Section 4 Flashcards
What does the appendicular system consist of?
The upper and lower limbs
What does the pectoral girdle do?
Connects the upper limb to the axial skeleton.
Describe the parts of the pectoral girdle.
- Clavicle
- An S-shaped bone
- joins with the manubrium of the sternum medially (proximally) and the scapula laterally (distally) - Scapula
- triangular in shape
seen on the anterior surface:
- the coracoid process is seen here. kind of pops out and helps to stabilize the shoulder joint along with the acromion.
seen on the posterior surface:
- acromion and the spine
seen on the lateral surface:
- the glenoid fossa, which articulates with the head of the humerus (arm bone) to contribute to the shoulder joint
Describe the distal aspect of the humerus
Anterior:
Two depressions and two bumps
On the lateral side we have a round shaped structure called the capitulum, which articulates radially with the radius of the forearm.
On the medial side there is a spool-shaped structure called the trochlea. This articulates with the ulna of the forearm.
The epicondyles (epi = upon). On the lateral side we have the lateral epicondyle which is upon our capitulum. On the medial side, the medial epicondyle is upon our trochlea.
Posterior:
There is one single depression or fossa called the olecranon fossa which articulates with the olecranon process of the ulna.
How do you know if the humerus is left or right bone
The head always faces medially. On the anterior side we find two depressions and two bumps, whereas posteriorly there is only one single fossa.
If the two depressions and two bumps are in the front (anterior) it would be a left humerus.
What is the difference between the anatomical neck and surgical neck of the humerus?
The anatomical neck is what connects the head to the rest of the bone.
The surgical neck is immediately below the tubercles. Its called this because its a common site for humeral fractures that require surgery.
Where are the lesser and the greater tubercles on the humerus?
Opposite to the head:
- head is medial
- the tubercles are lateral
What is the humerus and what does it connect?
The humerus the single main bone found in the arm.
The head of the humerus faces medially. This part articulates proximally with the glenoid fossa of the scapula to form the shoulder joint
Also distally with the radius and ulna to form the elbow joint.
What are the two bones in the forearm?
Radius and ulna
Describe the radius bone of the forearm.
The radius is laterally placed (thumb side) with reference to the forearm.
It has:
- Head (proximal end): round disc-shaped head with articulates with the capitulum (distal end) of the humerus. it also articulates with the ulna
- Shaft
- Neck
- Distal end: wide and flat, articulates with the carpal (wrist) bones to form the wrist joint. styloid process is there.
Describe the ulna bone of the forearm.
The ulna is medially placed (pinky finger side) with reference to the forearm. It looks like a pipe wrench.
It has:
- Proximal end: articulates with the distal end of the humerus. The olecranon fits into the olecranon fossa of the humerus. The trochlear notch is a c-shaped depression which interlocks with the trochlea of the humerus
- Shaft
- Neck
- Head (distal end): has styloid process
Name the kinds of bones found in the wrist and hand.
They are composed of many smaller bones:
Wrist:
- 8 carpal bones (short bones)
Palm/hand:
- 5 metacarpal bones (long bones)
Digits/fingers:
- 14 phalanges (long bones)
How many bones are in the lower limb?
30, or 31 including the innominate bone.
What does the lower limb consist of?
- Pelvic Girdle
- Thigh (femur)
- Leg (tibia and fibula)
- Ankle and foot
What does the pelvic girdle do?
- Attaches the lower limb to the axial skeleton
- Is formed by the hip (innominate) bones
What does the hip bone consist of?
The ilium, ischium and pubis.
Describe the location and structure of the ilium
- It is the largest bone of the pelvic girdle
- It makes up the superior portion of the pelvic girdle
Consists of:
- Posterior superior iliac spine (PSIS)
- Posterior inferior iliac spine (PIIS)
- Iliac crest
- Anterior superior iliac spine (ASIS)
- Anterior inferior iliac spine (AIIS)
The pubis fuses with both the ilium and ischium. It also unites with the other pubic bone at the pubic symphysis.
The pubic symphysis is made of which type of cartilage?
Fibrocartilage
The bones of the pelvic girdle fuse to form two structures. Describe the parts of these structures.
The greater sciatic notch: located between the PIIS and the ischial spine. It allows the passage of major nerves and vessels from the pelvic cavity into the posterior region of the lower limb.
The lesser sciatic notch: located between the ischial spine and the ischial tuberosity. It permits the passage of structures from the pelvic cavity to the genital region.
Acetabulum: Deep curved depression for articulation with the head of the femur.
Obturator foramen: Large opening on the anterior and inferior aspect of each pelvic girdle for the passage of nerves and blood vessels.
Which bones contribute to the obturator foramen?
The ischium and pubis
Which bones contribute to the acetabulum?
The ilium, ischium and pubis
Compare and contrast the structure and bony features of the pelvic girdle (lower limb) and the pectoral girdle (upper limb) by listing similarities and differences. Explain why you think the differences exist.
Both the pelvic girdle and pectoral girdle function to connect the appendicular skeleton to the axial skeleton. Additionally, the glenoid fossa (pectoral girdle) and acetabulum (pelvic girdle) are both structures that articulate with the rounded head of long bones, the humerus and femur respectively.
There is a difference in the number and size of the bones between the girdles. Since the lower limb plays a critical role in bearing weight and locomotion, the pelvic girdle is larger and has more bones as compared to the pectoral girdle.
What is the bone of the thigh?
The femur
Describe the proximal end of the femur
The head of the femur faces medially and articulates with the acetabulum of the pelvic girdle, forming the hip joint.
In addition to the head and neck, the proximal end of the femur has other bumps/projections and ridges that serve as surfaces for muscle attachment. (won’t be talked about in the course)
