Anatomy of the Upper and Lower Limbs

Bones of the Upper Limbs

• Forearm: Consists of the radius (lateral to the thumb) and ulna (medial to the little finger).
  • Radius: Has a radial tuberosity where the biceps brachii muscle attaches.
  • Ulna: Has a trochlear notch that forms the elbow joint, a coronoid process, an olecranon process, and a styloid process that articulates with the wrist bones.
• Wrist: A short region between the forearm and hand, consisting of 8 carpal bones: scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezium, and trapezoid.
• Hand: Consists of 5 metacarpal bones attached to the carpal bones and phalanges (3 small bones on each finger).

Bones of the Lower Limbs

• Leg: Located between the knee and ankle, consisting of the tibia (shinbone) and fibula.
  • Tibia: The larger, weight-bearing bone, has a medial malleolus.
  • Fibula: A thin and stick-like bone forming the lateral side of the leg, has a lateral malleolus.
• Ankle: Consists of 7 tarsal bones: talus (ankle bone), calcaneus (heel bone), cuboid, navicular, and 3 cuneiforms.
• Foot: Consists of metatarsal bones and phalanges, arranged and numbered like the hand.
  • Possesses 3 primary arches.

Skull

• Sphenoid Bone: Butterfly-shaped bone spanning the width of the skull.
  • Sella Turcica: Saddle-shaped structure containing the pituitary gland.
• Ethmoid Bone: An irregularly shaped bone lying anterior to the sphenoid bone.

Facial Bones

• 14 bones, 13 are solidly connected, 1 is movable (mandible).
• Hold facial muscles in place.
• Connected by sutures (immovable, interlocking joints).
• Maxillae: Main bones of the face, carrying the upper teeth.
• Palatine Bones: Lie posterior to the palatine processes of the maxilla.
• Zygomatic Bones: Cheek bones.
• Lacrimal Bones: Form part of the medial wall of each orbit.
• Nasal Bones: Form the bridge of the nose.

Vertebral Column

• Vertebrae: Consist of a body, vertebral arch, and various processes.
  • Body: The weight-bearing portion.
  • Vertebral Arch: Surrounds the vertebral foramen (protects the spinal cord), made up of pedicles and laminae.
  • Processes: Transverse processes, spinous processes.
  • Vertebral Canal: Encloses the spinal cord.
  • Intervertebral Foramina: Where spinal nerves exit the spinal cord.
• Cervical Vertebrae (7): First two are unique (atlas and axis).
  • Atlas (C1): Lacks a body and has two lateral masses.
  • Axis (C2): Has a dens that projects upwards, allowing the head to rotate.
• Thoracic Vertebrae (12): Articulate with ribs.
• Lumbar Vertebrae (5): Largest vertebrae, designed for weight bearing.
• Sacrum (5 fused vertebrae): Posterior to the pelvic girdle, forming part of the pelvic cavity.
  • Sacral Promontory: The anterior edge of the first sacral vertebra, a landmark used in vaginal examinations.
• Coccyx (4 fused vertebrae): Tailbone, easily broken.

Rib Cage

• Also called the thoracic cage.
• Protects vital organs and prevents thorax collapse during respiration.
• Consists of 12 pairs of ribs:
  • True Ribs (1-7): Attached directly to the sternum.
  • False Ribs (8-12): Do not attach directly to the sternum, with 11-12 being floating ribs.
• Sternum: Breastbone.
  • Jugular Notch: Depression between the clavicles.
  • Sternal Angle: Marks the junction of the manubrium and sternum.
  • Xiphoid Process: Important landmark for CPR.

Joints and Movements

• Cartilaginous Joints: Unite bones with cartilage, allowing slight movement (e.g., epiphyseal plates, cartilage between ribs and sternum).
• Synovial Joints: Freely movable joints with a fluid-filled cavity surrounding the ends of bones.
  • Articulating Cartilage: Covers articular surfaces.
  • Joint Cavity: Filled with fluid.
  • Joint Capsule: Encloses the cavity.
• Movements:
  • Flexion: Movement in the frontal/coronal plane (e.g., plantar flexion, dorsiflexion).
  • Extension: Movement in a posterior direction.
  • Lateral Flexion: Movement of the trunk in the coronal plane.
  • Abduction: Movement away from the median plane.
  • Adduction: Movement towards the median plane.
  • Pronation: Rotation of the forearm to make the palm face down.
  • Supination: Rotation of the forearm to make the palm face up.
  • Eversion: Movement of the foot with the sole facing laterally.
  • Inversion: Movement of the foot with the sole facing medially.

Test your knowledge of the bones in the upper and lower limbs with this quiz. You will explore key features of bones in the forearm, wrist, hand, leg, and ankle. Prepare to delve into the details of anatomical structures and their functions.