3. Pubic crest

4. Pubic tubercle

5. Pubic symphysisfibrocartilage joining two pubic bones

 

VII. Lower Limb

 

A. Thigh

1. Femur: largest, strongest bone in the body

            a. Proximal articulation with hip

            b. Distal articulation with tibia

            c. Courses medially

                        i. Center of gravity

2. Structure of femur

            a. Head

            b. Fovea capitis

                        i. Ligamentum teres connects with acetabulum of coxal bone

            c. Angled neck

                        i. Femur articulates with lateral aspect of pelvis

            d. Greater and lesser trochanters

                        i. Muscle attachment sites

            e. Intertrochanter line and crest

            f. Gluteal tuberosity

            g. Lateral and medial condyles

                        i. Articulate with tibia

            h. Medial and lateral epicondyles

                        i. Muscle attachment

            i. Patellar surface

                        i. Articulates with patella

3. Patellar

 

            a. Sesamoid bone enclosed in tendon

 

 

B. Leg: two parallel bones connected by interosseous membrane; articulate with each other proximally and distally (tibiofibular joints do not allow movement)

 

1. Tibia

            a. Receives weight of the body from femur and transmits it to foot

            b. Second strongest bone in body

2. Structure of tibia

            a. Medial and lateral condyles

            b. Tibial tuberosity

                        i. Patellar ligament attachment

            c. Lacks muscle on anterior crest and medial surface

            d. Medial malleolus

                        i. Medial bulge of ankle

            e. Fibular notch

                        i. Distal tibiofibular joint

3. Fibula

            a. Head—superior end

            b. Lateral malleolus

                        i. Articulates with talus

                        ii. Lateral ankle bulge

C. Foot: segmented; lever-like; support

 

1. Tarsus—7 tarsal bones (corresponds to carpus of the hand)

            a. Talus

                        i. Articulates with tibia and fibula

            b. Calcaneus (heel)

                        i. Carries talus on its superior surface

                        ii. Tuber calcanei touches ground

                        iii. Calcaneal tendon attaches to posterior surface

            c. Other bones

                        i. Cuboid

                        ii. Navicular

                        iii. Medial, intermediate and lateral cuneiform bones

2. Metatasus—5 small long bones (metatarsal bones)

            a. Metatarsal 1-5

3. Phalanges—14 bones; smaller and less moveable than those of hand