Chapter 8: Appendicular Skeleton Flashcards Part 1

Axial skeleton: Consists of the bones that lie around the longitudinal axis of the body.
Appendicular skeleton: Consists of bones of the upper and lower limbs plus the bones forming the girdles (connecting limbs to the axial skeleton).

Pectoral girdle attaches the bones of the upper limbs to the axial skeleton.
Consists of:
- clavicle: articulates with the manubrium at the sternoclavicular joint;
- scapula: articulates with the clavicle at the acromioclavicular joint; articulates with the humerus at the glenohumeral (shoulder) joint.

Has a prominent ridge called the “spine” that runs diagonally across the posterior surface.
The lateral end of the spine projects as a flattened, expanded process called the acromion.
Glenoid cavity accepts the head of the humerus to form the glenohumeral (shoulder) joint.
Medial border: thin edge closer to the vertebral column.
Lateral border: thick edge closer to the arm.
Superior border: superior edge of the scapula; joins the medial border at the superior angle.

Upper limb contains $30$ bones in $3$ locations:
- the humerus;
- the ulna and radius;
- the 8 carpals in the carpus, the 5 metacarpals (palm), and the 14 phalanges (bones of the hand).

Humerus is the largest, longest bone of the upper limb.
Projections around the intertubercular sulcus (bicipital groove).
Provides attachment for:
- tendons of the biceps brachii;
- deltoid muscle.
Accommodates the radial nerve.
Articulates with:
- head of the radius (at the capitulum region);
- trochlear notch of the ulna (at the trochlear region).
Anterior depression; Posterior depression (surface features for muscle/ligament attachment).

Radius and ulna articulate with the humerus at the elbow joint in two places:
1. Where the head of the radius articulates with the capitulum of the humerus;
2. Where the trochlear notch of the ulna articulates with the trochlea of the humerus.

8 small bones of the wrist joined to one another with ligaments.
Proximal row (from lateral to medial):
- scaphoid (boat-like),
- lunate (moon-shaped),
- triquetrum (triangular/cornered),
- pisiform (pea-shaped).
Distal row (from lateral to medial):
- trapezium (4-sided with no two sides parallel),
- trapezoid (4-sided with 2 sides parallel),
- capitate (head-shaped),
- hamate (hooked).
Mnemonic for carpal bones:
- Stop Letting Those People Touch The Cadaver's Hand.
- Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform.
- Distal row: Trapezium, Trapezoid, Capitate, Hamate.
Proximal/distal orientation shown in diagrams; radially biased in some views (scaphoid, lunate, etc.).

Each metacarpal bone consists of:
- proximal base,
- intermediate shaft,
- distal head.
Metacarpals numbered $1-5$ , starting with the thumb, from lateral to medial.
Phalanges are the bones of the digits; each finger has a proximal, middle, and distal phalanx, except the thumb, which is missing a middle phalanx (i.e., the Hallux is a foot term; in the hand the thumb has two phalanges).

Pelvic girdle consists of 2 hip bones (also called coxal bones or 'coxa').
Joints:
- Pubic symphysis: where the two hip bones join anteriorly.
- Sacroiliac joint: where the hip bones meet posteriorly with the sacrum.

Hip bone is formed by three fused bones: Illeum, Ischium, and Pubis.
Note: Ilium, ischium, and pubis are separate bones that fuse during adolescence (approximately $15-17\,\text{years}$ ).
Ilium details:
- Ilium is the largest of the three components.
- Superior border of the ilium articulates with the head of the femur; accommodates nerves and blood vessels.
Ischium: inferior, posterior portion of the hip bone.
Pubis: anterior and inferior part of the hip bone.

Lower limb consists of $30$ bones in $4$ locations:
- the femur,
- the patella (kneecap),
- the tibia and fibula,
- the 7 tarsals in the tarsus, the 5 metatarsals in the metatarsus, and the 14 phalanges in the foot.

The longest, heaviest, strongest bone in the body.
Articulates with the acetabulum of the hip at the proximal end.
Projections serve as attachment points for tendons of thigh and buttock muscles.
Attachment points for tendons of several thigh muscles.
Articulates with the medial and lateral condyles of the tibia at the distal end.

Small, triangular bone located anterior to the knee joint.
Base (superior) and apex (inferior).
Articular facets on the posterior surface that articulate with the medial and lateral femoral condyles.

The larger, medial weight-bearing bone of the leg.
Articulates with the condyles of the femur to form the tibiofemoral (knee) joint.
Attachment point for the patellar ligament.
Connects to the fibula.
Articulates with the talus (ankle) and forms the prominence that can be felt on the medial surface of the ankle.

Parallel and lateral to the tibia but considerably smaller.
Unlike the tibia, it does not articulate with the femur but helps stabilize the ankle joint.

7 bones of the tarsus.
Mnemonic for tarsals:
- Tall Centers Never Take Shots From Corners.
- Talus, Calcaneus, Navicular, Third cuneiform, Second cuneiform, First cuneiform, Cuboid.
Key bones shown in superior and inferior views:
- Calcaneus (heel bone),
- Talus (ankle bone),
- Navicular, Cuboid, and the three cuneiforms (medial, intermediate, lateral).
Metatarsals lie distal to tarsals; Phalanges are the bones of the digits; Sesamoid bones may be present in the plantar foot.

Metatarsals: $5$ bones of the metatarsus.
Each metatarsal consists of a proximal base, an intermediate shaft, and a distal head.
Metatarsals numbered $1-5$ starting with the hallux (great toe) from medial to lateral.
Phalanges (toes): bones of the digits; generally three phalanges per toe except the hallux which lacks an intermediate phalange (i.e., two phalanges: proximal and distal).

Arches are held in position by ligaments and tendons.
Functions:
- Enable the foot to support the body's weight.
- Provide an ideal distribution of body weight over the soft and hard tissues of the foot.
- Provide leverage while walking.
Longitudinal arch: has two parts (medial and lateral); formed by tarsal and metatarsal bones arranged to form an arch from the anterior to the posterior part of the foot.
Transverse arch: found between the medial and lateral aspects of the foot; formed by the navicular, three cuneiforms, and the bases of the five metatarsals.
Weight distribution: ball of foot carries $40\%$ of weight; heel carries $60\%$ of weight.