Cardiac Muscle

Fibres anastomose through cross bridges

Fibres are short, connected end to end at intercalated discs, also striated,  contract automatically

Light microscopic Structure:

Short fibres connected at intercalated disks,  85 - 100 µm long,  15 µm

same bands as in skeletal muscle,  1 or 2 nuclei - oval and central,  in perinuclear area is a sarcoplasmic reticulum, intercalated discs lie at the Z line

Electron microscopic structure:

 Between myofibrils lie the mitochondria,  2,5 µm long mitochondria,  dense cristae

and are as long as the sarcomere, fibres have more glycogen than skeletal muscle fibres

myofilaments, actin and myosin are the same as in skeletal muscle,  the sarcoplasmic reticulum differs in that there is no terminal sisterna. The sarcotubules end in little feet that

sit on the T-tubule

Intercalated Disc:

on Z lines,  fibres interdigitate,

 3 types of junctions in the disc

Transverse Part:

zonula adherens

desmosomes

Lateral Part:

Gap junctions (nexus) - for impulse transfer

Mechanism of Contraction:

slide - ratchet like in skeletal muscle, certain fibres are modified for conduction,  Impulses spread from cell to cell through gap junctions,  Purkinje cells are found in the AV bundle

they have less myofibrils,  lots of glycogen and intercalated discs

Connective tissue coverings:

Only endomycium in cardiac muscle,  Blood vessels, lymph vessels and nerves lie in the endomycium

The Sublingual Glands

• These are the smallest of the three paired salivary glands and the most deeply situated.
• They are almond-shaped and lie in the floor of the mouth between the mandible and the genioglossus muscle.
• The paired glands unite to form a horseshoe-shaped glandular mass around the lingual frenulum.

• Numerous small ducts (10 to 12) open into the floor of the mouth.
• Sometimes one of the ducts opens into the submandibular duct.

• The nerves the accompany the submandibular and sublingual glands are derived from the lingual and chorda tympani nerves and from the sympathetic nerves.
• The parasympathetic secretomotor fibres are from the submandibular ganglion.

-> This bone forms much of the base and posterior aspect of the skull.
-> It has a large opening called the foramen magnum, through which the cranial cavity communicates with the vertebral canal.
-> It is also where the spinal cord becomes continuous with the medulla (oblongata) of the brain stem.
-> The occipital bone is saucer-shaped and can be divided into four parts: a squamous part (squama), a basilar part (basioccipital part), and two lateral parts (condylar parts).
-> These four parts develop separately around the foramen magnum and unite at about the age of 6 years to form one bone.
-> On the inferior surfaces of the lateral parts of the occipital bone are occipital condyles, where the skull articulates with C1 vertebra (the atlas) at the atlanto-occipital joints.
-> The internal aspect of the squamous part of the occipital bone is divided into four fossae: the superior two for the occipital poles of the cerebral hemispheres, and the inferior two, called cerebellar fossae, for the cerebellar hemispheres.

The Nose

• The nose is the superior part of the respiratory tract and contains the peripheral organ of smell.
• It is divided into right and left nasal cavities by the nasal septum.
• The nasal cavity is divided into the olfactory area and the respiratory area.

A. Anatomic position-erect body position with the arms at the sides and the palms  upward

B. Plane or section

1. Definition-imaginary flat surface formed by an extension through an axis

2. Median plane-a vertical plane. that divides a body into right and left halves

3. Sagittal plane

• Any plane parallel to the median plane
• Divides the body into right and left portions

4. Frontal plane

• Vertical plane that forms at right angles to the sagittal plane
• Divides the body into anterior and posterior sections
• Synonymous with the term coronal plane

5. Transverse plane

• Horizontal plane that forms at right angles to the sagittal and frontal planes
• Divides the body into upper and lower portions
• Synonymous with the term horizontal plane

C. Relative positions

1. Anterior

• Nearest the abdominal surface and the front of the body
• Synonymous with the term ventral
• In referring to hands and forearms, the terms palmar and Volar are used

2. Posterior

• Back of the body
• Synonymous with the term dorsal

3. Superior

• Upper or higher
• Synonymous with the term cranial (head)

4. Inferior

• Below or lower
• Synonymous with the term caudal (tail)
• In referring to the top of the foot and the sole of the foot. the terms dorsal and plantar are used respectively

5. Medial-near to the median plane

6. Lateral-farther away from the median plane

7. Proximal-near the source or attachment

8. Distal-away from the source or. attachment

9. Superficial-near the surface

10. Deep-away from the surface

11. Afferent-conducting toward a structure

12. Efferent-conducting away from a structure