Axial Skeleton Notes PDF

The Axial Skeleton Part I SCTM2002 – 501/502 Lecture 2 January 20/21, 2025 1 Lecture 2 Overview – Axial Skeleton 1. Bones 2. Skull a) Cranium b) Facial 3. Vertebral column 4. Bony thorax 19  1. Bones Purpose of bones Types of bone...

The Axial Skeleton Part I SCTM2002 – 501/502 Lecture 2 January 20/21, 2025 1 Lecture 2 Overview – Axial Skeleton 1. Bones 2. Skull a) Cranium b) Facial 3. Vertebral column 4. Bony thorax 19  1. Bones Purpose of bones Types of bones 20 1. Bones  1. Purpose of Bones Body's framework Muscle attachment sites Protective covering for organs and regions of the body Bone marrow which produces new red blood cells (hemopoietic tissue) 21 1. Bones  1. Purpose of Bones Body's framework Muscle attachment sites Protective covering for organs and regions of the body Bone marrow which produces new red blood cells (hemopoietic tissue) 24 1. Bones  1. Types of Bones Morphology: study of the form and structural features Long bones Short bones Flat bones Irregular bones Sesamoid bones 25 1. Bones  1. Types of Bones: Long Hard and dense Structure the body Mobility Radius, ulna 26 1. Bones  1. Types of Bones: Short Cube shaped & compact Spongy interior (marrow) Support & stability Little movement Carples, tarsles 27 1. Bones  1. Types of Bones: Flat Flat shape Protection (cranium) Broad surface for muscle attachment (scapula) Shoulder blade 28 1. Bones  1. Types of Bones: Irregular Cannot be grouped to be long/short/flat Various purposes Vertibre 29 1. Bones  1. Types of Bones: Sesamoid Embedded in muscle or tendon Act like pulleys Increase muscular forces & mobility Knee cap 30 1. Bones  2. Skull Bones Cranium Cranial fossa Facial bones 31 2. Skull  2. Skull Brain’s protective shell with Foramina: openings for passage of nerves and blood vessels in skull Holes for spine and optic nerves etc Foramen: same thing, singular 32 2. Skull  2. Skull Human skull: More cranium for brain storage Smaller face 33 2. Skull  2. Skull Racoon skull: More jaw, teeth, nose & eyes Less cranium 34 2. Skull  2. Skull Humans: cranium got bigger; facial bones got smaller. 35 2. Skull  2. Skull 36 2. Skull  2a. Cranium protects brain Cranium: 8 large bones Frontal Parietal x2 Temporal x2 Occipital Sphenoid Ethmoid 37 2. Skull  2a. Cranium Cranium: 8 large bones Frontal (flat) Parietal (flat) Temporal (irregular) Occipital (flat) Sphenoid (irregular) Ethmoid (irregular) 38 2. Skull  2a. Cranium bones Unpaired bones Frontal bone: defines the forehead Occipital bone: the back of the skull and posterior base Sphenoid bone: completes the base behind the eyes Ethmoid bone: fits behind the facial bones 39 2. Skull  2a. Cranium bones Paired bones Parietal bones: parts of the arch of the cranium Temporal bones: parts of the lateral sides and the base of the skull. Form the thickened platform in the middle of the skull for the jaw and inner ear 40 2. Skull  2a. Cranium – Frontal bone Forms the forehead and roofs / superior border of the orbits (eye socket) 41 2. Skull  2a. Cranium – Parietal bones Parietal bones form superior and lateral parts of skull Shaped like curved rectangles 42 2. Skull  2a. Cranium – Temporal bones Inferior to parietal bones Form the inferolateral portion of the skull Articulates with Mandible 43 2. Skull  2a. Cranium – Temporal bones Articulation: (in anatomy language) The joining of 2+ bones at a joint 44 2. Skull  2a. Cranium – Temporal bones Articulates with Mandible (jaw) at the Temporal Mandibular Joint (TMJ) 45 2. Skull  2a. Cranium – Occipital bone Posterior portion & base of cranium 46 2. Skull  2a. Cranium – Occipital bone Spinal cord passes through occipital bone's foramen magnum 47 2. Skull  2a. Cranium – Occipital bone EXAM Occipital condyles are protuberances / “rockers” on either side of the foramen magnum that control skull movement on the first cervical vertebra. 48 2. Skull  2a. Cranium Soft spots(dont press) Joined via fibrous joints aka Sutures Synarthrodial (vs. amphiarthrodial and diarthrodial) 49 2. Skull  2a. Cranium - craniosynostosis Fusion of bones Fibrous tissue before turns to connective tissue 50 2. Skull  2a. Cranium - Sutures Four sutures of the cranium Coronal suture – runs in the coronal plane Located where parietal bones meet the frontal bone Sagittal suture – occurs where right and left parietal bones meet superiorly Squamous suture – occurs where each parietal bone meets a temporal bone inferiorly Lambdoid suture– occurs where the parietal bones meet the occipital bone posteriorly 51 2. Skull  2a. Cranium - Sutures 52 2. Skull 2. Skull 2a. Cranium – Sphenoid bone Spans the width of the cranial floor Resembles a butterfly or bat 53 2. Skull 2a. Cranium – Sphenoid bone Spans the width of the cranial floor Resembles a butterfly or bat 54  2a. Cranium – Ethmoid bone Between nasal and sphenoid bones 55 2. Skull  2a. Cranium – Ethmoid bone Forms most of the medial bony region between the nasal cavity and sphenoid bone 56 2. Skull  2a. Cranium – Ethmoid bone Not apparent externally 57 2. Skull  2a. Paranasal sinuses Protect you from external environment 4 sinuses (paired) All connected Airways & mucus production / drainage 58 2. Skull  2a. Cranium bones - Pterion The pterion is the region where the frontal, parietal, temporal, and sphenoid bones join. Side of the skull, just behind the temple Weak spot 59 2. Skull  2a. Skull – Cranial fossa Fossa: depression or hollow, usually in a bone anterior middle middle posterior 60 2. Skull  2a. Skull – Cranial fossa anterior middle posterior 61 2. Skull FACIAL BONES 62  2b. Skull - Facial bones Small part of the head – Facial characteristics Unpaired Mandible, vomer Paired Maxillae, zygomatic, Nasals, lacrimals 63 2. Skull Mütter museum of human pathology (Philadelphia) Real human skulls 64  2b. Facial bones - Mandible The lower jawbone is the largest and strongest facial bone Composed of two main parts Horizontal body Two upright rami 65 2. Skull  2b. Temporomandibular joint (TMJ) TMJ connects your jawbone to your skull Allows for elevation, depression, protraction, retraction Lateral motions (side to side for chewing) 66 2. Skull  2b. Temporomandibular joint (TMJ) 67 2. Skull  2b. Facial bones - Mandible 68 2. Skull  2b. Facial bones - Maxillary The upper jawbone Forms the superior dental arch Articulates with all other facial bones except the mandible Contain maxillary sinuses – largest paranasal sinuses 69 2. Skull  2b. Facial bones - Zygomatic Cheekbones Defines important shapes of the face Inferior portion of orbit 70 2. Skull  2b. Facial bones – Nasal bones Form bridge of nose 71 2. Skull  2a. Cranium – Vomer bone Small, thin, midline bone that divides the nasal cavity 72 2. Skull  2a. Cranium – Vomer bone It articulates inferiorly with midline of the maxillae, superiorly with the sphenoid, and anterosuperiorly with the ethmoid. 73 2. Skull  2b. Facial bones – Lacrimal bones Located in the medial orbital walls 74 2. Skull  2b. Bones that form the orbit / eye socket 75 2. Skull  2b. Facial bones - Bonus The Hyoid Bone Lies inferior to the mandible The only bone with no direct articulation with any other bone; Sesamoid bone Acts as a movable base for the tongue Colimbian necktie is when this bone is removed 76 2. Skull