Bone Practical Review: Axial and Appendicular Skeleton Study Guide

Bone Practical Review

Overview of the Human Skeleton

The human skeleton is divided into two main parts: the axial skeleton and the appendicular skeleton. Understanding the structure, function, and identification of bones and bone markings is essential for anatomy and physiology students.

• Axial Skeleton: Consists of the skull, vertebral column, and thoracic cage. It supports and protects the organs of the head, neck, and trunk.

• Appendicular Skeleton: Includes the bones of the limbs and girdles (shoulder and pelvic) that attach them to the axial skeleton.

Axial vs. Appendicular Skeleton

• Axial Skeleton: Skull, vertebral column, ribs, sternum.@hello

• Appendicular Skeleton: Pectoral girdle (clavicle and scapula), upper limbs, pelvic girdle (hip bones), lower limbs.

• Key Difference: The axial skeleton forms the central axis, while the appendicular skeleton facilitates movement.

Vertebral Column: Types and Numbers

The vertebral column is composed of individual vertebrae, classified by region:

• Cervical Vertebrae: 7 (C1–C7)

• Thoracic Vertebrae: 12 (T1–T12)

• Lumbar Vertebrae: 5 (L1–L5)

• Sacrum: 5 fused vertebrae

• Coccyx: 4 fused vertebrae

Order: Cervical → Thoracic → Lumbar → Sacrum → Coccyx

Bone Articulations

Articulation refers to the connection between bones. Understanding which bones articulate is crucial for identifying joints and movement types.

• Example: The humerus articulates with the scapula at the shoulder joint.

• Example: The femur articulates with the pelvis at the hip joint.

Cranial Sutures

Sutures are immovable joints found only in the skull. Major cranial sutures include:

• Coronal Suture: Between frontal and parietal bones

• Sagittal Suture: Between the two parietal bones

• Lambdoid Suture: Between parietal and occipital bones

• Squamous Suture: Between parietal and temporal bones

Identification of Carpals and Tarsals

• Carpals (Wrist Bones): 8 per hand. Examples: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate.

• Tarsals (Ankle Bones): 7 per foot. Examples: calcaneus, talus, navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, cuboid.

• Identification: Each carpal and tarsal has a unique shape and position; practice with models or diagrams is recommended.

Identification of Individual Vertebrae

• Cervical Vertebrae: Small body, transverse foramina (holes in transverse processes), bifid spinous process (except C7).

• Thoracic Vertebrae: Heart-shaped body, long downward-pointing spinous process, facets for rib articulation.

• Lumbar Vertebrae: Large, kidney-shaped body, short and thick spinous process.

Types of Cartilage in the Skeleton

There are three main types of cartilage found in the human skeleton:

Type	Location	Function
Hyaline Cartilage	Nasal cartilage, articular surfaces, costal cartilage, embryonic skeleton	Provides support with flexibility; reduces friction at joints
Elastic Cartilage	External ear, epiglottis	Maintains shape while allowing flexibility
Fibrocartilage	Intervertebral discs, pubic symphysis, menisci of knee	Resists compression; absorbs shock

Male vs. Female Pelvis

• Male Pelvis: Narrower, deeper, heavier, with a more acute pubic arch angle.

• Female Pelvis: Wider, shallower, lighter, with a broader pubic arch angle to facilitate childbirth.

• Key Differences: Shape of pelvic inlet, width of sacrum, and angle of pubic arch.

Counting Bones in the Hands and Feet

• Phalanges (Fingers/Toes): 14 per hand or foot (3 per finger/toe except thumb/big toe, which have 2).

• Metacarpals (Hand): 5 per hand

• Metatarsals (Foot): 5 per foot

• Carpals: 8 per hand

• Tarsals: 7 per foot

Left vs. Right Bone Identification

• Many bones are asymmetrical; identifying left from right requires knowledge of anatomical landmarks and orientation.

• Example: The head of the humerus faces medially, and the olecranon fossa is posterior.

Summary Table: Major Bone Groups and Counts

Bone Group	Number per Body	Notes
Cervical Vertebrae	7	Neck region
Thoracic Vertebrae	12	Articulate with ribs
Lumbar Vertebrae	5	Lower back
Carpals	8 per hand	Wrist bones
Tarsals	7 per foot	Ankle bones
Phalanges	14 per hand/foot	Fingers and toes
Metacarpals	5 per hand	Palm bones
Metatarsals	5 per foot	Foot bones

Additional info:

• Practice with bone models or diagrams is highly recommended for mastering identification and orientation.

• Understanding bone markings (e.g., foramen, process, condyle) is essential for practical exams.