Module 2 - Skeletal system

vertebrae structure

cervical, thoracic, and lumbar vertebrae all differ from each other, they all have same basic structures Basically features of a vertebra: 1. *body* (anterior) 2. *vertebral arch* (posterior): extends into the following processes: - spinous process: extending posteriorly - transverse process: paired, extending laterally 3. *vertebral foramen* (canal): houses the spinal cord

the intervertebral discs are tough cartilaginous layers that saves to resist compression on spine. what type of cartilage is found in intervertebral dies and why?

*fibrocartilage*, bc it is *tough and inflexible* which is necessary to resist compression on the spine

Ribs

*ribs* - 12 pairs - *true ribs* (pairs 1-7) - *false ribs* (pairs 8-12) - pairs 11 and 12 are called; *floating ribs*

ankle and foot

- *ankle*: 7 tarsal bones - *foot*: 5 metatarsal bones - *digits/toes*: 14 phalanges

Wrist and hand

- *wrist*: 8 carpal bones - *palm/hand*: 5 metacarpal bones - *digits/fingers*: 14 phalanges

Facial bones of the skull

- 14 bones that make up the face (7 discussed) *Maxillary bones (maxillae)*: paired, upper jaw bones *Nasal bones*: paired, articulate with the frontal bone, forms bridge of the nose *Zygomatic bones*: paired, forms the cheekbones, a feature of these bones is the *temporal process*, which articulates with the zygomatic process of the temporal bone *Mandible*: single, forms the lower jaw - ramus, body, and angle

Bones of the skull

- 22 bones in total - two sets: *cranial and facial bones*

Appendicular skeleton: upper limb

- 31 bones, extending from the pectoral girdle to the hand - whole upper limb referred to as *arm*, this is incorrect bc composed of the arm (shoulder to elbow), forearm (elbow to wrist), wrist, and hand 1. *pectoral girdle* - clavicle - scapula 2. *Arm-humerus* 3. *forearm* - radius - ulna 4. *wrist & hand*

Appendicular skeleton: lower limb

- 32 bones, from pelvic girldle to foot - the term *leg* commonly used, but not anatomically correct - the term *thigh* refers to the area from hip to the knee, the rest of the lower limb is made up of the *leg* (knee to ankle), *ankle* and *foot* 1. *pelvic girdle* 2. *femur (thigh)* 3. *leg* - tibia - fibula 4. *ankle and foot*

cranial bones of the skull

- 8 bones make up cranium (7 discussed), providing protection for the brain. - 7 bones form a roof (*cranial vault*) and floor (*cranial base*) that enclose the brain in a space called the cranial cavity *frontal bone*: single bone, forms the forehead and roof of the orbits (eye sockets) *Parietal bones*: paired, forms superior and lateral surges of skull *temporal*: paired, forms the lateral and inferior walls of the skull - zygomatic process - external auditory (acoustic) meatus (ear hole) - mastoid process *occipital bone*: single, forms posterior wall and base of skull - occipital condyles - foramen magnum (big hole) *sphenoid*: single, knowns as the "keystone of the skull because it owns the cranium and facial bones by attaching with almost every other bone of the skull

organization of the skeletal system

- composed of bones, cartilages, joints, and ligaments - accounts for apprx. 20% of body mass - it includes 206 named bones - divided into two divisions - axial and appendicular skeletons

thoracic cage

- consists of the thoracic vertebrae posteriorly, ribs laterally, and sternum anteriorly - house and protect the lungs

Veteran articulations

- individual vertebrae articulate (or join) to stack on tope of one another - the ventral articulations give rise to *two structures*: 1. *intervertebral discs* - like 'jelly filled donut' located between two vertebra it acts as a shock absorber 2. *intervertebral foreman* - lateral openings bw adjacent vertebra that allow for the passage of spinal nerves

Atypical vertebrae

- not all vertebrae are the same - distinct regional diff observed in the 3 regions of the vertebral column *C1 (atlas)* - two features that are important for attachments with other bones: 1. *anterior arch*: provides attachment with the dens (a feature of C2) 2. *lateral masses*: provides attachment with the occipital condyles of the occipital bone *C2 (axis)* - main feature of C2 is the dens, which rests within the anterior arch of C1 *movement of C1 and C2 * - skull rest on top of the lateral masses of C1 via the *occipital condyles*. this joint allows for the 'yes' movement of the head - the *dens* of C2 articulates, or attaches, with the *anterior arch* of C1. this allows for the 'no' movement of the head from side to side

Legs

- similar to forearm, led is composed of 2 bones: 1. *tibia*: contains - - *medial and lateral condyles*: articulate with the medial and lateral condyles of the femur. Anterior to the joining of the femur and tibia sits the *patella* (or knee cap) - *intercondylar eminence* - *tibial tuberosity* - *shaft*: anterior border and medial surface - *distal end*: medial malleolus 2. *fibula*: contains - - *head* (proximal end): articulates with the tibia - *neck* - *shaft* - *distal end*: lateral malleolus

Femur (thighs)

- similar to upper arm, has a single bone - the femur. - femur has a *head*, *neck*, and *shaft* *proximal end* - greater trochanter (lateral) - lesser trochanter (posteromedial) - linea aspera: the ridged posterior surface of the smooth anterior surface *distal end* - linea aspera - medial and lateral condyles - intercondylar notch - patellar (knee cap) surface

what is Scoliosis and why do patients with this often have breathing problems?

- the lateral curvature of the spine - forming what appears to be an 'S' shape of the vertebral column ans: the lateral curvature places the thoracic vertebrae in an atypical position. this can cause abnormal development and placement of the ribs and thoracic cavity. the abnormal form of the thoracic cavity can compress the lungs, causing breathing problems in ppl with scoliosis.

Pelvic girdle

- the pelvic girdle attaches the lower limb to the axial skeleton. it consists of the: 1. *ilium*: largest bone is the ilium, making up the superior portion of the pelvic girdle , *ischium*, and *pubis* - PSIS = posterior superior iliac spine - PIIS = posterior inferior iliac spine - ASIS = anterior superior iliac spine - AIIS = anterior inferior iliac spine - GR = greater sciatic notch - iliac crest 2.*ischium*: fuses with the ilium superiorly and posteriorly. feature are - - ischial tuberosity (when you sit you sit on this) - ischial spine - lesser sciatic notch - ischial ramus 3. *Pubis*: fuses with both the ilium and ischium. It also unites with the other pubic bone at the *pubic symphysis* - made up of *fibrocartilage* The bones of the pelvic girdle fuse to form two structures: 1. *acetabulum*: deep curved depression for articulation with the head of the femur 2. *obturator foramen*

sacrum and coccyx

- unlike the other 3 divisions of the vertebral column that composed of individual vertebrae, the sacrum and coccyx are located inferiorly and formed from fused vertebrae *sacrum*: fusion of five vertebrae composed of - apex - base - sacral foramina - sacral canal *coccyx*: fusion of three - five vertebrae (usually four)

Cranial sutures

1. *coronal*: junction bw frontal and parietal bones 2. *sagittal*: junction between parietal bones 3. *lambdoid*: junction bw occipital and parietal bones 4. *squamous*: junction bw temporal and parietal bones

structure of long bones

1. *epiphysis* - knobby, enlarged regions at the end, strengthens joints, and the attachment sites for tendons and ligaments 2. *metaphysis* - regions bw the diaphysis and epiphysis 3. *diaphysis* - elongated cylindrical shaft *additional features of the long bones* 1. *articular cartilage*: layer of catilarge that covers the epiphysis, reduces direction bw joints, and absorbs shock in moveable joints. *hyaline cartilage found here*. 2. *Periosteum*: a tough sheath of dense irregular connective tissue that covers the surface of bone, except for areas covered by articular cartilage 3. *Medullary cavity*: blood cell production occurs in the inner cavity of the long bone, or medullary cavity.

types of bones

1. *flat bones* - e.g. bones of the skull 2. *irregular bones* - e.g. vertebrae 3. *long bones* - elongated cylindrical shaft e.g. femur 4. *short bones* - e.g. bones of the ankle and wrist

functions of the skeletal system

1. *support and protection*: structural support as framework for entire body. protect many delicate tissues and organs from injury and trauma. The *rib cage* protects the heart and lungs, the *cranial bones* enclose and protect the brain, the *vertebrae* enclose the spinal cord, and the *pelvis* cradles some digestive, urinary, and reproductive organs 2. *movement*: serve as *attachment sites* for skeletal muscles, other soft tissue, and some organs. Muscles attached to the bones of the skeleton contract and evert a pull on the skeleton that then functions as a system of *lever*. the bones of the skeleton can *alter the direction and magnitude* of the forces generated by the skeletal muscles. Potential movements range from *powerful contractions* needed for running and jumping to delicate, precise movements required to remove a splinter from a finger. 3. *hemopoiesis*: is the process of *blood cell production*. It occurs in a connective tissue called red bone marrow, which is located in some spongy bone 4. *storage of mineral and energy reserves*: More than *90%* of the body's reserves of the minerals *calcium and phosphate* are stored within and released by bone. Calcium is an essential mineral for body functions such as muscle contraction, blood clotting, and nerve impulse transmission. Phosphate is a structural component of ATP, nucleotides, and phospholipids. When calcium or phosphate is needed by the body, some bone CT is broken down, and the minerals are released into the blood. In addition, potential energy in the form of *lipids is stored in yellow bone marrow*, which is located in the shafts of adult long bones.

basic form of bone

2 layers: like sandwich of spongy bone, with compact bone on either side of spongy bone in the middle *outer layer*: made up of compact bone which is hard and strong. *inner layer*: made up of spongy bone - blood cell production occurs in the inner cavity of the bone, or medullary cavity

Cranial base

a *fossa* is defines as a depression in a bone. the floor of the cranium or cranial base, contains three fosse: 1. *anterior* cranial fossa 2. *middle* cranial fossa 3. *posterior* cranial fossa

articulations (joints)

an articulation, or *joint*, is the place where a bone meets another bone, cartilage, or teeth. Articulations vary in stability and mobility, and are classified into categories based on: around of movement they permit and stability

Femur vs. humerus

both humerus and the femur are similar in structure. both have heads, neck and medial and lateral condyles (the capitulum and trochlea on the humerus). however, the femur is larger than the humerus, with a wider shaft, larger and more circular head, and larger condyles. the femur is larger bc it plays a critical role in supporting the body's weight

pelvic girdle vs. pectoral girdle

both the pelvic girdle and pectoral girdle function to connect the appendicular skeleton to the axial skeleton. the glenoid fossa (pectoral girdle) and acetabulum (pelvic girdle) are similar in that they both articulate with a rounded head of another bone (humerus or femur) there observable diff are the number an size of bones bw the girdles. the pelvic girdle is larger and has more bones bc the lower limb plays critical role in weight bearing and locomotion. lower limb bones must be larger and stronger in order to support the body's weight

forearm

composed of two bones: 1. *radius* *head* (proximal end): - round disc-shaped head - articulates with the capitulum of the humerus - articulates with the ulna *neck* *shaft* *distal end* - wide and flat, articulates with the wrist joint - styloid process 2. *ulna* - *olecranon*: fits into the olecranon fossa of the humerus - *coronoid process*: fits into the coronoid fossa of the humerus - *trochlear notch*: interlocks with the trochlea of the humerus

pectoral girdle

connects the upper limb to the axial skeleton and is formed by two parts: 1.*clavicle*: an s-shaped bone. it joins with the manubrium proximally and the scapula distally 2.*scapula* - triangular in shape - *anterior surface*: is the *coracoid process*. which with the acromion (posterior surface feature), stabilizes the shoulder joint - *posterior surface*: has *acromion* and *spine* - *lateral surface*: is the *glenoid fossa*, which articulates with the head of the humerus (arm bone) to contribute to the shoulder joint

divisions of the vertebral column (spine)

consists of five divisions: 1. *cervical* (7 vertebrae) 2. *thoracic* (12 vertebrae) 3. *lumbar* (5 vertebrae) 4. *sacrum* (5 fused vertebrae) 5. *coccyx* (4 fused vertebrae)

leg vs. forearm

similar bc both have two bones each (radius/ulna and tibia/fibula). However, there is a size diff. specifically in the forearm, the radium and ulna are similar in size to one another. In the lower leg, however, the tibia is much wider than the fibula due to the weight-bearing function of the lower limb

Arm-humerus

single bone of the arm is the *humerus*

sternum

sternum (breastbone) makes up the anterior portion of the thoracic cage. consists three parts: - *manubrium*: articulation with rib 1 - *body*: articulation with ribs 2-7 - *xiphoid process*

movements made at synovial joints

synovial joints include the shoulder, knee, hip, etc, and permit for a ida range of movements. 4 categories: 1. *gliding*: the motion of bones sliding on one another. - back and fourth - side to side - ex. carpals/tarsals (toes and fingers) 2. *angular*: motion that changes a joint angels. these motions can be classifies as: - *flexion*: bending/decrease angel ex. bending elbow/arm (decrease angle at elbow) - *extension*: straighten. increasing angle. ex. straightening elbow - *abduction*: taking away from midline (laterally). lifting arm further from body (moving upwards) - *adduction*: bringing toward. opposite of abduction 3. *rotation*: when a joint pivots around its own axis. two types - *medial rotation*: towards the midline - *lateral rotation*: away from the midline 4. *special movements* - *supination & pronation*: rotation of the radius over the ulna (forearm bones). Supination occurs when the forearm rotates so the palm faces anteriorly, vs. pronation when the forearm rotates so the palm faces posteriorly - *inversion & eversion*: twisting motion of the ankle. inversion occurs when the ankle is twists so the soles of the feet turn medially, vs. eversion occur when the ankle is twisted so the soles of the feet run laterally - *circumduction*: a continuous movement that combines flexion, auction, extension, and adduction in succession

Vertebral column (Spine)

the adult spinal cord is made up of 26 bones: - 24 vertebrae - 1 sacrum - 1 coccyx fact: apprx. 70 cm long in avg adult