Chapter 8 - The Skeletal System

Question 0

How many bones are in the adult skeletal system?

Answer 0

Approximately 206 bones

Question 1

What are the regions of the skeleton?

Answer 1

1. Axial skeleton - skull, auditory ossicles, hyoid bone, vertebrae, and thoracic cage.
2. Appendicular skeleton - upper limb bones, pectoral girdle, lower limb bones, and pelvic girdle.

Question 2

Most of the bones in the skull are connected by..?

Answer 2

Immovable joints called sutures which are visible as seams on the surface

Question 3

What are the para nasal sinuses?

Answer 3

a. Named for the bones they are in - frontal, sphenoid, ethmoid, maxillary.
b. They are connected with the nasal cavity, lined with mucous membrane, and filled with air.

Question 4

What are the cranial bones?

Answer 4

The bones that enclose the brain:

1. Frontal bone - forms the forehead, part of the roof of the cranium and part of the roof of the orbit.
2. Parietal bone - forms most of the cranial roof and part of its walls.
3. Temporal bones - anterior to the ear.
4. Occipital bone - rear of the skull.
5. Sphenoid bone.
6. Ethmoid bone - located behind the eye.

Question 5

What are the main parts of the temporal bones?

Answer 5

a. External acoustic meatus - opening into the ear canal.
b. Petrous part - houses the middle and inner-ear cavities.
c. Internal acoustic meatus - an opening that allows passage of the vestibulocochlear nerve.

Question 6

What are the main parts of the occipital bone?

Answer 6

a. Foramen magnum - hole that allows spinal cord to meet the brain.
b. Occipital condyle - where the skull rests on the vertebral column.

Question 7

What is the main part of the sphenoid bone?

Answer 7

a. Optic foramen - permits passage of the optic nerve and an artery.
b. Sella turcica - a saddle-like surface which houses pituitary gland.

Question 8

What is the main part of the ethmoid bone?

Answer 8

a. Cribriform plate - perforated with cribriform foramina which allow passage of olfactory nerves to the olfactory bulb.

Question 9

What are the facial bones?

Answer 9

1. The maxilla - forms the upper jaw
2. Palatine bones - form posterior 1/3 of the hard palate.
3. Zygomatic bones - form the angles of the cheeks.
4. Lacrimal bones - house the lacrimal sacs where tears collect and drain into the nasal cavity.
5. Nasal bones - form the bridge of the nose.
6. Vomer - forms the interior 1/3 of the nasal septum.
7. Mandible

Question 10

What are the main parts of the maxilla?

Answer 10

a. Alveola - deep sockets for the roots of each upper tooth.

b. Palatine process - roof of mouth and the floor of the nasal cavity.

Question 11

What is the main part of the mandible?

Answer 11

a. Alveoli - sockets for lower teeth

Question 12

What are the bones associated with the skull?

Answer 12

1. Auditory ossicles (malleus, incus, and stapes) - for hearing.
2. Hyoid bone - attachment site of muscles that control the mandible, tongue, and larynx.

Question 13

The skull at infancy

Answer 13

1. The skull bones at birth are not yet fused.

2. Fontanels - spaces between the infused cranial bones.

Question 14

What are the types of fontanels?

Answer 14

a. Anterior fontanel - between the frontal and parietal bones.
b. Posterior fontanel - between the parietal and occipital bones.
c. Sphenoid fontanels - between the frontal, parietal, temporal, and sphenoid bones.
d. Mastoid fontanel - between parietal, occipital and temporal bones.

Question 15

What is the vertebral column?

Answer 15

The vertebral column physically supports the skull and trunk, allows their movement, protects te spinal cord, and absorbs stress

Question 16

What are the general features of the vertebrae?

Answer 16

a. Body - weight-bearing portion.
b. Vertebral foramen - passage way for the spinal cord.
c. Intervertebral foramen - opening between the pedicles of two vertebrae which allows for passage of spinal nerves.

Question 17

What is the intervertebral disc?

Answer 17

Cartilage pad between the bodies of vertebrae that support the weight if the body and absorb shock

Question 18

What does the cervical vertebrae do and what does it consist of?

Answer 18

Supports the head and allows for its movement.

a. Atlas (C1) - supports the head.
b. Axis (C2) - allows rotation of the head.
c. Transverse foramen - passage way for the vertebral arteries .

Question 19

What does the thoracic vertebrae do?

Answer 19

(T1 - T12) support the thoracic cage enclosing the heart and lungs

Question 20

What does the lumbar vertebrae do?

Answer 20

(L1 - L5) support the lower back

Question 21

What does the sacrum do and what are its parts?

Answer 21

(S1 - S5) forms the posterior wall of the pelvic girdle.

a. Sacral foramina - allow for passage of spinal nerves and arteries.
b. Sacral canal - contains spinal nerve roots.

Question 22

What does the coccyx do?

Answer 22

Provides attachment for the muscles of the pelvic floor

Question 23

What makes up the thoracic cage?

Answer 23

1. Sternum (breastbone) - articulates with the clavicles and where costal cartilages of ribs attach.
2. Ribs - protect the thoracic and upper abdominal organs.

Question 24

What does the pectoral girdle do and what makes it up?

Answer 24

Supports the arm and links it to the axial skeleton.

1. Clavicle- braces the shoulder keeping the upper limb away from the midline of the body.
2. Scapula- overlies ribs 2-7 and attaches to the thorax by muscles.
   a. Acromion- articulates with the clavicle and forms the bridge from the appendicular to the axial skeleton.

Question 25

What are the regions of the upper limb?

Answer 25

a. Brachium (arm)- from shoulder to elbow.
b. Antebrachium (forearm)- from elbow to wrist.
c. Carpus (wrist)- contains 8 bones.
d. Manus (hand)- contains 19 bones.

Question 26

What is the main part of the humerus?

Answer 26

a. Trochlea- pulley like structure that articulates with the ulna.
b. Medial epicondyle- protects the ulnar nerve, which passes close to the surface.

Question 27

What is the main part of the radius?

Answer 27

a. Head- spins on the capitulum of the humerus and the radial notch when the forearm rotates.

Question 28

What are the main parts of the ulna?

Answer 28

a. Olecranon- bony point of the elbow.

b. Trochlear notch- wraps around the trochlea of the humerus.

Question 29

What do the carpal bones do?

Answer 29

Allow movement of wrist from side to side and anterior to posterior

Question 30

What are the metacarpal bones?

Answer 30

Bones of the palm numbered I-V with I below the thumb

Question 31

What are the phalanges?

Answer 31

Finger bones, numbered I-V with I at the thumb

Question 32

What is the pelvic girdle?

Answer 32

1. The pelvic girdle consists of a complete ring composed of three bones - two hip bones and the sacrum.
2. The pelvic girdle supports the trunk on the lower limbs and encloses and protects the viscera of the pelvic cavity.
3. The pelvic brim- the opening that the infant’s head passes through on its way through the pelvic inlet and outlet regions.
4. The adult hip bone forms by the fusion of the ilium, ischium, and pubis.
5. Greater sciatic notch- where the sciatic nerve passes through.
6. Pubis symphysis- fibrocartilage pad that joins the pubic bones.

Question 33

What are the regions of the lower limb (bones adapted for weight bearing and locomotion)?

Answer 33

a. Femoral (thigh)- from hip to knee.
b. Crural (leg)- from knee to ankle.
c. Tarsal- ankle.
d. Pedal- foot.

Question 34

What are the main parts of the femur (thigh)?

Answer 34

a. Head- articulates with the acetabulum of the pelvis.

b. Condyles- processes that allow the femur to rock on the tibia.

Question 35

What is the patella (kneecap)?

Answer 35

Sesmoid bone embedded in the tendon of the knee

Question 36

What is the main part of the tibia (weight bearing bone)?

Answer 36

a. Condyles- flat articular surfaces for the condyles of the femur.

Question 37

What is the fibula?

Answer 37

Slender bone that helps to stabilize the ankle

Question 38

What are the foot bones?

Answer 38

a. Tarsals (ankle)- includes the calcaneus which forms the heel and is attachment for the calcaneal tendon of the calf muscles.
b. Metatarsals- foot bones numbered I through V.
c. Phalanges- toe bones with I starting at great toe (hallux).

Question 39

What are the foot arches and what do they do?

Answer 39

Distribute the body’s weight between the heel and the heads of the metatarsal bones and absorb the stress of walking.

a. Medial longitudinal arch-
b. Lateral longitudinal arch- from heel to little toe.
c. Transverse arch- across the distal tarsal bones and the heads of the metatarsals.

Question 40

What are the disorders and problems?

Answer 40

1. Mastoiditis- infection and inflammation of the mastoid sinus which can erode the bone and spread to the brain.
2. Cleft palate- failure of the palatine processes to join.
3. Scoliosis- abnormal lateral curvature of the spine.
4. Kyphosis- exaggerated thoracic curvature.
5. Lordosis- exaggerated lumbar curvature.
6. Herniated disc- crack in the annulus of intervertebral disc that causes nucleus to ooze out.
7. Pes planus (fallen arch)- stress or congenital weakness stretches the ligaments of the arches.